Post by SKYSUMMIT on Apr 28, 2016 9:06:58 GMT -6
MESOSCALE DISCUSSION 0481
NWS STORM PREDICTION CENTER NORMAN OK
1002 AM CDT THU APR 28 2016
AREAS AFFECTED...COASTAL AREAS AND BARRIER ISLANDS OF SOUTHEAST
LA...SOUTHEAST MS...SOUTHWEST AL AND PART OF THE FAR WESTERN FL
PANHANDLE
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 281502Z - 281730Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...AN ISOLATED THREAT FOR WATERSPOUTS AND/OR A TORNADO AND
LOCALLY STRONG WIND GUSTS CANNOT BE RULED OUT IN VICINITY TO
OFFSHORE OF COASTAL AREAS OF SOUTHEAST LA...SOUTHEAST MS...SOUTHWEST
AL AND PERHAPS PARTS OF THE FAR WESTERN FL PANHANDLE. LOCALIZED
SPATIAL THREAT CURRENTLY PRECLUDES THE ISSUANCE OF A TORNADO
WATCH...THOUGH CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED.
DISCUSSION...THE MERGING OF CONVECTIVE OUTFLOW BOUNDARIES WILL
CONTINUE TO BE PRODUCED BY NEW STORM DEVELOPMENT WITHIN THE
SOUTHWEST PERIPHERY OF A BACK-BUILDING MCS NEAR AND OFFSHORE THE
CENTRAL GULF COAST REGION OF SOUTHEAST MS AND SOUTHWEST AL. THESE
STORM-SCALE BOUNDARY MERGERS WILL BE OF GREATEST CONCERN IN THE
SHORT-TERM AS THEY RESULT IN AN ENHANCED KINEMATIC /STRONGER SRH/
ENVIRONMENT FOR LOW-LEVEL ROTATION. THIS HAS BEEN OBSERVED IN THE
MOB WSR-88D IMAGERY WITH A ROTATIONAL COUPLET LOCATED 20-25 SOUTH OF
KPQL. MESOSCALE ANALYSIS INDICATED THE LEADING EXTENT OF THE
CONVECTIVE COLD POOL EXTENDED FROM EXTREME SOUTHWEST AL TO OFFSHORE
AND SOUTH OF THE AL/MS BARRIER ISLANDS...AND THEN WNWWD INTO
SOUTHEAST LA IN ST TAMMANY PARISH.
THE ENVIRONMENT IN THIS REGION IS QUITE MOIST AS SAMPLED BY THE LIX
12Z SOUNDING /PRECIPITABLE WATER NEAR 1.9 INCHES/...AND WITHIN A
CORRIDOR OF PW RANGING FROM 1.6-1.8+ INCHES FROM SOUTH OF LA INTO
SOUTHERN AL. ALTHOUGH THE LOW-LEVEL WINDS ARE FORECAST TO BACK TO A
SOUTHERLY COMPONENT THIS AFTERNOON...A CONTINUED MOIST/UNSTABLE
INFLOW INTO THE SOUTHWEST PERIPHERY OF THIS MCS SUGGESTS IT SHOULD
PERSIST FOR A FEW MORE HOURS. THIS WILL BE FURTHER SUPPORTED BY
THIS REGION LOCATED BENEATH DIFFLUENT FLOW REGIME ALOFT AND 30-40 KT
OF WLY 500-MB WINDS SPREADING ACROSS THIS AREA...MAINTAINING
EFFECTIVE BULK SHEAR FOR STORM ORGANIZATION.
..PETERS/CORFIDI.. 04/28/2016
