MESOSCALE PRECIPITATION DISCUSSION 0118
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
145 PM EDT MON JUN 09 2014
 
AREAS AFFECTED...SOUTHEASTERN AR/NORTHERN MS/NORTHERN
AL/SOUTHWESTERN TN... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 091745Z - 092130Z
 
SUMMARY...FLASH FLOODING MAY REOCCUR AS A LONG DURATION MCS HAS
MOVED INTO AN AREA WHICH HAS ALREADY SEEN HEAVY RAINFALL EARLIER
IN THE DAY. 1 INCH HOURLY RATES MAY BE ENOUGH TO LOCALLY EXCEED
FFG VALUES.


DISCUSSION...AN MCS WHICH HAS BEEN MOVING THROUGH THE SOUTHERN
PLAINS DURING THE PAST 8 TO 10 HOURS HAS WORKED ITS WAY INTO THE
LOWER MS VALLEY. IN SPITE OF BEING PROGRESSIVE IN NATURE...HOURLY
GAUGE DATA FROM LOCAL COOP SITES SUPPORT 1 INCH OF RAINFALL IN A
SHORT PERIOD OF TIME. IN ADDITION...THE ATMOSPHERE HAS BECOME
INCREASINGLY UNSTABLE DOWNSTREAM AS THE REGION HAS BEEN NEARLY
CLOUD-FREE MUCH OF THE MORNING. AN EXPANSIVE AREA OF AGITATED CU
AND POPCORN CONVECTION HAS BEEN OBSERVED WITHIN THE WARM/MOIST
SECTOR WITH TEMPERATURES SURGING WELL INTO THE 80S ACROSS LA/MS.
THE COMBINATION OF LOCALLY HEAVY RAINFALL FROM DOWNSTREAM
DEVELOPMENT COMBINED WITH THE EFFECTS FROM THE MCS MAY LEAD TO
AREAS OF FLASH FLOODING ACROSS THE SCALLOPED REGION. FFG VALUES
HAVE SIGNIFICANTLY DIMINISHED GIVEN THE EARLIER CONVECTION WITH
SUCH THRESHOLDS EASILY MET WITH THE APPROACHING THUNDERSTORM
COMPLEX.

HIGH-RESOLUTION GUIDANCE ARE IN AGREEMENT ON EXTENDING HEAVY
RAINFALL DOWN INTO SOUTHEAST TX/LA BUT ARE A BIT MORE AT ODDS WITH
WHAT HAPPENS FURTHER NORTH ACROSS THE AREA OF INTEREST. NOT SURE
IF THE GUIDANCE IS RESOLVING THE IDEA THAT THE ATMOSPHERE HAS
REBOUNDED CONSIDERABLY AS SURFACE-BASED CAPE VALUES HAVE ALREADY
APPROACHED 2000 J/KG IN EASTERN AR AS OF 17Z. LOW-LEVEL INFLOW HAS
REMAINED STRONG SINCE THE OVERNIGHT HOURS WITH 850-MB WINDS IN THE
25 TO 30 KT RANGE PER THE 16Z RAP. EXPECT THE STRONGEST CONVECTION
TO OCCUR ALONG THE DIFFERENTIAL HEATING ZONE AND WHERE SKIES HAVE
BEEN CLOUD FREE THE LONGEST.


RUBIN-OSTER

ATTN...WFO...BMX...HUN...MEG...JAN...LZK...SHV...

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

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            34939180 35179076 35239006 35238940 35088846 34608786
            33848749 33118779 33098848 33349008