We’re surroundedĚýby more weather data than we could ever use. Our phones chirp data points at us on command.ĚýSocial media is filled with analyses from meteorologists around the world. Even the weather segment on broadcast news turns into a college-level meteorology course when active weather is on the horizon. ButĚýout of all the data we process, an old-fashioned surface mapĚýis still the best way to keep tabs on weather conditions anywhere.

Meteorologists have maps for every occasion, from monitoring a winter storm that’s dumping fresh powder on the slopes to tracking thunderstorms that can crash a camping trip. Most weather maps are dedicated to showing us only one variable, though, like current temperatures or upper-level winds. But it’s the basic surface map, with itsĚýstation plots and wind barbs, that revealsĚýthe most information in the quickest way before weĚýheadĚýoutside. Still, detailed surface weather maps areĚýonly as useful as your ability to understand what they’reĚýtelling you. Here’s how to read them.

Station Plots

Scientists needed a way to conveyĚýas much information as possible without making aĚýmap completely unreadable. EnterĚýthe station plot, an ingenious way to print lots of information in a tiny space. ItĚýtakes a bit of deciphering to understand, but once you’ve got the hang of it, you can get the gist of a specific location’s weather in just a few minutes.Ěý

The basic station plot shows temperature, dew point, wind direction, wind speed, cloud cover, precipitation, and air pressure, which are all measured at weather stations around the globe. That’s a tremendous amount of useful information packed into one little graphic—and some maps contain even more data, such as visibility and cloud heights and types.

A station plot always shows the current temperature on the top left, dew point on the bottom left, and air pressure on the top right. The units for temperature and dew point depend on the source that made the map; most surface maps issued in the United States use Fahrenheit, while organizations in most other countries use Celsius.

How to Read Air Pressure

Air-pressure readings are important because they tell you how the atmosphere is moving around you. High pressure fosters calm skies perfect for hiking, while low pressure signalsĚýunsettled conditions and precipitation. Strong winds result from rapid pressure changes over short distances.

Decoding air pressure on weather maps takes memorization and context clues to translate. Most station plots will depict air pressure as a set of three numbers, such as 994 or 112. This number shows the last three digits of a station’s air-pressure reading to the nearest tenth of a millibar (mb); the last number actually comes after the decimal point. For example, 994 would indicate a pressure reading of 999.4 millibars, while 112 would convert to 1011.2 millibars.Ěý(Meteorologists put a nine in front of bigger numbers and a ten in front of smaller numbers.) It’s helpful to keep in mind that it’s rare to see an air pressure higher than 1,040 millibars outside of a deep cold snap. It’s just as uncommon to see an air pressure lower than 980 millibars outside the eye of a hurricane or a nor’easter.

How to Read Wind Barbs: Speed and Direction

Wind barbs are the most visible portion of a station plot. They tell you the speed and direction of winds at the station. The barb always points in the direction from which the wind is blowing: if the barb points toward the southeast, it means the wind is blowing from the southeast.

A wind barb contains half lines, fullĚýlines, and flags to denote wind speeds. Speeds are always displayed in knots (kts), regardless of the units used for temperatures and dew points. (One knotĚýapproximately equalsĚý1.151 miles per hour.)ĚýA half line represents fiveĚýknots, a full line denotes tenĚýknots, and flags are reserved for increments of 50 knots.

The wind barbs above show winds blowing from the northwest at 35 knotsĚý(plot A) and the southeast at 75 knotsĚý(plot B). If the winds are calm, a thin circle will appear around the station plot (plot C).

How to Read Cloud Cover and Precipitation

A station-plot icon conveys cloud cover by the amount of shading inside the plot’s center dot. A hollow circle indicates clear skies, while a solid circle denotes overcast conditions that could ruin a backpacking trip. Each successive quarter shading of the dot indicates scattered clouds (25 percent filled), partly cloudy (50 percent), and mostly cloudy (75 percent).

Symbols representing precipitation type and intensity will appear directly to the left of a station plot. Solid dots represent rain, while asterisks represent snow, with intensity shown through the use of two symbols (light precipitation), three symbols (moderate precipitation), or four symbols (heavy precipitation). A thunderstorm is denoted by a long arrow in the shape of the letter R.ĚýWhile these are some of the more common symbols, there are plenty of others for precipitation types, including freezing drizzle and thundersnow.

Pressure Systems and Isobars

Some surface maps are analyzed by computer programs or human forecasters to add extra information that helps you understand current conditions and predict what’s coming. The most common value-added analyses on surface maps are isobars, pressure systems, and boundaries.

What Isobars Mean

We’re used to seeing a blue H over a high-pressure center and a red L over a low-pressure system. Wind generally blows from areas of high pressure toward areas of low pressure. But even without those lettersĚýprinted on the map, it’s usually easy to spot these features using isobars—lines drawn on a map that connectĚýareasĚýexperiencingĚýequally high or low air-pressure readings.

These solid concentricĚýlinesĚýare helpfulĚýfor identifying pressure centers and getting a general idea of where it’s windy, making them especially useful for outdoor enthusiasts about to set out on theĚýnext adventure.ĚýIsobars that are closely packed together show greater pressure changes over short distances, indicating rapidly changing weather conditions and gusty winds.

Fronts, Decoded

A front is the boundary between two different air masses; they are ubiquitous on weather forecasts. The difference between the two regions can be subtle or dramatic—a strong cold front, for example, can drop temperatures dozens of degrees in a few minutes.

Cold fronts show cooler, drier air pushing into warmer, more humid air, which can produce powder-day snow. They’re typically shaded blue, with triangular flags pointing in the direction of the front’s forward movement. Warm frontsĚýexist along the leading edge of warmer, humid air pushing into cooler, drier air. They can sometimes bring stormy weatherĚýand areĚýusually marked by aĚýred line with semicircles pointing in the direction of the front’s movement.

