Tuesday, January 25, 2011

Big Snow Thump on the Way ! Light Snow & Mixed Precip on Wed, Followed By A Heavy Snow Thumping Wed Night ! Significant Snow Accumulations Likely !

Tuesday: 01/25/11
Issued: 12:30 PM
My Forecast and Discussion:
For The Delaware Valley Region.

A significant Winter storm is likely for the entire Delaware Valley ! Moderate to Heavy snow is likely for a 8-10 hour period during Wednesday night. This thump of heavy snow will bring significant snow accumulations across the entire Delaware Valley.

Part 1 of the storm !

A storm system now over the Northeast Gulf of Mexico, will move northeast to the NC/VA coast on Wednesday. Light precipitation will begin during the early morning hours on Wednesday, as some snow and sleet. This light mixed precip will continue into much of the morning and early afternoon hours. Some rain will mix in for points south and east of PHL.

This is the first, and weaker part of the storm, which will be rather insignificant. Only a C-2" of snow and sleet can be expected during the day on Wednesday. Highs will be in the mid to upper 30's. Expect occasional periods of light mixed precip during the early and mid afternoon hours. The precip could actually stop for a couple hours during the afternoon, before the heavier precip moves in towards evening. This is where it gets very interesting and what I call part 2 of the storm and most significant. This will occur during much of Wednesday night, bringing moderate to heavy snow !

Part 2 of the Storm !

This is where things get very interesting, and intense u/l (Upper Level) dynamics come into the picture. A strong and sharp, H5 trough will be following behind our developing surface low along the M/A coast, during later Wednesday and Wednesday night. This intense mid and upper level energy, will track northeast from the TN Valley and move to the Delmarva coast by later Wednesday night. This u/l energy with cause dynamics and tremendous lift in the atmosphere along and to the NW of it's path.

A 75 to 150 mile wide swath of moderate to heavy snow will likely develop from NE VA to Eastern MD, much of SE PA, DE, and NJ. This will begin over NE VA and Eastern MD later Wednesday afternoon and then spread northeast into the Delaware Valley towards Wednesday evening.

This second batch of precip could start as a couple hours of rain and mixed preicp for points South and East of PHL, before changing to all snow by 7:00 PM, possibly later towards the Coast of DE and SE NJ.

A prolonged period of moderate to heavy snow is likely from, Start time: (5:00 PM & 7:00 PM) into the overnight hours between (1:00 AM and 3:00 AM) before tapering off and ending, during the overnight. Snowfall rates of 1" per hour and isolated areas could see 2" per hour rates along with possile thundersnow, this mainly due to convective banding and strong lift in the mid and upper levels of the atmosphere.

I'm forecasting a general 6" to 10" of snow accumulation for the entire Delaware Valley Region, this forecast is for the Wednesday night snow thump. This includes: NE MD, All of SE PA, Central/Northern DE, Southern and Central NJ, with the exception of SE Coastal sections.
Coastal SE DE and SE NJ will see lesser amounts of 1"-3".

My Snowfall Map:



Take Care,
Ruggie

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