My 2011-2012 Winter Forecast Update !
Issued: Wednesday PM
Date: 12-28-2011
For: The Delaware Valley and M/A Region.


By John Ruggiano

October 8, 2011

From December 1, 2011 Through March 31, 2012 (D,J,F,M)

For The CONUS. (Continental USA)

It’s time again for my annual Winter Forecast. Over the past 2-3 years, a robust pattern has developed over much of the country. I study trends very carefully, and pay very close attention to teleconnections in making my winter forecast. It’s quite interesting how some patterns can really lock in once they are established. Sometimes they can come and go in 2 to 3 month cycles, or in seasonal cycles, but this overall pattern has become more of an annual or climate cycle change. May I also add, we are seeing more in the way of extremes, in certain parts of the country. So, the big question arises: Why is this happening, and what is causing this robust pattern change over the past 2-3 years. First I’ll present some solid facts and trends with the overall pattern, along with what I’m thinking for the winter season.

Some very solid trends over the past 2 years.
2009-2010 & 2010-2011 Seasons: Summer and Winter ! For much of the Central and Eastern United States.

So, let’s start with some solid facts and an overall dominant pattern I’ve been seeing over the past couple of years. The past 2 Summer and Winter seasons, have produced extremes relative to normal. We’ve seen very hot and record breaking heat with the past 2 Summers, and Bigger Storms with much above average snowfall over the past 2 Winter seasons. Interesting to say the least ! Now this past summer we’ve seen very wet conditions along with the record heat and many areas broke all time rainfall records in August. These very wet conditions have continued into September but more near normal temperatures as we head into early fall.

Overall temps during the past 2 winter seasons have been near to slightly below normal, but once again, We’ve seen much bigger storms (Miller A and Miller B’s) producing record breaking snowfall in the 2009-2010 season and continued MECS/HECS during last year’s 2010-2011 winter season.

The ENSO Signal:
Once again, big extremes and a huge flip, within a 1 year period !
2009-2010: Overall a Moderate to Strong El Nino Signal which quickly switched to:
2010-2011 : Overall a Moderate to Strong La Nina Signal.

This winter I’m forecasting a weak to possible moderate La Nina, so not as extreme as the past 2 years with ENSO, or are we seeing any big flip from El Nino to La Nina. We look to continue on the La Nina side this winter, after relaxing to a more near Neutral Enso signal, over the Spring and Summer months. Please see the chart below and the forecasted ENSO into this winter. The solid black line with the connected dots, are the actual ENSO results from December 2009 to September 2011. As we can see many models are forecasting a weak to possibly moderate La Nina signal for this winter season, with a few stronger, and a few more near neutral. So the overall anomaly is for a weak La Nina, for the 2011-2012 Winter Season.

Chart summary of forecasts issued over last 22 months
The following plots show the model forecasts issued not only from the current month, but also from the 21 months previous to this month. The observations are also shown up to the most recently completed 3-month period. The plots allow comparison of plumes from the previous start times, or examination of the forecast behavior of a given model over time.
The chart below shows forecasts for the dynamical models.

A Trending Negative PDO Signal: – PDO

The PDO has also been showing signs of a negative trend over the past couple of years, which I believe is the start of a possible new 20-25 year cycle. The last long term cycle occurred in the 50’s, 60’s and much of the 70’s which brought colder and snowy winters, especially in the Central and Eastern CONUS.

As we can see in the 80’s and 90’s the PDO which was in the Positive stage, this brought milder winters with less snowfall. During these decades we had more like 7 out of 10 winter seasons bringing milder winters, with only a few colder and snowy winter seasons.

As I’ve stated, the opposite occurring in the 50’s, 60’s and 70’s where we experienced more colder and snowy winters, with the PDO being negative. So the PDO is just another of many signals to watch in forecasting and making seasonal predictions.
Please see the PDO chart below from 1900 to 2011. As you can see the trend is heading back to a negative cycle.

Click on map to enlarge:

Teleconnections: The NAO/AO Couplet !

Steady as it goes with teleconnections and seasonal trends. We’ve been seeing more of a NEG. NAO/AO couplet, and a near Neutral to POS PNA, during the past 2 winter seasons. This along with the factors I’ve listed above, have contributed to bigger storms and Colder than normal temps over the northern Tier and much of the East. As we head into this Fall and Winter, I see these very similar trends continuing with our basic teleconnections.

