The First Major Winter Storm of The Season is On The Way ! Full Discussion & Prelim. Snowfall Estimates.

Sunday
5:30 PM Update:

There's a reason why I wanted too wait until this evening to do this writeup. I went ahead and did it early because things were looking very good and the trends were there. We'll guys the latest 12z and 18z runs are in and I have BAD NEWS ! All models have trended north and warmer, with one main system that strengthens and moves on a track much furthern north.

We'll get some accumulating snow, but all precipitation will mix with and change to sleet, freezing rain, then a COLD RAIN on Wednesday. As I said these were preliminary snowfall estimates and my final call will be out Monday Evening. I can assure you these amounts will be cut in half, due to more mixed precip and rain in the equation. What another disaster for PHL, SJ, and DE.

Areas from the Lehigh Valley, Pocono's to NW NJ will do the best (Whats New) I'll have more tomorrow with my final call, let's just hope it's not worse news, as this winter has been tortuous for snow lovers, and needs to get over with !

Enjoy the flurries this evening guys !

Ruggie

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Discussion:
Sunday AM: 1/25/09
Issued For: The Delaware Valley & M/A States.

I'm sure many of you know, I've been talking about this split flow pattern change for the past week or so, along with a major overrunning event for this upcoming week. I've been tracking and following the progression of these changes closely, and I'm now officially giving the green light for a Major Winter Storm for later Tuesday afternoon into Wednesday. This entire stretched out event could come in 2 pieces of energy, or should I say separate storm systems. I'll concentrate on the first system for Tuesday afternoon into Wednesday, as this looks to be the major event.

The Synoptic Setup for Tuesday into Wednesday:

One of the important ingredients is strong High Pressure setting up to our North and West for Monday into Wednesday. This will supply and hold the cold air in place, along with blocking and suppressing the energy and storm track to our south. In this split flow pattern, a baroclinic zone will develop and extend from the Southern Plains to the M/A States Monday through Wednesday. This will be the main avenue for all precipitation and the storm to move along. Energy now in the SW States will be ejected eastward and follow this baroclinic zone.

With High Pressure and cold air in place to the north of this zone, and milder and moist air to the south, a major overrunning setup is likely. A wave of low pressure will develop over the Tennessee Valley during Tuesday, and move ENE to the M/A coast, near the Delmarva coast on Wednesday morning. A 100 to 150 mile swath of moderate to heavy precipitation will occur along and north of this storm track. With cold air in place and a southern storm track, a majority, if not all of this precip will fall as snow, across northern MD into much of PA, NJ, and into the NYC area.

For Points south and east of BWI (Baltimore MD) to near PHL (Philadelphia, PA) could have some mixing issues with Sleet and Freezing rain, later Tuesday night or Wednesday morning, as the storm approaches the coast. I still expect significant snow accumulations even though some mixing could occur. The heaviest precip. will fall during Tuesday night in the form of Snow. All precipitation will wind down and should taper off during Wednesday afternoon. The second storm I spoke off, will follow quickly on it's heels, and could bring additional snowfall. I'll get more into that on Monday with my final Call.

My Preliminary Call with Snowfall Estimates:
Tuesday PM into Wednesday PM.

For the Delaware Valley Region:
Includes SE PA, Central/Northern DE, and Southern/Central NJ.

At this time (prelim) A general 4" to 8" can be expected over much of our region, but higher amounts of 6" to 10" are possible over SE PA into Central NJ.

I expect some light snow to move in during Tuesday. All snow will become steadier and heavier during later Tuesday/Tuesday Night, and continue into the morning hours on Wednesday. Snow will fall moderate to heavy at times during Tuesday night. This snow will possibly mix with sleet and freezing rain near PHL and over portions of DE and Southern NJ later Tuesday night or Wednesday AM.

I'll have my Final Call out Monday night and I'll make adjustments if needed. I'll also have additional thoughts for other areas: such as The Lehigh Valley, Northern NJ/NYC areas. Also estimates for MD, Northern VA, and the BWI/DCA metro areas of I-95 Corridor.

Stay tuned as I'm very confident with this storm, and I expect the NWS to issue winter storm watches on Monday.

Take Care,
Ruggie