MESOSCALE PRECIPITATION DISCUSSION 0348
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
759 AM EDT TUE JUN 14 2016
 
AREAS AFFECTED...ARKLATEX INTO SERN AR...NERN LA AND FAR WRN MS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 141156Z - 141630Z
 
SUMMARY...CONTINUED SLOW MOVEMENT AND TRAINING OF HEAVY RAINFALL
IS EXPECTED TO CONTINUE A FLASH FLOOD THREAT THROUGH AT LEAST 16Z.
LOCALIZED ADDITIONAL RAINFALL OF 4-6 INCHES IS POSSIBLE.

DISCUSSION...KLZK RADAR IMAGERY HAS SHOWN TRAINING RAINFALL WITH
DUAL POL ESTIMATED RATES OF 1-2 IN/HR OVER CALHOUN AND BRADLEY
COUNTIES OVER THE PAST HOUR OR TWO. MEANWHILE...A LINE OF TRAINING
RAINFALL HAS DEVELOPED OVER THE PAST HOUR ACROSS SWRN
ARKANSAS...ORIENTED FROM WNW TO ESE. A WEAK LOW AT 850 MB WAS
ESTIMATED TO BE LOCATED IN N-CNTRL ARKANSAS AT 11Z VIA RAP
ANALYSES AND AREA VAD WIND PLOTS. CONVERGENCE AT 850 MB ACROSS SRN
ARKANSAS APPEARS TO BE A KEY FACTOR IN CONVECTIVE PLACEMENT...WITH
DIFFLUENT UPPER FLOW HELPING TO ENHANCE LIFT. 11Z GPS SITES
INDICATE PRECIPITABLE WATER VALUES OF 2.4 TO 2.6 INCHES IN NERN
LOUISIANA. INSTABILITY CONTINUES TO BE GREATER ACROSS ERN TEXAS
AND NRN LOUISIANA WITH THE ONGOING CONVECTION IN ARKANSAS FALLING
ALONG THE INSTABILITY GRADIENT....WITH WSW LOW LEVEL FLOW
ADVECTING INSTABILITY INTO THE REGION.

THE 850 MB LOW IS FORECAST BY THE RAP TO WEAKEN AS IT SLOWLY LIFTS
NEWD...WHICH SHOULD CAUSE LOW LEVEL CONVERGENCE TO LESSEN TOWARD
16Z. HOWEVER...DEEP MOISTURE AND FAVORABLE UPPER LEVEL DIFFLUENCE
WILL REMAIN IN PLACE ALONG WITH UNIDIRECTIONAL FLOW FROM THE W OR
SW. 

THEREFORE...SOME UNCERTAINTY EXISTS WITH HOW LONG THE FLASH FLOOD
THREAT WILL LINGER...BUT THERE IS A STRONG CONSENSUS FROM THE
HI-RES GUIDANCE FOR HEAVY RAIN RATES OF LOCALLY 2+ IN/HR TO
CONTINUE UNTIL AT LEAST 16Z. TRENDS WILL BE MONITORED FOR
ADDITIONAL MESSAGES AS NEEDED BEYOND 1630Z.

OTTO

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

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

LAT...LON   34559365 34519288 34369142 34089052 33839009 
            33268996 32979002 32539064 32149199 32109237 
            32379265 32699294 33059371 33339435 33579460 
            33939469 34219458