Monday, December 8, 2014

Your Short and Long Range Weather Forecasts: Early Week Bi-Coastal Rainy Storms; Mild Month with Little Eastern U.S. Snow (and Brown Xmas)

NWS surface weather map forecast valid 12Z (7AM EST) Dec. 9, 2014 issued at 1930Z (2:30PM EST) Dec. 7, 2014.


Weather for first half of the work week ...

A coastal low is forecasted to develop right along the North Carolina Outer Banks late tomorrow and move northward to a position along the Jersey shore during the day Wednesday. There are already coastal flood advisories in effect for Long Island, New York City, the Jersey shore, and the Delmarva coastline.

Weather advisories in effect as of 12:52AM EST for parts of the mid-Atlantic as shown on the Mount Holly / Philadelphia NWS Forecast Office webpage and thus centered on its county warning (and) forecast area (CFWA).

Note: The term "CWA" and "CWFA" are used interchangeably by the NWS -- differing only by whether "(and) forecast" is implied.

The legend for the advisories on that map is included at left as another screen shot image. Light green are coastal flood advisories; blue is a winter storm watch; the orchid color are gale warnings; and the violet are storm warnings for the continental slope waters.


The position WOULD BE a highly favorable one in the winter time for a major snowstorm -- except the cold air is simply just lacking and the system isn't going to produce enough given its location between the coastline and the Gulf Stream.

True, it is a cold night tonight with a 1046mb high over southern Quebec tonight ridging down the Eastern Seaboard, but it isn't going to act as a block but instead will continue to chug along to the east.

Portion of the NWS high resolution surface weather map showing New England, the mid-Atlantic, and the Canadian Maritime provinces, valid 03Z December 8, 2014.


The Capital Weather Gang has already tried to quash any snow hysteria with this entry -- and expect much more detailed entries tomorrow on the site.

On a side note, concerning that the first entry, one of the commenters posted a link to this funny picture of predicted snowfall:

I love the yellow snow amount contour (isonif?) and its caption: 0" for wherever Ian is in NW DC. Ha ha


Now there are some discrepancies -- the ECMWF (Euro) model has been showing a strong cut-off low developing with the surface low pivoting around it and throwing lots of precipitation back into the mid-Atlantic region including toward the Baltimore area with D.C. sort of on the edge.

The NAM continues to advertise huge amounts of precipitation -- in the ballpark of 2 to 3 inches liquid even in the Baltimore / Washington corridor. However, the operational GFS (see next image below) has consistently shown far less here in its last three runs -- 1/4 to 1/2 inch.

Left: The 0Z Dec. 8, 2014 NAM showing total precip. for the Eastern U.S. and Southeastern Canada valid through hour 72 at 0Z Dec. 11, 2014.


Left: The 0Z Dec. 8, 2014 operational GFS showing total precip. for the eastern U.S. and Canadian Maritimes valid through hour 72 at 0Z Dec. 11, 2014.

The current NWS quantitative precipitation forecast (QPF) map for days 1 - 3 cumulative shows about 1.5 inches right over D.C. but with a tight gradient running from 3+ inches over central and northern New Jersey to under 0.5 inches in interior central Virginia.

That map is as follows:

NWS/NCEP/WPS QPF valid days 1 - 3 for the period 0Z 08 Dec2014 - 0Z 11 Dec2014 issued at 2151Z (4:51PM EST) on Dec. 7, 2014.

Note the forecasted amounts of up to 12 inches (1 foot) of rain in parts of the Olympic Peninsula of Washington and and Vancouver Island, British Columbia for a powerful Pacific system slamming into that region.

For the mountains, this translates into fantastic amounts of snow. However, snow levels are forecasted to be rather high -- in the 7,000 to 8,000 foot range for the Cascades and Olympics.

Forecast information graphic issued by the Seattle, Washington NWS Forecast Office at 5:51PM PST Dec. 7, 2014 showing expected weather highlights for the next few days.


Returning to the impending Eastern Seaboard coastal low and the impact on the D.C. area, in these scenarios, and unlike in the Boston or even New York City areas, one almost never goes wrong in forecasting the lower precipitation amounts for the Metro D.C. area. As for snow, it's highly unlikely in our area. It just doesn't play out that way.


The Palka-Cabra Creature wouldn't have it any other way.

There she is ...


Oh, and for a more hysterical take on these matters, check in with or, even better, I'm not going to link to those sites.

Also, I wanted to mention that the long-range forecast for the end of the month into early January calls for well above normal temperatures across much of the United States including the eastern and central regions.

The NCEP coupled forecast system model version 2 (CFSv2) 16-member ensemble temperature anomaly forecast (in Kelvins) for week 4, valid 28 Dec 2014 - 05 Jan 2015.

For more info on the CFSv2, see here.


As such, that hoped-for snowy Christmas in Buffalo with me and Gary -- where we have already arranged to go -- might not come to pass. That is, it might not even be sno in Buffalo. As for the D.C. area, it's as lost of a cause as Democrats ever regaining the House or the working class vote for the next decade or more. Just a brown and red Christmas. And neither climate change nor demographic change are going to make either happen more quickly.


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