MESOSCALE PRECIPITATION DISCUSSION 0100
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
124 AM EDT THU MAR 31 2016
 
AREAS AFFECTED...LOWER MS VALLEY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 310523Z - 310923Z
 
SUMMARY...AREAS OF HEAVY RAINFALL WITH A CONTINUED FLASH FLOOD
THREAT OVER THE NEXT SEVERAL HOURS.

DISCUSSION...SYNOPTICALLY A BROAD AREA OF ISENTROPIC LIFT AND
UPPER LEVEL DIVERGENCE IN THE LEFT EXIT REGION OF THE SUBTROPICAL
JET IS ALLOWING FOR A DISORGANIZED AREA OF CONVECTION TO CONTINUE
TO STREAM NORTHEAST WITH THE MEAN STORM LAYER WINDS ACROSS LA/AR
AND WESTERN PORTIONS OF MS/TN/KY. NOT MUCH IN THE WAY OF
INSTABILITY...BUT ENOUGH FOR EMBEDDED CONVECTIVE ELEMENTS. AND
GIVEN THE EFFECTIVE RAINFALL ENVIRONMENT...WITH THE LAYERED
PRECIPITABLE WATER PRODUCT SHOWING A MOISTURE CONNECTION TO BOTH
THE GULF OF MEXICO AND THE TROPICAL PACIFIC...WITH PWATS VALUES
NEAR RECORD LEVELS FOR THIS TIME OF YEAR (1.6-1.8)...THESE
EMBEDDED CONVECTIVE ELEMENTS CONTINUE TO PRODUCE HOURLY RAINFALL
RATES OF 1-2" AN HOUR DESPITE THE LIMITED INSTABILITY.

BEGINNING TO SEE MORE OF AN EASTWARD MOVEMENT TO THE PRECIPITATION
SHIELD AS A SHORTWAVE EJECTING EAST ACROSS AR IS HELPING PUSH THE
AREA OF BEST 850MB CONVERGENCE AND THE MOISTURE AXIS EAST. THIS
SHORTWAVE IS HOWEVER ALLOWING CONVECTIVE REDEVELOPMENT ACROSS
CENTRAL AR...WHICH WILL MOVE EAST NORTHEAST OVER AREAS ALREADY
SEEING FLOODING. 

NOT REALLY EVOLVING LIKE THE 12Z ARW AND NSSL WRF WERE
DEPICTING...AS THESE SOLUTIONS SHOWED MORE OF AN EAST/WEST
TRAINING SITUATION. INSTEAD THE LACK OF ORGANIZATION IS ALLOWING
FOR MORE PROGRESSIVE STORM MOTIONS OFF TO THE NORTHEAST. HOWEVER
STILL SEEING A CONTINUED SOUTHWEST TO NORTHEAST TRAINING AS CELLS
FORM OVER LA AND MOVE NORTHEAST BACK OVER THE SAME AREAS. THUS
WHILE WIDESPREAD RAINFALL AMOUNTS AS HIGH AS THE 12Z ARW/NSSL WRF
DEPICT OVER THE NEXT SEVERAL HOURS SEEM UNLIKELY...STILL LOOKING
AT AMOUNTS GENERALLY AS HIGH AS 2" IN AN HOUR...WITH 2-4" OVER THE
NEXT 6 HOURS...WHICH MAY CAUSE AT LEAST AN ISOLATED FLOOD THREAT
TO EXPAND EAST INTO MS AND WESTERN TN. NONE OF THE 0Z HIGHER RES
GUIDANCE HAVE A PERFECT HANDLE ON THINGS...BUT A CONSENSUS OF
RECENT HRRR RUNS AND THE 0Z ARW/NMMB AND NSSL WRF WOULD LIKELY
WORK WELL FOR QPF AMOUNTS THE NEXT SEVERAL HOURS. HIGHLIGHTED THE
REGION APPEARING TO HAVE THE BEST CHANCE OF LOCAL 4" AMOUNTS OVER
THE NEXT SEVERAL HOURS BASED ON RECENT HIGH RES RUNS...ALONG WITH
RADAR TRENDS.

CHENARD

ATTN...WFO...JAN...LZK...MEG...PAH...

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

LAT...LON   36938960 36788919 36508892 36118883 35738877 
            35518866 34398846 33608833 32898886 32298964 
            31959018 31849112 32209149 32359151 32519147 
            33019178 33389205 33629247 33599279 33679301 
            33769298 34749214 35999109 36639041 36899001