February 25, 2023

2023's First Moderate Severe Storm Risk Targets Oklahoma With 75+ MPH Winds

This year's first big threat for severe weather will target Oklahoma this weekend as forecasters expect a dangerous squall line to sweep across much of the state on Sunday.

A robust low-pressure system will develop over the central Plains this weekend as a trough crests the Rockies. This is the same trough responsible for all that wild snow in California—that's a lot of energy heading east.

Plenty of warm, humid air bathed over the southern Plains will provide ample fuel for vigorous thunderstorms to develop along and ahead of this low-pressure system's cold front through the day Sunday.

There's enough wind shear that forecasters with the Storm Prediction Center expect a powerful line of thunderstorms to develop along the front. They've issued a moderate risk—a 4 out of 5 on the scale measuring the threat for severe weather—for a chunk of western Oklahoma, with an enhanced risk extending east to cover the rest of the state into southwestern Missouri.

This is the highest risk issued by the SPC since December, and it's especially noteworthy because it's for Day 2—they usually wait until the day of the event to upgrade to a high-end risk, a move that conveys their confidence in widespread severe storms on Sunday.

Damaging winds in excess of 75 mph are the main threat with the storms on Sunday, covering the Oklahoma City and Tulsa metro areas, as well as Joplin and Springfield in southwestern Missouri.

Widespread severe wind gusts can cause tree damage and power outages. Folks are often taken by surprise by the strength of severe squall lines, swearing that they witnessed a tornado or "inland hurricane" instead of a line of bad storms.

In addition to the risk for widespread damaging winds, we could see tornadoes develop within the squall line and in any discrete thunderstorms that bubble up ahead of it. Tornadoes embedded in squalls can happen very quickly, sometimes reducing tornado warning lead time down to a few minutes at best.

Folks on the Plains are well versed in tornado safety, but given that it's February and these tornadoes could happen quickly, it's worth taking a few minutes to prepare.

Make sure you (or anyone you know in the area) has a way to receive warnings and get to safe shelter the moment they're issued. Take a look at your phone's settings and ensure that wireless emergency alerts are turned on and activated for tornado warnings.

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February 22, 2023

Thursday Could Be One Of The Southeast's Hottest February Days On Record

The winter that's barely wintered rolls on across the southeastern U.S. this week as a ridge over the eastern half of the country threatens all-time monthly records on Thursday.

February 23, 2023, could be the hottest February day ever recorded for multiple cities from the Gulf to the Chesapeake, with predicted high temperatures in the low 80s more common of late spring than late winter.

A highly amplified pattern over North America gave rise to a significant winter storm plaguing folks across much of the northern U.S. and Canada, with a widespread blizzard ongoing in the Upper Midwest while a major ice storm looms for folks near Toronto.

The East Coast drew the long stick on this setup—as we have for most of the season—coming in on the warm side of the equation. A big upper-level ridge will combine with blustery southerly winds feeding into that winter storm to send temperatures to levels almost unheard of in February.

Here's a peek at the National Weather Service's predicted highs for Thursday afternoon:

That's pretty darn warm! The average high in Birmingham, Alabama, doesn't reach 80°F until about May 5, and the average high doesn't climb to 80°F in Greensboro until June 1st. 

(*Note: The temperatures on my map don't line up perfectly with the National Weather Service's point forecast because of the pixel-based process I use to add temperature labels to my map.)

It's so unusually warm that we're on the cusp of breaking all-time monthly heat records across the southeastern states.

Based on current forecasts, Birmingham, Charlotte, and Charlottesville all stand to break their all-time February temperature records, with cities from Mobile to Baltimore coming awfully close to shattering their respective records.

If breaking yet another round of all-time temperature records sounds familiar...it is. Many of these records have only stood for a couple of years, as late-winter warm spells in 2017, 2018, and 2019 each shattered all-time monthly records of their own. 

This follows an overall trend in heat records vastly outnumbering cold records as the climate warms. Average temperatures are on the rise across the United States, and the greatest warming trends have been observed during the winter months, according to Climate Central.

Thursday's predicted temperatures are all 20+ degrees above normal for this time of year.

[Top Image: Tropical Tidbits]

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February 20, 2023

Record Snows Possible As Major Winter Storm Aims For Northern U.S.

A high-end, highly impactful winter storm will sweep through much of the northern half of the country this week, producing deep snowfall and blizzard conditions along its path. The storm's worst will focus on southern Minnesota, where more than a foot-and-a-half of wind-driven snow is possible.

The Setup

The upper-level pattern developing over the U.S. this week will resemble a case study from a meteorology textbook.

Source: Tropical Tidbits

A vast trough over the western half of the country will give rise to the sprawling low-pressure system that'll cause all the headaches for folks up north, while a formidable ridge over the east will give some areas a run at the warmest temperatures they've ever recorded in the month of February.

