SWODY1
SPC AC 151925
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0225 PM CDT TUE SEP 15 2009
VALID 152000Z - 161200Z
...NO SVR TSTM AREAS FORECAST...
...ERN GREAT BASIN TO SRN HIGH PLAINS...
SCATTERED THUNDERSTORMS DEVELOPING FROM UT THROUGH CO AND NM MAY
BECOME CAPABLE OF PRODUCING ISOLATED HAIL AND DOWNBURSTS THIS
AFTERNOON...BUT THREAT IS TOO MARGINAL TO WARRANT MORE THAN 5%
SEVERE PROBABILITIES. SEE PREVIOUS DISCUSSION FOR FURTHER DETAILS.
...LOWER MS VALLEY...
THIS AFTERNOON AT LEAST A COUPLE OF WEAK CONVERGENCE BOUNDARIES
EXTENDS FROM A SURFACE LOW OVER SERN AR THROUGH CNTRL AND SRN MS
INTO SWRN AL. NUMEROUS SHOWERS AND THUNDERSTORMS ARE DEVELOPING IN
THE WEAKLY CAPPED MOIST WARM SECTOR ACROSS MUCH THE GULF COASTAL
STATES WHERE THE BOUNDARY LAYER HAS BEEN DESTABILIZED BY DIABATIC
WARMING. VWP DATA CONTINUES TO INDICATE SUBSTANTIAL 0-1 KM VEERING
ALONG AND NORTH OF THE SURFACE BOUNDARIES...BUT HODOGRAPH SIZE WILL
REMAIN SMALL DUE TO WEAK WINDS IN THE 0-3 KM LAYER. SOME TRANSIENT
WEAK UPDRAFT ROTATION HAS BEEN OBSERVED WITH A FEW CELLS. WILL
MAINTAIN LOW END PROBABILITIES FOR A BRIEF ISOLATED TORNADO THIS
AFTERNOON. AN ISOLATED WET MICROBURST OR TWO ALSO CANNOT BE RULED
OUT...BUT OVERALL THREAT WILL REMAIN QUITE LIMITED.
..DIAL.. 09/15/2009
.PREV DISCUSSION... /ISSUED 1113 AM CDT TUE SEP 15 2009/
...ERN GREAT BASIN TO SRN HIGH PLAINS...
AS EXPECTED UPPER LOW HAS DEVELOPED OVER CENTRAL UT AND WITH
BLOCKING PATTERN IN PLACE WILL DRIFT SEWD ACROSS UT. GIVEN COLD
NATURE OF LOW AND A RELATIVELY MOIST AIR MASS WITHIN ITS
CIRCULATION...PRIMARILY DIURNAL SHOWERS/THUNDERSHOWERS WILL BE
COMMON. WITH GENERALLY WEAK SHEAR AND MLCAPES NOT MUCH ABOVE 500
J/KG BY MID AFTERNOON...SEVERE POTENTIAL WILL BE LIMITED TO ISOLATED
HAIL AND LOCALIZED DOWNBURST WINDS ASSOCIATED WITH STRONGEST
UPDRAFTS. THIS REGIME WILL EXTEND EWD ACROSS SRN CO/NRN NM INTO
ADJACENT SRN HIGH PLAINS.
...LOWER MS VALLEY...
REF MCD 2017
ANOTHER DAY OF THE WEAK UPPER LOW SURFACE AND ALOFT DRIFTING SLOWLY
NEWD AND LOCATED THIS MORNING VICINITY SWRN AR/NRN LA BORDER. AIR
MASS CONTINUES VERY MOIST/TROPICAL IN NATURE ACROSS THE LOWER MS
VALLEY TO E OF THIS CIRCULATION...HOWEVER THE SHEAR PROFILES REMAIN
MARGINAL TO SUPPORT ANY ORGANIZATION TO THE EXPECTED WIDESPREAD
DIURNALLY DRIVEN CONVECTION/THUNDERSTORMS. THERE WILL BE SOME
ENHANCED LOW LEVEL SHEAR VICINITY SUBTLE BOUNDARY/WEAK WARM FRONT
THAT EXTENDS NW/SE ACROSS CENTRAL MS. THIS WOULD BE A MOST FAVORED
REGION FOR ROTATING UPDRAFTS AND AN ISOLATED TORNADO THREAT.
HOWEVER THERE WILL ALSO BE POTENTIAL FOR BRIEF ROTATION AND/OR WET
MICRO BURST COASTAL REGIONS OF MS TO FL PANHANDLE GIVEN THE 15-20KT
OF LOW LEVEL SHEAR AND INTERACTION WITH THE GULF SEA BREEZE.
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