MESOSCALE PRECIPITATION DISCUSSION 0036
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
318 PM EDT FRI MAY 10 2013
 
AREAS AFFECTED...SOUTHERN LA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 101914Z - 102314Z
 
SUMMARY..FLASH FLOODING POSSIBLE THROUGH THE AFTERNOON AS A
WEST/EAST CONVECTIVE BAND SETS UP AHEAD OF AN APPROACHING
CONVECTIVE COMPLEX AND FOSTERS AN ENHANCED THREAT FOR TRAINING
CONVECTION.

DISCUSSION...THE LATEST VIS SATELLITE IMAGERY INDICATES A
WEST/EAST ORIENTED CONVECTIVE BAND OVER SOUTHERN LA EXTENDING EAST
FROM THE UPSTREAM MCS THAT IS EXITING SOUTHEAST TX. A FAIRLY
ROBUST CONVECTIVE VORT IS ASSOCIATED WITH THE MCS AND APPEARS TO
BE DYNAMICALLY AIDING THE CONVECTIVE LINE TO THE EAST...WITH AT
LEAST SOME INTENSIFICATION TO THE WARM AIR/MOISTURE ADVECTION
PATTERN INTO SOUTHERN LA OUT OF THE GULF OF MEXICO. THE CONVECTION
THOUGH IS GENERALLY ROOTED IN THE 850MB TO 925MB WITH THE BOUNDARY
LAYER QUITE STABLE IN THE WAKE OF AN OUTFLOW BOUNDARY PASSAGE FROM
EARLY MORNING CONVECTION OVER THIS AREA. SOUTH-SOUTHWESTERLY FLOW
IN THE 850MB TO 925MB BASED ON THE LATEST RAP ANALYSIS HAS
ACTUALLY INCREASED THE LAST FEW HOURS TO AROUND 30 KTS AHEAD OF
THE APPROACHING MCS...AND WITH A POOL OF MUCAPE VALUES JUST OFF
SOUTHWEST LA AT OR ABOVE 2000 J/KG. THIS ENERGY WILL BE ADVECTED
NORTHEAST INTO SOUTHERN LA IN AN ELEVATED FASION THROUGH THE
AFTERNOON AHEAD OF THE MCS AND SHOULD SUSTAIN THE THREAT FOR
TRAINING CONVECTION FOR A FEW MORE HOURS UNTIL THE MCS ARRIVES AND
CLEARS THE REGION. PWATS OF 1.6 TO 1.7 INCHES AS PER LATEST
GOES-SOUNDER DATA WILL SUPPORT RAINFALL RATES OF 1 TO 2 INCHES/HR.
DESPITE HIGH FFG VALUES...THESE PERSISTENT CONVECTIVE RAINS MAY
LEAD TO SOME RUNOFF PROBLEMS.

ORRISON


ATTN...WFO...LIX...LCH...

LAT...LON   30269070 30159011 29918978 29658989 29439048 29459120
            29539205 29769240 30069222 30219166 30269070 


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