DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 291942
SWODY1
SPC AC 291940

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0240 PM CDT WED AUG 29 2012

VALID 292000Z - 301200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR THE LOWER MS VALLEY...

...LOWER MS VALLEY...
NO CHANGES NEEDED THIS UPDATE...PLEASE SEE PREVIOUS DISCUSSION.

...NRN PLAINS...
PREVIOUS FORECAST REASONING IS WELL ON TRACK. SMALL EXPANSION TO THE
WIND PROBABILITY WITH ISOLATED TSTMS FORMING OFF THE BLACK HILLS AND
DOWNSTREAM SURFACE DEW POINT DEPRESSIONS OF 50-70 F.

...SE GA/SC...
HAVE REMOVED WIND PROBABILITIES GIVEN DCAPE VALUES REMAINING BELOW
PREVIOUS FORECAST...AMIDST A WEAKLY SHEARED ENVIRONMENT. LOCALLY
STRONG CONVECTION IS LIKELY DURING THE NEXT FEW HOURS...BUT AN
ORGANIZED SEVERE RISK IS NOT ANTICIPATED.

..GRAMS.. 08/29/2012

.PREV DISCUSSION... /ISSUED 1130 AM CDT WED AUG 29 2012/

...LOWER MS VALLEY...
HURRICANE ISAAC IS DRIFTING NWWD OVER SRN LA AND LATEST NHC FORECAST
INDICATES THE SYSTEM WILL REACH CENTRAL LA BY THE END OF THE PERIOD.
12Z RAOB AT SIL AND LATEST VAD PROFILES AT KLIX AND KMOB EXHIBIT
VERY STRONG LOW LEVEL VERTICAL SHEAR ASSOCIATED WITH 50-65 KT SELY
WINDS IN THE LOWEST 1 KM...WITH ENLARGED CLOCKWISE TURNING
HODOGRAPHS IN THE LOWEST 3 KM. INCORPORATION OF OBSERVED STORM
MOTIONS RESULTS IN SRH OF 150-400 M2/S2 SUPPORTIVE OF CONVECTIVE
UPDRAFT ROTATION. AREA RADARS CONTINUE TO SHOW SMALL TRANSIENT
ROTATIONAL COUPLETS EMBEDDED WITHIN SEVERAL CONVECTIVE BANDS OVER
EXTREME SERN MS AS CELLS MOVE RAPIDLY NWWD. EXTENSIVE CLOUD COVER
SUGGESTS THAT DIURNAL HEATING WILL BE LIMITED THIS AFTERNOON AMIDST
A MOIST ADIABATIC THERMODYNAMIC PROFILE WITH GENERALLY WEAK CAPE.
HOWEVER...THE FAVORABLE KINEMATIC FIELDS INDICATE A CONTINUED THREAT
FOR SHALLOW SUPERCELLS AND ISOLATED TORNADOES WITHIN THE MORE
FAVORABLE NERN QUADRANT OF ISAAC AS IT DRIFTS NWWD THROUGH TONIGHT.

...NRN PLAINS...
WATER VAPOR IMAGERY SHOWS A STRONG UPPER TROUGH/VORTICITY MAX MOVING
ONSHORE INTO THE PACIFIC NW. THIS SYSTEM IS FORECAST TO MOVE ENEWD
AND FLATTEN THE NRN PORTION OF THE UPPER RIDGE EXTENDING FROM THE
CENTRAL HIGH PLAINS INTO THE CANADIAN PRAIRIES. A STRONG SURFACE
COLD FRONT IN ADVANCE OF THE UPPER TROUGH IS EXPECTED TO PROGRESS
EWD ACROSS THE NRN PLAINS THIS AFTERNOON AND TONIGHT AND PROVIDE A
FOCUS FOR THUNDERSTORM DEVELOPMENT. GENERALLY CLEAR SKIES WILL
RESULT IN SUBSTANTIAL DIABATIC HEATING THIS AFTERNOON WITH A DEEP
WELL-MIXED BOUNDARY LAYER DEVELOPING AHEAD OF THE ADVANCING COLD
FRONT. MODEL GUIDANCE INDICATES ISOLATED STORMS MAY FROM DURING THE
LATE AFTERNOON AND EVENING NEAR THE FRONT. ALTHOUGH THE STRONGER
WINDS ALOFT AND ATTENDANT VERTICAL SHEAR WILL REMAIN WEST/NORTH OF
THE WARM SECTOR...SUFFICIENT SHEAR /25-30 KT IN THE LOWEST 6 KM/ FOR
ORGANIZED MAINLY MULTICELL STORMS TO DEVELOP WITH POTENTIAL TO
PRODUCE GUSTY SURFACE WINDS AND POSSIBLE HAIL.

...SE GA/SC...
THE NERN EXTENT OF THE MOISTURE PLUME ASSOCIATED WITH ISAAC AND
DIURNAL HEATING S OF THE THICKER CLOUDS AND A WEAK SURFACE FRONT IN
THE CAROLINAS WILL CONTRIBUTE TO AFTERNOON MLCAPE VALUES OF
1500-2000 J/KG. DCAPE OF 600-1000 J/KG AND MODERATE BUOYANCY COULD
RESULT IN SUFFICIENTLY STRONG PRECIPITATION LOADING AND DOWNDRAFTS
FOR A MARGINAL DAMAGING WIND RISK WITH THE STRONGEST MULTICELL
CLUSTERS.

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