Today's Featured Post: Updated Long Range Outlook Will be Issued Wednesday at 4:30 PM Central Time.

Sunday, December 9, 2012

December 17-20 Potential Major Winter Storm

There is now increasing potential for a major winter storm to occur over the East US. Let's jump right in.

Many of you know how I follow the Lezak Recurring Cycle (LRC), and track it every year to nail down who could get the best out of this winter. Well, thanks to the research of some fine folks at the AccuWeather Forums, it appears that this year's cycle will be 53 days. I tried to apply that timeframe to this potential storm system, and here's what I found.

This is the 500mb geopotential height anomaly for December 18th over North America. As the legend indicates, cool colors depict below normal heights, while warmer colors describe above normal heights. The forecast shows a deep low pressure system in the South Plains and near the Gulf Coast. In response to this deep disturbance, a positive PNA is trying to form. As we know, a positive PNA favors a storm track through the Ohio Valley/Midwest. Notice the presence of an east-based negative NAO as well. While a negative NAO is favorable for cold and snow in the Northeast, an east-based negative NAO (the ridge is east of Greenland) can favor the Plains and Midwest for cold and storms.

Using the 53 day LRC timetable, I traced back December 18th to October 28th, and here is the 500mb pattern observed that day.

Look at that! We see a strong system in the Ohio Valley on this day, as well as a weak high pressure system in the Southwest indicating a possible positive PNA. There is a negative NAO in place, though we can't tell whether it is west or east based. Does this look familiar to the first image shown? You bet. It looks like our 53 day cycle is working. **For future reference, ignore Hurricane Sandy in these observation images.**

This is the sea level pressure (SLP) forecast for December 18th, and we can see a strong storm system emerging from the Plains at this time. This system is likely to move northeast in response to the previously-mentioned negative NAO, but not towards the coast, as a positive PNA interjects and may try to send this system into the Ohio Valley.

The models are having some trouble, so let's go a day ahead to October 29th and see what happened.

(Again, IGNORE SANDY.) Our storm system has now moved to the east, wobbling a bit as it did so, and combined with Sandy. Notice we still had our positive PNA showing itself with high pressure in the West US. If we were to follow this system and discount Sandy, I still believe an eastward movement would have prevailed, likely not as fast if Sandy were not present. The lack of Sandy in this potential storm system, combined with a positive PNA and east-based negative NAO leads me to believe that this forecast system should go a little more to the north and east than it did in October.

Now, we are on December 19th with the ECMWF forecast, and we see our storm system has indeed moved to the northeast in response to the PNA and NAO, and the LRC. The system's strength is now holding at a very nice 987 millibars, with tight isobars indicating strong winds are ongoing across New England and parts of the Ohio Valley and Midwest. Despite this, 850mb temperatures tell me rain would be the big story, but with a positive PNA, negative NAO and possible negative AO, that could very well change.

It does look like the ECMWF has a pretty darn good handle on this system, especially with such a good match-up with the LRC. I believe that this storm system will happen, the question is, who will get hit the worst?

Andrew

2012-2013 Personal Winter Forecasts: VA/WA/WV

VIRGINIA
Linden
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Woodbridge
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

McLean
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Spotsylvania
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Chester Gap
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Caroline County
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Warren County
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Front Royal
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Midlothian
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Henrico
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Danville
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Blacksburg
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Manassas
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

WASHINGTON
-

WEST VIRGINIA
Charles Town
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Bruceton Mills
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Martinsburg
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

2012-2013 Personal Winter Forecasts: TX/UT/VT

TEXAS
Rockwall
Temps: Slightly Above Average
Precip: Above Average
Snow: Average

College Station
Temps: Above Average
Precip: Above Average
Snow: Average

Fort Worth
Temps: Slightly Above Average
Precip: Above Average
Snow: Slightly Above Average

Odessa
Temps: Above Average
Precip: Above Average
Snow: Average

Houston
Temps: Above Average
Precip: Above Avergae
Snow: Average

Denton
Temps: Slightly Above Average
Precip: Above Average
Snow: Slightly Above Average

Bergheim
Temps: Above Average
Precip: Above Average
Snow: Average

UTAH
North Ogden
Temps: Slightly Above Average
Precip: Above Average
Snow: Above Average
**Confidence unusually low**

VERMONT
Montpelier
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Mt. Mansfield
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Stowe
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Bondville
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

2012-2013 Personal Winter Forecast: CT/DE/FL

CONNECTICUT
Danbury
Temps: Average
Precip: Above Average
Snow: Average

Somers
Temps: Average
Precip: Above Average
Snow: Average

Uncasville
Temps: Average
Precip: Above Average
Snow: Average

Hartford
Temps: Average
Precip: Above Average
Snow: Average

Stratford
Temps: Average
Precip: Above Average
Snow: Average

DELAWARE
Millsboro
Temps: Average
Precip: Above Average
Snow: Slightly Above Average

