November 25, 2018

A Midwest Blizzard Could Snarl Air Travel in Chicago on Sunday

Blizzard warnings are in effect for parts of the central Plains and Midwest as a potent snowstorm gets ready to crank out a heavy dose of winter weather to close the holiday weekend. Track means everything for this classic winter storm, as a dozen miles to the north or south will determine both the location of the rain/snow line and the axis of deepest snowfall accumulations.

A strong low-pressure system developed in southwestern Kansas during the day on Sunday. The low will continue to strengthen as it swiftly moves to the northeast. Precipitation will fall in the form of snow to the north and west of the center of low pressure. The greatest snowfall totals will fall along a path that lies a few dozen miles to the northwest of the low's center.

Right now, the Weather Prediction Center expects the heaviest swath of snow to follow along a path from northeastern Kansas through central Michigan. It's already snowing across the central Plains and it'll quickly spread east across the Midwest through Sunday morning. The snow will probably last most of the day on Sunday in the Midwest before tapering off through the night. The storm will pull out of the Great Lakes by Monday night.

The sharp rain/snow line and relatively narrow band of intense snow will make the final outcome reliant on the precise track of the storm. If the low-pressure system strays a dozen or so miles to the right or left of its current predicted track, it'll pull the rain/snow line and deepest accumulations right along with it.

That's a scary prospect for travelers heading through Chicago this weekend. Sunday is historically one of the busiest travel days of the year as people rush to get back home after the long Thanksgiving weekend. The most impressive snow totals from this blizzard will come perilously close to Chicago's O'Hare and Midway Airports, which combined handle more than a thousand flights every day. Heavier snow will lead to heavier travel disruptions. The delays and cancellations in Chicago will ripple through flight schedules across the country due to the sheer volume of connections that funnel through Chicago's two airports.

Winds will grow pretty intense along the track of the storm on Sunday. Blizzard conditions are possible in that heavy swath of 6"+ snowfall totals. A blizzard occurs when winds of 35 MPH reduce visibility below 1/4 of a mile for three consecutive hours. These whiteout conditions are so disorienting that it's easy for motorists to crash into unseen obstacles like ditches, poles, and other cars. It's also dangerous for people who are out on foot, since you can quickly lose track of where you are and get stuck in the open in the extreme cold.

It's also worth pointing out that winter storms are not officially named in the United States. The Weather Channel unilaterally names winter storms; the National Weather Service does not participate in the private company's naming program. Some companies and even local/state governments have chosen to use these names. However, most major international news conglomerates (yours truly included) do not use The Weather Channel's names.

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November 21, 2018

Tranquil Weather Breaks With Rains Out West (Finally!) And A Frigid Thanksgiving In The East

Clouds to the left of me, icicles to my right, here I am, stuck in the middle with you. That's pretty corny, but we're going to be knee-deep in mashed potatoes and green bean casserole tomorrow, so who cares, right? It's going to be a wild couple of days for weather across the United States. Well, unless you live in the central part of the country, in which case it'll be pretty nice until early next week.

Western Rains

Rain is a welcome sight across California as the state reels from the deadliest and most destructive round of wildfires in the state's recorded history. Hundreds of residents of Paradise, California, remain missing or unaccounted for after fast-moving wildfires completely engulfed the town, located in the northern part of the state near Chico. The fire killed at least 81 people and burned more than 153,000 acres—an area equivalent to the size of the city limits of Chicago.

California is in the second month of its (until now, rainless) rainy season, which begins in the middle of fall and typically stretches through the end of winter. Most of California has been downright parched after a long, hot summer, and the extended dryness exacerbated the conditions that allowed the Camp Fire in Paradise and the Woolsey Fire in Malibu to grow into firestorms.

Most of the focus is on California because it's, well, on fire, but really the entire Pacific Northwest—especially interior parts of Oregon and Washington—could really use the rain that's on its way. The rain will continue in waves over the next couple of days. The Weather Prediction Center expects several more inches of rain to fall between this evening and next Wednesday, with the heaviest totals expected along coastal areas between southern British Columbia and central California, as well as the higher elevations.

Most of the mountain areas out west will see precipitation fall in the form of snow. The highest elevations could measure snowfall in feet over the next couple of days. This is great news for both the region's water resources and the tourism industry, which is heavily reliant on winter sports.

Coastal Cold and Central Comfort 

The old cliché about "roller coaster" weather seems pretty apt this weekend, especially if you look at upper-level charts and temperature maps. The gyrations in winds and temperature patterns across the United States over the next couple of days kind of does trace a child's rendition of roller coaster tracks if you squint hard enough.

Source: Tropical Tidbits

We're in a pretty wavy upper-level weather pattern right now. The United States and Canada are bookended by two troughs on either coast with a large ridge of high pressure across the central part of the continent. This trough-ridge-trough sequence is allowing for chilly temperatures and precipitation to prevail out west, generally sunny and mild conditions in the center of the country, and frigid weather in the Northeast giving way to a chilly, dreary rain this weekend.

We'll probably hear quite a bit about the cold in the Northeast this Thursday and Friday. Both the high and low temperatures could be some of the coldest recorded on Thanksgiving in many years. Anyone watching the Macy's Thanksgiving Day Parade in New York tomorrow will likely hear the hosts make bad jokes about the cold every 12 seconds or so.

Here's a better look at the National Weather Service's expected low temperatures on Thursday morning (forecasts as of Wednesday afternoon)...

...and the highs on Thursday...

...and the low temperature on Friday morning...

...and the high on Friday for all the folks returning home from the hospital after getting into a fist fight over a $7 lamp at Target:

The only regions that really make out okay temperature-wise over the next couple of days will be the Plains, parts of the Midwest, and much of the Southeast. The trough over the West Coast will continue moving east through the weekend, and the cooler weather—including a potential snowstorm!—will pick up across the central part of the country early next week.

Does Cold Weather Disprove Climate Change?

Every year, we get people—some less firmly rooted in reality than others (hi Donald!)—who claim that every burst of below-normal temperatures that washes over the United States solidly refutes all of the evidence of "global warming," so take that, Al Gore.
Source: Tropical Tidbits

It helps to remember that the world is bigger than your backyard.

Happy Thanksgiving!

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November 16, 2018

Devastating Fires Continue to Burn as California's Rainless Rainy Season Continues

California's worst wildfire in recorded history continues to burn this evening as rescue crews comb through the ashes of an entire town to recover the remains of those who couldn't escape in time. The billowing smoke from the latest round of historic wildfires has grown so thick at times over the past week that much of the region appeared shrouded by a toxic supercell on satellite imagery. This scene has repeated itself too many times in recent years, and there's no indication that it'll let up in the future.

There are currently about a dozen fires burning out of control across California's vast countryside. Five of the fires are significant and one of them is unprecedented. The Camp Fire, located just east of the northern California city of Chico, is now both the deadliest and the most destructive wildfire ever recorded in California, and will likely end up as one of the worst in modern U.S. history.
Source: Cal Fire

The Camp Fire destroyed almost every building the town of Paradise, California. Many of the 10,000 residential and commercial buildings that have burned down so far were destroyed not long after the fire started early in the morning on November 8. The latest update from local officials reported that there were more than 600 people either missing or unaccounted for. It's possible that a significant number of them may have been caught in the fire. But it's also possible that many of them just haven't been contacted since they fled with what little they could last week.

Crews have worked at a feverish pace to knock down the flames, but adverse weather conditions and ample dry fuel has made stopping the fire a significant challenge.The fire has consumed more than 141,000 acres of land in the past week—placing the fire among the top-20 larges ton record, in addition to all the other tragic records—and it's just 40% contained as of November 15.

Hundreds of miles away in southern California, another fire sparked around the same time as the Camp Fire up north. Called the Woolsey Fire, this fast-spreading conflagration prompted the evacuation of the entire city of Malibu, which is best known around the world as the home to multi-million dollar celebrity homes.

