By John Ruggiano

October 8, 2010

From December 1, 2010 Through March 31, 2011 (Dec, Jan, Feb, and Mar)

I’m forecasting a strong La Nina Signal, with a very progressive pattern for the Northern half of the CONUS.

The PAC JET and POLAR JET will dominate the overall pattern, bringing numerous cold shots and periodic stormy conditions for the norther tier. The STJ will be very weak, if not non-existent, keeping any southern storms/Miller A type, too a minimum for much of the winter season.

My General Winter forecast for the Continental US.

Let me start by saying, this winter will be quite different than last year, where much of the storminess and chill, was concentrated from the Southern Rockies, the Southern tier, and into the Mid-Atlantic States. As we all know, a blockbuster, record breaking snow season occurred over much of the M/A States, with VA, MD, DE, and NJ really taking it on the chin. The combination of a moderate to strong El Nino, and perfect teleconnections, were the contributing factors for the M/A in receiving the record breaking snowfall, with 4 major winter Storms.

As we head into the fall and winter months, the ENSO signal is expected to continue on it’s trek towards a strong La Nina signal. This is an extreme flip, and opposite of last year’s Strong El Nino signal. Overall the 3 primary teleconnections (The NAO, AO, and PNA) during the past 3-4 months, have been constant with no major extremes. The NAO and AO have been running slightly Negative to near Neutral, with the PNA being near Neutral to slightly Positive.

With an expected strong La Nina, and rather flat teleconnections, I’m Forecasting the most active and stormy weather to occur over the Northern Rockies, much of the Plains, The Midwest, and The Great Lakes regions. Both the PAC and Polar Jets, will have there way this winter, producing a more stormy and snowy winter in these regions. Opposite from last winter, the Sub-tropical or Southern branch, will be quite weak and non-existent for much of the winter.

During the later part of winter, from early February through mid March, the STJ or Southern branch could have just enough influence to produce a more widespread over-running event, or possibly a Miller A type storm for M/A States and Southern New England, bringing a more significant snow and ice event.

Most of the snowfalls in the NE and M/A States will come from Clipper type systems, strong cold fronts, and a couple of Miller B coastal storms.

Much of the Northeast and Northern M/A will have a “Near Normal” Winter, with both temperatures and snowfall. Northern and interior portions of New England will have the best chance for Below Normal temperatures and Above Normal snowfall.

The lower M/A and the SE States should have “Slightly Above Normal” temps and “Below Normal” snowfall. Overall precipitation for the entire Eastern 1/3 of the country will be Near to Below normal.

The Southwest, The Deep South, and much of the SE States will see Above Normal temps and Below Normal Precip. The Deep South, Tenn. Valley, and into the SE States, will have a greater than normal threat for Severe weather this winter, especially in the months of December and February.

The Northern Rockies, Much of the Plains, and into portions of the Midwest and G/L’s Regions will have the best shot at “Below Normal Temps” and “Near to Above Normal Snowfall”

A More Detailed Look at The M/A States and The Northeast !

The overall pattern for the Eastern U.S., will be quite progressive and fast moving for much of the winter season. The coldest weather and best chance for snow events, will most likely occur during the early and later stages of the winter season. During the mid winter time frame, from mid January into mid February, we can expect more wild swings in temperatures, and a drier pattern, but yes We’ll still have some snow and ice events during the heart of the winter season.There will be several Arctic outbreaks throughout the winter season in which temps will really plummet for a 2-3 day period. But as I’ve mentioned the mild periods will also occur, and we could even break out the T-Shirts for a few days. Though all will average out close to normal, I think the milder periods win out, especially during mid-winter and in the M/A States.

We’ll start off the winter season quite cold and blustery for much of December into early January, with numerous Clipper type systems and strong cold fronts . An overall progressive pattern during this time, driven by the polar jet, and a more Negative NAO and AO couplet. Relative to average, I’m forecasting below normal temperatures and near normal to slightly above normal snowfall during this time frame. The LES (Lake Effect Snow) belts of the NE and Midwest will see near to above normal activity in both November and December of this year.

From early January through mid February, I’m forecasting a roller coaster ride of both cold and mild periods, with the mild periods winning out. Most snow and ice events will be on the light or minor side in the M/A, and light to moderate snow events and a couple ice events for the NE States. Some CAD signatures and WAA events, will be more common with several ice events possible for the interior and Northern M/A, into Southern New England. Most storm systems during this time, will track overhead, or just to the north and west. Apart from this activity, it will be drier and milder overall, especially in the M/A region.

During the later part of winter, from early February through mid March, La Nina will begin to weaken somewhat, giving way for the STJ or Southern branch too have just enough influence to produce a more widespread over-running event, or possibly a Miller A type storm for M/A States and Southern New England. This is where I see the best chance of a more significant snow and ice event. This will likely be our best shot for a 6”+ snow event in the M/A or I-95 Corridor cites from DCA to NYC.

Overall, this will not be a great winter for the snow lovers looking for the 8”+ snowstorms along and east of the I-95 Corridor. Most snow events will be on the lighter side, ranging from the 1” to 3” and 3” to 6” variety, from DCA, BWI, PHL, and NYC to the coast. Only The interior sections of the Central and Northern M/A and into much of the NE, will likely have a several 6”-12” snow events this winter.