A stationary front lies along the edge of cooler and warmer air masses that aren’t advancing toward one another. These are denoted by alternating flags and semicirclesĚý(alternating in the same colors outlined above), each pointing toward their respective air mass.

Occluded fronts are shown in purple on weather maps. An occlusion occurs when cold air overtakes warm air near the center of a low-pressure system, pinching a region of warm air above the earth’s surface. AĚý“triple point”—where a cold front, warm front, and occluded front meet—can sometimes serve as the focus for severe thunderstorms, which may ruin an afternoon run.

Dry lines, depicted on surface maps in beige, with hollow semicircles pointing in the direction of movement, are a type of front typically only seenĚýon the southern plains. They’re a dividing line between humid air flowing in from the Gulf of Mexico and extremely dry air from the desert region out west. A dry line moves eastward in big leaps during the afternoon as a result of daytime heating. These fronts can serve as the catalyst for intense springtime tornado outbreaks in Texas and Oklahoma.

Resources

With these basics in mind, the best place to download reliable, up-to-date weather maps isĚýthe U.S. National Weather Service—just make sure you save them to your phone or bookmark the direct link in your phone’s browser before you head out. The agency’s products are free for public use, and the entire organization only costs each taxpayer a little more than a dollar a year. Various branches of the NWS issue a multitude of surface maps covering the United States. The Ěýmostly handles everyday weather, like fronts and temperatures, while theĚýĚýhandles severe thunderstorms and fire-weather outlooks.ĚýThe offers detailed analyses of weather across the Atlantic, Pacific, and Arctic Oceans.

International weather organizations also provide fantastic services for their coverage areas, including , the UK’s , and Australia’s . Private companies and academic institutions also issue weather maps, such as the College of DuPage’s .

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According to the National Weather Service, a five-day temperature projection in 2018 as a two-day outlook back in 1988. NowĚýthe accuracy and timeliness of weather forecasts are about to get even better, thanks toĚýthe National Oceanic and Atmospheric Administration’s (NOAA) to the country’s flagship weather model, the Global Forecast System (GFS), this month. The improvementĚýwill reportedly grow the range of reliable forecasts to a week or longer.

Here’s how it works:ĚýWhen you check the weather to plan for that camping trip next weekend, the information you’re currently looking at comes from meteorologists using computer-based models to predict conditions. However, they’re not just copying those predictionsĚýlike a student cribbing answers from a textbook. They only use those for guidance. Each representation has different strengths and specialties, and it’s up to users drawing onĚýtheir experience to figure out which ones would help them the most toĚýcreate an accurate forecast.

Some models focus on large-scale weather systems around the world, while others zero inĚýon smaller-scale conditions,Ěýlike thunderstorms and sea breezes. The GFS, as its name suggests, operates on a global scale, running four times per day to provide meteorologists around the world with guidance on what’s coming their way.

These models are powered by a dynamical core—a collection of mathematical equations that explain atmospheric physics using available data and makingĚýpredictions based on that information. That’s where the GFS is getting a boost.

The GFS’s new core—called (FV3)—is designed to partially account for a global model’s general inability to resolve smaller-scale features. The upgraded physical equations in the FV3 give it a more accurate, detailed view of the atmosphere, allowing it to “see” storm systems and different weather features much more clearly than previous iterations.Ěý

There are plenty of perks to building a new foundation for a major weather model. The FV3 core allows itĚýto run faster and more efficiently on new computers, which is necessary forĚýmeteorologists to keep it fresh and current in the coming years. The upgrade will also remedy some clunkiness of the previous versionsĚý(for example, it will offer smoother, more realistic rainfall maps), giving forecasters a truer sense of what the model thinks will happen in a certain area.

Previous dynamical cores couldn’t resolve the updrafts that power storm development. The FV3 core gives the GFSĚýthe ability to resolve that issue, a boon to forecasting since thunderstorms have such a large influence over regional weather.

This is not the first time NOAA has upgraded the GFS. rangeĚýfrom minor tinkering to major overhauls. For example, the resolution quadrupled between 2002 and 2015, and that resolution will likely improve in coming years. This is the first time the core has been upgraded in 40 years.Ěý

NOAA originally planned to roll out this upgrade at the end of 2018, but the government shutdown—which hit the National Weather Service particularly hard—pushedĚýthe planned release date back to March 2019. That lengthy delay gave meteorologists a chance to in the model, which meant the model routinely ran too cold and produced too many “phantom”Ěýsnow and ice storms. Experts kept the model on hold for a couple of months until they were satisfied they’d resolved the issues.Ěý

The GFS has lagged behind other countries’Ěýglobal-forecacsting models in terms of overall accuracy. This upgrade is part ofĚýthe agency’sĚýEarth Prediction Innovation CenterĚýplan to advance whatĚýĚý“will advance U.S. weather modeling and reclaim international leadership in the area of numerical weather prediction.”ĚýThe code for the FV3 core will also be available to a wider research community for continuous testing and upgrades for the model.

On a more practical level, having more accurate forecasts a week or more in advance will helpĚýeveryone from emergency officials preparing for dangerous conditions to someone planning their next adventure.ĚýĚý

The GFS and many of its counterparts are from the U.S. government, which means there are a ton of sites out there that offer weather-model output. and are two of the most widely used modeling websites in the field. However, it’s only a good idea to check the weather models if you know what you’re looking at. For the average user who just wants to check the weather, there are a handful of trustworthy apps available that use the GFS and other sources to make informed forecasts. And they are about to get a lot more accurate.Ěý

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Spring is here, and that means warmer temperatures. It also means we have to be prepared for the threat of tornadoes, large hail, damaging winds, and floods. But bad storms don’t take us by surprise as much as they once did, thanks to weather radar.

How Weather Radar Works

Weather radar works by sending out two perpendicular beams of microwave radiation into the atmosphere. Some of the radiation reflects offĚýobjects in the atmosphere—rain, hail, snow, you name it—and returns to the radar. Software measures the strength of returning radiation and how long it took to bounce back in order to determine the location and intensity of the precipitation. The shape of the beam, which resembles a plus sign if you look at it head-on, also allows the radar to detect the size and shape of the objects it detects, which is useful in spotting hail and tornado debris.

The best way to stay safe from dangerous weather, whether you’re hiking or hanging out at home, is to invest in a good radar app for your phone and learn how to read what it’s telling you.

How to Read Weather Radar: 4 Useful Tips

1. Look at More Than Just Precipitation

Just about everyone who’s ever used a weather app or watched a weather forecast on television knows the basics about spotting precipitation on weather-radar imagery. Most color scales are simple rainbows, andĚýwarmer colors indicate heavier precipitation.

However, just looking at the precipitation alone won’t tell you everything you need to know about a storm. A patch of dark red moving toward your location means there’s a thunderstorm on the way. A line of heavy precipitation moving in unison is a sign of a squall line that could pack gusty winds.

A storm that looks like a fishhook is particularly concerning. The image above shows a classic supercell—a thunderstorm with a rotating updraft—in Alabama on March 3. The rotating updraft allows the storm to produce largeĚýhail, highĚýwind gusts, and strongĚýtornadoes. This particular thunderstorm produced an EF-4 tornado with estimated winds of 180 miles per hour. (EF refers to the Enhanced Fujita scale, which rates tornado damage from 0 to 5.)

2. Know What’s Going on Inside a Storm

In the 1990s, weather-radar technology developed enough to let us see the winds within a thunderstorm. By using the Doppler effect to measure how fast and in whichĚýdirection rain, hail, and snow are moving, it can accurately tell us the wind speed and direction ofĚýa storm. Velocity imagery is critically important, because it tells you what’s going on inside of a storm, something you wouldn’t inherently know just by looking at the precipitation. This technological advance has saved countless lives over the past couple of decades.

The tornado that hit Greensboro, North Carolina, in April 2018 is a great example of why it’s so important to look at the wind within a storm. The following radar image shows precipitation within the line of thunderstorms while the EF-2 tornado was in progress.

Nothing appearsĚýtoo suspicious, right? But looking at the rain alone is deceiving. It becomes apparent that there’s a tornado on the ground once you flip over to velocity imagery and look at the wind swirling within the storm.

Velocity imagery is almost always displayed with red and green colors. Red shows winds blowing away from the radar, and green shows winds blowing toward it. Stronger winds usually equate to brighter colors on the radar imagery. You can spot rotation and a possible tornado in a thunderstorm by looking for strong winds blowing in different directions right next to each other. Bright colors all moving in one direction are a sign of damaging straight-line winds like you’d see in a squall line.

3. Recognize the Limits of Radar

Like any technology, there are limitations. Mountains are a significant barrier to radar useĚýin the western United States. Vast swaths of land in Oregon, Nevada, and Utah have little useful radar coverage at the lower levels of the atmosphere dueĚýto the region’s rough terrain, which can make it more difficult to spot hazards in these areas.

The height of the radar beam itself also presents a challenge. The beam rises higher off the ground with distance as it distances itselfĚýfrom the radar, because of the curvature of the Earth. This means that the radar beam is above 10,000 feet once it’s a few dozen miles away from the radar site, makingĚýit difficult to see low-level features in thunderstorms, like damaging winds and tornadoes, especially in parts of the Plains and Midwest where relatively poor radar coverage coincides with frequent thunderstorm activity.

4. Get the Best Radar App

You can see the weather radar on just about any weather app for your phone. Unfortunately, most of those apps are lacking in detailed radar imagery, limited to an oversmooth, nebulous blob of precipitation chugging toward your location. That can help in a pinch, but sometimes it’s just not enough—especially if you’re out hiking.

The best radar app you can put on your phone is . This professional-level app lets you track storms just like the meteorologists—in fact, most meteorologists use the app on a day-to-day basis. The app isn’t free—it costs $10Ěýfor both Android and iOS—but it’s worth it, especially if you’re involved in activities that require close monitoring of rapidly changing weather conditions.

You have more options if you’re at home or in the office and have access to a computer. The best radar software for your computer is produced by Gibson Ridge. Programs like GR2Analyst, which is the software I used for the radar images in this article, are great for analyzing radar imagery down to the pixel, just like you’d see on television during severe-weather coverage.

Weather-related injuries and fatalities have steadily dropped over the decades due to better detection, warning, and prevention, but it’s important to frequently check the weather if you plan to spend any significant time outdoors. Even if you can track the radar like a pro, making sure you have the ability to receive and heed severe-weather warnings should always be a part of your weather-safety plan when you’re out and about on a bad-weather day.

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This spring saw two historic “bomb cyclones” sweep across the country. On top of the problems caused by blizzards, high winds, and severe storms, theseĚýweather systems also made for a lot of achy knees as barometric pressure bottomed out. It’s not a myth: active weather patterns, and low-pressure systems in particular, have a noticeable effect on our bodies, including joint pain, headaches, and even the occasional induced labor.

Joint pain is the most widely known effect weather has on your body. Our joints are full of fluid that allows bones to glide across one another without grinding together. This fluid is susceptible to changes in atmospheric pressure as weather systems come and go. Higher air pressureĚý. Lower air pressure means that there’s more pressure inside your joint than outside of it, causing those joint fluids and surrounding tissues to expand, leading to nagging aches and pains.

Cooler air temperatures can also make your joints feel stifferĚýby thickening the fluid in your joints and tightening up the tissues around them. This makes your discomfort even worse when you’re in the midst of a winter storm with low pressure. Everyone is susceptible to it, but theĚýeffects are more pronounced in people who have arthritis or existing joint injuries. Retirees don’t just move to the Sun Belt for golf and lower taxes. The warmer, calmer weather helps soothe aches and pains.Ěý

Our sinuses and ears are also sensitive to changing weather conditions. As anyone who’s ever suffered from a severe cold can attest, these cavities in our head are prone to internal pressure increases that lead to intenseĚýand sometimes even debilitatingĚýpain. Just like our joints, lower air pressure can increase the relative pressure in our head and lead to sinus pain and earaches.

The effect weather can have on headaches is a little muddier, because the stressors and triggers that instigate each episode varyĚýfrom person to person. Some people who suffer from headaches are incredibly sensitive to small changes in weather, and an approaching storm system can lay them upĚýfor a day or more. Others can soldier on through even the worst conditions without so much as a dull throb. The American Migraine Foundation says that a correlation between migranes and drops in atmospheric pressure and air temperature, as well as increased humidity, which can trigger pain in people who suffer from this intense form of headaches.

Despite the effects of weather on your body, you definitely can’t catch a cold because of the weather.

We often hear reports of a “baby boom” occurring in communities that have endured a hurricaneĚýĚýit makes landfall, but a sudden drop in air pressure, like you would see during a hurricane or major winter storm, can induce labor for some pregnant women in the storm’s path. Several Japanese doctors over a seven-year period and found that there was a significant relationship between a drop in air pressure and patients experiencing their water breaking or a “spontaneous delivery.”

Extreme temperatures can also take a hefty toll on our body, especially when combined with aggravating factors such as humidity and wind. Despite the misplaced cynicism of people who think they’re fake numbers meant to hype people up, the summertime heat index and wintertime wind chill are two important measurements that tell you how safe it is to venture outdoors unprotected.

The heat index tells us how much hotter it feels due to the amount of moisture in the air. Our bodies cool off through the evaporation of sweat. Less sweat evaporates from our skin when the humidity ticks up on a hot day. This process prevents us from cooling off effectively, which can quickly lead to heat exhaustion or heat stroke. A humid, 90-degreeĚýafternoon can cause problems for you quicker than a 90-degreeĚýday that’s dry as a bone.

Wind chill, on the other hand, tells us how much colder a winter day feels when you add in the effect of the wind. Human skin cools off much faster on a cold and windy day than it would if the wind wasn’t blowing. This allows frostbite and hypothermia to set in quicker than you would otherwise expect given the raw air temperature.Ěý

Despite the different waysĚýweather affects your body, you definitely can’t catch a cold because of the weather. Both the cold and the flu are caused by viruses contracted from another person. You have a better chance of contracting the cold or flu during the winter months since viruses —conditions that also weaken our immune systems and drive us into close proximity indoors. Cold weather can give you a runny nose, chills, and a headache, all of which mimic symptoms of viruses, but the cold itself can’t give you a cold.

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After a long winter that’s seen record-setting warmth, a couple of rounds of the polar vortex, and a constant barrage of rain and snow out West, the U.S. could use a break as we head into spring. Unfortunately, it doesn’t look like we’re going to catch much of a reprieve from the atmosphere’s tantrums.

How El Nino's Played Out So Far

The pattern we’ve seen over the last couple of months is typical of a year influenced by a mild El Niño in the Pacific Ocean. An El Niño occurs when the water of the eastern Pacific Ocean is abnormally warm for many months at a time. The warmer-than-normal water in this part of the Pacific can warmĚýthe air over the ocean, altering upper-level jet streams that cross the country.Ěý

Jet streams largely exist because of the temperature gradient between the warm tropics and cooler air at higher latitudes. The northward expansion of warm air during an El Niño strengthens the subtropical jet stream over the southern U.S.Ěýand shoves the polar jet stream farther north toward the Canadian border, changing weather patterns across the country.

El Nino’s effects on U.S. weather are most pronounced in the winter. The hallmark of an El Niño winter is heavy rain and snow in the western U.S. and warmth in the southeast. We’ve seen that in abundance so far this year. After a slow start to the rainy season, storms started washing over the West Coast with a vengeance last month, bringing almost weekly bouts of flooding rains and torrential mountain snows from Washington to California.

There's plenty of upside to moisture like this, of course.ĚýIncreased mountain snow has been a boon to the ski industry. Farmers will benefit from the snowmelt in the warmer months, and the drought situation across the region has improved. California began February with 76 percent of the state experiencing abnormal dryness or full-on drought conditions, thenĚýthat number plummeted to just 32 percent after three weeks of steady rainfall. The Four Corners region of the Southwest has also seen relief from its exceptional drought—the worst category on the —over the last couple of months thanks to wetter weather resulting from the El NiñoĚýpattern.

Here’s What Kind of Weather Pattern You Can Expect This Spring

Taking a look back at the weather we’ve seen this winter helps put into context the weather coming up this spring. Seasonal precipitation in California comes to a dramatic halt between April and November, while cities like Las Vegas and Phoenix historically see little precipitation between the start of spring and the onset of the summer monsoon season. The seemingly-endless precipitation out West—including the healthy snowpack in the mountains—will serve as a nest egg once the rainy season comes to an end.