Around 500 homes and businesses have been destroyed in the week since the fast-spreading Woolsey Fire sparked on November 8, killing two people and consuming nearly 100,000 acres of land. Crews have had better luck getting this fire under control; by the evening of November 15, the fire was 62% contained.

The story behind these fires is the story behind just about every other significant fire we've seen in recent years. Exceptionally dry vegetation caused by too little rain allows even the tiniest spark to grow into a fire that spirals out of control faster than many can react.

It's undeniable that the fires in California—really the entire western half of North America—are getting worse.

The state's largest-ever fire burned just this past summer. The Mendocino Complex charred more than 450,000 acres of land. If you have no frame of reference for how much land that is—I sure don't—it's an area roughly the size of the Hawaiian island of Maui, or about the same amount of land covered by the suburban D.C. counties of Prince William and Fairfax combined.

In fact, 15 of the 20 largest fires ever recorded in California have occurred since 2000, and 7 of those fires burned between 2010 and 2018.

There isn't one specific factor we can point to as the cause behind these horrendous wildfires. It's a combination of several hazards. The fires are largely caused by humans. The fires grow enormous thanks in large part due to conditions brought about by a changing climate. And the fires are so destructive because we're building entire communities on land that was previously undeveloped woodland not long ago.

The conditions that allow for California's wildfires to grow bigger than ever before—including lengthier and more frequent droughts and hotter temperatures—are all likely consequences of climate change that we're already dealing with. And things aren't going to get any better unless current global temperature trends start to reverse.

California's rainy season is usually ramping up by the middle of November, but you wouldn't know it by looking at conditions across the state right now.
Source: xmACIS2

The above rainfall graph is taken from Oroville Municipal Airport, which is located just a couple of miles south of Chico and the raging Camp Fire. The graph, which begins on July 1, shows the progression of the rainy season through the fall and winter months. The flat green line at the bottom of the chart shows the almost-imperceptible amount of rain that's fallen across north-central California since the middle of this summer. They've seen virtually no precipitation even though they should have nearly five inches of rain on the books already.

And so the story goes for much of the western United States. The land will continue to be ripe for explosive fire development when weather conditions allow for it as long as there's no rain to quench the parched vegetation that blankets the region. Fires spread most efficiently when the ground is parched from a lack of rain, the air is extremely dry with relative humidity levels in the single digits, and strong winds that help spread the flames faster than they can be contained. This is why the Santa Ana winds of southern California are so spectacularly dangerous, as we saw with the incredible speed at which Malibu's Woolsey Fire spread.

The Storm Prediction Center, which also issues fire weather outlooks, shows no areas at risk for critical or extremely critical fire weather conditions over the next couple of days. The agency shows the risk for elevated fire weather conditions across higher elevations near the coast in southern California through the evening on Thursday, but no other areas with weather conditions favorable for explosive fire growth. These improved weather conditions should help firefighters—thousands of whom are prison inmates who work long hours for just a few dollars a day and no chance of getting a firefighting job after they're released, might I add—get a handle on the fires that are already burning.

Rain-free conditions will prevail for the next week or so across California, though there is some hint in the models that there could be chances for rain around or after Thanksgiving, but it's a long way off and sadly it's way too early for specifics.

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November 15, 2018

Florida Will Participate In Autumn If It's The Last Thing The Other 47 States Do, So Help Us

Florida will soon learn that the terms of autumn are non-negotiable. The Sunshine State will participate in chilly fall mornings even if it's the last thing the other 47 contiguous states do, so help us. (Alaska can send moose if they want. Hawaii can sit this one out.)

When the state isn't exporting weird headlines or conducting horrendously-flawed elections, residents spend much of the year looking for ways to keep cool. It's no surprise that it stays toasty pretty late into the year in Florida. The state is a huge attraction during the winter months because its enduring warmth seems unshakable outside of the biggest, meanest storms that envelop the eastern half of the country.

