MESOSCALE PRECIPITATION DISCUSSION 0557
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
923 AM EDT SAT AUG 13 2016
 
AREAS AFFECTED...AR...SOUTHEAST MO...FAR WESTERN KY...SOUTHERN
IL...SOUTHWEST IN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 131320Z - 131920Z
 
SUMMARY...THE THREAT FOR SLOW-MOVING AND INTENSE BANDS OF SHOWERS
AND THUNDERSTORMS WILL INCREASE LATE THIS MORNING AND INTO THE
AFTERNOON. THE THREAT FOR FLASH FLOODING WILL INCREASE.

DISCUSSION...A VERY SLOW-MOVING FRONT IS SITUATED THIS MORNING
FROM SOUTHERN IL SOUTHWEST DOWN ACROSS FAR SOUTHEAST MO...CENTRAL
AR AND INTO NORTHEAST TX WHERE THERE ARE MULTIPLE WAVES OF LOW
PRESSURE ALONG THE BOUNDARY. MEANWHILE...LOW TO MID LEVEL LOW
PRESSURE CONTINUES TO DRIFT EVER SO SLOWLY TO THE WEST-NORTHWEST
INTO CENTRAL LA WHICH IS FOCUSING THE VERY HEAVY RAINFALL OVER
THAT STATE THIS MORNING. AROUND THE NORTHERN AND EASTERN FLANKS OF
THIS CIRCULATION IS A RATHER WELL-DEFINED LOW LEVEL TRANSPORT
REGIME OF VERY DEEP TROPICAL AIR...WITH PWATS OF 2.25 TO 2.5
INCHES.

TOWARD MIDDAY AND BEYOND...THE FRONTAL ZONE WILL ESSENTIALLY BE
QUASI-STATIONARY BUT WILL INCREASINGLY BEGIN TO INTERACT WITH THE
BROADER LOW AND MID LEVEL CIRCULATION OVER LA. DEEPER MOISTURE AND
DIURNALLY ENHANCED INSTABILITY WILL INCREASINGLY POOL ALONG THE
BOUNDARY. IN FACT...THE LAST FEW RAP MODEL RUNS SHOW AS MUCH AS A
40 TO 50 KT SOUTHERLY LOW LEVEL JET AT 850 MB SURGING UP ACROSS
WESTERN MS AND ACROSS THE MS RIVER WHICH WILL FACILITATE THIS
PROCESS. THERE IS ALREADY A FEW BROKEN CLUSTERS/BANDS OF SHOWERS
ORIENTED FROM SOUTHWEST AR NORTHEAST INTO SOUTHEAST MO AND PARTS
OF FAR WESTERN KY AND SOUTHERN IL. THIS ACTIVITY SHOULD TEND TO
EXPAND IN COVERAGE AND INTENSIFY BY MIDDAY AND ESPECIALLY THIS
AFTERNOON AS GREATER INSTABILITY THROUGH SOLAR INSOLATION BECOMES
ESTABLISHED. ADDITIONALLY...THE LATEST MODEL GUIDANCE SHOWS THE
DEVELOPMENT AND ARRIVAL OF FAVORABLE 250 MB RIGHT-ENTRANCE REGION
JET DYNAMICS TODAY WHICH WILL FOSTER A MORE ORGANIZED CONVECTIVE
THREAT WITH HEAVY RAINFALL.

RAINFALL RATES WILL BE AS HIGH AS 2.5 INCHES/HR AND COUPLED WITH
THE SLOW-MOVEMENT OF THE CELLS AND POTENTIAL FOR
TRAINING...RAINFALL TOTALS WILL LOCALLY BE VERY HEAVY. EXPECT AS
MUCH AS 3 TO 5 INCHES LOCALLY THROUGH THIS PERIOD...WITH HEAVIER
AMOUNTS POSSIBLE LATER IN THE DAY WITH ADDITIONAL CONVECTIVE
ORGANIZATION. THE FLASH FLOOD THREAT WILL INCREASE AS A RESULT
WITH TIME.

ORRISON

ATTN...WFO...ILX...IND...LMK...LSX...LZK...MEG...PAH...SGF...
SHV...

ATTN...RFC...ABRFC...LMRFC...NCRFC...OHRFC...

LAT...LON   38938774 38718695 38088712 37548783 37088852 
            36878894 36089031 35289145 34029255 33869328 
            34429381 35399336 36369263 37479146 37969078 
            38518960