Severe Weather Outlook for Monday, August 10, 2009...

Discussion...
Couple things to point out. First off, setup up Today does not look as favorable for widespread severe weather as most of us saw on Sunday. Couple of differences exist, one of which is the amount of Storm relative helicity in place across the area Today. The 00z NAM shows next to none anywhere Today, so for intent and purpose, did not delineate any areas of Tornado probability because of this. Taking Sunday's severe weather reports and overall storm mode into consideration, expecting the hail threat to be somewhat minimal Today as well. For this reason, hail probability was capped at a minimal 5% for all areas. Thus, primary severe threat should be straight-line damaging winds associated with linear convective modes, which could include bows/segments, as well as clusters.

Onto the Severe weather areas, there are 2 areas of Slight Risk in play for Damaging Winds only. Leaned heavily toward the High-Res WRF once again for delineating the Slight Risk areas. This strategy paid off markedly as you saw in the August 8-9 thread in Mike and I's verification post. Basically, there appears to be a potential for 3 MCS type systems that could produce some Damaging Winds. The first is shown to be across Northeastern KY into Southern Ohio, where a potential Bow Echo is shown to develop and track eastward from here into the mountains of WV, before weakening as it encounters the rugged terrain along the Appalachian spine.

The 2nd MCS is shown to develop over northwestern PA by Early Afternoon and track east-southeast toward areas of Eastern PA and adjacent western NJ thru the Early Evening hours. It is possible that may need to upgrade to a 30% Damaging Wind probability later this Morning after surface obv's and morning 12z runs can be taken into account. For now, left at broad 15% probability here.

The last potential MCS looks to arrive toward the end of the outlook period Monday Evening as cold front begins to approach western areas by 00z Tuesday. The WRF hints at an organized band of convection sweeping across from Lower MI into Southern Ontario before re-emerging into areas of Western/Central NY. Given this potential, northern edge of 15% Damaging Wind probability will stretch across Lake Ontario to roughly the I-81 corridor in Central NY.

Outside of these 2 Slight Risk areas, I expect thunderstorm development to be somewhat isolated with the lack of large scale forcing for ascent.

..EGAN.. 08/10/2009