MESOSCALE DISCUSSION 0960
NWS STORM PREDICTION CENTER NORMAN OK
0333 PM CDT TUE MAY 13 2003
AREAS AFFECTED...ERN/NERN OK...WRN/NWRN AR
CONCERNING...SEVERE THUNDERSTORM WATCH 361...
VALID 132033Z - 132200Z
A SCATTERED LINE OF CONVECTION CONTINUES TO AFFECT PORTIONS OF WW
#361 IN ERN/NERN OK INTO WRN/NWRN AR. WW EXPECTED TO REMAIN IN
EFFECT THRU EXPIRATION WITH AN ADDITIONAL ISSUANCE FURTHER SOUTH A
POSSIBILITY.
RADAR/SATELLITE IMAGERY INDICATES CONVECTION CONTINUES TO MOVE SSE
/320 DEGREES/ AT AROUND 25 KT INTO ERN OK...WRN/WCNTRL ARK. RECENT
SURFACE MESOANALYSIS SHOWS THE AIRMASS IN THESE AREAS IS RATHER
STABLE WITH TEMPERATURES IN THE MID-UPPER 70S AND DEWPOINT VALUES
FROM THE UPPER 50S INTO THE MID 60S. THIS TEMPERATURE-DEWPT.
COMBINATION YIELDS 100MB MIXED CAPES FROM 250-1000 J/KG IN THESE
AREAS WITH THE HIGHER INSTABILITY VALUES IN ECNTRL OK. MOST RECENT
SURFACE OBJECTIVE ANALYSIS FIELDS INDICATES WEAKEN CIN VALUES FROM
AN OKMULGEE-PITTSBURGH COUNTY LINE WHERE DEWPOINTS HAVE CREPT BACK
INTO THE UPPER 60S HELPING 100MB MIXED CAPES TO RISE TO BETWEEN
1000-1500 J/KG.
EXPECT ERN PORTIONS OF CONVECTIVE SEGMENT TO GRADUALLY WEAKEN AS IT
APPROACHES A MORE STABLE BOUNDARY LAYER REGIME IN CNTRL/WCNTRL
AR...WHILE FURTHER WEST...INTO ECNTRL OK CONVECTION SHOULD REMAIN
STRONG FOR THE NEXT SEVERAL HOURS. RECENT MESONET REPORTS INDICATE
WIND GUSTS TO BETWEEN 35-45 KTS AMIDST THE RELATIVELY STABLE REGIME
IN ERN OK...SO CONVECTION HAS BEEN STRONG ENOUGH TO MIX STRONGER
WINDS DOWN TO THE SURFACE AND EXPECT THIS TREND TO CONTINUE AS
CONVECTION MOVES MORE SWD INTO HASKELL/SEQYOYAH/MUSKOGEE/AND
MCINTOSH COUNTIES.
..NADEN.. 05/13/2003
ATTN...WFO...LZK...TSA...
34459384 34719550 35209590 36299586 36089356
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