January 18, 2020

Newfoundland Just Endured A Historic Blizzard That Buried People In Their Homes

Residents of eastern Newfoundland spent Saturday conducting an archaeological dig in a valiant attempt to remember what life was like before Friday's historic blizzard. The impressive snowstorm dropped more than two feet of snow on parts of the island in Atlantic Canada, an insult made even worse by 75+ MPH sustained winds that drifted the snow so high that many folks had to tunnel out of their homes.

Friday's snowstorm is widely considered to be one of eastern Newfoundland's worst blizzards in living memory by folks who were in the thick of it. St. John's, Newfoundland, the easternmost major city in both Canada and North America, recorded 30" of snow during the storm and reported blizzard conditions for about 17 consecutive hours between 8:30 AM on Friday and 1:30 AM on Saturday.

The airport's weather station saw a minimum air pressure of 970.5 mb on Friday evening as the center of the winter storm passed just offshore. Some communities around St. John's saw even greater snowfall totals, with Mt. Pearl—the name of a city, not a mountain—reporting just over three feet of snow by the end of the storm.

The pure volume of snow, combined with the immense size of the drifts, quickly transformed this storm from a quirky novelty into a serious situation. The most populated area of the province is at a standstill at the moment while crews attempt to clear away the steep drifts of snow.

Tropical Tidbits

This was the perfect setup for an epic blizzard in Newfoundland. A strong jet stream dipped over eastern Canada at just the right angle to allow a sprawling low-pressure system to rapidly strengthen off the island's southern coast. The storm then underwent bombogenesis, or the process of strengthening 24+ mb over the course of 24 hours...hence all the "bomb snowstorm" and "bomb cyclone" headlines you've seen this weekend. The northwestern side of the storm rode directly over the Avalon Peninsula, exposing St. John's and its suburbs to the storm's heaviest snow and strongest winds.

The St. John's area could see another 5-8 inches of snow on Sunday as another winter storm moves across the region. Temperatures could briefly jump above freezing on Monday before dropping back below freezing through next weekend.

[Top Image: NOAA]

You can follow me on Twitter or send me an email.

Please consider subscribing to my Patreon. Your support helps me write engaging, hype-free weather coverage—no fretting over ad revenue, no chasing viral clicks. Just the weather.

January 11, 2020

An Inch Of Ice From Freezing Rain (!) Is Possible In Parts New York And Quebec This Weekend

A significant ice storm appears likely across the U.S./Canadian border this weekend as a winter storm moves across the region. Conditions appear favorable for a prolonged period of freezing rain near the border from Michigan to Maine, with some areas potentially seeing as much as 1.00" of ice accretion on exposed surfaces. If the highest totals come to fruition, it will cause significant tree damage and widespread, long-lasting power outages.

The threat for wintry precipitation lies on the northern side of the dynamic low-pressure system that's causing all the severe weather in the southern United States right now. It's cold enough for some areas to see all snow—it's pouring snow in most of Iowa!—but warm air in the lower levels of the atmosphere will make a mess of things in many of the areas expecting wintry precipitation.

Significant Icing Possible

Forecasters expect a prolonged freezing rain event to unfold from Michigan to Maine—including our friends in Ontario and Quebec—as the system moves through the area on Saturday and Sunday. The National Weather Service issued ice storm warnings for eastern Michigan and portions of northern New York ahead of the system, while freezing rain advisories are in effect for parts of southern Ontario and Quebec, including the Montreal metro area.

Precipitation will start as rain early on Saturday, slowly transitioning to freezing rain from west to east on Saturday night as warm air takes over aloft and cold air entrenches at the surface. The storm will likely end with snow on Sunday.

Environment Canada warns of the potential for 15-30 mm of ice accretion from freezing rain in and around Montreal, which translates to about 0.60" to 1.20" of ice. That's a major ice storm anywhere, let alone a heavily populated metropolitan area.

The National Weather Service in Burlington, Vermont, calls for similar ice accretion totals in northern parts of New York and Vermont. The official NWS forecast on Friday night called for 1.00" of ice from freezing rain around Ogdensburg and Massena in New York, with around 0.50" of ice in northwestern Vermont.

It only takes about 0.25" of ice to begin doing damage to trees and power lines. Anything greater than that and the damage increases by a great deal. Significant and widespread damage to trees and power lines is likely once ice accretions exceed 0.50". Areas that see a full inch of ice could see power outages that last for a week or longer and roads made impassable by parts of (or entire) downed trees.

It's also going to be windy in many of the areas expecting freezing rain. Wind will only create additional stress on trees and power lines already struggling under the weight of ice. The additional weight of accumulating snow on the back-end of the system would complicate matters even further.

How Freezing Rain Forms

Freezing rain forms when a layer of subfreezing air hugging the surface is capped by a thick layer of warm air above it. Snowflakes melt as they fall into the layer of warm air. The melted snowflake—now a raindrop—falls into the subfreezing air at the surface, supercooling the liquid and allowing it to freeze on contact when it touches an exposed surface.
Tropical Tidbits

Data collected by weather balloons (or, in this case, simulated by weather models) do a fantastic job showing the temperature profile behind the formation of freezing rain. Take a look at the above sounding from Friday night's run of the GFS model near Montreal, Quebec, showing the atmosphere there just after midnight on Sunday.

The red line traces the temperature of air over Montreal from the surface to the top of the atmosphere. This particular model run shows a surface temperature of -9°C (about 16°F), while temperatures are firmly above freezing between 700 mb and 850 mb, or between about 5,000-10,000 feet above ground level. That's a freezing rain profile if there ever was one.

Freezing rain is finicky. It takes slow and steady freezing rain for ice to build into a thick crust. If it rains too heavily, the water won't be able to freeze on contact, simply running off and freezing into puddles on the ground instead. The worst ice storms are the ones that see hours and days of persistent freezing rain and drizzle. This won't be historic, but it has the potential to be memorable for folks in the hardest-hit areas. 1.00" of ice accretion from freezing rain is enough to fell thousands of trees and damage a power grid for a week or longer. That's no small inconvenience.

[Top Image: Tropical Tidbits]

You can follow me on Twitter or send me an email.

Please consider subscribing to my Patreon. Your support helps me write engaging, hype-free weather coverage—no fretting over ad revenue, no chasing viral clicks. Just the weather.

January 10, 2020

Dangerous Severe Thunderstorms Are Likely Across The South On Friday And Saturday

A dangerous mid-winter severe weather outbreak will roll across several southern states on Friday and Saturday, bringing the potential for all types of severe weather, including flash flooding. The threat will begin late Friday morning in Texas and slowly shift east through Saturday night.

Severe Weather Risk

The Storm Prediction Center issued a moderate risk for severe weather for parts of the Deep South on Friday, which is a risk more common of mid-April than mid-January. A moderate risk is a 4 out of 5 on the ascending scale used to measure the risk for severe weather.

The moderate risk covers a large portion of Texas, Louisiana, Oklahoma, and Arkansas, including Dallas, Shreveport, and quite a few smaller cities in between. Forecasters pulled the trigger on the moderate category due to the risk for significant, widespread wind gusts in excess of 70 MPH. While the red shading will get all the headlines, it's important to remember that damaging winds, tornadoes, large hail, and flash flooding certainly aren't confined to the moderate risk area. The overall threat for severe storms covers a swath from the U.S./Mexico border to St. Louis.

Damaging winds are the main threat with the storms on both Friday and Saturday, but don't discount the potential for some strong tornadoes. Supercells that develop ahead (or within) the lines of thunderstorms will be able to produce tornadoes, especially if they manage to break away from surrounding storms and take full advantage of the environment around them.

Saturday's storms carry much the same risk as Friday's storms—damaging winds in excess of 70 MPH, tornadoes (some potentially strong), large hail, and flooding rains—just farther east toward the northern Gulf Coast.


Severe thunderstorms are possible across Texas and Oklahoma as early as midday Friday, growing in coverage and intensity as the day wears on. The storms will organize and move into the most favorable environment for severe weather by Friday evening. The line (or line segments) will continue tracking east through Louisiana and Arkansas overnight on Friday into Saturday, reaching Mississippi and Alabama by Saturday morning.

It's helpful to think of this as one long severe weather event. Once the storms develop on Friday afternoon, the threat for severe thunderstorms marches east straight through Saturday night. A broken line of strong storms could even make it to the Carolinas by Sunday morning.

Severe weather taking place after dark makes it even more difficult to get the word out and keep up with rapidly changing conditions. It's tough to deal with nighttime severe weather because 1) people are asleep and 2) people like looking outside before they take cover. Make sure you've got emergency alerts activated on your smartphone so you can hear a tornado warning the moment one is issued for your location. If possible, it's a good idea to hold off going to sleep until the threat for severe weather passes.

The Setup

The GFS model's guidance for winds about 5,000 feet above ground level around 12:00 AM on Saturday, January 11. (Tropical Tidbits)

A low-pressure system will develop over Oklahoma on Friday morning, setting the scene for the severe weather we'll see over the next couple of days. The real story is the wind.

Winds will be ripping in the lower levels of the atmosphere ahead of the cold front, where a "low-level jet"—a localized area of strong winds—could produce winds stronger than 100 MPH just a few thousand feed above the surface. It's dangerous to deal with such strong winds so low in the atmosphere because it wouldn't take much of a downdraft for a thunderstorm to push those damaging winds down to the surface (hence the hullabaloo). A strong low-level jet can also increase the risk for supercells and tornadoes.

Flooding Risk

Damaging winds and tornadoes aren't the only threat over the next couple of days. Showers and thunderstorms will bring a risk for flash flooding for a huge swath of the country from Texas to upstate New York. Several inches of rain are possible even in areas that aren't expecting any severe thunderstorms. This kind of heavy, persistent rain will push natural waterways and drainage systems to their limit, especially if the rain falls quickly. The heaviest totals are likely across areas where severe thunderstorms as possible, where the Weather Prediction Center calls for more than 5 inches of rain in some spots.

You can follow me on Twitter or send me an email.

Please consider subscribing to my Patreon. Your support helps me write engaging, hype-free weather coverage—no fretting over ad revenue, no chasing viral clicks. Just the weather.

January 8, 2020

Twitter's Proposed "No Replies" Feature Could Be A Nightmare During Weather Emergencies

Twitter announced on Tuesday that they would test a new feature to give users another tool to deal with the site's rampant and often-unchecked harassment problem. Twitter users will be able to limit who can reply to their tweets, even allowing users to shut off replies to their tweets altogether. This feature could have major unintended consequences when it comes to countering false or misleading information. This is especially true during weather emergencies like tornado outbreaks or hurricanes, where every second counts and even a short-lived viral weather hoax can do significant damage to the safety and trust of those in harm's way.

Last year, Twitter rolled out a feature that let users hide individual replies to their tweets, which is great if you get one hateful bonehead yelling at you or saying something completely off-the-wall. In practice, though, it's often used to hide dissenting opinions or replies that attempt to debunk hoaxes and conspiracy theories. Today's proposal goes a step further by allowing users to completely prohibit replies to tweets altogether.

As someone who's been on the receiving end of more hate mail and death threats than anyone should ever see, it's a positive step that Twitter is at least attempting to create tools that help people shake off nasty or harmful replies, even if it's far from enough to address the overall problem. But this new feature fundamentally alters how people interact with each other on Twitter. Limiting or prohibiting replies to certain tweets could have serious unintended consequences when it comes to the spread of fake weather news.

Imagine the scenario I posted on Twitter this morning. We're in the middle of an intense springtime tornado outbreak and a line of supercell thunderstorms is marching across the southern Plains. Amid the flurry of reports comes an ominous tweet: "TAKE SHELTER—MASSIVE TORNADO HEADING TOWARD DOWNTOWN DALLAS!" Attached to the tweet is a picture of the EF-5 tornado that devastated Moore, Oklahoma, on May 3, 1999.

Seasoned meteorologists spot it immediately and try to wave people off of the malicious hoax as it rapidly goes viral in the growing panic, but the person who published the hoax shut off all replies. Meteorologists can't directly reach people seeing the tweet as it crosses their feeds. The only thing most people see is the warning, the old picture, and the fact that it's going viral. Meteorologists have to put the warning on their own feeds and hope that, in the fog of harried warnings about real storms, enough people see the corrections to make a difference.

It's not unrealistic. People pass off old pictures or false information all the time in the midst of severe weather events—tornadoes, hurricanes, floods, blizzards, fires, you name it. Some folks do it for the thrill of going viral, while others just get a sick pleasure out of tricking others in a time of crisis.

That very situation has played out before during tornado outbreaks, but other Twitter users were able to blunt the impact by quickly and forcefully pointing out the hoax. Right now, you have a chance to reach people who are seeing the false information by replying to a tweet. "Hey, this is false. This is an old tornado picture." People do click tweets and look through the replies.

This feature will remove the ability to directly reach those who are taken in by the false information. If there are no replies, that false weather report just hangs out there for thousands of people to see with no indication that it's not true. Under the new system, anyone who tries to refute the incorrect information has to implore their followers to help them spread word that it's bunk. It's a mess, and the corrections don't reach the people who are seeing the viral hoax.

Misinformation and outright hoaxes have plagued the weather community since social media came into widespread use. It's easy for anyone to sound authoritative and go viral. However, unlike politics where stories can take days or weeks to play out, severe weather occurs over a matter of minutes. A major tornado can touch down, destroy neighborhoods, and dissipate in just a couple of minutes. The decision to evacuate ahead of a hurricane needs to be made quickly. False information about the weather isn't just a silly internet thing—it can have a serious, real-world effect on people's safety and well-being.

With the ability to turn off replies to tweets, anyone can craft themselves into an authority figure on any subject without consequential pushback. Folks try to do that anyway, of course, but if you post "this blizzard will hit Washington tomorrow," you're going to get 200 people telling you you're wrong, and anyone who looks at your tweet will see all the people who corrected your misinformation. Eliminating replies will remove that pressure to skew toward truth. In practice, the tweet with the most retweets will become the uncritical truth on the subject, because now who will say otherwise?

After I posted that scenario on Twitter, the company's product lead reached out and said that they were taking this risk into consideration. Using the site's other features to respond to or highlight someone else's tweet simply isn't enough. It's important to be able to pipe up and say "no, this is wrong" when someone posts something that could lead people astray. Without some major tweaks or guards against it, this new feature will make it that much harder to get the word out during bad weather.

You can follow me on Twitter or send me an email.

Please consider subscribing to my Patreon. Your support helps me write engaging, hype-free weather coverage—no fretting over ad revenue, no chasing viral clicks. Just the weather.

December 31, 2019

The April 27, 2011 Tornado Outbreak Shaped How We Viewed The Weather In The 2010s

This was the first decade that allowed us to track every weather event on social media in excruciating detail. We went into 2010 getting weather info from big companies, a few apps, and a handful of popular blogs. We're ending 2019 with more apps and Facebook and Twitter pages than any one person could ever hope to download or follow. The technological advances we've seen in the last ten years changed how we consume weather information, but the storms themselves—and one outbreak in particular—did just as much to shape how we approach future weather events.

April 27 was a seminal moment in meteorology. The peak of the generational tornado outbreak that unfolded that day shaped severe weather communication for every major outbreak since. Much of the day's legacy involves personal impacts and the emotional toll it took on people affected by the storms and the meteorologists who watched them unfold.

216 tornadoes touched down on April 27, 2011, setting the record for the most tornadoes ever recorded in a single day. National Weather Service meteorologists surveyed the damage left behind by dozens of major tornadoes, including 4 scale-topping EF-5s. More than 300 people died as a result of tornado-related injuries.