It’s not just the West that’s seen plentiful precipitation. Many areas east of the Rockies have seen so much rain and snow that their soil is oversaturated for this time of the year. The above map shows for February 18, ranked by percentiles. The darkest green shows soil moisture in the 99th percentile, which tells us that the ground is about as wet as it can get for the middle of February.

This has big implications for the coming spring rains. Showers and thunderstorms can produce more and heavier precipitation because the air can hold more moisture with spring's warmer temperatures. The combination of saturated soil from recent rains and the opportunity for heavier precipitation will dramatically increase the risk of flooding as we head into the warmer months.

The latest long-term forecast from the shows a general ridge-trough-ridge pattern across the U.S. this spring. A setup like this would place ridges of high pressure—fostering drier, warmer weather—over the coasts while the center of the country experiences troughing, leading to an active and stormy pattern. A ridge of dry air parked over the West, could cut the rainy season short,Ěýallowing groundwater to evaporate and snowpack to melt more quickly than under normal conditions. However, the extensive precipitation the region received this winter will help delay the ill-effects of abnormally dry stretches for several months longer than we would have seen otherwise.

Upper-level troughs moving over the center of the country will allow frequent low-pressure systems to develop at the surface, leading to regular bouts of stormy conditions east of the Rocky Mountains. Thunderstorms can develop if the cold and warm fronts extending off of these lows have enough instability to work with. Not only would that heighten the risk for flooding from even modest amounts of heavy rain, but an active pattern would crank up the risk for severe storms as we get into the peak months for dangerous wind, hail, and tornadoes.

We’ve already seen one such storm tear through Alabama this month, killing a reported 23 people. That storm was an EF-4 on the , and the deadliest since 2013. Ěý

Start Preparing for Spring Weather Now

The dry and warm weather that’s likely out West isn’t inherently dangerous—it’s a slow-motion pain that’s easy to ignore until you fall into a water crisis. The best thing folks out West can do is to conserve water as if there was a raging drought. Preemptive water conservation is a surefire way to help a region prepare for extended periods without precipitation.

Folks east of the Rockies can prepare for the potential for severe thunderstorms and flooding by making emergency plans for hazardous weather. Make sure you have plenty of emergency supplies at home and in your vehicle. It’s important to know in advance where you would take shelter from threats like tornadoes, destructive winds, or large hail if you’re at home, work, on the road, or caught outdoors. If you have to go out during flooding, it’s a good idea to plan out multiple routes between home, work, and school so you’re not caught off-guard by water-covered roadways.

The post This Spring’s Weather Could Be Just as Wild as Winter’s appeared first on ąú˛úłÔąĎşÚÁĎ Online.

Not only do we have to worry about large-scale weather patterns affecting our daily lives in the winter, but local geography can also dictate the atmospheric flavor of the day, leaving parts of the country racked with gloomy skies and stagnant air.

Inversions make for many a problem in some areas during the colder months, including ice storms, air pollution that results inĚýhealth issues, and even enhancedĚýeffects of explosions and other loud noises. A temperature inversion occurs when a layer of warm air develops on top of a layer of cooler air. This warm layer, the inversion, acts like a cap that seals the cooler atmosphere beneath it. We sometimes hear about a “cap” in thunderstorm forecasts, since air in an updraft has a hard time rising through the inversion to produce thunderstorms.

If the fast-moving air of an updraft has a hard time breaking through a temperature inversion, imagine how much harder it is for the atmosphere to churn itself up when one of these events occurs during the winter months.

There are several different kinds of inversions you can encounter when it gets chilly. Each type of inversion comes with its own set of inconveniences and hazards.

Here’s what you need to know about each one.

Valley Inversions

Cold air is dense. It drains from higher elevations to lower elevations and hugs as close to the ground as possible. This makes valleys especially vulnerable to inversions in the winter. And few areas in the United States more susceptible to valley inversions than Utah’s Salt Lake Valley.

The bowl-shaped topography that surrounds Salt Lake City’s metro area exposes the region to several hazardous inversion events every winter. These inversions occur when cold air gets trapped in the valley and a layer of warm air seals it from above. The region’s terrain prevents thatĚýbubble of cold air from draining away, and the mountains stop winds from easily scouring it out and ushering in fresher air.

The end result is a spell of nasty, stagnant air that to the health of anyone in the region. The stale air of an inversion allows for the buildup of pollutants created by vehicles, factories, fireplaces, and wildfires. These pollutants most often affect those with health problems such as asthma, but particularly unhealthy air can lead to respiratory problems even in folks without preexisting conditions.

Salt Lake City has some of the worst air quality in the United States during the winter as a result of these inversions. Officials encourage people to carpool and use public transportation to reduce the amount of pollution when these inversions take place.

Valley inversions can also lead to some unintended consequences. Blasting at quarries and munitions testing at military bases usually come to a halt during inversions due to the risk of causing damage and injuries to people many miles away. The capping effect of an inversion in the atmosphere can reflect the blast wave from an explosion back down toward the surface, spreading the effects of an explosion farther than intended.

A famous instance of this occurred about ten years ago Esparto, California,Ěýduring the filming of an episode of Mythbusters that required a huge explosion. The larger-than-expected blast Ěýfrom the blastĚýas a result of an inversion overhead.

Cold-Air Damming

Mountains are a significant source of inversions when it’s cold outside. Not only can valleys trap cold air and force cities to choke on their own exhaust, but mountains can trap cold air blown by the wind. This can lead to significant cold snaps and even ice storms for folks who live in the foothills of certain mountain ranges.

Cold-air damming occurs when winds blow cold air up against the side of a mountain range. The surge of cold, dense air can’t ride up and over the ridges of the mountains, forcing it to pool up, instead,Ěýat the base and hang around until the wind changes direction.

It’s frequently cold, gloomy, and drizzly in states like Virginia and North Carolina during the fall and winter ĚýblowingĚýcold air up against the eastern side of the Appalachian Mountains. This setup can lead to more than just a raw drizzle. A low-pressure system approaching the mid-Atlantic from the south can force warm air into what would otherwise be a snowstorm, sometimes leading to a surprise ice storm in the region’s Piedmont.

is also a result of cold-air damming. Beijing, which is home to more than 20 million people, sits at the horseshoe-shaped confluence of two mountain ranges in northeastern China. Prevailing winter winds from the south and east subject the cityĚýto days-long inversions through cold-air damming. The shape of the terrain prevents incoming weather systems from easily scouring out the stagnant air, exacerbating itsĚýalready-treacherous pollution problem. The city’s air can off the charts during the winter, threatening the health of even an otherwise healthy person.

Marine Layer

The famed marine layer that bathes cities like San Francisco is another example of an inversion. The Pacific waters off the coast of San Francisco are quite cold, often significantly colder than the temperature of the air moving over the region. The cold water chills the air immediately above the ocean surface through conduction, leading to an inversion.

Warm air moving over cooler water is a recipe for fog, which is the most notable impact of an inversion caused by the marine layer. San Francisco’s fog is so famous that it even earned its own name . But fog isn’t the only impact this inversion can have. Concerts in San Francisco can be notoriously loud due to sound waves bouncing off the cap above the city and reflecting back down toward the surface. This was a particular problem during , which was made so loud by an inversion layer that residents miles away from the stadium where it took place complained about it.

Learning to Adapt to Inversions

Unfortunately, there’s nothing we can do to prevent inversions from developing during the winter months, so we have to adapt to the challenges they present. Places like Salt Lake City can reduce the air-pollution risk posed by inversions through emissions-reduction efforts like investing in public transit, stricter emissions standards on factories, and an overall shift toward clean energy. PeopleĚýwith respiratory problems should try to avoid going outside on high-pollution days and wear respiratory masks if they can’t stay inside.

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Folks who live in coldĚýareas pride themselves on their ability to handle snow better than their southern counterparts. However, whether you liveĚýin Minnesota or North Carolina, a quick glance at the news reveals a string of wrecks and pile-up accidents whenever snow starts.

Learning how to drive in snow is a tough task no matter where you live. The first step to safer driving is knowing what kind of winter weather you’ll encounter. Snow is more manageable than sleet or freezing rain. If it is going to snow, will it be a blizzard or a quick-hitting clipper? You’re more likely to wreck in a short, fast moving storm or snow squall, and you’re more likely to get stranded during a blizzard or lake effect snow.

The best thing to do in either case is to be proactive. Here’s how.

How to Drive in Snow: 3 Tips for Noobs

Don’t Underestimate a Light Snow (and Don’t Panic)

Most people worry about getting stranded by a foot of snow, but a foot of snow isn’t always what you need to worry about. A dusting of snow can be . A thin layer of snow on roads easily melts under the heat from heavy traffic. Subfreezing temperatures can refreeze the snowmelt and turn roads into a sheet of ice. The resulting ice can lead to horrendous traffic disasters, like the ones inĚý or .

If you hit an icy patch, the worst thing you can do is panic.ĚýThe second worst thing you can do is slam on the brakes. Hitting the brakes when you’re on ice turns you into a curling stone without anyone there to steer you in the right direction. You can easily lose control.

The simple fact is, youĚýcan’t do much when you’re sliding on ice. There’s no real way to bring your vehicle to a stop without regaining traction or coming to rest against something like the guardrailĚýor another vehicle. What you can doĚýis try to keep your vehicle going as straight as possible by turning your wheel into the spin. Keeping the vehicle straight lowers the chances that you’ll regain traction when you’re sideways, which could subject you to a rollover.

Unfortunately, not everybody is able to keep control of their car when they slide on ice. A wreck is bad enough. A pile-up wreck is many magnitudes worse. Each winter, somewhere in the United States, we inevitably hear about some stretch of highway closed because dozens of vehicles got into a chain-reaction accident.

If you’re ever caught in a pile-up accident, odds are high that people are going to hit you from behind. That could be exceptionally dangerous if the traffic is moving at high speeds. Sometimes the best option is to get out of the vehicle and get away from the road. However, you only want to get out if you have a clear shot to the side of the road or behind a barrier or wall. The most dangerous place to be in a pile-up wreck is a pedestrian at risk of getting hit by oncoming cars or flying debris.

Don’t Accelerate Your Way Out of a Jam

In deep snow, it’s common for travelers to get stuck on roadways or evenĚýstranded.

If you’re ever stuck in the snow or ice while driving, don’t try to floor your way out of the situation. Attempting to get unstuck through acceleration could suddenly launch you forward or lurch you to the left or right, endangering anyone outside of the car and putting you at risk, too. It’s also not good for your vehicle. Remember the infamous in Raleigh, North Carolina, a couple of years ago? That car caught fire because the driver revved the engine too hard trying (and failing) to drive up that icy, snow-covered hill.

It’s helpful to have a couple of simple supplies in your trunk to help you get out of a sticky situation for when you do get stuck. Carry something like kitty litter or a long strip of cardboard to help your tires gain enough traction if they become stuck. Keep a small shovel in your car to clear snow away from your tires.ĚýDon’t forget to stock some food and water just in case you’re stranded on the road for the long haul.

