Severe wx threat next 3 days 5-5-04 to 5-7-04

[WXBUFFJIM]

Good morning everyone. A potentially very active mid and late week as far as severe weather is concerned as conditions will favor several complexes of strong to severe thunderstorms over the next few days across the Great Lakes, midwest, and upper Mississippi Valley.

For today, a marginal severe threat exists in two areas. One area of concern will be the Mid Atlantic later today as a cold front moves through. Limited moisture should preclude a severe weather threat. However with deep layer northwesterly shear, the potential for an isolated damaging gust exists from any bowing segment that develops later today from Philadelphia through Baltimore and Washington as well. Another area of concern will be across northern Minnesota where a line of storms could flare up later this afternoon into this evening. Once again, limited moisture should preclude a significant severe weather threat. However a 90-100 knot jet streak should enhance the threat of wind and hail in northern Minnesota later this evening. A cold front is also in the vicinity, which will provide the lift needed for sctd strong storms.

For Thursday, a more active severe weather period maybe occurring across the Great Lakes and into the midwestern United States as a frontal boundary digs southeastward throughout the day. This combined with westerly flow aloft, heating/destablization, and 30-40 knot 0-6 km shear supports severe thunderstorms in the form of small line or bowing segments. The area of greatest concern will be across south central lower Michigan. Damaging wind is the most likely threat from this.

Further southwestward, capping should preclude storm development across Iowa and into portions of Illinois. However strong heating and instability could result in deep convection with severe wind and large hail by later in the day on Thursday. While conditions do not favor long lived supercell storms in this region, we cannot rule out supercell storms either across Iowa and into parts of Illinois, southern Wisconsin, and into northern Missouri as well.

On Friday, the severe thret shifts southeastward toward the Ohio Valley and remains in place across the upper Mississippi Valley. The biggest severe threats will be large hail and damaging wind.

More updates will be issued on this as the day wears on.

Jim

[Brett Adair]

I have to agree with Jim on this one. Looks like an active three days for the upper mid west and OH Valley region. Friday could be active along that baroclinic zone in WI/IL/IN and Western OH if the cap breaks. Increased vertical shear on the models has brought the 0-3KM SRH values up over 500m*2/s*2. Going to be active if we can get some instability to build.....can we say "loaded gun" ?

[WXBUFFJIM]

A tornado warning was issued earlier today for southern Maryland for Charles, St Marys, and Calvert Counties. As of 7:15 PM, the tornado warning expired for all three counties. However a special marine warning is in effect for the Maryland portion of Chesapeake Bay from Drum Point down to Smith Point. Mariners in the southern portion of Maryland on the Chesapeake can expect wind gusts to over 50 knots, large hail, high waves, dangerous lightning, and torrential rains. Severe thunderstorms can produce waterspouts with little or no advanced warnings.

The weather was a bit turbulent in Baltimore too with strong storms, some wind gusts and a brief bout of heavy rain and small hail. This is despite drier air with dewpoints near 50 degrees and air temps in the low 70s. Strong shear was in place for this hail, tornado threa to occur today. Cold air aloft resulted in the destablization neccessary for this and the cold front was the focusing area for thunderstorms, low topped storms with 20000 foot tops.

Jim