Wednesday, February 28, 2007

High Risk

The Storm Prediction Center has placed much of Alabama under a very unusual "HIGH RISK" of severe weather today for a possibility of an outbreak of potentially strong or violent tornadoed.

A "HIGH RISK" means that there may be an outbreak of at least 20 tornadoes in a 50,000 square mile area (roughly the size of the state of ALabama) with at least two rated EF3 or greater or an extreme straight line wind event with over 50 areas of 80+ mph wind and major structural damage.

Following is the text of this outlook from the SPC:

…THERE IS A HIGH RISK OF SVR TSTMS TODAY ACROSS PARTS OF ERN
MISSISSIPPI AND ALABAMA…WHERE POTENTIAL EXISTS FOR AN OUTBREAK OF
TORNADOES…SOME POSSIBLY STRONG OR VIOLENT….

…THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK
AREA…ACROSS MUCH OF THE LOWER HALF OF THE MISSISSIPPI VALLEY AND
GULF/SOUTH ATLANTIC COAST STATES….

…THERE IS A SLGT RISK OF SVR TSTMS TODAY/TONIGHT ACROSS A LARGE
PORTION OF THE CENTRAL/EASTERN STATES….

LARGE SCALE PATTERN ACROSS THE U.S. DURING THIS FORECAST PERIOD WILL
BECOME DOMINATED BY A DEEP CYCLONE NOW DEVELOPING ACROSS THE CENTRAL
PLAINS…IN RESPONSE TO AN INTENSE MID/UPPER JET STREAK NOSING
NORTHEAST OF THE SOUTHERN ROCKIES. UPPER JET CORE IS PROGGED TO
SHIFT THROUGH THE SOUTHERN PLAINS/NORTHERN GULF STATES AND SOUTHERN
APPALACHIANS TODAY THROUGH EARLY FRIDAY…WITH SURFACE CYCLONE
GRADUALLY OCCLUDING AS IT LIFTS THROUGH THE UPPER MISSISSIPPI
VALLEY/UPPER GREAT LAKES REGION. AS THIS OCCURS…A COLD FRONT WILL
SURGE EAST OF THE MISSISSIPPI VALLEY…LIKELY REACHING ATLANTIC
COASTAL AREAS BY 12Z FRIDAY. AND…MODELS SUGGEST SECONDARY SURFACE
CYCLOGENESIS MAY OCCUR FROM THE LEE OF THE NORTH CENTRAL
APPALACHIANS INTO NORTHERN MID ATLANTIC COASTAL AREAS.

No comments: