US Extended Forecast thru Mar 1

Overview...

Very Cold Upper-Level Trough Anchors Across Eastern Canada The
First Half Of This Forecast Period--Sending Two Separate Arctic
Surges Southward Into The Lower 48...Day 3 And Day 5.

Negative-Tilt Trough In The Eastern Pacific Edges Inland Across
The West Coast And Great Basin Day 5...And Begins Working Eastward Across The Central Divide And Generating Surface Wave Development Along The Leading Edge Of The Modified-Arctic Boundary From The South Central Plains Eastward To The Outer Banks Before Exiting Into The Western Atlantic.

By Day 7...The Bulk Of This Pacific Trough Is Moving Through The West...Spreading Deep Over-Running Pacific Moisture Along The Continental Divide...The Great Basin And Desert Southwest.

Downstream...Another Disturbance Migrating Through The Southeast...Begins To Shape Up Into A Deepening Surface Cyclone
Off The Carolina Coast Line.

Model Preferences And Uncertainty Assessment...

Generally Blended The 21/12z Ecens And 21/18z Gefs Means To Handle The Character Of The Flow Pattern Aloft For The Eastern Trough And Slow-Moving Pacific Trough.

The Challenge This Morning Was To Keep Continuity With Temperatures Days 4-5 In The High Plains From Eastern Wyoming Southward Into The Texas Panhandle.

For Days 6-7 Over Much Of Oklahoma And Texas...With Very Different
Solutions Over The Gulf Coast And Mid-Atlantic Coast Along The
Leading Edge Of The Modified-Arctic Airmass. Was Able To Mitigate
The Fluctuations To Some Extent And Manually-Adjusted Temperatures Slightly Using Some Of The Deterministic 21/12z Ecmwf And 21/18z Gfs Runs--In Combination With Their Respective Means.

These Deterministic Runs Generally Capture The Large-Scale Features And Bulk Of The Arctic Airmass Spreading Across The Northern Plains...Great Lakes And Northeast Through Day 5... But Used More Of A 70/30 Blend Of The 12z Ecens/18z Gefs For Days 6-7 To Preserve Some Surface Troughing Across The Southeast And Carolinas.

Sensible Weather Highlights...

Back To The Bitter Winter Cold Across The Northern Plains...Great
Lakes And Northeast For Much Of This Medium Range Period. With
Projected Temperatures A Good 25+ Below Normal... Plenty Of
Single-Digit High Temperatures For Portions Of North Dakota...
Minnesota... Wisconsin And Michigan.

Only In The Teens To Lower 20s For Highs For Much Of Northern Illinois...Indiana...Iowa...The Eastern Lakes And Northern New England.

Low Temperatures Will Likely Drop Below Zero Along Much Of The I-80 Corridor From Eastern Nebraska To The Poconos.

The Leading Edge Of The Arctic Airmass Drops Into The Southern
States...For Days 4-5...With Highs Struggling To Reach The 40s...And Overnight Lows Near To Below Freezing Into The Morning Of Day 6 (Feb 28th).

Out West...Rain Returns To Central And Southern California...With
The Flow Ahead Of The Slow-Moving Negative-Tilt Trough Out Of The
South And Southeast.

Lesser Rainfall Chances Over Oregon And Washington In This Pattern...And By Day 6-7...Cooler Weather With High-Elevation Snows For The Desert Southwest...Great Basin And Western Continental Divide.

No Measurable Rainfall In The Phoenix Area So Far In 2014...But During The Latter Half Of This Medium Range Period...The Rainless Streak May Just Come To An End.


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