The tornado outbreak was a well-predicted event. Meteorologists sounded the alarm days in advance that an unusually potent tornado outbreak might take place that afternoon. Long-track tornadoes allowed meteorologists to give people hours of notice ahead of the storms. Just about every local television and radio station preempted programming to carry live coverage of the storms.

Despite the advanced warning and extensive live coverage of the storms, hundreds were killed and thousands more were injured in the day's tornadoes. The high death toll was a combination of infrastructure failures and the sheer strength and number of tornadoes.

A powerful squall line swept through Alabama early in the morning on April 27, causing widespread power outages across the state. Several weather radio transmission towers went offline during the power outages, leaving many Alabama residents with no electricity and no NOAA Weather Radio going into that afternoon's storms.

The raw power of the tornadoes also contributed to the immense death toll. Many homes in the path of the strongest tornadoes were scrubbed from their foundations. There's no amount of walls separating you from the outdoors that can save you when your entire house is simply swept away.

That single afternoon built a culture of weather awareness in the south. To this day, Alabama's most beloved living resident is probably James Spann. People who normally wouldn't care about the weather can decipher radar products without needing any help. The physical, emotional, and mental scars left behind by that day's tornado outbreak did more to instill weather awareness and storm education than just about any event before it.

That day's events also shaped how we cover the weather. That afternoon is the reason I write about the weather today. Every meteorologist and weather enthusiast who was around and paying attention uses that day as the benchmark for how to measure their coverage of potential tornado outbreaks.

Think back to Hurricane Sandy in 2012, the EF-5 tornado in Moore in 2013, blizzards, major flooding, Matthew, Harvey, Irma, Maria, Florence, Michael, Dorian...all the major weather events that came after April 27, 2011, were covered through a lens adjusted on that horrible day.

It strengthened the resolve to push back against hype-filled weather coverage. It taught millions of people to pay attention to the weather and take everything seriously. The closest that weather folks as a whole have come to ringing the alarm as loudly as April 27, 2011, was back on May 20, 2019, a day when the atmosphere appeared primed for an intense tornado outbreak in Oklahoma, but the storms ultimately had trouble forming.

We'll have historic disasters in the next ten years. It's likely that some of them will set new benchmarks for storms in the years that follow. Thankfully, technology today is better than it was back on April 27. Smartphones are more prevalent than ever and they're all equipped with wireless emergency alerts that receive tornado warnings instantly. Weather radar was upgraded with dual-polarization in the 2010s, giving us the ability to see tornado debris in a storm.

The next decade will see more advances in forecasting, detection, and alerting, progress that will help us stay ahead of storms even better than we can right now. People change. Tech changes. The weather is changing. It's up to all of us—meteorologists, reporters, the public—to learn the lessons of the past and apply them to whatever storms lie ahead.

You can follow me on Twitter or send me an email.

Please consider subscribing to my Patreon. Your support helps me write engaging, hype-free weather coverage—no fretting over ad revenue, no chasing viral clicks. Just the weather.

December 25, 2019

This Was The Warmest Christmas On Record For Much Of The Midwest

The sun just set on one of the warmest Christmases in recent memory. The abnormal blast of winter warmth stretched from the Rocky Mountains to the East Coast, with the bulk of the above-average temperatures focused on the central part of the country. Temperatures climbed as much as 30°F above normal in parts of the central United States on Wednesday afternoon, leading several cities to their warmest December 25 on record.

A strong ridge of high pressure over the eastern two-thirds of the United States is responsible for the current burst of above-average temperatures. The most significant and widespread warmth occurred on Wednesday afternoon, but the unseasonably comfortable temperatures will stretch into Thursday and Friday for some in the eastern part of the country.

This kind of warmth doesn't seem like much. It's pretty nice out! How often do you get to throw the windows open on Christmas and air out the house before the cold of winter sets in? However, just because it's comfortable doesn't mean that this isn't an unusually warm stretch for late December. It's easy to lose sight of the fact that it's not supposed to feel like late September in late December when that eye-popping temperature anomaly's practical effect is "ooh, this is comfy."

Dozens of reporting stations broke their daily high temperature record for December 25, cementing this as the warmest Christmas on record for many parts of the Midwest. The animation above shows the high temperatures that fell (in red) on Wednesday.

Moline, Illinois, saw its warmest December 25 on record, topping out with a high of 62°F. That doesn't seem like much until you consider that the city's average high for this date is 32°F. The high in St. Louis, MO, clocked in at 70°F, which is also a solid 30°F above what the city should see this time of year.
City Average High
for Dec. 25
Observed High
on Dec. 25, 2019
Departure From
St. Louis, MO 40°F 70°F +30°F
Moline, IL 32°F 62°F +30°F
Kansas City, MO 38°F 66°F +28°F
Chicago (MDW), IL 33°F 61°F +28°F
Wichita, KS 42°F 68°F +26°F
Indianapolis, IN 36°F 62°F +26°F
Oklahoma City, OK 49°F 70°F +21°F
Memphis, TN 50°F 70°F +20°F
Buffalo, NY 34°F 50°F +16°F
Mobile, AL 61°F 73°F +12°F
Sources: xmACIS2 / NWS
Extremes beget extremes. Folks east of the Rockies often have to endure relentless wintertime teasing from friends and family basking in California's mild winters. A strong ridge is usually paired with a strong trough nearby, and this ridge's companion found itself right over California on Wednesday. Chicago Midway recorded a warmer high temperature (61°F) than Los Angeles (58°F),

The ridge will slide east through the end of the week, briefly allowing more seasonable temperatures to wash across the Midwest before a ridge redevelops this weekend and pumps 50s and 60s back toward the Great Lakes. It's likely that above-average temperatures will continue across parts of the eastern U.S. through next week.

Here's a look at the National Weather Service's forecast high temperatures through Sunday.

Thursday, Dec. 26

Friday, Dec. 27

Saturday, Dec. 28

Sunday, Dec. 29

[Top Image: Tropical Tidbits]

You can follow me on Twitter or send me an email.

Please consider subscribing to my Patreon. Your support helps me write engaging, hype-free weather coverage—no fretting over ad revenue, no chasing viral clicks. Just the weather.

December 19, 2019

Those New 'Snow Squall Warnings' Are Designed To Prevent Deadly Pileup Accidents

Millions of smartphones across the Northeast flashed an unfamiliar warning on Wednesday afternoon. The message came across as a push alert with the iconic screeching tone and an abrupt vibration: "Emergency Alert. Snow squall warning until 4:15 PM. Sudden whiteouts. Icy roads. Slow down! -NWS" These alerts may seem a little excessive on first glance, but they're targeted at motorists who need to know that they're approaching a potential whiteout that could cause a deadly pileup accident like the one that occurred in Pennsylvania on Wednesday.

The National Weather Service created snow squall warnings as a way to warn people in the path of snow squalls that they could experience sudden whiteout conditions, giving them enough time to pull off the road and wait for things to calm down before driving again.
Source: NWS New York

A local NWS office can issue more than a hundred different types of watches, advisories, and warnings. Some of the products are more urgent than others. The most important warnings—the ones that require you to stop what you're doing and pay attention to the weather instead—are usually issued using polygons, which allow forecasters to target warnings to only the areas at risk for life-threatening hazards like tornadoes and severe thunderstorms.

There's a different target audience for each of those polygon-based warnings. Tornado warnings and severe thunderstorm warnings are "everyone" warnings, no matter who or where you are. Flash flood warnings are important to people who live in flood-prone areas and motorists who may approach a flooded roadway, but the vast majority of us can usually ignore them if we're going about our business at home or work.

Beginning in November 2018, the National Weather Service officially began issuing polygon-based snow squall warnings, giving forecasters the ability to instantly warn people that they could be in the path of a sudden burst of snow. Snow squall warnings are "driver" warnings. They're not targeted to people sitting in their living room or working at their cubicle. They're targeted at people on the road or those who are getting ready to head out.

