Afternoon Day 1 Severe Weather Outlook for June 30, 2009

Midday D1 update complete. Overall, not much change to previous Overnight D1 Outlook(s), see Post #73. Based on latest RUC guidance, locally expanded Slight Risk northward to include a few more counties in VT/NY as moderate instability is forecasted to reach into this region. Based on latest convective trends, also locally extended risk to include a few more counties in Eastern PA. Last tweak was to bump up Damaging Wind probability to 15% and also include a low 2% Tornado Probability.

Tornado threat is still very low, but given some decent helicity being indicated by the latest RUC guidance (highest in the north), tornado threat is non-zero. Best chance for a brief isolated tornado will be with any discrete low-topped supercells that manage to develop this afternoon.

Newly updated Slight Risk includes the following counties...

New York: Albany, Chenango, Columbia, Delaware, Dutchess, Essex, Fulton, Greene, Hamilton, Herkimer, Madison, Montgomery, Oneida, Orange, Otsego, Putnam, Rensselaer, Rockland, Saratoga, Schenectady, Schoharie, Sullivan, Ulster, Warren, Washington, West Chester

Pennsylvania: Adams, Berks, Bucks, Carbon, Chester, Columbia, Cumberland, Dauphin, Delaware, Juniata, Lackawanna, Lancaster, Lebanon, Lehigh, Luzerne, Monroe, Montgomery, Northampton, Northumberland, Perry, Philadelphia, Pike, Schuykill, Snyder, Susquehanna, Wayne, York.

New Jersey: Bergen, Essex, Hudson, Hunterdon, Mercer, Middlesex, Morris, Passaic, Somerset, Sussex, Union, Warren.

Connecticut: Fairfield, Hartford, Litchfield, New Haven.

Massachusetts: Berkshire, Franklin, Hampden, Hampshire.

Vermont: Addison, Bennington, Rutland, Windham.