So, Will the Delaware Valley see a Major snowstorm (MECS) this winter ? I’ll have to say: NO, but a significant snowstorm (SECS) of 6”-10” is possible in February.

The NAO (North Atlantic Oscillation) And other key Teleconnections.

Those of you who follow my winter forecasts and storm calls during the winter seasons, know how much I rely on, and factor in key teleconnections, to making my calls and mid range forecasts. Last year I forecasted a Negative NAO/AO couplet for much of the winter season, which would help drive the overall pattern. This forecast worked out very well, and the results transpired nicely with the overall winter forecast.

This year’s teleconnections will be more variable than last year, and not as negative, with both the NAO and AO signals. A more near neutral, to slightly negative signal will be most common for the 2010-2011 winter season. The PNA will also be near neutral, but will also be variable, going slightly positive and negative at times.

So overall our 3 main teleconnection will average out rather flat. The result of this, along with a strong La Nina Signal, will produce a much faster and more progressive flow with the PAC and POLAR Jet streams. A less amplified flow and more zonal for the southern half of the CONUS, and more amplified, for the northern half of the country. Below is my best estimate for the NAO signal with a monthly breakdown.

Here’s my forecast for the NAO signal, with Monthly breakdowns.
(Dec, Jan, Feb, and Mar)

December: Slightly NEG.

January: Neutral to Slightly POS.

February: Neutral to Slightly NEG.

March: Neutral to Slightly NEG.


In this segment I’ve attached all my maps, to summarize my overall Winter Outlook. Please see the (4) maps below: Temperature, Precipitation, Snowfall, and Overall Storm Track’s. These maps best illustrate my outlook for the month’s of: December, January, February, and March.

These maps indicate the overall Anomalies for both “Temperatures” and “Precipitation” for the 4 month period.
In addition I have included a “Total Snowfall Map”, relative to normal and a “Mean Storm Tracks Map”, to show the type of pattern I‘m forecasting for the winter months.

TEMPERATURE MAP: (Click on map to enlarge)

PRECIPITATION MAP: (Click on map to enlarge)

SNOWFALL MAP: (Click on map to enlarge)

MAIN STORM TRACK MAP: (Click on map to enlarge)

My Forecast for Philadelphia, PA. (PHL)
(Including extreme SE PA, Interior Southern NJ, and Northern DE.)
Dec 1, 2010 – Mar 31, 2011 (Dec, Jan, Feb, and Mar)

Mean Temperature: +0.3 F
(Near Avg.)

Mean Temp Range: +1.0 to -1.0 F
(Near Avg)

Total Snowfall Range: 18″ to 24″
(Near Normal)

Target Snowfall Prediction: 21″

Total Precipitation: (Near Normal)

The Monthly Breakdown for PHL (Philadelphia, PA:

December: – 1.5 F
Mean Temp Range : -1.0 to -3.0 (Slightly Below Avg.)
Snowfall: 3″ to 4″ or (Near Normal.)

January: + 1.5 F
Mean Temp Range: +1.0 to +3.0 (Slightly Above Avg.)
Snowfall: 5 to 7″ or (Near Normal.)

February: +1.0 F
Mean Temp Range: 0.0 to +2.0 (Near to Slightly Above)
Snowfall: 7″ to 9″ or (Slightly Above Normal.)

March: – 1.5 F
Mean Temp Range: -1.0 to -3.0 (Slightly Below Avg.)
Snowfall: 3″ to 4″ or (Near Normal.)

Selected I-95 Corridor Cities:
(Dec, Jan, Feb, and Mar)

NYC (New York City, NY)

Temps: +1.0 to -1.0 F (Near Avg.)
Total Snowfall: 22″ to 28″ (Near Normal)
Overall Forecast: Temps: -0.3 F / Snowfall: 25″

BOS (Boston, MA)

Temps: +1.0 to -1.0 F(Near Avg.)
Total Snowfall: 38″ to 44″ (Near Normal)
Overall Forecast: Temps: -0.5 F / Snowfall: 42″

BWI (Baltimore, MD)

Temps: +1.0 to -1.0 F (Near Avg.)
Total Snowfall: 16″ to 22″ (Near Normal)
Overall Forecast: Temps: +0.5 F / Snowfall: 18″

DCA (Washington DC)

Temps: +1.0 to -1.0 F (Near Avg.)
Total Snowfall: 12″ to 18″ (Near Normal)
Overall Forecast: Temps: +0.8 F / Snowfall: 15″

RIC (Richmond, VA)

Temps: +1.0 to +3.0 F (Slightly Above Avg.)
Total Snowfall: 6″ to 12″ (Below Normal)
Overall Forecast: Temps: +2.2 F / Snowfall: 8″

Here’s the archived podcast from the Barometer Bob show on Thursday evening, Oct 7th. We covered my winter forecast on the show.

For additional weather discussion and comments on this Winter Forecast and upcoming winter weather events, please register and sign up today !

Ruggie Weather Forum:

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My Preliminary Winter Forecast: Issued Aug 4 th, 2010:

Take Care,