October 8, 2008

From December 1, 2008 Through March 31, 2009 (D,J,F,M)

A Near Neutral ENSO, or Weak La Nina Signal, along with favorable teleconnections, will drive the winter pattern. This will produce Colder and Stormy conditions, for much of the Northern Rockies and Eastern half of the Nation !

This upcoming 2008-2009 winter season, will be quite progressive and active, as a stormy pattern will likely setup early, and continue for much of the winter season. As we all know, last years winter season (2007-2008) was also very active, with near record, and record breaking snowfall, for much of the Midwest, into SE Canada, and also parts of northern New England. The pattern was driven by a moderate to strong La Nina signal and a neutral to Positive NAO. This was text book, in keeping the main storm track further North and West, thus resulting in more stormy and slightly colder conditions over the Midwest and much New England.

On the flip side, and further south into the Mid-Atlantic and the SE States, the results were: “Below” to “Much Below” Normal snowfall, and slightly warmer than normal temperatures. However all of these areas did experience very stormy conditions as well, along with a very progressive and active pattern. The Norm last year was: More cold rain events, or snow and ice quickly changing over to rain.

This year things will be much different, as I’m forecasting a more suppressed storm track, and colder temperatures for the East, as this winter’s pattern will be driven by a: “Neutral” to “NEG. NAO”, along with a Near Neutral ENSO/Weak La Nina Pattern. A mean “Broad Based Trough” will setup for much of the Eastern 2/3 rds of the nation. At times this trough will become very amplified, and sharp along the East Coast, due to Atlantic Blocking, and the NEG. NAO. This will lead to more storminess and Coastal Development, with Miller A and Miller B type storm potential. Overall this pattern will result in Below normal temperatures, (See Temperature Map) and Above Normal Snowfall, for much of the Eastern US (See Snowfall Map)

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

The NAO signal will be one of the key players this winter for the Eastern US. Unlike the past several winter’s the NAO has been mainly in a Neutral to Positive state. This along with an unfavorable ENSO State, has prevented any prolonged cold periods or above normal snowfall, for much of The M/A Region and the SE States. The only exception being, much of New England, and parts of the Great Lakes.

I’ve been studying the NAO over the past 6-8 months, and I believe it’s constant state, of “Neutral” to “NEG”, is a very strong indication that a long term switch to a Negative decadal cycle, is starting to take place. I’m forecasting this long term pattern to carry into the winter months. With the NAO being mainly Neutral to NEG, this will help in allowing for a Colder, and Stormy pattern to evolve. These factors will also help squash the SE Ridge, and prevent any long term, mild/dry periods to occur. So much of the SE and M/A regions will benefit, if you like colder weather, and wintry precipitation.

As we take a closer look at the actual readings of the NAO (Black Line) we can see that over the past 2 months, the trend has become more wavy or amplified with the mean being: Slightly Negative to Neutral. The biggest Dip in values of -1.5 to -2.5 have occurred near or at the 1st of August and the 1st of September.

The peak values of + 1.0 to +1.5 have occurred towards mid month. This trend appears to be carrying itself, into a similar pattern as we head into October. So this wavy (Not Extreme) pattern has been quite consistent over the past 2 to 3 months. I see this continuing into much of the Fall months. (See NAO Chart #1)

NAO CHART # 1 : (Click on chart to enlarge)

During the winter months, we revert back to a more steady Neutral to Negative signal, similar to what We’ve seen during the Spring and early Summer months. There will be times when the NAO signal does goes POS, but this will occur less frequently and briefly. (See NAO Chart # 2)

NAO CHART # 2 : (Click on chart to enlarge)

With the ENSO State being near neutral to weak La Nina, this will allow for the Pacific (PNA) pattern to be more relaxed and less dominate as we head into the Fall and Winter months. This alone gives the NAO a better chance to be more neutral to negative. The trends I’ve outlined are enough evidence to show where we’re going, and why I’m forecasting the NAO to be neutral to negative, as a mean for this upcoming winter.

The SST (Sea surface temperatures) are somewhat favorable, but as a forecaster I find using this information, for nearly 3 months out is useless. A large storm or two, such as a Nor’easter or Tropical system in the Atlantic, can change the entire SST profile in a matter of days or weeks. So I usually stay away from trying to present this as evidence or reasoning.
Here’s my thinking for the NAO signal, with a monthly breakdown.

