Thursday, November 8, 2012

My 2012-2013 Winter Forecast For The Delaware Valley And The CONUS. Discussion and Maps

My 2012-2013 Winter Forecast.

By John Ruggiano

November 9, 2011

From December 1, 2012 Through March 31, 2013 (D,J,F,M)

For The CONUS. (Continental USA)

It's time again for my annual Winter Forecast. A quick recap from last year’s Winter forecast, proved to be a huge bust for me, and this includes everyone else who put out a seasonal forecast. This was my worst forecast in 5 years ! Mother nature threw us a big curve ball and the weather in general, threw all of our forecasts to the bottomless pit !

As we know, much of the CONUS and Southern Canada, wound up being much above normal with temps, and much below normal with snowfall. Both the NAO and AO remained more positive, which locked all the cold air and PV’s near the AK and Greenland regions. As a result, very little cold air was able to press south and east into Southern Canada and the CONUS. This pattern also prevented our snow producing coastal storms from occurring, which were not part of the equation last year along the entire east coast.

I’m now thinking with better teleconnections and with a near Neutral to weak El Nino, we should see a much better winter this year with more cold shots and snow. The best chance will be over much of the Eastern half of the CONUS, as I’m mainly forecasting for slightly below normal temps, and near to slightly above normal snowfall. The western half of the country will have more variable conditions this winter, with near to below normal snowfall, and near to slightly above normal temps.

The ENSO Signal:

This winter I’m forecasting a near Neutral signal to a weak El Nino that will at times produce a weak to even moderate subtropical jet. This will also help allow for a split flow pattern to develop. When this subtropical activity occurs, more storms will develop to our south and southwest, then move up the eastern seaboard. It’s during this time we should see our best chances for Miller A type systems, that will result in a couple snowstorms. My best estimate for this activity will be in January and February !

Teleconnections: The NAO/AO Couplet !

Both teleconnections and seasonal trends are much better than last year. We've been seeing more of a Neutral to Negative NAO/AO couplet redeveloping during the past 6-9 months. This should help contribute to bigger coastal storm threats and Slightly Colder than normal temps over the much of the East. As we head into the winter season, I see these very similar trends continuing with our basic teleconnections.

As we head into and through the winter months, both the NAO and AO will remain near slightly negative values. I’m forecasting mainly a negative NAO and AO for ½ to 2/3 rds of the winter season, but at times will go neutral to slightly positive.

This combined negative NAO and AO will help drive the pattern and with a weak El Nino, much of the 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.

These teleconnection are very hard to predict 1 to 4 months in advance, so I can only give it my best shot based on trends and SST’s in certain regions of the Pacific and Atlantic.

My Forecast Maps: (Click on maps to enlarge)
Includes: Temperature, Precipitation, Snowfall, and Storm Tracks

Please be advised, these maps represent the overall averages I’m forcasting for a 4 month period. An example, If I have temperatures being below normal at 1- to -3, this does not mean it will be colder than normal for the entire 4 month period, it’s an average ! There will be times when temps will be above normal or warmer during periods of time throughout the winter season, but in the end, when I add it all up and average the 4 month period, I expect the temps to be averaged at -1 to -3 as per this example, the same goes for where I have near or above average.

Temperature Map: (Click on map to enlarge)

I’m forecasting “Below Average” temperatures of -1 to -3, for the following locations. This will include much of the Northern Plains, Midwest, Great Lakes, TN Valley, Interior SE, The Mid-Atlantic, and into New England. Parts of the Pacific Northwest, Southern TX and LA, will also see slightly below normal temperatures.

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

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

Precipitation Map:  (Click on map to enlarge)

“Above Average Precipitation” and more stormy conditions will cover parts of the Northern Plains and Northern Rockies from an active Northern branch. Then also further east, mainly along and east of the Apps, which will be associated with coastal storms and a weak subtropical jet stream

“Near Average Precipitation” for much of the West Coast, The Plains, Great Lakes and Midwest.

“Below Average Precipitation” can be expected for portions of the west mainly near Nevada and Utah.

Snowfall Map: (Click on map to enlarge)

Above Normal Snowfall can be expected over portions of the TENN Valley and Lower Ohio Valley, into much of The Mid-Atlantic States and The Northeast, due to a weak El Nino Pattern, a weak subtropical jet and better teleconnections. The Northern Plains and portions of the Upper midwest will also see above normal snowfall with Northern Branch systems and Clippers.

Below Normal Snowfall can be expected over much of Rockies, and parts of The NW States, this mainly due to a Plateau High, producing drier conditions and milder temperatures with a Southwest Ridge setting up there.

Storm Track Map: (Click on map to enlarge)

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, as Storm track #2 will bring the cold and snow package to much of the Northern Plains and Upper Midwest. Storm track #1 will be associated with our weak Subtropical Jet and bring Above Normal Snowfall to portions of The Tennessee and lower Ohio Valley, then into much of The Mid-Atlantic and Northeast.

I see the best chance for my storm track #1, being in both January and February. 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 type events on the East Coast. A Negative NAO will also aid this process.

Storm track #3 is my Apps runner track and will produce more in the way of rain and mixed events east of the Apps and into the Mid-Atlantic. But this track will produce more snow and cold for the Midwest, Great Lakes, and Ohio Valley.


My Final Thoughts and Summary.
For the Mid-Atlantic States And The Northeast:
The Overall Pattern for the 2012-2013 Winter Season.

I’m forecasting a slightly colder winter with slightly above normal snowfall for much of the Mid-Atlantic States and the Northeast. The overall teleconnections this year will be more favorable than last year, with a predominant Neutral to Negative NAO and AO for much of the winter season. There will be times when the NAO and AO are near neutral to slightly positive, but overall I’m forecasting both teleconnections to average more negative from December through March and include more blocking. This will once again help drive the overall pattern, resulting in a colder and more stormy pattern for much of the Eastern CONUS.

The ENSO: I'm forecasting a weak El Nino 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 this winter season. The STJ will be active at times but on the weak side with the El Nino Signal, but with the mean trough axis more focused over the Central and Eastern CONUS, storm development is likely in these areas (See Storm Tracks #1 & 2).

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

I'm forecasting this winter to be Slightly Colder than Average at -1.0 to -3.0 F, with Above Average Precipitation, and Slightly Above Normal Snowfall. Look for the coldest and snowiest months to be in January and February. Any mild periods will be brief, not lasting more than a week of so during the heart of the winter season. Both December and March will likely be the mildest of the 4 month period, with December being near Avg. and March coming in slightly milder than normal.

I see a better than even chance for 2 storms producing 6"+ events, with Storm Track #1, 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 #2 and #3. (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 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: -1.2 F (Slightly Below Avg.)

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

Total Snowfall: 24" to 30" (Slightly Above Normal)

Target Call: 27”

Precipitation: (Slightly Above Normal)

The Monthly Breakdown for PHL/PA:

December:   +0.5 F
Mean Temp Range:  +1.0 to -1.0 (Near Avg.)
Snowfall:  (Near 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:  -2.0 to -4.0 (Below Avg.)
Snowfall:  (Above Avg.)

March:   +1.0 F
Mean Temp Range:  0.0 to +2.0 (Near to 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: -2.0 F / Snowfall: 46"

NYC (New York City, NY)
Temps: -1.0 to -3.0 (Slightly Below Avg.)
Total Snowfall: 28" to 36" (Above Normal)
Overall Forecast: Temps: -2.1 F / Snowfall: 32"

BWI (Baltimore, MD)
Temps: -1.0 to -3.0 (Slightly Below Avg.)
Total Snowfall: 20" to 28" (Above Normal)
Overall Forecast: Temps: -1.7 F / Snowfall: 24"

DCA (Washington DC)
Temps: -1.0 to -3.0 (Slightly Below Avg.)
Total Snowfall: 18" to 26" (Above Normal)
Overall Forecast: Temps: -1.3 F / Snowfall: 22"

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

Take Care,


john said...

nice forecast

Andrew Skaggs said...


I sure like your projections for my area, middle TN! Your forecast is the only Winter forecast I look forward to all year! :) Let it snow! Take care!


Anonymous said...

So many little information.

Where's the "For entertainment purposes only" disclaimer?

Analysis: awful

Diagnosis: D-

Forecast: fee-for-service customers would be well advised to demand an immediate refund.

NotATroll said...

Good Job John.. just enough information for the folks that visit.. hopefully we see a good winter here in the Mid Atlantic and VA!. Far as that "Mr. Anonymous" comment, that one is nut'n but a TROLL and an insecure child, probably has had mommy issues ! Man the nerve of sum folk, Anyway good stuff !