7/03/2009

Afternoon Severe Weather Outlook for July 3, 2009...

Discussion...as of 12:43PM 7/3/09

No changes needed to current SWO product already on the street as this looks like an excellent forecast. Latest RUC evaluation yields a similar scenario for this Afternoon compared to the 00z NAM/GFS in terms of severe potential. MLCAPE values continue to come in at or below 1500 J/KG almost everywhere. The best axis of destabilization looks to occur from Western ME southwest into NJ. Within this axis of destabilization, low level bulk shear values are still progged below 30kts, and Negative LI's from -3 to -5. All in all, most storms should remain below severe limits, with an outside chance that a few reach short-lived severe status. If this should happen... best chance will be from far Western ME southwest to NJ.

Previous Discussion below...

..EGAN..

Discussion...as of 12:51AM 7/3/09

Updated D1 SWO product is now on the street. As has been the case the past few days, yet another shortwave will rotate in tonight across NY/PA and into New England during the day on Friday. Based on latest radar, general Thunder line for D1 will start in place south of I-80 as showers, with perhaps an embedded rumble of thunder move thru PA/NY during the Overnight. This shortwave will be the focal point for producing yet another round of showers/storms over much of the Northeast on Friday.

0z NAM keeps MLCAPE generally under 1250 J/KG over the entire area, and coupled with weak lift/shear, storms will have a very hard time undergoing strong vertical development. Even the usual more robust GFS downplays the severe threat today as well. Based on latest NAM/GFS, debated whether to even include a severe threat today given the overall lack of favorable ingredients for severe convection.

As is, I can probably see a few (likely less than 5, most certainly less than 10) locally damaging wind gusts/marginally severe hail reports today with the strongest of cells, especially given added lift from the rather mountainous terrain of New England. Therefore, will carry a low 5% severe wind/hail probability to account for this. With very low helicity/destabilization expected, tornado threat will be less than 2%.

..EGAN..





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