The heat of late really has been unshakable. Not only has it been unusually warm so far this fall even by Florida standards, but the months-long extension of summer has approached record territory across the peninsular portion of the state.

The period between September 1 and November 14 saw the warmest average daily temperature ever recorded at Miami International Airport. The average of all the daily average temperatures—that is, the high and low temperature averaged together each day, and all those averages then averaged together for the entire 76-day period—came in at 81.8°F, which is the warmest recorded during climatological fall since records at the airport began in 1937.

Here's a breakdown of temperatures in Miami so far this fall:

You can see that daily highs have been above-average, but they only deviated from normal by a degree or two each day. The difference is in the lows. Most days saw a low temperature dramatically higher than what you'd expect to see for this time of the year. Except for the a couple of days at the end of October, the low temperature in Miami has remained in the mid- to upper-70s almost every day since the end of summer.

Hot and humid days fading into warm and humid nights provides residents no respite from the heat. Warming nighttime temperatures is a noticeable trend across much of the United States. The increase in the number of warm nights is one of the concerning effects of climate change.

Making matters worse is that it's a wet heat. The Iowa Environmental Mesonet shows that Miami has seen dew points of 76°F or warmer for nearly 1,700 hours so far in 2018, an excessively-muggy length of time that's second only to 2005. Dew points are generally considered to be oppressively humid once the value rises above 75°F.

I've focused on Miami in this post because it's an extreme example of summerlike heat and humidity lasting well beyond its expiration date, but it's not just Miami that's suffering. The average daily temperature since September 1 is also sitting in record territory up at the major airports in Orlando and Tampa. It remains to be seen how much averages for the entire fall will moderate back toward normal with the upcoming cooldown.

Thankfully, things are going to change soon, even if it's only by a little bit. Look at this GFS model animation of dew points over the next couple of days:

Source: Tropical Tidbits

Ahhhh. That's nice. Air temperatures are likely going to remain warm for the next couple of weeks—hovering at or slightly above average most days—but the break in oppressive humidity will make it feel nicer and the relatively drier air will allow nighttime temperatures to finally fall back near normal for this time of year.

Communities near Pensacola will likely see a hard freeze on Thursday morning, and morning lows on Friday could dip into the 30s across inland areas as far south as Ocala. Low temperatures in the 40s may even reach the northern shores of Lake Okeechobee on Friday and Saturday.

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November 13, 2018

An Early-Season Winter Storm Will Bring Snow and Ice to the Midwest and Eastern States

The raw chill that's settled over the eastern half of the United States over the past couple of weeks set the stage for winter weather to follow closely behind. There's a decent chance that many areas will see their first significant snow and ice storm between Wednesday and Friday, with the heaviest snow falling in the Midwest and Northeast, while freezing rain will coat much of the Appalachian Mountains in a crust of ice.

Our storm developing tonight comes fresh on the heels of a storm that brought heavy snow to the southern Plains and heavy rain to just about everyone else east of the Mississippi River. More than half a foot of snow fell in parts of Texas and Oklahoma as the system met cold air locked firmly in place over the region. Farther to the south on the warm side of the system, persistent heavy rains and thunderstorms led to flooding and even a couple of reported tornadoes in North Carolina.

Source: Tropical Tidbits

That storm is out of here and the next one isn't far behind. An upper-level low will develop over the Mississippi River valley on Wednesday and slowly make its way east over the following two days. The system will bulk up in a hurry as it moves east, producing yet another prolonged round of heavy precipitation along its path.


Cold air on the northern side of the system will allow precipitation to fall in the form of snow, sleet, and ice. The heavy snow will start falling in and around southern Illinois on Wednesday night and Thursday morning. Some areas could see more than half a foot of snow, though widespread shovelable totals will make it difficult to get around on Thursday.

