MESOSCALE PRECIPITATION DISCUSSION 0441
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
538 AM EDT TUE JUL 04 2017

AREAS AFFECTED...FAR EASTERN KS...SOUTHWEST MO...NORTHERN AR

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 040940Z - 041445Z

SUMMARY...CONVECTION AHEAD OF AN MCV OVER NORTHEAST OK COULD BEGIN
TRAINING ACROSS PORTIONS OF SOUTHERN MO AND NORTHERN
AR...RESULTING IN A FLASH FLOOD THREAT THIS MORNING.

DISCUSSION...REGIONAL RADARS OVER EASTERN OK/SOUTHWEST MO SHOWED
THE NORTHERN END OF A LONG SQUALL LINE BEGINNING TO SLOW DOWN AS
IT REACHES NORTHWEST AR EARLY THIS MORNING. THE KSRX RADAR SHOWED
SOME TURNING IN BACK OF THE LINE OVER NORTHWEST AR...AS AN MCV
OVER NORTHEAST OK TRACKS EASTWARD.

CURRENTLY...THE CONVECTION HAS WEAKENED SOME AS MUCH OF AVAILABLE
INSTABILITY HAS BEEN EXHAUSTED. HOWEVER...THE LATEST RAP ANALYSIS
SHOWED AN AXIS OF 500-1000 J/KG OF MUCAPE AHEAD OF THE NORTHERN
PORTION OF THE LINE OVER FAR SOUTHWEST MO AND FAR NORTHWEST AR. A
25 TO 30 KNOT LOW LEVEL SOUTHWEST FLOW EXTENDING AHEAD OF THE MCV
FROM NORTHERN LA INTO WESTERN AR CONTINUES TO FEED 1.75/2.00 INCH
PRECIPITABLE WATER AHEAD OF THE LINE.

LIFT FROM THE MCV SHOULD PROVIDE SUFFICIENT ASCENT TO SUPPORT
CONVECTION AS IT TAPS THE DEEPER INSTABILITY PRESENT OVER
SOUTHWEST MO AND NORTHWEST AR. A REGENERATION OF THE CONVECTION IS
EXPECTED HERE...AND AS PROPAGATION VECTORS SLOW (AND EVEN BECOME
OPPOSED TO TO THE 850-300 MB FLOW)... TRAINING BECOMES POSSIBLE.
THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE AS LOW AS 1.50 ACROSS
PORTIONS OF NORTHWEST AR...AND THE MOST RECENT HRRR SOIL
SATURATION MAP SHOWED NEARLY SATURATED CONDITIONS HERE.

IT SHOULD BE NOTED THAT WHILE MUCH OF THE HIGH RESOLUTION GUIDANCE
DOES INDEED SHOW A SOME RESURGENCE OF CONVECTION...IT IS AS MUCH
AS 1-3 HOURS SLOWER THAN REALITY AS OF 09Z. THUS...THE RAINFALL
PLACEMENT AND SIMULATED REFLECTIVITY HAVE BEEN ADVANCED TO ACCOUNT
FOR THE TIMING DIFFERENCE. THE MOST RECENT HRRR SHOWED LOCAL 2.00
TO 3.00 INCH RAINFALL AMOUNTS OVER NORTHWEST AR... BEFORE THE
ACTIVITY WEAKENS EVEN FURTHER.

THESE RAINFALL AMOUNTS...ADJUSTED FOR THE MODEL TIMING...COULD BE
ENOUGH TO INITIATE FLASH FLOODING IN AREAS WITH LOWER FLASH FLOOD
GUIDANCE VALUES. BECAUSE OF THIS... FLASH FLOODING IS ONLY
CONSIDERED POSSIBLE.

HAYES

ATTN...WFO...EAX...ICT...LZK...SGF...TOP...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...

LAT...LON   39159495 38599463 37839416 37299309 36879214
            36359162 36349162 35379167 35319325 35639427
            35949453 36919470 37109561 37499619 38379606
            39099572