December: NEG, to Near Neutral.

January: Neutral to POS.

February: Mainly NEG.

March: NEG to Neutral.

So December and February are where I’m forecasting the coldest and stormiest (snowiest) month’s. January will be mainly Neutral, but at times will go POS, this will allow for some mild periods, as temps will average slightly above average, with a continued active pattern, producing both Rain and Snow, along with some Ice. During March, a Neutral to NEG signal will continue from February to close out the winter with Slightly colder than normal temps, and a continued active and stormy pattern.

With a near Neutral ENSO, the PNA signal will likely be Neutral to POS for much of the winter.

The AO (Arctic Oscillation) will be Neutral to at times NEG, this will allow for a strong Northern and Arctic branch to evolve early (December) & also be predominant in (February) and drive down the colder air, allowing for a more suppressed storm track. (See Storm Track’s Map). The overall result will produce “Above Average Snowfall” and “Below Normal Temperatures” from the Northern Rockies and Southern Plains on eastward into The Tennessee and Ohio Valley’s, Parts of the Midwest, Much of the M/A States and into Southern and Central New England. (See Snowfall & Temperature Map).

The question to be answered is this: Will The Delaware Valley, The M/A States, and NE, see a big snowstorm this winter ? I would say yes, based on my predictions of the ENSO and NAO signals.

My best estimate for a Snowstorm of 4″ or more, would be in mid or late December between the 15th and 30th, and an even better chance in late January and early February, between Jan 20th and February 10th. During both of these time frames, the NAO signal will be going through a transitional period, from Neutral/NEG, to POS during late December, then from a Neutral/POS back to a NEG signal in early February. It’s during these transitions that East coast storms are most likely to develop.

So once again the best chance for a SECS/MECS, for the M/A and NE States, will be between Dec 15th-30th and also between Jan 20th-Feb 10th.


In this segment I’d like to go over all my maps, and summarize my overall outlook for the upcoming winter season. I’ve made several maps: 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, 2008 – Mar 31, 2009 (D,J,F,M)

Mean Temperature: -1.3 (Slightly Below Avg.)

Mean Temp Range: -1.0 to -3.0 (Slightly Below Avg)

Total Snowfall: 22″ to 28″ (Above Normal)

Target Prediction: 26″

Precipitation: (Above Normal)

The Monthly Breakdown for PHL/PA:

December: -3.0 F
Mean Temp Range : -2.0 to -4.0 (Below Avg.)
Snowfall: 4″ to 6″ (Above Avg)
January: +1.0 F
Mean Temp Range: 0.0 to +2.0 (Near to Slightly Above)
Snowfall: 6″ to 8″ or (Near Avg)

February: -2.0 F
Mean Temp Range: -1.0 to -3.0 (Slightly Below Avg)
Snowfall: 8″ to 10″ or (Above Avg.)

March: -1.0 F
Mean Temp Range: 0.0 to -2.0 (Near to Slightly Below Avg.)
Snowfall: 2″ to 4″ or (Near Avg.)

Selected I-95 Corridor Cities:

Dec 1, 2008 – Mar 31, 2009 (D,J,F,M)

BOS (Boston, MA)
Temps: -1.0 to -3.0 (Below Avg.)
Total Snowfall: 44″ to 50″ (Above Normal)
Overall Forecast: Temps: -2.1 F / Snowfall: 47″

NYC (New York City, NY)
Temps: -1.0 to -3.0 (Below Avg.)
Total Snowfall: 28″ to 34″ (Above Normal)
Overall Forecast: Temps: -1.5 F / Snowfall: 33″

BWI (Baltimore, MD)
Temps: -1.0 to -3.0 (Below Avg.)
Total Snowfall: 22″ to 28″ (Above Normal
Overall Forecast: Temps: -1.5 F / Snowfall: 26″

DCA (Washington DC)
Temps: -1.0 to -3.0 (Below Avg.)
Total Snowfall: 20″ to 26″ (Above Normal)
Overall Forecast: Temps: -1.7 F / Snowfall: 23″

RIC (Richmond, VA)
Temps: -1.0 to -3.0 (Below Avg.)
Total Snowfall: 10″ to 16″ (Near/Slightly Above Normal)
Overall Forecast: Temps: -1.3 F / Snowfall: 13″
Take Care,