Snow will be more widespread across the Ohio Valley, Great Lakes, and Northeast on Thursday and Friday. Many areas west of I-95 are on track to see several inches of snow, with much higher totals in higher elevations and where lake effect snow enhances snowfall totals. It won't take much for the rain/snow/ice line to shift a dozen miles to the east or west, so if you live right on that line between nothing and something, it's wise to watch the forecasts and make sure you're ready with the ice scraper or snowbrush just in case.


Temperatures hovering right around freezing with above-freezing temperatures above the surface will allow for freezing rain and sleet to fall in the Appalachians and parts of the Mid-Atlantic. The most significant ice accretion will occur in the Appalachians, where one-quarter of an inch or more of ice is possible on exposed surfaces.

1/4" of ice doesn't seem like much, but that's a lot of weight on power lines and tree limbs, and it could lead to downed trees and power outages in some areas. The ice will also make travel difficult or impossible for a time on Thursday until temperatures climb back above freezing.

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November 5, 2018

Nighttime Severe Thunderstorms and Tornadoes Are Likely Tonight in the South

The Storm Prediction Center has issued a tornado watch for portions of Louisiana and Mississippi as a dangerous nocturnal severe weather outbreak gets underway. An enhanced risk for severe thunderstorms—a three out of five on the scale that measures the threat for severe weather—is in place tonight for the Mid-South. Severe weather, especially tornadoes, are extremely dangerous after dark because you can't see and many people start tuning out the weather as they head off to bed.

The situation tonight is a classic setup for severe weather in November. A developing low-pressure system over the Midwest is dragging a cold front across the southern states. In fact, you could apply just about everything I wrote about last Wednesday's risk for severe weather to today's risk, just moving all the locations a bit to the north and east. Warm, unstable air ahead of the cold front will foster the development of thunderstorms, and wind shear ahead of the storm system will allow the individual thunderstorms to turn severe.

All modes of severe weather are possible, including damaging straight-line winds, large hail, and tornadoes.

The Storm Prediction Center has issued a 10% risk for significant tornadoes across much of Mississippi and central Tennessee. The black hatching indicates the area where the environment is capable of support tornadoes that could be strong or long-lived. Tornadoes are most likely in discrete (individual) thunderstorms that pop up ahead of the main lines of thunderstorms that develop along the cold front pushing into the region.

The threat for damaging winds is greatest in the line (or lines) of storms as they organize ahead of the cold front tonight. However, tornadoes are also possible in those lines of storms. Just like we saw last week a bit farther to the southwest, we could see little kinks develop along the leading edge of the lines of thunderstorms. These rotating kinks can lead to tornadoes that develop quickly, sometimes with little or no lead time before it hits.

The storms will move from west to east through the nighttime hours, reaching the Appalachian Mountains by early Tuesday morning. The line will regenerate on the eastern side of the mountains by Tuesday afternoon, bringing the risk for severe weather to parts of the southeast and Mid-Atlantic during the day tomorrow. If you haven't voted yet, it's a good idea to vote early so the weather doesn't affect your ability to cast your ballot.

Severe weather is dangerous anytime, but storms pose a greater threat to life in the cold months and even more so again after dark. Many people want to see a tornado coming at them before they act. On top of the many, many reasons that's a bad idea, the least of which is the fact that you can't see tornadoes after dark. What's worse is that the tornadoes in a setup like this are likely to be rain-wrapped, adding an additional shroud to the tornadoes that makes it impossible to see them even when they're backlit by lightning.

Make sure the emergency weather alerts are activated on your phone. I know quite a few people who tried to disable them in the lead-up to last month's nationwide test of the Emergency Alert System. There are people alive today only because they acted when the Wireless Emergency Alerts pushed a tornado warning to their smartphones. If you don't have a smartphone or live in an area with a bad signal, keep a television or radio on when you go to sleep so you have a chance to hear warnings when they're issued. Do not rely on tornado sirens for severe weather alerts. I know your parents and grandparents swore by them, but these systems are aging, they're not designed to be heard indoors, and (ironically) they're unreliable during a storm.

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