MESOSCALE PRECIPITATION DISCUSSION 0651
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1027 AM EST TUE NOV 17 2015
 
AREAS AFFECTED...SERN TEXAS/NWRN LOUISIANA INTO SRN MISSOURI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 171526Z - 172030Z
 
SUMMARY...FLASH FLOODING IS EXPECTED FROM A SLOW MOVING SWATH OF
HEAVY RAIN WITH BETTER TRAINING POTENTIAL INTO NRN ARKANSAS/SRN
MISSOURI THROUGH 21Z. TO THE SOUTH...HIGHER RAINFALL RATES INTO
SRN ARKANSAS/LOUISIANA MAY LEAD TO ADDITIONAL FLASH FLOODING. 

DISCUSSION...WATER VAPOR IMAGERY AS OF 15Z SHOWED A SLOW MOVING
CLOSED LOW OVER THE TEXAS/OKLAHOMA PANHANDLES WITH WEAKER EMBEDDED
IMPULSES OUT AHEAD OF THE LOW SEEN OVER SERN TEXAS AND NEAR THE
RED RIVER. 12Z RAOB DATA SHOWED THAT MOISTURE AHEAD OF THIS UPPER
LOW IS 3-4 STANDARD DEVIATIONS ABOVE THE MEAN OR 250 TO 300
PERCENT OF NORMAL FROM LZK TO SGF. STRONG LOW LEVEL SLY FLOW OF 55
TO 65 KTS IS SUPPORTING HIGHLY ANOMALOUS MOISTURE TRANSPORT FROM
THE SOUTH AND NEARLY UNIDIRECTIONAL FLOW HAS ALLOWED FOR TRAINING
OF CELLS. INSTABILITY IS GENERALLY WEAK ACROSS MOST OF THE THREAT
...12Z LZK SOUNDING SHOWING 765 J/KG MU CAPE...BUT STRONG DYNAMICS
ARE MAKING UP FOR THE LACKING INSTABILITY.

RADAR IMAGERY HAS RECENTLY SHOWN AN UPTICK IN ECHO INTENSITY SHOWN
AS A BROKEN LINE OF HEAVY RAIN EXTENDING FROM ROUGHLY CLL TO TXK
BENEATH STRONGLY DIFFLUENT FLOW ALOFT. OCH PICKED UP 2.18 INCHES
IN 2 HOURS ENDING 14Z AND THIS LINE SHOULD WORK ITS WAY INTO NRN
LOUISIANA AND SRN ARKANSAS BY 21Z...WITH 3 HRLY RAINFALL RATES IN
EXCESS OF CURRENT 3 HR FFG OF 2-3 INCHES POSSIBLE DESPITE THE 00Z
ARW AND RECENT RUNS OF THE OPERATIONAL HRRR PERHAPS BEING TOO WET
HERE VIA RECENT WET BIAS THROUGH 15Z. FARTHER NORTH...ANTECEDENT
RAINFALL HAS LOWERED 1 AND 3 HR FFG VALUES TO AS LITTLE AS 1-2
INCHES WHICH IS CERTAINLY POSSIBLE GIVEN CLOSER ALIGNMENT OF THE
CLOUD BEARING MEAN FLOW TO LOW LEVEL INFLOW VECTORS.  

OTTO

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

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

LAT...LON   37249164 35479066 33649151 32149250 30889380 
            30959448 31669454 32399432 33299397 35519354 
            37199296