MESOSCALE PRECIPITATION DISCUSSION 0077
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
906 AM EST FRI MAR 11 2016
 
AREAS AFFECTED...NORTHERN LA...SOUTHEAST AR...CENTRAL/SOUTHERN
MS...SOUTHWEST AL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 111406Z - 111800Z
 
SUMMARY...DEEP MOISTURE AND INSTABILITY FOCUSED AHEAD OF A FRONT
ACROSS THE PORTIONS OF THE GULF COAST WILL RESULT IN FLASH
FLOODING INTO EARLY AFTERNOON.

DISCUSSION...THE FOCUS OF THE DEEPEST MOISTURE (WITH PRECIPITABLE
WATER VALUES NEAR 2.00 INCHES...SUPPORTED BY THE LATEST BLENDED
TPW AND CONFIRMED BY THE 12Z KLIX SOUNDING) AND LOW LEVEL FLOW (30
TO 40 KNOT SOUTH SOUTHEAST AT 850 MB...PER REGIONAL VWP) CONTINUES
TO SHIFT EASTWARD AHEAD OF A BOWING CONVECTIVE SEGMENT ACROSS
SOUTHEAST MS INTO SOUTHWEST AL. THE BEST INSTABILITY (WITH SBCAPE
VALUES NEAR 2000 
J/KG PER THE 12Z KLIX SOUNDING) LAGS THE BOWING CONVECTIVE
SEGMENT...AS EVIDENCED BY THE CONVECTIVE ACTIVITY MOVING INTO
NORTHERN LA.

ALMOST ALL OF THE HIGH RESOLUTION GUIDANCE (SAVE THE 00Z WRF-ARW)
IS TOO SLOW WITH THE FOCUS OF HEAVIEST RAINFALL WITH THE BOWING
CONVECTIVE BOW)...INSTEAD FOCUSING ON THE BEST INSTABILITY AND
DEEPER MOISTURE FURTHER WEST INTO SOUTHEAST LA AND SOUTHERN MS. IN
THE NEAR TERM...THE BEST THREAT FOR EXCESSIVE RAINFALL SHOULD BE
FOCUSED ON THE BOWING SEGMENT ACROSS SOUTHEAST MS AND SOUTHWEST
MS. THIS IS SUPPORTED BY THE 00Z WRF ARW. 

OVERALL...LOCAL RADARS HAVE INDICATED A DECREASE IN HOURLY
RAINFALL RATES ACROSS THE REGION...WITH THE HIGHEST RATES OVER
SOUTHEAST MS/SOUTHEAST AL. GIVEN TRENDS IN MOISTURE AND
INFLOW...LOCAL 2.00 HOURLY RAINFALL RATES ARE POSSIBLE... WHICH IS
SUPPORTED BY THE LATEST MRMS PRECIPITATION RATE PRODUCT.  

FURTHER NORTH...STRONG ISENTROPIC LIFT OVER THE WEAKENING SURFACE
BOUNDARY STRETCHING ACROSS SOUTHEAST LA/SOUTHERN MS WILL CONTINUE
TO PUSH MOISTURE INTO NORTHERN LA/SOUTHEAST AR/CENTRAL MS. WHILE
THE RAINFALL RATES HERE ARE LOWER...ONE AND THREE HOUR FLASH FLOOD
VALUES ARE AS LOW AS 1.00 TO 1.50 INCHES. THE ADDITIONAL RAINFALL
COULD EXACERBATE ONGOING FLOODING.

HAYES

ATTN...WFO...BMX...JAN...LIX...LZK...MEG...MOB...SHV...

ATTN...RFC...LMRFC...SERFC...

LAT...LON   33929060 33828991 33798984 33788903 33708880 
            33418806 33198774 32788737 32498723 31738708 
            31268703 30648708 30598711 30048735 29978744 
            29918912 29898922 30088999 30369036 31209082 
            31609183 31839317 32479326 33129298 33459264 
            33479214 33829138