ralph lauren outlet store

EPAWA 2013-2014 Winter Outlook

Written by on November 15, 2013 in Seasonal Outlooks with 0 Comments

Winter Outlook Blog Song: “Let it snow” by Dean Martin

Outlook effective dates: December 1st, 2013 through March 31st, 2014

Well it’s that time of year again when we look to the long range a bit further than we’d like and take a stab at the Winter forecast. Since June 1st, we have gained support to our growing staff with now four meteorologists, and as a result, we’d like to think that our previous two seasonal outlooks (Summer and Fall 2013) have been spot on with advance prognostication as a direct result of that. Since Winter is undoubtedly our most popular time of year, whether you love snow or hate it, it is always a hot topic. The past two Winters were lackluster for most, and a third straight below average Winter would serve to send a few snow lovers into depression. However, statistically, a third straight below average Winter is unlikely. We do have some good news for the snow lovers for some areas, and others not so much. We will give you the expectations of this Winter and how we arrived at such a conclusion throughout the remaining content of this outlook.


The Winter Forecast Factors:

State of the ENSO:


ENSO

From the above, we expect this Winter to have an ONI index in the months of December and January to be near neutral (0.0) with a margin of error of +/- 0.3. So this means neither an El Nino nor a La Nina. Often referred to as “La Nada”. There are some indications that warming in ENSO regions 3.4 and 4 would suggest a weak El Nino may begin to develop sometime in January. This, combined with some other factors (especially a declining QBO – see below) is a grand slam for snow lovers.

Climatological Factors:

We matched up analogs to the following factors, each of which are present or projected for this Winter in the table below. Matched most closely to a cold Pacific Decadal Oscillation (PDO), a warm Atlantic Multidecadal Oscillation (AMO), a warm Eastern Pacific Oscillation (EPO), a slow year in the tropics (as was the case this year), and weighted a multi-year neutral ENSO (since last year was also near neutral).

Winter Year Cold EPO? Warm AMO? Warm PDO? Slow Tropics? Multi-year neutral ENSO?
1961-1962 YES YES YES YES YES
1978-1979 YES NO YES YES NO
1967-1968 YES NO YES YES YES
1968-1969 YES NO YES YES NO

 


From the above, we selected our closest two matches, and top two we chose are the Winters of 1961-1962 and 1978-1979. For those that viewed our preliminary Winter outlook in mid-October, we heavily favored the 1961-1962 analog, which was a year that featured slightly above normal snowfall. However, we will discuss some wildcards in this outlook that will enable this year to be more reminiscent of the 1978-1979 season, which featured good blocking and much above normal snowfall area wide. Speaking of blocking…

The North Atlantic Oscillation (NAO)

The illustration below is a simple graphic that shows what a positive and negative NAO can do for our area:

Positive Phase:
posnao

Negative Phase:
negnao

So what do we expect this year? Well we look for signs of that from the stratosphere and SST anomalies, and both would suggest a dominant negative NAO pattern. In addition, according to advanced statistical methods used to calculate and predict advanced NAO signals, this Winter is expected to have very good blocking as a whole:

Image Credit: Al Marinaro

nao

Canadian Snow cover

What happens in Canada this time of year has a direct correlation to our weather here in the United States. The more snow cover, the less chance the cold air seeping south from Canada will moderate as it reaches our latitude. So that in a sense “locks in” cold periods and arctic outbreaks in our region last longer in duration. The past two years saw Canadian snow cover lacking, and you saw the result. Transient shots of cold followed by warm ups, and the warmer periods lasted longer than the cold periods. Below is a graphic that shows Canadian snow cover this time last month on the left, and the current snow cover in Canada this month in comparison on the right. HUGE differences:

snowcover

Sea Surface Temperatures in the Atlantic

Due to the lack of tropical activity this year, there was little to disrupt ocean temperatures and no upwelling occurred bringing colder waters to the surface as is typical of tropical cyclones. This has rendered water temperatures along the eastern seaboard WARMER than average. What does this mean? This would suggest that any coastal systems that take shape and move up the coast as nor’easters have the potential to go through rapid cyclogenesis and “bomb out”, dumping tremendous amounts of snow inland. Coastal areas typically would not do as well in this setup since the warmer fetch off of the ocean would keep temperatures too warm to see snow. Warmer sea surface temperatures in the Atlantic ALSO would promote better blocking over Greenland, keeping the NAO predominantly negative. Here is that current temperature graphic for the coastal Atlantic:

sst

The Quasi-biennial Oscillation (QBO)