My town in north-central North Carolina could hit 83°F on Thursday afternoon—the second-warmest February day since records started here in 1901. Raleigh could rocket up to 87°F, shattering their monthly all-time temperature record by a couple of degrees.

When it comes to direct impacts, though, this spate of record heat is a relative footnote to the mammoth winter storm brewing beneath this impressive setup.

The seed that'll grow into our disruptive storm is over British Columbia right now, bringing widespread gusty winds to the South Coast and more than a foot of snow to the mountain passes.

We'll see this disturbance move southeast over the Rockies on Tuesday, laying the foundation for a very large winter storm to develop on the western Plains by Tuesday night.

Source: Tropical Tidbits

A push of Pacific moisture with that initial disturbance will meet up with a surge of tropical moisture from the south (gawk at the animation above to see it in action).

This atmospheric doubletake will provide a vast reservoir for this developing storm to produce all the rain and snow it wants—and it sure seems like it'll live up to its potential.

Heavy Snow

Snow is the biggest concern with this system. Here's the Weather Prediction Center's latest forecast showing the probability of 4 or more inches of snow through Thursday evening.

Source: Weather Prediction Center

That's a significant swath of land expecting a healthy blanket of snow!

Here's the same forecast showing the probability of more than 12 inches of snow:

Source: Weather Prediction Center

Forecasters are increasingly confident that a huge chunk of the Upper Midwest stands to see more than a foot of snow through the end of the week, with parts of Minnesota and Wisconsin—including the Twin Cities—possibly seeing 18+ inches of snow from this system.

A foot-and-a-half of snow is common with a nor'easter on the East Coast, but it's a solid, high-end storm for the Upper Midwest. If that scenario played out, it would be at least the 8th largest snowstorm on record at Minneapolis-St. Paul.

Snowstorms in the middle of the country typically don't have this much moisture to work with—it's usually their winds that cause issues more than the immobilizing amounts of snow. 

Source: National Weather Service

Blizzard Conditions

This storm certainly won't be short on winds. 

Widespread gusts of 40-50 mph will create a lengthy period of blizzard condition from the Rockies through the Upper Midwest.

The combination of heavy snow and fierce winds will reduce visibility to zero for many hours during the height of the storm. People caught on highways could get stranded without aid for a life-threatening period of time. Air travel will be a headache days after the storm, with the ripple effects of delays and cancellations at major hubs affecting flights across the country.

Bitter Cold Soon To Follow

Source: National Weather Service

Adding insult to injury, a burst of extremely cold temperatures will immediately follow behind the storm as it exits to the east. Subzero daytime highs will be the norm in Montana and North Dakota. The National Weather Service predicts a low in Minneapolis of -7°F after the snow stops on Thursday night. Highs will struggle to reach the teens there on Friday.

Very cold temperatures across the northern Plains and Upper Midwest will combine with lingering breezy conditions to make for dangerous wind chills across the region. Frostbite and hypothermia will be a concern for anyone spending a while outside after the storm trying to clear the snow. 

[Top Image: Weather Prediction Center]

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February 2, 2023

Dreaded Polar Vortex Drags Intense Freeze Over New England To End The Week

The much-maligned polar vortex will live up to its reputation over the next couple of days as some of the coldest temperatures on the planet dive south over New England on Friday and Saturday.

The polar vortex is a large-scale circulation that wraps around the Arctic Circle. It's strongest in the winter months, when it acts like a moat keeping the winter's coldest air confined to the far northern latitudes.

Every once and a while, this circulation will become unstable, creating troughs and upper-level lows that break off and head south. When this happens, it drags that bitterly cold air south right along with it.

A model image showing the upper-level pattern responsible for New England's deep freeze on Friday and Saturday. (Tropical Tidbits)

A fast-moving upper-level low—once part of the polar vortex circulation—swooping over eastern Canada is responsible for this impending blast of very cold air sagging into New England.

Temperatures will dive well below zero for many areas, with wind chill values in the double-digits below zero. The wind chill in Boston will dip below -30°F on Saturday morning, with wind chill values reaching the -40s in western Massachusetts. The National Weather Service predicts wind chill values all the way into the -60s for northern parts of New Hampshire and Maine.

(NWS Caribou)

Don't underestimate the risk posed by such low temperatures. This is dangerous cold, the kind that can cause serious injury in just a couple of minutes. Frostbite can develop on unprotected skin in as fast as two minutes with temperatures and wind chill values this cold.

It's not going to last long, thankfully.

The pattern is pretty progressive, so the upper-level low responsible for the extreme cold will move along in a hurry. A ridge will build in behind it, allowing temperatures to rebound to above-normal territory in time for next week.

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