Day 1 Severe Weather Outlook (Thursday 6/25/09)...

D1 Outlook is now on the street. Most noticeable difference in latest model runs is to pull back on the timing with the frontal passage. This will keep the best forcing back thru interior PA/NY thru the afternoon into the Evening hours as front approaches from Southern Canada. It is here where Slight Risk was most justifiable at the present time. Slight Risk will run north/west of a line from roughly Morgantown-State College-Binghamton-Burlington. Pending on how things look heading into Thursday Afternoon, further adjustments may be needed with Midday update.

While MLCAPE and negative lifted indices will be favorable for thunderstorm development during the Afternoon and Evening hours across interior parts of NY/PA, weak low level vertical shear and wind flow will prohibit much in the way of organized and widespread convection. However, given the amount of cold air aloft, cells that do manage to develop will need to be watched for associated hail threat. This event could be very reminiscent to recent June 15th event.

Given this setup, expect most of the convection that does manage to develop to be of the Pulse-type variety, with large hail, damaging wind, and heavy rainfall to be the primary threats. With weak helicity in the lower levels, tornado threat appears rather low at the present time.

..EGAN..