QBO

One thing we couldn’t talk about much in the preliminary outlook was the QBO, since we didn’t have enough data to speculate on it. The QBO is the periodic oscillation of the equatorial zonal wind between easterlies and westerlies in the tropical stratosphere. There are distinct phases which represent the direction that these winds are blowing. A negative QBO means that the winds are blowing from east to west, and a positive QBO is the opposite. Generally you want this number to be as close to neutral if you are a snow lover, but anything within the range of +/-8.00 is considered “good” for snow and blocking. August was a little scary with the QBO rising to +14.66… but then September saw a drop off to +13.12. In October, we saw another drop to +11.69, which continues to be encouraging. Although not in the range we want yet, it is dropping toward that favorable range. November numbers will not be available until the first week of December, but right now a falling QBO is a good sign if you want snow and a lot of it. Should the decline cease or head back to a higher positive number, it would correlate to a milder Winter with less snow.


Winter highlights – Click on any graphic below to enlarge:

Active storm track and precipitation departures:

The active track promotes a lot of overrunning events this year, as illustrated in the active storm tracks map below. Although precipitation will be above normal with this track, that doesn’t always translate to cold timed with snow. A battle zone may set up many times this Winter where split somewhere within our coverage area will be a tough rain/snow/ice line to deal with, making our job calling individual storms that much more difficult. December we are going with above normal precipitation, below normal precipitation in January (storms suppressed due to severe cold) and February looks like it will yield much above normal precipitation and snowfall. March keeps the wetter theme and could produce a few snow events unlike previous years recently.

Breakdown of precipitation by month:

December 2013: Above normal precipitation
January 2014: Below normal precipitation
February 2014: Much above normal precipitation
March 2014: Above normal precipitation

prelimprecip1

Temperatures departure from normal:

After a relatively mild start to Winter in the beginning of the month of December, a flip to sustained cold can be expected the 2nd half of the month. January tanks into the cold with arctic outbreaks abound, and February returns to near normal temperatures. March sees a return to transient cold and warm spells.

Breakdown of temperatures by month:

December 2013: -1°C below normal, +1°C first half, -2°C 2nd half
January 2014: -3°C below normal for the month
February 2014: Entire month averages -1°C, -2°C first half, near normal 2nd half
March 2014: Flip to a transient pattern of cold and mild, month averages +1°C

prelimtemps1

Snowfall departures from normal issued in the preliminary outlook in October:

Given the battle zone setting up over our area that we expect, this would favor areas in the interior for above normal snowfall, but only slightly above normal as a whole, less in coastal areas. New data we have looked at since the preliminary outlook last month suggests a more active pattern, and a possible weak El Nino taking shape by the middle of Winter. Coastal storm(s) that form would also favor the interior, as warm sea surface temperatures won’t help snow get to the NJ coastal areas.

prelimepawa


The EPAWA Winter Snowfall Map:


The Winter starts off on the slower side, but makes up for it in the 2nd half. We are expecting 50-60% of these totals to occur after January 15th this year:

winteroutlook2014



SELECT CITIES AND TOWNS EXPECTED SNOWFALL

State College, PA 59″
Mount Pocono, PA 54″
Sussex, NJ 52″
Williamsport, PA 51″
Towanda, PA 50″
Hazleton, PA 49″
Pottsville, PA 48″
Stroudsburg, PA 48″
Harrisburg, PA 47″
Hackettstown, NJ 46″
Scranton/Wilkes-Barre, PA 42″
York, PA 40″
Allentown/Bethlehem, PA 38″
Easton, PA 37″
Reading, PA 36″
Lancaster, PA 34″
Quakertown, PA 34″
Pottstown, PA 33″
Somerville, NJ 33″
Newark, NJ 29″
Wilmington, DE 27″
Trenton, NJ 27″
Philadelphia, PA 25″
Freehold, NJ 22″
Mount Holly, NJ 20″
Dover, DE 19″
Vineland, NJ 18″
Toms River, NJ 16″
Atlantic City, NJ 13″
Cape May, NJ 12″



Wildcards

Every year we include wildcards that could increase or decrease amounts listed above, and this year our wildcards favor the above map totals to be ABOVE rather than below. The wildcards are listed below:

(1) Blocking. Blocking ends up higher than normal timed with the cold air, producing one or two mega-storms along the US eastern seaboard… it is very possible to see a few 12″+ type snowfalls that can skew totals higher. The major to historic snow storms that hit our area, most occurred when the QBO was decreasing and stalled and decreased further. The odds are high the QBO will be decreasing, so if we can get a stall period somewhere between D-J-F-M we could very well see the blockbuster storm.

(2) Sea Surface Temperatures. Also contributing to blocking, this factor can cause coastal storms to undergo rapid cyclogenesis faster, and bigger storms can form as a result. It can easily turn a storm that has 6-12″ potential into a 1-2 foot+ event with the sea surface temperatures as warm as they are.

(3) Active Southern Jet. Although an El Nino is not expected to develop, El Nino-like characteristics of a juiced southern jet and Gulf of Mexico connection may be realized. If that happens, storms will have that much more moisture to play with and areas that do receive snow will receive more.

(4) Teleconnections. The most idea situation for cold and snow as illustrated below is for a -EPO, +PNA, -AO, -NAO combination. If this is the dominant pattern for this upcoming Winter, even snow lovers may be waiving the white flag begging for mercy.

sst2

(5) Solar activity. Lower solar activity like which is occurring this year promotes a warmer stratosphere, and a warmer stratosphere usually indicates a colder United States. Higher solar activity results in more UV rays escaping through the ozone layer and cooling the stratosphere. This allows us to warm in the troposphere (our weather).

(6) November snowfall. Although not included in this outlook, any snow in November we consider bonus. There are some indications that the end of November could produce a wintry threat at the time this outlook was released, but we are not confident on a true pattern change until the 2nd week of December. Until then, transient shots of cold and warm will alternate.

What can go wrong?

Blocking potential is not realized, and the Pacific jet continues to dominate with a general west to east flow (zonal) across the country. Although unlikely, we have to allow for that possibility. Also a possibility is the QBO does not continue to fall as it is currently and stays strongly positive. This would also promote milder conditions with less snow. A dominant ridge over Alaska would kill our Winter for us as well, as was the case over the past two years, more so two years ago in the 2011-2012 Winter. The Arctic Oscillation (AO) according to the SAI index is expected to be predominantly positive, but EPAWA does not put much stock into this index and believes the opposite will occur. Although we listed several variables here, the wildcards favor our snowfall totals and they stand a better chance at being low rather than too high.

Please continue to follow the Facebook page for rapid updates as storms approach this Winter. We could be in for quite a wild ride if everything works out the way we foresee it. The My Pocket Meteorologist™ text/email alert program is a great program we started this year, and you can receive text or email alerts sent directly to your phone or PC specific to your county you live and/or work in… for more information on this great program, please click here: MY POCKET METEOROLOGIST PROGRAM INFO

Thanks for reading, and THINK SNOW!

The Eastern PA Weather Authority, LLC Staff

Tags: , , , ,

Subscribe

If you enjoyed this article, subscribe now to receive more just like it.

Subscribe via RSS Feed Connect on Google Plus Connect on YouTube

Leave a Reply

Your email address will not be published.

Current ye@r *

Top