The AO


The Charts above show the trends of the NAO and AO, with the solid black line showing the actual plots over the past 4 months. A couplet is where we see 2 teleconnections trending together, in this case the NAO and AO. As we can clearly see this couplet continues.
As we head into and through the Fall months, both the NAO and AO will remain near neutral to slightly negative.

During the late fall and into winter, I’m forecasting a mainly negative NAO and AO with this overall couplet continuing. This will help drive the pattern and with a weak La Nina and –PDO, much of the Central and Eastern CONUS will see below normal temperatures and more stormy conditions. This will help in setting up the mean trough over the Central and Eastern US. The Southwest and parts of the west will have the best chance in seeing slightly above normal temperatures and Drier conditions with more ridging setting up there.

A Positive NAO or + NAO
During its positive phase, NAO shows a stronger than usual subtropical high pressure center around the Azores and a deeper than normal Icelandic low, with increased pressure generating more and stronger winter storms crossing the Atlantic Ocean on a more northerly track. Europe tends towards warm and wet winters while northern Canada and Greenland will usually have winters are cold and dry, with the eastern United States generally experiencing mild, wet winter conditions.

A Negative NAO or – NAO
During its negative index phase, NAO is characterized by weak subtropical highs and weak Icelandic lows, with fewer and weaker winter storms that cross on a more west-east pathway, bringing cold air and snowy weather conditions to the U.S. east coast during the winter months, cold air in northern Europe, and moist air to the Mediterranean

Click on map to enlarge:

Hurricane Seasons: 2010 and 2011

The past 2 hurricane seasons have both produced below average land falling Tropical Storms or Hurricanes, even though the named storms have been near to slightly above average. I really think this data needs to somehow be considered and factored into the overall forecast. As we can see, the 2010 hurricane season and this year’s 2011 season look very similar with storm tracks, so the pattern continues here as well.
See maps below with the tracks of all tropical systems in 2010 and 2011 (so far).

Click on maps to enlarge:

My Forecast Maps:
Includes: Temperature, Precipitation, Snowfall, and Storm Tracks

Temperature Map:

I’m forecasting “Below Average Temperatures” of -1 to -3 for nearly half of the country. This will include much of the Plains, Midwest, Great Lakes, TN Valley, Interior SE, The Mid-Atlantic, and into Central New England. Some portions of the Midwest could see “Much Below Average” temperatures of -3 to -5.

On the flip side, “Above Average Temperatures” of +1 to +3 can be expected over much of CA and into the Southwest States.

“Near Average Temperatures” of -1 to +1 will cover the Pacific Northwest, much of the Rockies, The Deep South, and a good portion of the SE States. These areas will also see some cold shots, so don’t let near normal fool you over the 4 month period !

Click on map to enlarge:


Precipitation Map:

“Above Average Precipitation” and more stormy conditions will cover parts of the Pacific Northwest and Northern Rockies. Then also further east, over much of the Midwest, The Great Lakes, The TN Valley, The Mid-Atlantic, and into parts of New England.

“Near Average Precipitation” for Northern CA, The Central Rockies and into much of the Plains. The Deep South from Eastern Texas to much of the SE States and also Northern New England.

“Below Average Precipitation” can be expected for Central and Southern CA, into much of the Southwestern States, including western portions of Texas.

Click on map to enlarge:

Snowfall Map:

“Above Normal Snowfall” can be expected over portions of the interior NW and much of the Northern Rockies, due to a La Nina type Pattern, and weak trough axis. Further east over parts of the Northern Plains, into much of the Midwest, The Great Lakes, The Mid-Atlantic, and much of New England, Above Normal snowfall can also be expected.

LES (Lake effect snow) events will be near to above normal this winter, with many CAA events from late November into early January, along with numerous clippers producing additional snowfall for the remainder of the winter season.

“Below Normal Snowfall” can be expected over much of Central and Southern Rockies, mainly due to a Plateau High, producing drier conditions and milder temperatures with a Southwest Ridge setting up there.

Click on map to enlarge


Storm Track Map:
On this map I have 3 main storm tracks, used as a general anomaly.

Both Storm tracks #1 and #2, will likely be the most active during the winter season, and will bring the cold and snow package to much of the Plains, Midwest, Great Lakes, and portions of New England.

Storm track #3 will be the least active due to our La Nina signal and a weak STJ. But this track will pack a punch, and deliver a couple SECS/MECS, from the Mid-Atlantic States into a good part of New England. I see the best chance being from mid December into early February for my #3 storm track. At times our northern branch will bring down strong u/l energy, along with a deep amplified trough setting up over the Eastern CONUS.
This will likely promote storm development near the TN Valley and lower MS Valley, thus producing our Miller A and Miller B events on the East Coast.