Snow squall warnings are handled with the same urgency as tornado and severe thunderstorm warnings for good reason.
We hear about pileup accidents all the time during the winter. A chain-reaction crash is pretty much the worst-case scenario for anyone out on the roads when a sudden burst of snow turns the roads to ice and drops visibility down near zero. Pileups can involve hundreds of cars in the most serious incidents, amassing dozens of injuries and fatalities as people get stuck in the wreckage and absorb the blow of every car and truck careening toward them.

The warnings worked exactly as expected on Wednesday. Several snow squalls moved across portions of the Northeast today, bringing whiteout conditions and dropping up to two inches of snow in under an hour. It doesn't look like much on radar (shown at the top of the post), but the tweet above shows how abruptly a cloud of snow can drop visibility down near zero.

Unfortunately, a snow squall in central Pennsylvania actually did cause a deadly pileup on I-80 about 20 miles east of State College. The Daily Item reported that two people died and dozens more were injured during the chain-reaction crashes.

There's only so much meteorologists can do to warn people of what's on the horizon. Just like a tornado or severe thunderstorm warning, it's not always possible to pull off the road or avoid a wreck when you find yourself driving into a snow squall. The new warnings are designed to give you an opportunity to seek safety that wasn't available before. It's all worth it if each warning helps even a couple of people stay safe.

[Top Image: Gibson Ridge]

You can follow me on Twitter or send me an email.

Please consider subscribing to my Patreon. Your support helps me write engaging, hype-free weather coverage—no fretting over ad revenue, no chasing viral clicks. Just the weather.

December 16, 2019

A Quick-Hitting Storm Will Bring Midwest Snows And Severe Thunderstorms To South

A low-pressure system will develop over the Mid-South on Monday and dominate weather east of the Mississippi River for the next couple of days. The storm will start with a quick thump of snow across the Midwest and Ohio Valley, with severe thunderstorms developing in the storm's warm and humid airmass across the Deep South. Snow and ice will spread toward the Northeast on Tuesday before the storm races out to sea on Wednesday.

Wintry Weather

Winter storm warnings are in effect across central Missouri and central Illinois ahead of a period of heavy snow expected during the day on Monday. The snowfall forecast map above shows all the snowfall forecasts issued by local National Weather Service offices across the country. The NWS forecast shows up to five inches of snow across the winter storm warning, which isn't a whole lot, but it's enough to snarl traffic and make travel a headache when roads are at their worst.

Winter weather advisories exist from the central Plains to the Northeast, with more advisories and warnings likely as the storm moves east. It doesn't take much snow or ice to make travel difficult or even impossible. I've long argued that an inch of snow is more dangerous than a foot of snow, and the danger only grows when there's freezing rain, sleet, or roadway refreezing in the mix.

Severe Thunderstorms

It's not all cold and snow. Warm and humid air will rotate around the southern end of the low-pressure system, providing a decent amount of instability to fuel severe thunderstorms.

The Storm Prediction Center issued an enhanced risk for severe weather—a three out of five on the scale measuring the risk for severe thunderstorms—across portions of Louisiana, Mississippi, and Alabama, on Monday afternoon.

The greatest risk from the strongest thunderstorms is damaging wind gusts in excess of 60 MPH and the possibility for tornadoes. The threat for tornadoes appears maximized around central Louisiana and Mississippi, where the SPC painted a 10% risk for tornadoes on Monday. Tornadoes are most likely in discrete thunderstorms, while damaging wind gusts are favored in squall lines.

If you have any friends or family in the area, it's a good idea to give them a heads-up about the risk for severe thunderstorms on Monday and Monday night, especially since a decent number of the storms will roll through after sunset. Nighttime storms are dangerous both because people tune out as they wind down before bed and the fact that the urge to look for approaching storms and tornadoes can be overwhelming. Make sure you've got a way to receive severe weather warnings once you go to bed, and please trust that they're real and resist the temptation to look for the storm before seeking shelter.

You can follow me on Twitter or send me an email.

Please consider subscribing to my Patreon. Your support helps me write engaging, hype-free weather coverage—no fretting over ad revenue, no chasing viral clicks. Just the weather.