Strong gravity waves over OK with moderate STP.
Posted by JAC on 5/23/2011, 3:45 pm
    MESOSCALE DISCUSSION 0896 NWS STORM PREDICTION CENTER NORMAN OK 0208 PM CDT MON MAY 23 2011 AREAS AFFECTED...WRN OK...NW TX CONCERNING...SEVERE POTENTIAL...WATCH LIKELY VALID 231908Z - 232045Z A SEVERE THREAT WILL LIKELY DEVELOP ACROSS WRN OK AND NORTHWEST TX LATE THIS AFTERNOON AS STORMS INITIATE. INITIALLY...LARGE HAIL WILL THE GREATEST THREAT BUT A TORNADO THREAT WILL ALSO BE POSSIBLE AS THE STORMS BECOME MORE MATURE LATE THIS AFTERNOON. WW ISSUANCE WILL BE LIKELY ONCE INITIATION OF MULTIPLE STORMS BECOMES MORE CERTAIN. AT THE SFC...A 1002 MB LOW IS LOCATED IN FAR NE TX PANHANDLE WITH A DRYLINE EXTENDING SWD INTO WEST TX. EAST OF THE DRYLINE...SFC DEWPOINTS ARE IN THE UPPER 60S AND LOWER 70S F WITH MESOANALYSIS ESTIMATING MLCAPE VALUES FROM 3500 TO 4500 J/KG ACROSS MUCH OF WRN OK AND NW TX. VISIBLE SATELLITE IMAGERY SHOWS SOME CUMULUS TOWERS IN BECKHAM COUNTY OK. ATTM...THE CUMULUS FIELD IS VERY SMALL BUT IS EXPECTED TO EXPAND OVER THE NEXT HOUR OR TWO AS LOW-LEVEL CONVERGENCE INCREASES ALONG AND TO THE EAST OF THE DRYLINE. THIS ALONG WITH INCREASING LARGE-SCALE ASCENT ASSOCIATED WITH A SHORTWAVE TROUGH MOVING INTO THE SRN PLAINS FROM THE WEST SHOULD RESULT IN VIGOROUS STORM INITIATION. AS STORMS INCREASE IN COVERAGE...THE STRONG INSTABILITY AND DEEP LAYER SHEAR OF 40 TO 45 KT SHOULD SUPPORT SUPERCELL DEVELOPMENT. LARGE HAIL WILL BE LIKELY AND A TORNADO THREAT MAY ALSO DEVELOP ESPECIALLY AS THE STORMS MATURE AND THE LOW-LEVEL JET INCREASES EARLY THIS EVENING. ..BROYLES.. 05/23/2011 URGENT - IMMEDIATE BROADCAST REQUESTED TORNADO WATCH NUMBER 345 NWS STORM PREDICTION CENTER NORMAN OK 230 PM CDT MON MAY 23 2011 THE NWS STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH FOR PORTIONS OF WESTERN OKLAHOMA NORTHWEST TEXAS EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 230 PM UNTIL 1000 PM CDT. TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES NORTHEAST OF ALVA OKLAHOMA TO 40 MILES SOUTH SOUTHEAST OF ALTUS OKLAHOMA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5). 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 338...WW 339...WW 340...WW 341...WW 342...WW 343...WW 344... DISCUSSION...TCU/INCIPIENT TSTM DEVELOPMENT IS IN PROGRESS ALONG DRYLINE IN WRN OK SW OF CSM. MODIFICATION OF 19Z OUN SOUNDING FOR AIR MASS IMMEDIATELY E OF DRYLINE SUGGESTS THAT ENVIRONMENT IS NEARLY UNCAPPED WITH MLCAPE OF 4000-5000 J/KG. WHILE PASSAGE OF SHORT WAVE TROUGH TO THE NE IS NOT PARTICULARLY WELL-TIMED...STRONG DIABATIC HEATING W OF DRYLINE SHOULD SERVE TO FOSTER AT LEAST ISOLATED STORM DEVELOPMENT THIS AFTERNOON INTO EVENING. INITIALLY...VERY LARGE HAIL WILL BE THE PRIMARY HAZARD WITH MATURE SUPERCELLS GIVEN THE LOCALLY HIGHER T-TD SPREADS AND WEAK LOW-LEVEL FLOW. THE POTENTIAL FOR TORNADOES WILL INCREASE THIS EVENING AS LOW-LEVEL SHEAR STRENGTHENS AND LCL HEIGHTS LOWER. AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600. MEAN STORM MOTION VECTOR 27020. ...MEAD |
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Looks like a rough ride this week - severe weather is back - JAC, 5/23/2011, 7:04 am
- MO Under-the-Gun again for Tuesday - JAC, 5/23/2011, 7:22 am
- Official-casts - JAC, 5/23/2011, 7:16 am
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