Clear Your Car

The most usefulĚýsafety advice for winter driving is the one too many people ignore—clean the snow off the roof of your car. There’s nothing more infuriating after a snowstorm than to see someone flying down the road with a roof full of snow, locked and loaded like an icy gun, ready to cause an accident. Slabs of snow and ice could fly off the back of your car and hit the vehicles behind you. The snow could also slide forward when you hit the brakes, completely obscuring your view of what’s ahead. Driving around with snow still covering your roof or windows is illegal in some states and it’s not safe. Invest in aĚýsnow brush. It takes a little bit of work, but it’s worth it to avoid an accident or hefty fine.

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Let’s get one thing straight: Weather is not climate.

Look, I get it. It’s easy to conflate theĚýtwo. After all, climate is the average of all the weather recorded over a period of time. But it’sĚýincredibly dangerous when we mix the twoĚýup when it comes to climate change. Intense cold and snow in the winter, like what the Midwest is experiencing right now,Ěýdoes not disprove the fact that our planet is warming, yet political leaders prey on that fuzzy distinction to lie about the science. Case in point:Ěý

Climate change is real. The vast majority of scientists agree that our planet is warming as carbon dioxide accumulates in our atmosphere . A warmer climate will lead to longer and more intense , devastating , more frequent , rising , and a bevy of otherĚý.ĚýClimate change does not mean that winter weather will cease. The world didn’t stop warming because it started snowing in Washington, D.C. A week of bone-chilling cold in the Midwest doesn’t negate the fact that five of the 10 warmest years on record in Minneapolis and four of the 10 warmest yearsĚýin Chicago have occurred since the beginning of this decade.

The best analogy scientists use to differentiate weather and climate is to compare weather to your mood and climate to your personality. Your mood can change each day, but how people perceive your personality depends on your mood every day over the course of years. You can have some down days and still be considered an upbeat person. It gets really cold and snows in New Orleans every couple of years, but the city’s climate is considered subtropical because it’s usually warm there.

The Upper Midwest and Great Lakes saw some of the coldest air in the entire world this week. However, if you zoom out beyond our backyard, it’s obvious that this cold spell is a small blip in a global sea of abnormal warmth. The above image shows an analysis of temperature anomalies on Thursday, January 31. The world is glowing with warmth. It’s been like that for years now. If you were born in 1977 or later, you have never been alive during a year when the world as a whole . This abnormal warmth serves the dual purpose of making cold snaps seem even colder as a warming atmosphere begins to warp our perspective of what constitutes truly cold weather.

Forecasters expect temperatures in the Midwest to undergo a tremendous swing from near-historic lows to dozens of degrees above normal by this weekend. International Falls, Minnesota, will experience a 79-degree-Fahrenheit swing from a minus-49 low on Thursday morning to a 29 high on Sunday afternoon. Over the same period, Chicago will see a temperature swing of almost 70 degrees and Minneapolis will see one of 73 degrees.

We’re not just talking drastic temperature ranges. Highs in the Midwest will be 15 to 20 degrees warmer than normal on Sunday and Monday. But you won’t see the President—or anyone who disputes the science of climate change—tweet out a snarky crack about global warming when the temps rise this weekend, let alone during the summer when the heat index is 100 degrees or hotter for weeks.

When we're comfortable, itĚýeasy to forget how much warmer than normal temperatures are. Most of us only sense that something is wrong during extreme events—and, because of how we conflate weather and climate, usually only when those extreme events bring the heat.Ěý

Daily weather is a symptom of a changing climate. A record-setting cold snap in a handful of states won’t do much to alter the world’s temperature profile for 2019. In fact, this winter probably would have been colder if the planet wasn’t warming. Our political leaders can ignore the science on climate change all they want, but lying about it won’t make it go away. And we might only have .

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Private weather companies like AccuWeather and The Weather ChannelĚýwould be lost without the federal government’s robust network of radars, satellites, sensors, and weather models. The good National Weather ServiceĚýmeteorologists keeping their eyes on the sky are working through the shutdown without pay—and we’re much safer for their efforts.

These folks are considered “excepted” federal employees, meaning that they’re forced to work a normal 40-hour-per-week schedule without pay during a partial government shutdown. That’s in large part because they’re responsible for a wide array of crucial forecasting tasks, ranging from predicting the path of blizzards to issuing tornado warnings.

The shutdown, which entered its 28th day on Friday, is starting to take a financial toll on these hard-working scientists. “I'm lucky to have had some savings built up, but the longer this shutdown lasts the more nervous I get about having to rely on credit cards to pay bills,” says one NWS meteorologist who asked to remain anonymous for fear of losing his job. He noted that federal employees who are required to work through the shutdown can’t benefit from the financial help often offered to those going without a paycheck, such as filing for unemploymentĚýor taking on temporary part-time jobs.

While meteorologists are feeling the personal effects of the shutdown, most news coverage () has focused on how the shutdown is affecting weather models and forecast accuracy. Yet concerns that the shutdown is affecting everyday forecasting may be somewhat overblown, say my sources. “We have not seen any measurable issues with our forecasting,” says a senior meteorologist working for another NWS office. “Our focus is on good science, good forecasts, but even more so, good communication. The forecast means very little if people don't understand the impact to them.”

The shutdown may not have an effect on day-to-day forecasting, but it is starting to affect efforts like hurricane predictions in ways that aren’t immediately obvious. The National Hurricane Center’s union steward Eric Blake posted explaining how the shutdown will have a negative effect on hurricane forecasting this summer by, for example, delaying improvements to hurricane modeling and cancelling important training sessions for local emergency managers.

The government’s widespread efforts to improve weather information gathering and advance the science of meteorology is one of its greatest success stories. Thousands of scientists and support staff work out of more than 120 individual NWS offices, serving as the backbone of this country’s weather infrastructure. Every severe weather watch and warning you hear for your location is issued by your local NWS office. The agency also operates , a critical piece of technology that benefits everyone from office workers to campers. It maintainsĚý, which provides detailed local forecasts for every square mile of the U.S. There are plenty of specialized agencies under the NWS that keep us abreast of dangerous weather, too. The issues forecasts ahead of severe thunderstorm outbreaks and dangerous wildfire days. The forecasts the track and strength of hurricanes around North America.

