MESOSCALE PRECIPITATION DISCUSSION 0114
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
140 AM EDT MON JUN 09 2014
 
AREAS AFFECTED...NORTHERN MS AND EXTREME SOUTHWEST TN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 090539Z - 090909Z
 
SUMMARY...CONVECTION HAS BECOME MORE ACTIVE ALONG AN INVERTED
TROUGH NORTH OF A STATIONARY FRONT WITHIN AN AREA SATURATED BY
RAINFALL OVER THE PAST FEW DAYS.  RAINFALL RATES OF 2" AN HOUR IN
STRONGER STORMS COULD CAUSE A FEW INSTANCES OF FLASH FLOODING.

DISCUSSION...A NEW BATCH OF THUNDERSTORM ACTIVITY HAS FORMED ALONG
AN INVERTED TROUGH NEAR MEMPHIS TN AT THE LEADING EDGE OF A COLD
POOL FROM EARLIER CONVECTION, WITH INCREASING RAINFALL RATES NOTED
DURING THE PAST HOUR.  THE 00Z MESOSCALE GUIDANCE TRENDED STRONGLY
TOWARDS THIS AREA RECEIVING HEAVY RAINFALL INSTEAD OF AREAS
FARTHER SOUTH.  THE SYSTEM IS PROGRESSING EASTWARD AS A WHOLE, BUT
INCREASING 850 HPA INFLOW (WHICH IS BEGINNING TO EXCEED THE MEAN
850-400 HPA WIND IN THE REGION) IS CAUSING RENEWED CONVECTION
ACROSS NORTHERN MS.  PRECIPITABLE WATER VALUES ARE IN THE 1.75-2"
RANGE AND CAPE VALUES ARE IN THE 1000-1500 J/KG RANGE.  THE REGION
HAS BEEN SATURATED BY RAINFALL OVER THE PAST FEW DAYS, LEAVING
FLASH FLOOD GUIDANCE VALUES LOW.

THE EXPECTATION IS THAT RAINFALL RATES OF 2" AN HOUR SHOULD
CONTINUE ACROSS NORTHERN MS AND FAR SOUTHWEST TN OVER THE NEXT FEW
HOURS AS 850 HPA INFLOW CONTINUES TO RAMP UP.  THE WILD CARD HERE
IS IF CONVECTION FORMS CLOSER TO THE STATIONARY FRONT ACROSS LA
AND CENTRAL MS.  IF SO, THIS BATCH OF THUNDERSTORMS COULD FADE
RATHER QUICKLY.  UNCERTAINTY IN THE EVOLUTION OF THIS CONVECTIVE
AREA IS HIGH.  THE SYSTEM'S PROGRESSION, EASTWARD AROUND 20 KTS,
SHOULD LIMIT THE SCOPE OF THE FLASH FLOOD THREAT, THOUGH CELL
MERGERS AND SOME BACKBUILDING OF CONVECTIVE CELLS IS POSSIBLE DUE
TO INCREASING LOW-LEVEL INFLOW.  A FEW INSTANCES OF FLASH FLOODING
ARE POSSIBLE IN THIS REGION.

ROTH

ATTN...WFO...HUN...MEG...JAN...LZK...

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

LAT...LON   34998805 35318942 35009066 34079134 33749086 33678909
            34088823 34998805