Saturday, March 29, 2008

MESO: Mesoscale Discussion 0494

ACUS11 KWNS 291634
SWOMCD
SPC MCD 291633
ALZ000-MSZ000-LAZ000-TXZ000-291830-

MESOSCALE DISCUSSION 0494
NWS STORM PREDICTION CENTER NORMAN OK
1133 AM CDT SAT MAR 29 2008

AREAS AFFECTED...PARTS OF ERN TX...LA...MS

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 291633Z - 291830Z

A GRADUAL INCREASE IN THUNDERSTORM ACTIVITY APPEARS PROBABLE THROUGH
MID AFTERNOON AND BEYOND. ALTHOUGH ISOLATED CELLS COULD APPROACH OR
BRIEFLY EXCEED SEVERE CRITERIA...SEVERE POTENTIAL GENERALLY APPEARS
LOW. HOWEVER...TRENDS WILL BE MONITORED.

AN IMPULSE EMANATING FROM A WEAK SUBTROPICAL BELT OF WESTERLIES
CONTINUES TO SLOWLY PROGRESS ACROSS THE LOWER MISSISSIPPI VALLEY.
THIS IS ACCOMPANIED BY A DISCERNIBLE LOW/MID-LEVEL CIRCULATION
..WHICH IS EXPECTED TO SHIFT OUT OF NORTHEAST LOUISIANA...NEAR THE
INTERSTATE 20 CORRIDOR...THROUGH CENTRAL MISSISSIPPI BETWEEN NOW AND
20-21Z. ASSOCIATED FORCING FOR UPWARD VERTICAL MOTION IS EXPECTED
TO CONTRIBUTE TO CONVECTIVE DEVELOPMENT...AS A MOIST BOUNDARY LAYER
ACROSS UPPER TEXAS COASTAL AREAS...CENTRAL/SOUTHERN LOUISIANA AND
MISSISSIPPI WARMS WITH DAYTIME HEATING.

DEVELOPMENT WILL PROBABLY NOT BE PARTICULARLY RAPID...BUT MIXED
LAYER CAPE INCREASING TO AROUND 1000 J/KG BY 19-21Z SHOULD BECOME
SUPPORTIVE OF STEADILY INTENSIFYING STORMS. A STALLED SURFACE FRONT
MAY PROVIDE THE FOCUS FOR ACTIVITY...BOTH AHEAD OF THE CYCLONIC
VORTICITY CENTER...NEAR/EAST AND SOUTH OF JACKSON MS...AND IN THE
LOW/MID-LEVEL WARM ADVECTION REGIME TO ITS WAKE...NEAR/WEST AND
NORTH OF ALEXANDRIA LA.

LOW-LEVEL HODOGRAPHS ACROSS THIS REGION ARE WEAK...BUT 30-40 KT
WESTERLY 500 MB FLOW...AND MODERATELY STEEP MID-LEVEL LAPSE RATES
COULD SUPPORT A FEW RELATIVELY SHORT-LIVED STRONGER CELLS CAPABLE OF
PRODUCING HAIL/LOCALIZED WIND GUSTS NEAR SEVERE LIMITS.
OTHERWISE...SEASONABLY HIGH MOISTURE LEVELS...WITH PRECIPITABLE
WATER VALUES IN EXCESS OF 1.5 INCHES...MAY SUPPORT LOCALLY HEAVY
RAINFALL IN SLOW MOVING/TRAINING STORM CLUSTERS LATER THIS
AFTERNOON.

.KERR.. 03/29/2008

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MOB...JAN...LIX...LCH...SHV...

32419445 32389330 31969246 31989167 32509075 33138990
32948861 31918832 31018891 30719000 30439102 30349206
30769339 30929408 31659472 32139481

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