US: Weekend Storm To Bring Big Temp Contrast, Severe Threat, Rain, Snow

Written by on December 20, 2013 in United States of America with 0 Comments

A vigorous upper low is swinging across Southern California bringing heavy showers, gusty winds and heavy mountain snows surrounding the LA basin tonight. Moisture streaming out ahead of the upper low up into the Intermountain West is bringing heavy snows as far north as Salt Lake causing disruption to road and air traffic.

That system will push into Texas Friday with a surface low forming while a fresh surge of arctic air dives down the Plains out of Canada.

This cold will help intensity a Southern Plains storm system and as it winds up, so warm southerly winds begin to crank.

Warmth replaces cold up through the Mississippi/Ohio Valleys as well as up the East Coast.

Here was the scene from Boston a couple of morning’s ago when the thermometer hit 9.

Frigid Downtown Boston Monday morning. (Courtesy of WeatherBug)

Frigid Downtown Boston Monday morning. (Courtesy of WeatherBug)

The Storm Prediction Center has issued a whole load of various watches and warnings as this system is projected to track from Texas up into the Great Lakes. As the system pushes NNE, the thermal contrast will grow with increasingly warmer, moister air lifting up through the Ohio Valley where big rains will occur. Bands of rain is expected as thunderstorms fire within the warm sector which could drive 70s all the way to Missouri, southern Illinois, Indiana, Ohio and Pennsylvania at the same time temps fall through the teens on the other side of the boundary over Kansas, Oklahoma, even Texas.

Source: Storm Prediction Center

Source: Storm Prediction Center

Such cities as St Louis and Chicago where snow is expected, milder air runs north initially with rain but through Saturday, a sharp temperature drops occurs.

Here’s the ECMWF surface/precip chart for tomorrow and note the main upper low over Southern California with moisture streaming north out ahead.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

[s2If current_user_can(access_s2member_level1)]

By Saturday things gets interesting as the upper low and energy crosses the southern Rockies out into the Southern Plains where it catches up with the newly formed surface low. Notice the deeper moisture developing along and just ahead of the frontal boundary which is begin to separate an increasingly larger temperature contrast with likely 70s, perhaps even 8os in the warm sector while temps fall through the 20s, perhaps teens just on the other side of the front.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

Thunderstorms which fire ahead of the boundary will present flooding issues throughout the mid-south from east Texas across to New Orleans on north into the Tennessee, eventually the Ohio Valley.

Big temperature contrast is in place Saturday PM.

Source: weather.com

Source: weather.com

The Storm Prediction Center has rightly issued a SLIGHT risk Saturday afternoon and evening throughout the Mid-South where warm, moisture rich air, a powerful low level jet converge in the warm sector, ahead of the cold front. Capped by a powerhouse 160kt upper aloft.

Don’t be surprised to see a moderate risk closer to Saturday.

Source: Storm Prediction Center

Source: Storm Prediction Center

With a raging southerly low level jet driving flooding rains NE, cold air rushing in from the NW and a powerful upper jet ripping over top out of the SW, we have the perfect ingredients for severe weather and tornado potential Saturday afternoon and evening.

A lot of rain can be expected over the upcoming 72 hrs with localised flooding likely.

d13_fill

The thunderstorms which develop close to the front and near to the circulation center will swing into the cold, dry air, forcing heavy snow to break out on the backside of the low.

Here’s the anticipated snowfall over the next 72 hrs according to the ECMWF.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

Could see a decent swath of 6-12″ from southern Kansas up through Missouri, Illinois, Wisconsin, Michigan, southern Ontario.

Check out the Sunday afternoon projected surface temperatures according to the ECMWF.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

Forecasted highs according to TWC.

Source: weather.com

Source: weather.com

By Sunday the main front and corridor of moisture, even severe threat slides east while arctic air drives all the way into Texas. Heavy snow is likely along the north side of the boundary from Texas up to the Great Lakes with an accumulating snow through Wichita, St Louis, Springfield, Chicago and Toronto.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

By Monday the core of arctic air drops into the Upper Mississippi Valley presenting highs just above o for Minneapolis. As the storm lifts into the St Lawrence Valley, the arctic air sweeps across the Great Lakes bringing highs in the 10s back to Chicago, 20s throughout the northern Ohio Valley. Lows could go back below o in Chicago once skies clear. Heavy rain, storms is likely to impact the populated I-95 corridor with 70s reaching DC, possibly Baltimore, 60s up to NYC ahead of the front. Once the front pushes through and off the coast, the cold returns with backside snow a possibility later Monday into Tuesday. This sets the stage for a cold Christmas Eve and Day from DC up to Boston with highs perhaps returning to the 20s!

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

[/s2If][s2If is_user_logged_in() AND current_user_cannot(access_s2member_level1)]

That’s it, [s2Get constant=”S2MEMBER_CURRENT_USER_DISPLAY_NAME” /]!

To continue reading, you need to have a valid subscription to access premium content exclusive to members. Please join a subscription plan if you would like to continue.[/s2If][s2If !is_user_logged_in()]

Sign in to read the full forecast…

Not yet a member? Join today for unlimited access

Sign up to markvoganweather.com today to get unlimited access to Mark Vogan’s premium articles, video forecasts and expert analysis.
[/s2If]

Tags: , , , , ,

Follow us

Connect with Mark Vogan on social media to get notified about new posts and for the latest weather updates.

Subscribe via RSS Feed Connect on YouTube

Leave a Reply

Top