MESOSCALE PRECIPITATION DISCUSSION 0504
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
920 PM EDT FRI JUL 29 2016
 
AREAS AFFECTED...SOUTHERN AR...FAR SOUTHEAST OK 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 300120Z - 300515Z
 
SUMMARY...CONVECTION TRAINING OVER SOUTHERN AR COULD RESULT IN
HOURLY RAINFALL RATES NEAR 2.50 INCHES...WHICH COULD PRODUCE A
SHORT TERM FLASH FLOOD THREAT WHERE TRAINING OCCURS. 

DISCUSSION...THE KLZK RADAR SHOWED CONVECTION BEGINNING TO TAKE ON
A WEST TO EAST ORIENTATION ACROSS PORTIONS OF FAR SOUTHEAST OK
INTO SOUTHWEST AR. TOPS HAVE BEEN COOLING WITH THE DEVELOPING
ACTIVITY...WITH CLOUD TOP TEMPERATURES AS LOW AS -71 CELSIUS. THE
CONVECTION IS DEVELOPING/STRENGTHENING IN AN AXIS OF 1500-2500 OF
MLCAPE (PER THE LATEST RAP ANALYSIS)...AS WELL AS OF 2.00 INCH
PRECIPITABLE WATER AIR. 

THE KLZK RADAR SHOWED HOURLY RAINFALL RATES NEAR 2.50 INCHES
ACROSS PORTIONS OF PIKE...CLARK AND HOT SPRING COUNTIES. BOTH THE
00Z LZK AND OUN SOUNDINGS SHOWED DRY AIR IN THE MID LEVELS...SO
THESE AMOUNTS MAY BE HAIL CONTAMINATED (THOUGH THE KZLK KDP
PRODUCT SHOWED SEVERAL HEAVY RAIN CORES). THE ACTIVITY IS
GENERALLY PARALLEL TO THE MID LEVEL...SO THE THREAT FOR ADDITIONAL
TRAINING INCREASES WITH TIME. THERE SHOULD BE A SLOW SOUTHWARD
DRIFT... (PER RAP BASED CORFIDI VECTORS).

THE LATEST HRRR/PARALLEL HRRR HAD A DECENT HANDLE ON THE ACTIVITY
(BASED ON THE SIMULATED REFLECTIVITY)...WITH LOCAL 2-4 INCH
RAINFALL AMOUNTS IN AREAS WITH TRAINING. BASED ON THE KLZK RADAR
INFORMATION...THESE AMOUNTS SEEM REASONABLE. WHILE ONE AND THREE
HOUR FLASH FLOOD GUIDANCE VALUES ARE GENERALLY ABOVE 2.50
INCHES...TRAINING IN THE HIGH MOISTURE ENVIRONMENT SHOULD PRODUCE
HOURLY RAINFALL RATES NEAR OR IN EXCESS OF THESE
VALUES...RESULTING IN A FLASH FLOOD THREAT. 

THE LATEST RAP/HRRR SUGGEST THAT THE CONVECTION SHOULD BECOME MORE
OUTFLOWED DOMINATED BETWEEN 04-05Z...AHEAD OF AN APPROACHING WEAK
SHORT WAVE.

HAYES

ATTN...WFO...JAN...LZK...MEG...SHV...TSA...

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

LAT...LON   35049530 34729314 34119098 33409001 32999078 
            33059114 33469302 33779440 34129552