Claymont
Temps: Average
Precip: Above Average
Snow: Slightly Above Average

Laurel
Temps: Average
Precip: Above Average
Snow: Average

Odessa
Temps: Average
Precip: Above Average
Snow: Average

FLORIDA
Coral Springs
Temps: Slightly Below Average
Precip: Above Average
Snow: Average

Destin
Temps: Above Average
Precip: Above Average
Snow: Average

Orlando
Temps: Slightly Below Average
Precip: Above Average
Snow: Average

2012-2013 Personal Winter Forecasts: WI/WY

WISCONSIN
New Berlin
Temps: Below Average
Precip: Slightly Below Average
Snow: Average

Milwaukee
Temps: Below Average
Precip: Slightly Below Average
Snow: Average

Winnecone
Temps: Below Average
Precip: Slightly Below Average
Snow: Slightly Below Average

WYOMING
-

2012-2013 Personal Winter Forecasts: MO/MT/NE

MISSOURI
Springfield
Temps: Average
Precip: Slightly Above Average
Snow: Average

Columbia
Temps: Slightly Below Average
Precip: Average
Snow: Average

Licking
Temps: Average
Precip: Slightly Above Average
Snow: Average

Kansas City
Temps: Slightly Below Average
Precip: Average
Snow:  Slightly Above Average

Branson
Temps: Slightly Above Average
Precip: Above Average
Snow: Slightly Above Average

St Louis
Temps: Below Average
Precip: Average
Snow: Average

MONTANA
-

NEBRASKA
Omaha
Temps: Slightly Below Average
Precip: Average
Snow: Average

West Point
Temps: Slightly Below Average
Precip: Average
Snow: Average

McCool Junction
Temps: Average
Precip: Slightly Above Average
Snow: Average

2012-2013 Personal Winter Forecasts: KS/KY/LA

KANSAS
Columbus
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Hays
Temps: Slightly Above Normal
Precip: Slightly Above Normal
Snow: Slightly Above Normal

Manhattan
Temps: Average
Precip: Slightly Above Normal
Snow: Average

KENTUCKY
Louisville
Temps: Slightly Below Average
Precip: Above Average
Snow: Above Average

Fort Thomas
Temps: Slightly Below Average
Precip: Above Average
Snow: Above Average

Orlando
Temps: Slightly Below Average
Precip: Above Average
Snow: Above Average

LOUISIANA
Shreveport
Temps: Above Average
Precip: Above Average
Snow: Below Average

Lafayette
Temps: Above Average
Precip: Above Average
Snow: Below Average

2012-2013 Personal Winter Forecasts: GA/HI/ID

GEORGIA
Atlanta
Temps: Below Normal
Precip: Above Normal
Snow: Average/Slightly Above

Young Harris
Temps: Below Normal
Precip: Above Normal
Snow: Slightly Above

Braselton
Temps: Below Normal
Precip: Above Normal
Snow: Slightly Above

McDonough
Temps: Below Normal
Precip: Above Normal
Snow: Slightly Above

Stockbridge
Temps: Below Normal
Precip: Above Normal
Snow: Slightly Above

Rome
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

HAWAII
-
IDAHO
-

2012-2013 Personal Winter Forecasts: OR/PA/RI

OREGON
Zigzag
Temps: Slightly Above Normal
Precip: Slightly Below Normal
Snow: Below Normal

PENNSYLVANIA
Allentown
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Northampton
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Hellertown
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Doylestown
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Lancaster
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Philadelphia
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Altoona
Temps: Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Saltsburg
Temps: Below Normal
Precip: Slightly Above Normal
Snow: Slightly Above Normal

Pittsburg
Temps: Below Normal
Precip: Slightly Above Normal
Snow: Slightly Above Normal

State College
Temps: Below Normal
Precip: Slightly Above Normal
Snow: Slightly Above Normal

Titusville
Temps: Below Normal
Precip: Slightly Above Normal
Snow: Above Normal

RHODE ISLAND
Pawtucket
Temps: Average
Precip: Above Normal
Snow: Average

2012-2013 Personal Winter Forecasts: MI/MN/MS

MICHIGAN
Detroit
Temps: Below Normal
Precip: Average
Snow: Slightly Below Average

Gladwin
Temps: Below Average
Precip: Average
Snow: Slightly Below Average

Swartz Creek
Temps: Below Average
Precip: Average
Snow: Average

Brighton
Temps: Below Normal
Precip: Slightly Above Average
Snow: Slightly Above Average

