Updated Severe Weather Outlook for This Afternoon/Evening, August 5, 2009...

Updated discussion... as of 12:35PM 08/05/2009
I'll be the first to admit that this may not pan out, but for the most part, going to keep with overnight outlook, with a couple minor adjustments. First was to tighten up the General Thunderstorm/Severe probabilities to match latest frontal placement, as some areas are now in the clear. Decided to keep the 15% Damaging Wind probability in place, but extend it to the southwest thru Eastern New England. Last tweak was to contract the minimal tornado probability, and relegate it to southwestern ME where a modest pocket of helicity will be in place, as evident by this morning's RUC13 analysis, which could lead to a brief spin up if any discrete cells can develop in this corridor.

Current and forecasted instability for this Afternoon is plenty strong enough, as well as Negative LI, which will help to offset some of the other lacking ingredients. Effective low level shear will be in the 20-30 kt. range in the southern portion of the risk area, with up to 50 kts in the north. Latest radar shows storms beginning to fire over the higher terrain of western New England, and expect this trend to continue. Damaging winds should be the primary threat, along with an isolated hail threat.

Previous Discussion below...

..EGAN.. 08/05/2009
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Discussion... as of 2:00AM 08/05/2009
General thunderstorms will be possible along and south/east of a line from approximately Saranac Lake NY- Syracuse NY- Bradford PA. A Slight Risk for severe storms will be possible across Downeast ME and extreme eastern NH/MA.

On-going storms over Western NY down to adjacent northeastern OH will begin the outlook period. As stated earlier, despite ample destabilization and lift over parts of the forecast area, weak low level shear will hinder much in the way of storm coverage and organization. 00z WRF showing very little in the way of storms firing along and out ahead of the front Today over much of the area, likely due to the lack of large scale forcing and shear.

Axis of strong shear will be over northern New England, and this is where a 15% Slight Risk will be carried for Damaging wind potential. 00z WRF shows a organized line of convection firing in central ME by early Afternoon and working across the southeastern half of the state thru Early Evening. Thus, think damaging winds will be the primary threat in this area. Debated whether to tack a low 2% tornado probability with this potential, and did so with the idea there could be a brief spin-up if any embedded supercell structures emerge within the line.

Elsewhere, only other area of organized convection is shown to be over the southwest, across parts of WV eastward into VA. However, lack of low level shear will preclude any higher probabilities than 5% for wind/hail for now. Not out of the question that may need to re-visit this potential later this Morning with final outlook issuance.

..EGAN.. 08/05/2009