Storm Prediction Center Forecast
WW 549 TORNADO NE SD 292030Z - 300300Z
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 549
NWS STORM PREDICTION CENTER NORMAN OK
330 PM CDT THU JUL 29 2010
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
PARTS OF NORTHCENTRAL NEBRASKA
PARTS OF SOUTHERN AND WESTERN SOUTH DAKOTA
EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 330 PM UNTIL
1000 PM CDT.
TORNADOES...HAIL TO 3.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 90 STATUTE
MILES EAST AND WEST OF A LINE FROM 35 MILES EAST NORTHEAST OF
RAPID CITY SOUTH DAKOTA TO 40 MILES EAST OF MULLEN NEBRASKA. FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU9).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND 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.
OTHER WATCH INFORMATION...CONTINUE...WW 548...
DISCUSSION...AIR MASS NOW QUITE UNSTABLE ACROSS THE WATCH AREA AND
FAVORABLY SHEARED TO SUPPORT SUPERCELLS. A SUPERCELL HAS DEVELOPED
S END OF BLACK HILLS AND WILL LIKELY CONTINUE SEWD INTO A FAVORABLE
ENVIRONMENT FOR NOT ONLY LARGE HAIL BUT POSSIBLY TORNADIC
DEVELOPMENT. ADDITIONAL SEVERE STORMS ARE LIKELY SEWD INTO NCENTRAL
NEB WHERE SIMILAR CONDITIONS PREVAIL.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
550. MEAN STORM MOTION VECTOR 30015.
...HALES
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WW 548 SEVERE TSTM DC DE MD NJ VA CW 291555Z - 292300Z
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 548
NWS STORM PREDICTION CENTER NORMAN OK
1155 AM EDT THU JUL 29 2010
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
DISTRICT OF COLUMBIA
DELAWARE
SOUTHERN AND EASTERN MARYLAND
SOUTHERN NEW JERSEY
MUCH OF CENTRAL AND EASTERN VIRGINIA
COASTAL WATERS
EFFECTIVE THIS THURSDAY MORNING AND EVENING FROM 1155 AM UNTIL
700 PM 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 75
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES SOUTH
SOUTHWEST OF STAUNTON VIRGINIA TO 50 MILES SOUTH SOUTHEAST OF
ATLANTIC CITY NEW JERSEY. FOR A COMPLETE DEPICTION OF THE WATCH
SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).
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...WITH THE AIR MASS TO THE S OF COLD FRONT NOW NEAR MD/PA
BORDER BECOMING MDTLY UNSTABLE AND UNCAPPED...THUNDERSTORMS WILL
INCREASE IN NUMBER AND INTENSITY VICINITY OF THE FRONT. WITH 30KT
OF SHEAR...COLD POOL DEVELOPMENT IS LIKELY AS STORMS FORM CLUSTERS
AND LINE SEGMENTS...RESULTING IN A WIND DAMAGE THREAT. STORMS WILL
DEVELOP SEWD ACROSS THE WATCH THRU THE AFTERNOON.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.
A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION
VECTOR 29025.
...HALES
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WW 0550 Status Reports
STATUS FOR WATCH 0550 HAS NOT BEEN ISSUED YET
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MD 1497 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR S-CENTRAL AND SWRN AZ
MESOSCALE DISCUSSION 1497
NWS STORM PREDICTION CENTER NORMAN OK
0503 PM CDT THU JUL 29 2010
AREAS AFFECTED...S-CENTRAL AND SWRN AZ
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 292203Z - 292300Z
THREAT FOR ISOLATED DAMAGING WIND GUSTS POSSIBLE OVER S-CENTRAL AND
SWRN AZ THROUGH THE EVENING. HOWEVER...SVR COVERAGE IS NOT EXPECTED
TO BE WIDESPREAD...AND A WW DOES NOT APPEAR NECESSARY.
CLUSTER OF MULTICELL THUNDERSTORMS 55 SSE OF PHX ARE PROPAGATING WWD
INTO AN AIR MASS CHARACTERIZED BY TEMPERATURES IN THE 90S F AND
SHALLOW LAYER OF DEWPOINTS NEAR 70 F AT THE SURFACE...AND PWAT
VALUES AROUND 2 INCHES /PER GPS GUIDANCE/. THIS HOT/MOIST BOUNDARY
LAYER AIR MASS IS SUPPORTING MLCAPE VALUES RANGING FROM 500-1500
J/KG...IN ADDITION TO VERY STEEP LOW-LEVEL LAPSE RATES /AOA 9 C PER
KM IN THE 0-3 KM LAYER/. AS A RESULT...HOT/MOIST AND DEEPLY MIXED
LOW-LEVEL ENVIRONMENT MAY SUPPORT DAMAGING WIND GUSTS WITH THE
STRONGER MULTICELL UPDRAFT CORES AS CONVECTIVE OUTFLOW DRIVES STORMS
TOWARD THE GILA RIVER VALLEY.
..GARNER.. 07/29/2010
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...TWC...FGZ...PSR...
LAT...LON 31761231 32211382 33031405 33871355 34051235 33531163
32621164 31761231
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