MESOSCALE PRECIPITATION DISCUSSION 0084
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1022 PM EDT THU MAY 30 2013
 
AREAS AFFECTED......SOUTHERN MISSOURI THROUGH ARKANSAS INTO
NORTHWEST MS AND WESTERN TN... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 310230Z - 310830Z
 
SUMMARY...FLASH FLOODING IS POSSIBLE
ACROSS PORTIONS OF AR AND SOUTHERN MO THROUGH THIS EVENING WITH
MOVEMENT OF CLUSTERS INTO NORTHWEST MS AND WESTERN TN LATER
TONIGHT.

DISCUSSION...AN UPPER TROUGH OVER THE PLAINS IS FORECAST TO
PRODUCE UPPER DIVERGENCE/LOWER CONVERGENCE MAXIMA WHERE
BANDS/CLUSTERS OF SHOWER/THUNDERSTORMS PROPAGATE EAST NORTHEAST 
ACROSS SOUTHWEST MO AND AR.  

THE ACTIVITY IS EXPECTED TO DEVELOP INTO A MOIST AXIS WITH SURFACE
DEWPOINTS IN THE LOWER 70S F ACROSS SOUTHERN AR.  ADDITIONALLY THE
MOISTURE IS DEEP WITH PRECIPITABLE WATER (PW) VALUES OF 1.75-2.0
INCHES...SUPPORTED BY THE 00Z JACKSON MS SOUNDING WITH 1.8 INCHES
OBSERVED.  

THE RECENT OBSERVATIONS INDICATED 1-2 INCHES OF RAIN OVER A 2 HOUR
PERIOD WITH THE BANDS/CLUSTERS OF STORMS. LOW-MID LEVEL MOISTURE
FLUX CONVERGENCE ALONG OUTFLOWS COMBINES WITH NORTHEAST MOISTURE
TRANSPORT...HIGH PW VALUES...AND 700-500 MB LAPSE RATES OF 7-8 DEG
C/KM TO SUPPORT CONTINUED SHOWER/STORM DEVELOPMENT THE REST OF THE
EVENING AND EARLY OVERNIGHT.  18Z GFS FORECAST SOUNDINGS ALSO SHOW
VEERING LOW LEVEL WIND PROFILES WITH ABOUT 30 DEGREES CHANGE FROM
THE SURFACE TO 850 MB SO FORWARD PROGRESSION SHOULD CONTINUE. 
HEAVY RAINS OCCUR WHERE REGENERATION OF SHOWERS/STORMS CAUSES
REPEAT ACTIVITY...SUCH AS WE HAVE SEEN RECENTLY IN FAR NORTHEAST
OK.

THE MODELS AGREE ON SIMILAR POTENTIAL WITH THE NCEP 12Z WRF NMM
AND ARW AND 12Z NSSL WRF SUGGESTING HEAVIER RAIN WITH SEVERAL
INCHES POSSIBLE IN AR TONIGHT.  SINCE THE WIND PROFILES
ARE CHANGING IN DIRECTION WITH HEIGHT...THERE IS NOT HIGH
CONFIDENCE IN ANY ONE AREA BEING A NATURAL FOCUS FOR TRAINING.

PETERSEN 


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

LAT...LON   37009473 37169215 36888999 36278860 35088885 34028980
            33689127 33619232 33639364 34239432 35319458 35799509
            37009473