MESOSCALE PRECIPITATION DISCUSSION 0097
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1010 PM EDT FRI APR 13 2018

AREAS AFFECTED...SOUTHEAST MO

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

VALID 140210Z - 140600Z

SUMMARY...CELLS TRAINING ALONG A CONVECTIVE LINE MOVING EAST MAY
PRODUCE HOURLY RAINFALL RATES NEAR 1.50 INCHES...WHICH COULD POSE
A FLASH FLOOD THREAT OVER SOUTHEAST MO.

DISCUSSION...CONVECTION IS FIRING ALONG AN INSTABILITY AXIS
EXTENDING FROM CENTRAL AR INTO SOUTHEAST MO EARLY THIS EVENING.
ALONG THIS AXIS...00Z SOUNDINGS SHOWED SBCAPE VALUES BETWEEN
1000-1500 J/KG. A 40 TO 50 KNOT LOW LEVEL SOUTH SOUTHWEST FLOW
AHEAD OF THE CONVECTION CONTINUES TO TRANSPORT 1.50/1.75 INCH
PRECIPITABLE WATER AIR (WHICH IS BETWEEN TWO AND THREE STANDARD
DEVIATIONS ABOVE THE MEAN) AHEAD OF THE LINE INTO SOUTHEAST MO.

THE KLSX RADAR SHOWED HOURLY RAINFALL RATES NEAR 1.50 INCHES
ASSOCIATED WITH THE CONVECTION OVER PHELPS COUNTY MO...THOUGH THIS
COULD BE HAIL CONTAMINATED...AS 00Z SOUNDINGS UPSTREAM SHOWED
STEEPENING MID LEVEL LAPSE RATES. AS THE CONVECTIVE LINE MOVES
SLOWLY EASTWARD...CELLS COMPRISING THE LINE WILL TRAIN ACROSS
SOUTHEAST MO AND NEARBY SOUTHWEST IL THROUGH AT LEAST 14/05Z.

WHILE THE MOTION OF THE LINE COULD MITIGATE SOME OF THE FLASH
FLOOD THREAT...SHORT TERM TRAINING OF CELLS IN THE HIGH MOISTURE
CONTENT AIR COULD RESULT IN LOCAL 3.00 INCH RAINFALL AMOUNTS.
THESE VALUES ARE INDICATED BY THE MOST RECENT HRRR RUNS...AS WELL
AS THE 12Z WRF ARW. THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE
FAIRLY HIGH (GENERALLY ABOVE 2.50 INCHES)...SO TRAINING COULD BE
NECESSARY FOR FLASH FLOODING TO INITIATE. BECAUSE OF THAT...FLASH
FLOODING IS ONLY CONSIDERED POSSIBLE.

HAYES

ATTN...WFO...LSX...MEG...PAH...SGF...

ATTN...RFC...LMRFC...MBRFC...NCRFC...

LAT...LON   38779131 38539000 37408956 36658976 36399121
            36689161 37489177