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Heavy Rain, Wind & Snow Coming to the Mid-Atlantic

April 21, 2012

A very complex storm system will impact the Mid-Atlantic and New England beginning this afternoon and lasting through Monday. If this had been late March we would have been digging out from….

The current set up for this weekend’s storm reminds me of the March 13, 1993 “Storm of the Century” when an area of low pressure was developing over the Gulf of Mexico and the piece of energy over the upper Mid-West was “the match” that sparked the rapid cyclogenesis off of the east coast… if only it were mid March!

The devil will be in the details, especially regarding how ‘stacked’ the upper level low pressure becomes and exactly where it tracks and stalls.  Monday morning will be incredibly interesting across the northwestern suburbs of Washington as temperatures in the lower levels of the atmosphere plummet rapidly.  The mountains of PA will likely be buried with at least a half a foot or more of heavy, wet snow on Monday!

Today:  Strong Thunderstorms will move through the Washington Area between 4 and 7 PM, some may contain gusty winds in excess of 60 mph and hail.

WRF model depicts line of storms moving through the immediate Washington Area by 6 PM. This line of storms will likely impact the Shenandoah Valley and western suburbs between 3 and 6 PM* Notice the heavy rain over Florida - that is the developing storm that will bring heavy rain to DC on Sunday. Courtesy: NCEP http://mag.ncep.noaa.gov

As the coastal storm develops off of the Carolina coast Sunday afternoon, a shield of moderate to heavy rain will push up the eastern seaboard. Rainfall may begin in earnest around noon in the southern suburbs and the steady rain should begin falling by 2PM in downtown Washington (*timing could change slightly).

WRF "future-cast radar" shows moderate to heavy rain moving up the eastern seaboard Sunday afternoon at 3 PM. Courtesy: NCEP http://mag.ncep.noaa.gov

Steady, soaking Rain continues through the evening across the entire Mid-Atlantic:

WRF future-cast radar 6PM Sunday. Courtesy: NCEP http://mag.ncep.noaa.gov

North American Model (NAM) Predicts 1 to 3" of rain across the Washington Area. *At this time the heaviest totals would fall from Interstate 95 on east, any slight change in track would bring 3" totals further west. Courtesy: NCEP http://mag.ncep.noaa.gov

Global Forecast System (GFS) also agrees that a general 1 to 3" of soaking rain is possible across the Washington Area and Chesapeake Bay. Courtesy: NCEP http://mag.ncep.noaa.gov

Monday’s highs will struggle to get out of the upper 30s and some folks in the far northern and western suburbs could even see wet snowflakes mixing in:

Epic trough (dip in the jet stream) deepens across the eastern states... as the coastal low and upper level low become vertically stacked. Courtesy: weatherunderground.com

Precipitation Type Monday Morning: Cold rain across the Piedmont of Maryland and Virginia with heavy snow from western New York southward to the mountains of North Carolina!

Blue = Snow , Green = Rain: Notice the *snow* across the northern Shenandoah Valley. I expect snow to fall and accumulate on Skyline Drive Monday (Blue Ridge Parkway). Snow may mix in with the rain across parts of the Washington Area on Monday morning. Courtesy: weatherunderground.com

European forecast model shows heavy snow accumulating from the mountains of North Carolina to extreme northern New England. ** Biggest concern will be power outages as wet snow accumulates on trees that have already bloomed…

Potential 3 hour snow accumulation across the Northeast: higher elevations of western New York, central & western Pennsylvania, Garrett County MD, and mountains of WV: Prepare for possible power outages as tree limbs could come down under the weight of this late April snow. Courtesy: weatherunderground.com

Highs on Monday will range between 38 and 45 degrees in DC!

Wind chills will be in the upper 20s and lower 30s across the Washington Region with a gusty north wind!

Highs on Monday will be some 30 to 35 degrees below normal! Courtesy: weatherunderground.com

Interestingly this winter featured well below normal snowfall with the biggest storms occurring in late October (heavy wet snow crippled the higher elevations of the Mid-Atlantic and much of New England) and the second mega-storm in late April. Go figure!

I took this picture in late October 2011 as wet snow accumulated 2 to 5" across beautiful, western Loudoun County, Virginia. Fall foliage was still on the trees and route 7 was closed a few miles west of Leesburg due to downed trees and power lines.

 

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