Click on map to enlarge:


My Final Thoughts and Summary.
For the M/A & NE: The Overall Pattern for the 2011-2012 Winter Season.

I’m forecasting a colder winter with near to above normal snowfall for much of the Mid-Atlantic States and the Northeast. The overall teleconnections will once again be favorable, with a predominant Negative NAO and AO couplet. There will be times when the NAO and AO are near neutral, but overall I’m forecasting both teleconnections to average negative from December through March. This will once again help drive the overall pattern, resulting in a colder and stormy pattern. These trends continue to be following a similar pattern over the past couple years and I see no changes heading into this upcoming Winter Season.

The ENSO: I’m forecasting a weak to moderate La Nina signal. This combined with favorable teleconnections, will put most of these regions in a position, for a colder and more active winter pattern !
A couple “Miller A’s” and several “Miller B” type storms, look like a pretty good bet right now. The STJ will be on the weak side with the La Nina Signal, but with the mean trough axis digging into the TN Valley, storm development is likely in this area (Storm Track #3) then as Miller A’s and developing Miller B storms moving NE to the M/A coast.

For the Delaware Valley Region:
Including SE PA, Central and Southern NJ, and DE.

I’m forecasting this winter to be Colder than Average at -1.0 to -3.0 F, with Above Average Precipitation, and Above Normal Snowfall. Look for another early start to the winter season, starting in December and lasting into much of January. Any mild periods will be brief, not lasting more than a week of so during the heart of the winter season, so I’m not seeing any big January thaw this year in the east. March will likely be the mildest of the 4 month period, so winter should end on a milder note. The best chance for milder periods will be during the later part of winter, or mainly from later February into March, but I’m still forecasting February to be slightly below normal, so March will be the best chance for these milder temperatures.

I see a better than even chance for 1 or 2 storms producing 6″-12″ events, with Storm Track #3, so get the shovels and snow blowers ready ! I’m also concerned with a couple of Ice Storm threats, along with mixed precipitation events, as some storms will track overhead and to our North and west with Storm Track #1. (See Storm Track Map)

An active Northern Branch of the Jet Stream will also send down many Clipper type systems/Cold Fronts, delivering shots of very cold air, which will produce several minor snow events of 1”-3” and 2”-4”. Please see Storm Track #2 on my maps section.

My Call For PHL:
Including Nearby Areas of SE PA, Interior Southern NJ and Northern DE.
Valid: Dec 1, 2011 – Mar 31, 2012 (D,J,F,M)

Mean Temperature: -1.6 F (Below Avg.)

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

Total Snowfall: 28″ to 36″ (Above Normal)

Target Call: 32”

Precipitation: (Above Normal)

The Monthly Breakdown for PHL/PA:

December: -3.0 F
Mean Temp Range : -2.0 to -4.0 (Below Avg.)
Snowfall: (Above Avg

January: -1.0 F
Mean Temp Range: 0.0 to -2.0 (Near to Slightly Below Above.)
Snowfall: (Above Avg)

February: -2.0 F
Mean Temp Range: -1.0 to -3.0 (Below Avg.)
Snowfall: (Above Avg.)

March: +2.0 F
Mean Temp Range: +1.0 to +3.0 (Slightly Above Avg.)
Snowfall: (Near Avg.)

Some 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: -1.5 F / Snowfall: 46″

NYC (New York City, NY)
Temps: -1.0 to -3.0 (Below Avg.)
Total Snowfall: 30″ to 36″ (Above Normal)
Overall Forecast: Temps: -2.1 F / Snowfall: 34″

BWI (Baltimore, MD)
Temps: -1.0 to -3.0 (Below Avg.)
Total Snowfall: 22″ to 28″ (Above Normal)
Overall Forecast: Temps: -1.7 F / Snowfall: 25″

DCA (Washington DC)
Temps: -1.0 to -3.0 (Below Avg.)
Total Snowfall: 20″ to 26″ (Above Normal)
Overall Forecast: Temps: -1.3 F / Snowfall: 23″

RIC (Richmond, VA)
Temps: -1.0 to -3.0 (Below Avg.)
Total Snowfall: 12″ to 16″ (Near Normal)
Overall Forecast: Temps: -1.0 F / Snowfall: 14

Video Presentation of my Winter Forecast.

The Barometer Bob Show: Click on link below for the recorded show.

Take Care,