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February 1st-2nd Roidzilla, Part IV: Final Forecast

DT (Wrisk) latest Facebook post on current one:

2PM UPDATE

After looking at all the latest data ...the short-range models and the radar there are some changes to be made in the forecast because there has been a decisive and significant change here at the last minute with the formation of the coastal oh.

First lets look at some regional Radars and see what is going on. This recent radar image from 12:30 PM Sunday shows the dry slot which has pushed all the way through the Shenandoah Valley and into the Washington DC Metro area with significant brakes in the snow Shield. However there is still moderate and significant snow in the Northern Neck … Fredericksburg … into southern Maryland as well as the Eastern panhandle of West Virginia … central and northern Maryland and Baltimore. SEE IMAGE 1

Also note the significant rain in northern portions of West Virginia Southern Ohio.

IMABE #2 is the radar forecast for 313PM and 5PM this afternoon. As you can see the dry slot has pushed its way up into Washington DC but has halted across the DC suburbs in Northern Virginia. It has also pushed up into Winchester and close to Hagerstown. In Central Virginia; The precipitation is mostly rain and its heavy rain in southeast Virginia eastern North Carolina and the southern Delmarva.

The short-range radar forecast shows that the snow is going to fill back in across northern Virginia during the evening hours but I am not certain if that is actually going to happen. The data says it should but I am a bit skeptical that the snow is going to build back in that much by 5 or 6 p.m. this evening in northern Virginia the northern Shenandoah Valley and DC Metro.

By 9 p.m. this snow has pushed into the North and there are just areas of sleet and light snow mixed mostly north of DC in central and Northeast Maryland. Notice that nothing is occurring south of DC or in the Shenandoah Valley or the Eastern panhandle of West Virginia IMAGE #3 And at 3 a.m. not much is going on in northern Virginia Maryland eastern portions of West Virginia and the Delmarva either. It looks pretty quiet.

The initial forecast from back on Thursday and Friday had the formation of the coastal LOW close to the Delmarva or just offshore for much of Monday. Having the coastal LOW in that position would allow for the circulation of the large coastal LOW to pull the snow down from Pennsylvania New York and New Jersey into Maryland and Northern Virginia and the Eastern panhandle of West Virginia… and probably back into the Washington DC Metro area… the northern Shenandoah Valley and perhaps central and northeast Virginia. Moreover because the coastal LOW was going to stall close to the Delmarva Peninsula it would cause easterly winds to bring milder air into southeast Massachusetts Boston Rhode Island eastern Connecticut eastern Long Island changing the snow to rain and reducing the snow amounts in those areas that significantly

However as you can see the new data clearly does NOT do that. Instead the coastal LOW is much further to the north and east. This means that the Boston and Southeastern New England area see their winds stay North or Northeast so temperatures there are cold enough to support snow and all of eastern New England gets pounded with anywhere from 12 to 18 inches of snow.

But in the Maryland DC Baltimore Northern Virginia region ...the shift of this Coastal LOW for the to the north means that any wrap around snow on Monday is going to be significantly less than earlier forecasted. in addition... the area of moderate and heavy rain in the Ohio Valley which earlier forecasted to move into Northern Virginia Baltimore central Maryland for Sunday night into Monday … is going to stay further to the north because the actual costal LOW pressure area is tracking further to the north.

We can see the shift here on the models for tomorrow. At 7 a.m. IMAGE #4
on Monday the coastal LOW is significantly further east than what the data was showing either yesterday or on Friday. There is a huge dry slot across all of Virginia Maryland and even into Southeast Pennsylvania. Only yesterday the models for producing huge snow falls in Philadelphia and Southeastern interior PA. But now it looks like even that area will see much less snow.

During the day on Monday at 1 p.m. and 5 p.m. the coastal LOW is significantly further to the north when compared to what It was showing yesterday or on Friday or on Thursday. This keeps all the heavy precipitation north of Philadelphia into northeast Pennsylvania…. New York City / North Ne Jersey and New England. But it also means that any wrap around snow showers on Monday in northern Virginia the northern Shenandoah Valley in the Eastern panhandle of West Virginia will be minor if any.
IMAGE #5

And clearly this shift means that the snow forecast map in the LAST CALL as well as the FIRST CALL forecast maps for Northern Virginia and Central Maryland and even into Southeastern Pennsylvania are probably going to bust.

WHAT THREW ME OFF (and many other mets as well )-- was that fact that last week the coastal Low was forecast to be off Norfolk on Monday NOT south of eastern Long Island NY .