Riverview
Temps: Below Normal
Precip: Slightly Above Average
Snow: Slightly Above Average

Rochester
Temps: Below Normal
Precip: Average
Snow: Average

Fenton
Temps: Below Normal
Precip: Average
Snow: Average

Petoskey
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Novi
Temps: Below Normal
Precip: Average
Snow: Slightly Below Average

Flint
Temps: Below Normal
Precip: Average
Snow: Average

Three Rivers
Temps: Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

MINNESOTA
Minneapolis
Temps: Below Normal
Precip: Below Average
Snow:  Below Normal

St. Paul
Temps: Below Normal
Precip: Below Normal
Snow: Below Normal

Mankato
Temps: Below Normal
Precip: Slightly Below Normal
Snow: Slightly Below Normal

Springfield
Temps: Below Normal
Precip: Slightly Below Normal
Snow: Slightly Below Normal

Mora
Temps: Below Normal
Precip: Below Normal
Snow: Average

Carver
Temps: Below Normal
Precip: Below Normal
Snow: Average

MISSISSIPPI
Tupelo
Temps: Average
Precip: Above Average
Snow: Slightly Above Average

Senatobia
Temps: Average
Precip: Above Average
Snow: Above Average

2012-2013 Personal Winter Forecasts: SC/SD/TN

SOUTH CAROLINA
Greenville
Precip: Above Normal
Snow: Above Normal
Temp: Below Normal

Anderson
Precip: Above Normal
Snow: Above Normal
Temp: Below Normal

Easley
Precip: Above Normal
Snow: Above Normal
Temp: Below Normal

SOUTH DAKOTA
-

TENNESSEE
Milan
Precip: Above Normal
Snow: Average/Slightly Above
Temp: Average

Brentwood
Precip: Above Normal
Snow: Slightly Above Normal
Temp: Average

Knoxville
Precip: Above Normal
Snow: Slightly Above Normal
Temp: Slightly Below Normal

Nashville
Precip: Above Normal
Snow: Slightly Above Normal
Temp: Average

Memphis
Precip: Above Average
Snow: Slightly Above Normal
Temp: Near Average

2012-2013 Personal Winter Forecasts: AR/CA/CO

ARKANSAS
Booneville
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Fort Smith
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Van Buren
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Fayetteville
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Alma
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

CALIFORNIA
Mt. Shasta
Temps: Average
Precip: Below Normal
Snow: Below Normal

San Francisco
Temps: Above Normal
Precip: Below Normal
Snow: Below Normal

South Lake Tahoe
Temps: Average
Precip: Below Normal
Snow: Below Normal

Wrightwood
Temps: Slightly Above Average
Precip: Below Normal
Snow: Below Normal

Yucaipa
Temps: Slightly Above Average
Precip: Below Normal
Snow: Below Normal

COLORADO
Denver
Temps: Average
Precip: Slightly Above Normal
Snow: Average

Crested Butte
Temps: Above Normal
Precip: Average
Snow: Slightly Below Average

Palmer Lake
Temps: Average
Precip: Slightly Above Normal
Snow: Average

Durango
Temps: Above Normal
Precip: Slightly Above Normal
Snow: Average

2012-2013 Personal Winter Forecasts: ND/OH/OK

NORTH DAKOTA
Grand Forks
Temps: Well Below Normal
Precip: Average
Snow:

OHIO
Cleveland
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Cincinnati
Temps: Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Gallipolis
Temps: Below Normal
Precip: Slightly Above Normal
Snow: Slightly Above Normal

Dover
Temps: Below Normal
Precip: Slightly Above Normal
Snow: Above Normal

Holmesville
Temps: Below Normal
Precip: Slightly Above Normal
Snow: Slightly Above Normal

Columbus
Temps: Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Pickerington
Temps: Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Delaware
Temps: Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Mansfield
Temps: Below Normal
Precip: Slightly Above Normal
Snow: Above Normal

Kent
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Toledo
Temps: Below Normal
Precip: Average
Snow: Average

Walbridge
Temps: Below Normal
Precip: Average
Snow: Average

OKLAHOMA
Oklahoma City
Temps: Slightly Above Normal
Precip: Below Normal
Snow: Below Normal

2012-2013 Personal Winter Forecasts: ME/MD/MA

MAINE
Stetson
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Milford
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

MARYLAND
Baltimore
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Lusby
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Berlin
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Mt. Airy
Temps: Well Below Normal
Precip: Above Normal
Snow: Above Normal

Olney
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Greenbelt
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Reisterstown
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Chesapeake Beach
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

Edgewood
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

MASSACHUSETTS
Scituate
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Above Normal

