MESOSCALE PRECIPITATION DISCUSSION 0075
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1151 AM EDT TUE MAY 27 2014
 
AREAS AFFECTED...TX/LA/AR 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING UNLIKELY 
 
VALID 271551Z - 271951Z
 
SUMMARY...LOCALLY HEAVY RAINFALL IS EXPECTED TO CONTINUE IN
ASSOCIATION WITH A DECAYING MCS BUT IS NOT EXPECTED TO RESULT IN
SIGNIFICANT FLASH FLOODING DUE TO INSUFFICIENT RATES ACROSS A
LARGE AREA. 

DISCUSSION...PEAK HOURLY RAINFALL RATES APPROACHING 1.5 INCHES
WILL LIKELY OCCUR AS A LINE OF STRONG CONVECTION ALONG THE LEADING
EDGE OF A DECAYING MCS NEAR GALVESTON MOVES INTO THE NORTHWESTERN
GULF...WITH AREAS MOST LIKELY TO BE IMPACTED INCLUDING THE WESTERN
HALF OF LOUISIANA.  

LOWER RAINFALL RATES WILL ACCOMPANY NORTHERN PORTIONS OF THE LINE
INTO WESTERN ARKANSAS WHERE CAPE VALUES AND STORM RELATIVE
CONVERGENCE ARE EXPECTED TO BE WEAKER...AND ALSO TO THE REAR OF
THE MCS OVER CENTRAL TEXAS WHERE THE 850-700 MB LAYER FLOW IS
EXPERIENCING A LOCAL MAXIMA DUE TO THE REAR INFLOW JET.  THIS
REGION OVER CENTRAL TEXAS IS MORE SUSCEPTIBLE TO EXPERIENCING
FLASH FLOODING.  HOWEVER...GIVEN ANTICIPATED CELL MOTIONS TOWARD
THE EAST AT 30 KNOTS AND LOWER PRECIPITABLE WATER/INSTABILITY
VALUES...TOTAL RAINFALL AMOUNTS ARE NOT EXPECTED TO BE VERY HEAVY.

THE 12Z NAM CONUS NEST HAS A REASONABLY GOOD HANDLE ON THE CURRENT
EVOLUTION BUT IS TOO SLOW AND HEAVY WITH THE SOUTHWESTERN TIP OF
THE MCS...LIKELY DUE TO SPIN-UP ERROR. SOME NUMERICAL GUIDANCE
SUGGESTS THAT EXCESSIVE RAINFALL MAY RETURN TO PORTIONS OF THE
TEXAS COAST AS WELL AS LOUISIANA TONIGHT.  HOWEVER...IT REMAINS
UNCLEAR TO WHAT EXTENT IF ANY THE CURRENT MCS MAY IMPEDE NEW
DEVELOPMENT.

JAMES

ATTN...WFO...JAN...LZK...LCH...SHV...TSA...HGX...FWD...CRP...
EWX...SJT...

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

LAT...LON   35519321 34389216 32069188 29529282 28209519 28009739
            29269909 31379965 32929875 33039717 32139562 32289438
            33409403 34839477 35529440 35519321