Wednesday, January 20, 2016

The Snow Panic Machine Springs to Life: Blizzard Watch Issued for Entire Metro D.C. and Metro Baltimore Areas for Friday Noon - 6AM Sunday

UPDATED 12:22PM and 4:44PM 1/20/2016: See below.

Sterling (LWX) NWS weather advisories updated at 10:39AM EST January 20, 2016.

Note the legend ...

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The Baltimore/Washington National Weather Service has issued a BLIZZARD WATCH for the entire immediate Metro D.C. and Metro Baltimore areas starting noon Friday and running through 6AM EST Sunday morning.

Snow totals of 12 to 20 inches are likely, although this Capital Weather Gang entry provides the following probabilities for the immediate D.C. area:

At least one inch: 95 percent or higher

At least four inches: 85 percent

At least eight inches: 75 percent

At least 12 inches: 65 percent

At least 18 inches: 40 percent

At least 24 inches: 15 percent

Locations west of that Warrenton to Columbia line can add 5-10 percent to probabilities of at least 8 to 24 inches.

Blizzard conditions in the Cleveland Park section of Washington, D.C., Feb. 10, 2010. Picture by CWG staff writer and photographer Ian Livingston.

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UPDATED 12:22PM 1/20/2016: The 12Z GFS just came in and it continues that model's relentless storyline of a truly historic blizzard for the immediate D.C. area. While the KBWI number is "only" 21.2 inches (again, using that 10:1 ratio), the KDCA number shot up to 33.4 inches, which is absurd.

KDCA 180-hour cumulative snow total based upon the 12Z 1/20/2016 run.

Using a 10-1 snow-to-liquid equivalent ratio, that is 33.4 inches of snow, which I simply do not believe will happen.

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The snowfall map for the northeastern quadrant of the Lower 48 U.S. based upon the 12Z 1/20/2015 GFS run. Note that the bull's eye is right over D.C.

These are amounts that you are not likely to see again for a long time.

End of Update.

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SECOND UPDATE 4:44PM 1/20/2016:

NWS snow forecast for the Sterling CWA valid 7AM EST Jan. 22, 2016 through 7PM EST Jan. 23, 2016.

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This CWG has a good overview of what the different models as well as the different local TV channels are predicting in terms of amount (link embedded):
How much snow are local forecasters and computer models predicting?

Worthwhile quote from that entry:

"Generally, the amounts forecast by people are lower than those forecast by the computer. This is likely because human forecasters understand the climatology and storm history of the region and know how improbable the computer simulations are. So, bear in mind, the human forecasts may be a little conservative…"

For its part, the CWG is predicting the following with the usual boom/bust scenarios as book ends:
 
Capital Weather Gang snowfall totals and ranges for the D.C. / Baltimore Metro areas valid Jan. 22 - 23, 2016.

End of Second Update.

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The machinery has been set in motion (and only God Himself can stop it now) ...

--Regulus

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