MESOSCALE PRECIPITATION DISCUSSION 0214
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
601 AM EDT FRI JUL 18 2014
 
AREAS AFFECTED...EASTERN TX...CENTRAL AND SOUTHERN LA...SOUTHWEST
MS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 181000Z - 181600Z
 
SUMMARY...EXTREMELY HEAVY RAINS ARE EXPECTED OVER CENTRAL AND
SOUTHERN LA THROUGH THE MORNING...POSSIBLY IMPACTING PARTS OF
SOUTHWEST MS TOWARD MIDDAY. VERY INTENSE RAINFALL RATES AND
REPEATING CONVECTIVE CELLS WILL PRODUCE SEVERE FLASH FLOODING.

DISCUSSION...THE RADAR IMAGERY SHOWS VERY INTENSE CLUSTERS AND
ORGANIZED BANDS OF CONVECTION IMPACTING A LARGE PORTION OF CNTRL
AND ESP SWRN LA ATTM. THE CONVECTION IS BEING HEAVILY FAVORED BY
INCREASINGLY CONFLUENT AND VERY MOIST LOW LVL FLOW IN OFF THE WRN
GULF OF MEXICO WHICH IS INTERACTING WITH A FRONTAL ZONE. IN
ADDITION TO THIS...THERE IS A RATHER STRONG UPPER LEVEL TROUGH
THAT IS DIGGING THROUGH THE LWR MS VLY ATTM...WHICH IS PROVIDED
SOME ORGANIZED LARGER SCALE ASCENT OVER THE FRONTAL ZONE AND IS
ALSO RESPONSIBLE FOR A WAVE OF LOW PRESSURE ALONG THE FRONT.

THE LATEST RAP ANALYSIS INDICATES VERY UNSTABLE AIR POOLED OUT
OVER THE WRN GULF OF MEXICO...WITH MUCAPE VALUES OF OVER 3000
J/KG. MEANWHILE...GPS PWATS OVER SERN TX AND LA ARE AS HIGH NOW AS
2.2 TO 2.4 INCHES. THIS ENHANCED POOL OF MOISTURE AND INSTABILITY
WILL CONTINUE TO BE TRANSPORTED NEWD INTO THE AFOREMENTIONED
FRONTAL ZONE THROUGH THE MORNING AS BOUNDARY LAYER AND H85 FLOW
CONTINUE TO VEER SOMEWHAT...AND A DEFINABLE LOW LVL JET REACHES UP
TO 40 KTS.

STRONG SFC FORCING...DEEPER LYR ASCENT AND IMPRESSIVE
THERMODYNAMICAL ENERGY TRANSPORT LENDS SUPPORT TO THE IDEA OF
EXTREMELY HEAVY RAINS THIS MORNING OVER CNTRL AND ESP SRN
LA...WHERE RAINFALL RATES OVER 4 INCHES/HR WILL BE EXPECTED. THE
06Z NAM-CONEST...00Z ARW AND 05Z HRRR ALL SUPPORT BANDS OF
EXCESSIVE TOTALS WITH STORM TOTAL AMOUNTS APPROACHING OR
POTENTIALLY EXCEEDING 10 INCHES THROUGH MIDDAY. THIS WILL RESULT
IN POTENTIALLY LIFE-THREATENING FLASH FLOODING. WILL CONTINUE TO
MONITOR.

ORRISON

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

ATTN...RFC...LMRFC...WGRFC...

LAT...LON   32669123 32629019 31978925 31208898 30428912 29818945
            29428987 29199054 29199133 29419221 29479279 29639351
            29539405 29219491 29269524 29669553 30139539 30599497
            31249411 31949317 32319245 32669123