MESOSCALE PRECIPITATION DISCUSSION 0301
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1204 PM EDT SAT JUL 04 2015
 
AREAS AFFECTED...FAR NORTHEAST TX...SOUTHERN AR...NORTHERN
LA...NORTH CENTRAL MS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 041600Z - 042100Z
 
SUMMARY...CONVECTION TRAINING OVER PORTIONS OF SOUTHERNMOST
AR...NORTHERN LA AND NORTH CENTRAL MS WILL LEAD TO ADDITIONAL
FLASH FLOODING.

DISCUSSION...THE LINE OF TRAINING CONVECTION HAS SAGGED
SOUTHWARD...AS NEW CONVECTION FORMS ON THE OUTFLOW BOUNDARIES
MOVING SOUTH...CLOSE TO THE INSTABILITY AXIS. AS A SHORT WAVE
SLOWLY CROSSES THE LOWER AND MID MS VALLEY...THE SYNOPTIC SCALE
ASCENT SHOULD ALLOW CONVECTION TO DEVELOP ALONG THE OUTFLOW
BOUNDARIES THROUGH THE EARLY AFTERNOON HOURS.

AS THE LINE DROPS SOUTH...IT STARTS LOSING ITS CONNECTION TO THE
DEEP MOISTURE SOURCE TO THE NORTH (WHERE A 2.00 INCH PRECIPITABLE
WATER AXIS LIES). THIS SHOULD ALLOW THE CONVECTION TO SLOWLY
WEAKEN AS IT MOVES EAST...AND THIS IS INDICATED BY MOST OF THE
AVAILABLE HIGH RESOLUTION GUIDANCE. IN FACT...SLOWLY WARMING TOPS
ON THE IR LOOP SUGGESTS THIS WEAKENING IS BEGINNING TO OCCUR. 

ALMOST ALL OF THE AVAILABLE HIGH RESOLUTION GUIDANCE (INCLUDING
THE LATEST HRRR AND RAP) ARE TOO FAR NORTH WITH THE LINE OF
CONVECTION...KEEPING THE BULK OF THE ACTIVITY ACROSS SOUTHERN AR
INTO NORTHERN MS. WHILE CONVECTION COULD FORM IN THE TONGUE OF
INSTABILITY AHEAD OF THE SHORT WAVE OVER EASTERN OK INTO CENTRAL
AR...THE BEST INSTABILITY SHOULD RESIDE FURTHER SOUTH...CLOSEST TO
THE INSTABILITY AXIS.

AN ADDITIONAL 1 TO 3 INCHES OF RAINFALL IS POSSIBLE WITH THE
CONVECTION AS IT SLOWLY WEAKENS...WITH THE HIGHEST AMOUNTS
EXPECTED FROM SOUTHWEST AR INTO NORTHERN LA.

HAYES

ATTN...WFO...JAN...LZK...MEG...SHV...

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

LAT...LON   34359018 34358978 34298935 34228913 34088882 
            33728866 32748887 31909049 31879182 31879181 
            32209398 33009493 33569490 33769484 34119395 
            34149303 34299172 34309091