MESOSCALE PRECIPITATION DISCUSSION 0083
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
428 PM EST SAT MAR 12 2016
 
AREAS AFFECTED...NORTHERN LA...EASTERN AR....WESTERN MS...FAR
WESTERN TN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 122130Z - 130230Z
 
SUMMARY...CONVECTION MOVING ALONG THE MS RIVER ACROSS NORTHERN
LA/EASTERN AR/WESTERN MS WILL PRODUCE LOCALLY HEAVY RAINFALL IN
AREAS THAT RECEIVE TREMENDOUS AMOUNTS OF RAIN IN THE PAST WEEK.
THE ADDITIONAL RAINFALL COULD RESULT IN LOCALIZED FLASH FLOODING
THROUGH THIS EVENING.

DISCUSSION...CONVECTION OVER NORTHERN AND CENTRAL LA LATE THIS
AFTERNOON WAS SPREADING NORTH ALONG AN INSTABILITY AXIS (WITH
SBCAPE VALUES BETWEEN 500 AND 1000 J/KG) STRETCHING FROM NORTHERN
LA/SOUTHEAST AR INTO FAR WESTERN MS. THE CONVECTION IS FOLLOWING
THE WESTERN EDGE OF A PRECIPITABLE WATER GRADIENT ACROSS THE SAME
GENERAL AREA. IN THE PAST HOUR OR SO...RADARS ACROSS SOUTHERN LA
HAD BEEN SHOWING THE LOW LEVEL INFO BECOMES MORE
SOUTHEASTERLY...WHICH COULD ALLOW ACCESS TO THE BEST LOW LEVEL
MOISTURE PLUME OVER SOUTHEAST LA AND SOUTHERN MS/AL.

LOCAL RADARS AND THE MRMS PRECIPITABLE RATE PRODUCT INDICATED
HOURLY RAINFALL RATES BETWEEN 1.00 AND 1.50 INCHES...BUT SURFACE
OBSERVATIONS HAVE BEEN CLOSER TO 0.50 INCHES. AS THE UPPER LOW
OVER SOUTHWEST LA CONTINUES TO OPEN UP AND TRACK NORTH...THE
CONVECTION SHOULD CONTINUE TO MOVE/DEVELOP ALONG THE INSTABILITY
AXIS ACROSS NORTHERN LA/EASTERN AR INTO THE WESTERN HALF OF MS AND
FAR WESTERN TN. 

THERE IS GENERAL AGREEMENT AMONG THE HIGH RESOLUTION GUIDANCE TO
LIFT THE SHORT WAVE 
ACROSS NORTHERN LA INTO SOUTHEAST AR DURING THE EVENING HOURS. THE
LIFT AHEAD OF THE SHORT WAVE SHOULD SUPPORT AN EXPANDING AREA OF
CONVECTION RIDING NORTH ALONG THE MS RIVER. LOCAL 1-2 INCH
RAINFALL AMOUNTS ARE EXPECTED...ESPECIALLY WHERE TRAINING OCCURS. 

ONE AND THREE HOUR FLASH FLOOD GUIDANCE VALUES HAVE REBOUNDED TO
VALUES AS LOW AS 1.00 TO 1.50 INCHES. GIVEN HOW MUCH RAINFALL THIS
AREA RECEIVED IN THE LAST WEEK...SATURATED SOILS PROBABLY REMAIN.
THE ADDITIONAL RAINFALL COULD RESULT IN ADDITIONAL FLOODING...OR
EXACERBATION OF EXISTING FLOODING.

HAYES

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

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

LAT...LON   36428936 36368893 36238877 36068871 35938869 
            35628871 35448875 35338880 35118882 34668894 
            34158903 33578917 33128926 32718946 32408963 
            32118987 31779014 31649039 31579049 31469068 
            31379101 31369128 31399149 31449176 31569203 
            31949288 32469333 33489362 34089336 34369310 
            34979263 35629224 36109168 36309102 36309045 
            36118991 36178971 36328955