You might not know any of this because most people don’t get their weather forecasts directly from the NWS, which has no app. Private companies’ apps are the biggest source of weather information yet they’re basically parasiting onto the federal government's resources.ĚýThe ubiquitous weather radar imagery you see on every weather app, website, and television channel? It all comes from a network of more than 100 radar dishes maintained by the federal government. NOAA operates the vast majority of these, with the remaining ones operated by the or the military. Some local television stations have their own low-power dishes, but they’re vulnerable to obstructions and power outages, and have limited range.

Now, private weather companies do develop and use their own weather models. Take AccuWeather, which issued a marketing statement ragging on the NWS’s forecasting abilities on Thursday. The press release, which the company and , bragged about AccuWeather’s in-house weather model, which the company said would sustain them through the shutdown, no matter how lengthy. The Weather Channel has access to its own models as well, as do plenty of other weather forecasting companies.

The thing is, those private weather models don’t operate in a vacuum. Models are made using weather data collected throughout the atmosphere by weather balloons paid for and released by—you guessed it!—the federal government. These models also rely on government satellite data and a vast network of ground-based weather observing stations, many of which are also funded and operated by the government. If a company like AccuWeather or The Weather Channel wanted to match the level of service that we pay for with our tax dollars, they would have to charge way more than they already do for their forecasts. Even the sturdiest company would likely go bankrupt trying to build and maintain an analog to the vast network of satellites, radars, observation stations, and modelling provided by the feds.

Private weather companies and advocates of privatization are fully aware of the value of the federal government’s meteorological services. The only in recent history was a failed undertaking by former Senator Rick Santorum, a Pennsylvania Republican, back in 2005. The senator introduced a bill that would have prohibited the NWS from releasing any products or forecasts to the public, forcing them to route all of their services—radar, satellite, weather models, everything—through private companies to be sold back to the American people. The bill was soundly defeated.Ěý

So as the federal government shutdown enters its second month—and employees prepare to miss yet another paycheck—spare a kind thought for the thousands of dedicated scientists silently working to keep us safe from dangerous weather all across the country. And it doesn’t hurt to to demand that they reopen the government.

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ĚýandĚýĚýandĚý, oh my. No matter the flavor of the winter weather, you can bet someone’s designed an app to predict aĚýstorm’s size, distance, and intensity. But how do you know which apps to trust? There are too many out there for me to unilaterally say which ones are good and which ones are bad—you have to do that legwork on your own, downloading and then vetting the software that best syncs up with your lifestyle. Thankfully, that’s easy enoughĚýso long as you know what to look for. ĚýĚý

Make Sure the App Cites Its Sources

Very few apps actually create their own weather forecasts. They all get their information from somewhere else, and that somewhere else is important when you’re making potentially life-or-death decisions based on the forecast.

I rely on the National Weather Service (NWS)—the official weather-forecasting branch of the U.S. government—as well as private organizations like the Weather Company (the force behind the Weather Channel and Weather Underground)Ěýand the smart meteorologists at my local television news stations. These are allĚýknown entities, so look for apps powered by their data.

Don’t overlook theĚýapps published by your local television news stations. The folks you see on the local news aren’t just weather presenters; these days, most of them are degreed meteorologists. They’re fairly accurate, and they often know local climate quirks better than the bigĚýcompanies.

Finally, it’s a good rule of thumb to avoid the unknown. If you’ve never heard of an app—and itĚýdoesn’t explicitly tell you where itĚýgets itsĚýinformation—it’s best to avoid it altogether. If you still want to use a certain app but areĚýunsure about it, ask a meteorologist or a weather buff.

Remember: The National Weather Service Doesn’t Have Its Own App

This is an important thingĚýto remember when you’re looking for a good app. Any that uses NWSĚýor NOAAĚýin its name should be ignored. The National Weather Service doesn’t have an app, just the domain andĚýlinks toĚýthe sites of associated agencies like the and the .

You can easily on your smartphone’s home screen, giving any web page the same ease-of-access as anĚýapp. Not only does that give you quick access to sites like the Storm Prediction Center, but it also allows you to add the NWS’s forecast for your town right to your home screen.Ěý

Avoid Apps with Too Much (or Too Little)ĚýInformation

There is such a thing as information overload when it comes to weather forecasts. You have to find a source that strikes the right balance between providing enough information and enough good information.

A great example of too much information in a weather forecast is precise snowfall totals before a snowstorm. Some weather apps will provide you snowfall totals right down to the tenth of an inch. It’s scientifically unjustifiable to make such a precise forecast, even as the snow is falling. They’re usually just regurgitating what weather models are saying, but not only is that not a forecast, it’s also straight-up misinformation.

It’s also unsafe to rely on too little information. Some apps will only tell you that there’s a chance of isolated thunderstorms tomorrow. They strip away the important context, such as the chance that those thunderstorms could produce baseball-size hail or destructive tornadoes. You’d never know that little tidbit if you relied solely on an icon and a couple of numbers.

Pay Attention to Emergency Alerts

All modern smartphones are equipped with the capability to receive , a program rolled out this decade by the federal government in order to quickly alert people in the United States to dangerous weather in their area.

The National Weather Service has reportedĚýmultiple instances of thanks to the arrival of one of these push notifications. Even though many apps have the ability to alert you when a watch or warning is in effect for your location, the default emergency alerts on your phone are a simple feature that could save your life one day.

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