MESOSCALE PRECIPITATION DISCUSSION 0300
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
817 AM EDT SAT JUL 04 2015
 
AREAS AFFECTED...SOUTHERN AR...NORTHERN MS...NORTHERN AL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 041215Z - 041615Z
 
SUMMARY...CONVECTION WITH VERY HEAVY RAIN WILL CONTINUE TO TRAIN
ACROSS THE REGION THROUGH THE MORNING HOURS...LEADING TO FLASH
FLOODING.

DISCUSSION...SHOWERS AND THUNDERSTORMS WITH VERY HEAVY RAINFALL
CONTINUE TO TRAIN OVER THE SAME AREAS OF SOUTHERN AR...NORTHERN MS
AND NORTHERN AL. REGIONAL VWP PROFILES SHOWED THAT THE LOW LEVEL
CONVERGENT FLOW CONTINUES TO FOCUS MOISTURE (IN THE FORM OF A 2.00
PRECIPITABLE WATER AXIS) OVER THIS AREA...WHILE TRANSPORTING
INSTABILITY (BETWEEN 500 AND 1000 J/KG) UP AND OVER THE RESULTANT
OUTFLOW BOUNDARY. A SHORT WAVE CROSSING THE LOWER AND MID MS
VALLEY PROVIDES SYNOPTIC SCALE ASCENT...AND THE QUASI
UNIDIRECTIONAL LOW AND MID LEVEL FLOW SHOULD CONTINUE TO FOSTER
TRAINING ALONG THE OUTFLOW BOUNDARY.

THE LOW LEVEL FLOW FAVORS THE WESTERN END OF THE LINE FOR NEW
DEVELOPMENT (ACROSS  SOUTHERN AR AND NEARBY FAR NORTHEAST TX)...
WHICH THEN TRACKS ALONG THE LOW LEVEL CONVERGENCE TO THE EAST.
KLZK RADAR SHOWED HOURLY RAINFALL RATES AS HIGH AS 2 INCHES IN
SOUTHERN AR...WITH LESSER AMOUNTS TO THE EAST. 

THE CONSENSUS OF HIGH RESOLUTION GUIDANCE STRONGLY SUGGESTS THAT
NEW CONVECTION WILL CONTINUE DEVELOPING ALONG THE WESTERN EDGE OF
THE LINE...TAPPING THE DEEPER MOISTURE AND INSTABILITY TO PRODUCE
THE HIGHEST RAINFALL AMOUNTS ACROSS SOUTHERN AR. THE 10Z HRRR
INDICATED ANOTHER 2 TO 4 INCHES OF RAINFALL IS POSSIBLE ACROSS
SOUTHERN AR... WITH ADDITIONAL 1-2 INCH AMOUNTS EXPECTED OVER
NORTHERN MS AND NORTHWEST AL. THERE IS A SIGNAL IN THE HIGH
RESOLUTION GUIDANCE THAT THE ACTIVITY SHOULD BEGIN TO WANE BEFORE
17Z...AS THE SHORT WAVE LIFTS OUT AND THE AVAILABLE INSTABILITY
DROPS OFF. THIS SHOULD OCCUR FROM EAST TO WEST...WITH SOUTHERN AR
HOLDING ONTO THE FLASH FLOOD THREAT THE LONGEST.

EARLIER HEAVY RAINS HAS RESULTED IN SATURATED SOILS...SO THE
ADDITIONAL RAINFALL SHOULD RESULT IN FLASH FLOODING.

HAYES

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

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

LAT...LON   34648884 34638705 34518593 33538587 32948949 
            32989122 33039272 33009410 33009409 33589461 
            34629401 34629171