Monday, February 12, 2007

MY CALL: 2/13 & 2/14 SNOW & ICE STORM


FOR THE DELAWARE VALLEY & NEARBY SURROUNDING AREAS.

ISSUED: MONDAY 2/12/07
TIME: 6:00 PM
MY FINAL CALL:
Tuesday: 2/13/07
6:00 AM Update:
I'm quite confident with my call and have no changes, time to be "riders on the storm" the Doors style !
This is going to be a heck of a storm guys ! Snow spreads in this morning and into this afternoon throughout the Del Valley. My accumulation map is for the entire storm through Wed Night. Precip will mix with and change to IP and ZR tonight over SE PA, Most of south and central NJ and DE. Some of these areas will turn to rain for a time Wed morning.
I want to make it very clear that backlash and Wrap around snows will be intense, and the best thump of snow from this system will be from later tomorrow morning into Wednesday Evening for much of the Del Valley. Rain and mixed precip will quickly change to snow, as winds will increase and moderate to Heavy snow will fall for a 3 to 6 hour period, as far south as Central DE and Southern NJ.
As temps drop at the surface, flash freeze concerns with quick accumulations of snow for tomorrow afternoon and evening will cause some difficult travelling conditions.
Remember these accumulations are for the entire storm and likely will be a split with areas getting half or less in the front running thumps today into tonight and the additional accumulations Wednesday afternoon into Wednesday Evening, with backlash and wrap around snows as the storm intensifies and moves NNE into New England !
Enjoy !
Ruggie
DISCUSSION:

Let me begin by saying, I learned a very valuable and frustrating lesson with making a preliminary call on this storm. Forecasting snowfall amounts even though preliminary is just a very bad idea ! This will not happen again, period !!!

What appeared to be a major hit (MECS) for The I-95 Corridor, and much of the M/A States is now looking quite unlikely. Interior sections of the Northern M/A and interior New England will get hammered with a very good snowstorm Tuesday into Thursday Morning.

Some Snow Accumulations will still occur from DCA to BWI, PHL, NYC, and BOS but change to IP (Sleet) and ZR (Freezing Rain) then to Rain in some areas. A change back to snow is possible before the precip ends with some additional light accumulations, Wednesday and Wednesday Night, from PHL northward to NYC and BOS.

DCA and BWI will only see Flurries or a brief period of Light snow before ending.

This is going to be a very complex storm to forecast, as we are talking a primary low approaching from the west near VA and transferring it's energy to the M/A coast. The biggest question's are this:

Where does it transfer ?

How far Offshore ?

And how quickly does it Deepen and intensify ?

Well a general consensus of the models, suggest this transfer occurs near the Delmarva or Virginia Coast, Tuesday night into Wednesday AM. How far offshore this storm develops is very critical. The further offshore, and to the south near VA, the better if you want more snow for the Del. Valley. The GFS is trying to transfer the storm near the NC/VA region, which is the furthest south, this is interesting and trend watching, and Now casting will be needed tonight into tomorrow.

The faster the storm deepens, is also crucial, as heights would crash, and the wedge of milder air at mid levels to the West of the center, would quickly be replaced with cold air aloft being pulled down. This would cool the warmer layers aloft, to where more chance of snow and Ice would be supported. This will have to watch closely and will likely become a now casting situation Tuesday night into Wednesday. Transfers with these types of setup's are extremely tricky, and must be monitored closely and carefully, during the event.

Once the storm gets cranking off the NJ and Long Island coast, Late Wednesday, all precip. will change back to snow South and SW of the storm's center, and some backlash snows will develop as far south as. NE MD/ DE, into Eastern PA and NJ. Additional snow accumulations are possible in some of these areas, later Wednesday morning into Wednesday Evening. As this is occurring, Heavy snow will be falling from North Central and NE PA into interior sections of New England. These areas will likely see snow fall amounts of 12" to 18" with some areas getting over 20" (Isolated).

Please see My Snowfall & Ice Map for my best estimate of total snow accumulations and Ice threat regions ! This for the Delaware Valley and surrounding areas.


Good luck.

PHL/and Surrounding Suburbs


Interior South and Central NJ, Northern DE, and N.E. MD.


Total Snow and Sleet (IP) 2" to 5" with snow Tuesday, then mixing with and changing to Sleet and Freezing rain Tuesday night. light to moderate Icing is likely, before changing to some rain early Wednesday morning, the precip may end as some snow before ending during the late morning and afternoon possibly into the early evening hours.



Take Care,
Ruggie

No comments: