All this is from the Storm Prediction Center
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 672
NWS STORM PREDICTION CENTER NORMAN OK
540 PM EDT FRI JUL 22 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
FAR WESTERN MARYLAND
EAST CENTRAL OHIO
WESTERN AND CENTRAL PENNSYLVANIA
NORTHERN WEST VIRGINIA
EFFECTIVE THIS FRIDAY AFTERNOON AND SATURDAY MORNING FROM 540 PM
UNTIL 100 AM EDT.
HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 65
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 40 MILES NORTH
NORTHEAST OF ALTOONA PENNSYLVANIA TO 40 MILES SOUTH SOUTHWEST OF
AKRON OHIO. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).
REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.
DISCUSSION...TSTM CLUSTERS EXPECTED TO CONTINUE FORMING WITH SFC
HEATING/WAA ALONG STALLED W-E BOUNDARY IN WRN/CNTRL PA...WITH
ADDITIONAL ASCENT POSSIBLY PROVIDED BY CIRCULATION ASSOCIATED WITH
CNTRL OH MCS. STEEP LOW LVL LAPSE RATES /WITH SFC TEMPS IN THE 90S
TO AROUND 100 F/...COUPLED WITH MODEST DEEP WLY SHEAR AND POCKETS OF
HIGH PW WITH SIZABLE TEMP-DEW POINT SPREADS...SUGGEST POTENTIAL FOR
SMALL BOWING SEGMENTS/WET MICROBURSTS.
Tornadoes
| Probability of 2 or more tornadoes |
Low (<5%)
|
| Probability of 1 or more strong (F2-F5) tornadoes |
Low (<2%)
|
Wind
| Probability of 10 or more severe wind events |
Mod (40%)
|
| Probability of 1 or more wind events > 65 knots |
Low (10%)
|
Hail
| Probability of 10 or more severe hail events |
Low (10%)
|
| Probability of 1 or more hailstones > 2 inches |
Low (<5%)
|
Combined Severe Hail/Wind
| Probability of 6 or more combined severe hail/wind events |
High (8
|
