SWODY1
SPC AC 251954
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0254 PM CDT SAT JUN 25 2011
VALID 252000Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE LOWER MO/MID
MS/LOWER OH/TN VALLEYS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NRN PLAINS AREA...
...OZARKS/MID MS/LOWER OH/TN VALLEY REGIONS...
SEWD/SWD STORM PROPAGATION WITH MID MS VALLEY CONVECTION APPEARS
LESS LIKELY ATTM...AND THUS HAVE TRIMMED SLIGHT RISK NWWD IN THE
MS/AL REGION. ELSEWHERE...EXPECT AN INCREASE IN CONVECTION TO OCCUR
FROM SERN KS ACROSS MO LATER THIS AFTERNOON/EVENING IN THE WAKE OF
ONGOING STORMS. AS POST-CONVECTIVE AIRMASS RECOVERS...INSTABILITY
-- IN CONJUNCTION WITH AMPLE EXISTING SHEAR -- SUPPORTS CONTINUATION
OF THE SLIGHT RISK FORECAST. SEVERAL MODELS SUGGEST DEVELOPMENT OF
AN MCS LATER THIS EVENING/OVERNIGHT...WITH SEWD/SWD MOVEMENT ACROSS
MO -- AND POSSIBLY INTO NRN AR -- EXPECTED.
...NRN PLAINS AREA...
INCREASING CU EVIDENT FROM WRN ND SWD INTO SRN/ERN WY ATTM REVEALS
CORRESPONDING INCREASE IN LARGE-SCALE UVV...WITH FORECAST FOR
SCATTERED STORM DEVELOPMENT ACROSS THIS REGION STILL ON TRACK.
DESTABILIZATION ONGOING COMBINED WITH SUFFICIENT SHEAR INDICATED
ACROSS THIS REGION SUPPORTS CONTINUATION OF SLIGHT RISK FORECAST IN
THIS AREA.
..GOSS.. 06/25/2011
.PREV DISCUSSION... /ISSUED 1129 AM CDT SAT JUN 25 2011/
...LOWER MO VALLEY INTO THE LOWER MS VALLEY AND CNTRL GULF STATES...
RADAR DATA SUGGEST THAT NOCTURNAL MCS ONGOING OVER MO HAS GENERATED
A CONVECTIVELY INDUCED MCV WHICH SHOULD CONTINUE TO TRANSLATE EWD
INTO IL TODAY. FORCING ALONG THE SRN PERIPHERY OF THIS FEATURE
COMBINED WITH CONVERGENCE ALONG AGGREGATE CONVECTIVE
OUTFLOW-SYNOPTIC FRONTAL BOUNDARY...EXTENDING FROM E-CNTRL KS
THROUGH CNTRL MO AND FAR WRN KY INTO MIDDLE TN...WILL FOCUS THE MOST
INTENSE TSTM ACTIVITY THIS AFTERNOON INTO TONIGHT. AIR MASS ALONG
AND S OF THIS BOUNDARY IS QUITE MOIST WITH DEWPOINTS IN THE UPPER
60S AND LOWER 70S. WHEN COUPLED WITH DAYTIME HEATING AND STEEP
MIDLEVEL LAPSE RATES...ENVIRONMENT IS EXPECTED TO BECOME MODERATELY
TO STRONGLY UNSTABLE BY AFTERNOON WITH MLCAPE INCREASING TO
2000-3500 J/KG.
CURRENT INDICATIONS ARE THAT ONGOING STORMS OVER CNTRL MO SHOULD
CONTINUE TO INTENSIFY THIS AFTERNOON WITH ADDITIONAL STORM
DEVELOPMENT LIKELY ALONG ABOVE-MENTIONED BAROCLINIC ZONE. KINEMATIC
ENVIRONMENT WILL SUPPORT SUPERCELLS AND BOW ECHO-TYPE STORM
STRUCTURES WITH ATTENDANT RISKS OF A TORNADO OR TWO...LARGE HAIL AND
CORRIDORS OF WIND DAMAGE FROM THE OZARKS INTO LOWER OH VALLEY.
FOR ADDITIONAL NEAR-TERM GUIDANCE ON THIS AREA...SEE MCD 1382.
MEANWHILE...DOWNSTREAM TSTM CLUSTER OVER WRN KY MAY GROW UPSCALE
THIS AFTERNOON AS COLD POOL ENCOUNTERS AN UNCAPPED AIR MASS WITH
MLCAPE OF 2000-3000+ J/KG ACROSS PORTIONS OF WRN/MIDDLE TN INTO
MS/AL. DEEP-LAYER STEERING FLOW SUGGESTS THAT THESE STORMS WOULD
TEND TO MOVE MORE SWD WITH AN ATTENDANT RISK FOR DAMAGING WINDS AND
SOME HAIL THROUGH THIS EVENING.
...DAKOTAS/NEB/WY...
SHORTWAVE TROUGH AND ASSOCIATED 50-60 KT MIDLEVEL JET STREAK OVER
THE NRN ROCKIES WILL TRANSLATE NEWD INTO SRN SASKATCHEWAN BY THIS
EVENING WITH SRN FRINGE OF STRONGER FORCING FOR ASCENT GLANCING
REGION NEAR THE PEAK OF THE DIURNAL HEATING CYCLE. THIS COUPLED
WITH CONVERGENCE ALONG COLD FRONT SETTLING SEWD THROUGH THE WRN
DAKOTAS AND ASCENT ALONG FAVORED TERRAIN WILL SUPPORT THE
DEVELOPMENT OF SCATTERED TSTMS LATER THIS AFTERNOON INTO TONIGHT.
ELY LOW-LEVEL WIND COMPONENT OWING TO WEAK LOW PRESSURE OVER ERN WY
WILL MAINTAIN 50S BOUNDARY LAYER DEWPOINTS BENEATH NRN EXTENSION OF
EML...RESULTING IN MLCAPE VALUES OF 1500-2500 J/KG. THIS
INSTABILITY WILL COINCIDE WITHIN A KINEMATIC ENVIRONMENT FEATURING
VERTICALLY VEERING WIND PROFILES WITH 35-45 KT OF DEEP WLY SHEAR.
AS SUCH THE POTENTIAL WILL EXIST FOR SUPERCELLS WITH THE PRIMARY
HAZARDS BEING LARGE HAIL AND DAMAGING WINDS.
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