2012-2013 Personal Winter Forecasts: IL/IN/IA

ILLINOIS
Aurora
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Huntley
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Quad Cities
Temps: Average
Precip: Above Normal
Snow: Average

Urbana
Temps: Average
Precip: Above Normal
Snow: Average

Springfield
Temps: Average
Precip: Above Normal
Snow: Average

Vernon Hills
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

McHenry
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Champaign
Temps: Average
Precip: Above Normal
Snow: Average

Crystal Lake
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Chicago
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Mokena
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Marengo
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

Newark
Temps: Average
Precip: Above Normal
Snow: Slightly Above Normal

INDIANA
Valparaiso
Temps: Average
Precip: Above Normal
Snow: Above Normal

Fort Wayne
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Hebron
Temps: Average
Precip: Above Normal
Snow: Above Normal

Indianapolis
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Bloomington
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Shelbyville
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Noblesville
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

Mooresville
Temps: Slightly Below Normal
Precip: Above Normal
Snow: Slightly Above Normal

New Albany
Temps: Average
Precip: Above Normal
Snow: Average

IOWA
Dallas County
Temps: Average
Precip: Average
Snow: Slightly Below Average

Waukee
Temps: Average
Precip: Average
Snow: Average

Guttenberg
Temps: Slightly Below Average
Precip: Average
Snow: Slightly Above Average

Davenport
Temps: Slightly Below Normal
Precip: Slightly Above Average
Snow: Slightly Above Average

Manchester
Temps: Slightly Below Normal
Precip: Average
Snow: Slightly Above Normal

Colesburg
Temps: Slightly Below Normal
Precip: Average
Snow: Slightly Above Average

Cedar Rapids
Temps: Slightly Below Normal
Precip: Average
Snow: Slightly Above Normal

Hampton
Temps: Average
Precip: Average
Snow: Average

Homestead
Temps: Average
Precip: Average
Snow: Average

2012-2013 Personal Winter Forecasts: NM/NY/NC

NEW MEXICO
Albuquerque
Temps: Slightly Above Normal
Precip: Above Normal
Snow: Average
**Unusually Low Confidence**

Taos
Temps: Average
Precip: Above Normal
Snow: Average
**Unusually Low Confidence**

NEW YORK
Gloversville
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Albany
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Ellicottville
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Rome
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Walworth
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Springwater
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Endicott
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Middle Island
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Kingston
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

New York City
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Peru
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Spring Valley
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Smithtown
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

Earlton
Temps: Below Normal
Precip: Above Normal
Snow: Above Normal

NORTH CAROLINA
Kinston
Temps: Average
Precip: Above Normal
Snow: Average

Ellenboro
Temps: Average
Precip: Above Normal
Snow: Average

Winston Salem
Temps: Average
Precip: Above Normal
Snow: Average

Kings Mountain
Temps: Average
Precip: Above Normal
Snow: Average

Hendersonville
Temps: Average
Precip: Above Normal
Snow: Average

Asheboro
Temps: Average
Precip: Above Normal
Snow: Average

Boone
Temps: Average
Precip: Above Normal
Snow: Average

2012-2013 Personal Winter Forecasts: NV/NH/NJ

NEVADA
-

NEW HAMPSHIRE
-

NEW JERSEY
Medford
Temps: Average
Precip: Above Average
Snow: Above Average

Hackettstown
Temps: Average
Precip: Above Average
Snow: Above Average

Hopewell
Temps: Average
Precip: Above Average
Snow: Above Average

Vernon
Temps: Average
Precip: Above Average
Snow: Above Average

Teaneck
Temps: Average
Precip: Above Average
Snow: Above Average

Princeton
Temps: Average
Precip: Above Average
Snow: Above Average

Tabernacle
Temps: Average
Precip: Above Average
Snow:  Above Average

December 9 Severe Weather Event

There is potential for a severe weather event across the South Plains and Southeast today, as the Storm Prediction Center has issued a Slight Risk of severe weather across these areas.

Image from WeatherBell
The storms should begin to ramp up around the evening hours tonight. The above image is simulated radar reflectivity, which means this is what you could see on the radar in coming hours. This is the forecast for 5:00 PM central time, and we can see some strong singular celled storms developing in Arkansas, west Tennessee, west Kentucky and southeast Missouri.
My concern is that a tornadic threat will develop with the cells in Arkansas, while a more linear structure will start the severe threat as wind and hail in Texas. While you can see that big, lone cell in southeast Texas, I doubt it will happen to a 'T'.

5 hours later, we now see that the severe weather threat has evolved into a wind and hail threat, as the storms are now linear. The strongest storms look to be in Tennessee, Arkansas and Kentucky, while Texas should be on the end of this severe weather potential.

Andrew