MESOSCALE PRECIPITATION DISCUSSION 0043
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1031 PM EST SAT FEB 24 2018

AREAS AFFECTED...TN...KY...NRN MS/AL...SRN IN...WRN WV

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 250331Z - 250901Z

SUMMARY...AN MCS WILL BRING INTENSE SHORT TERM RAIN RATES FOLLOWED
BY LONGER DURATION STRATIFORM RAIN...AND NEW RAINFALL TOTALS AS
HIGH AS 1.75 INCHES. SATURATED SOILS MAKE FLASH FLOODING A NEAR
CERTAINTY. WATER RISES COULD BE ESPECIALLY RAPID / AGGRESSIVE WITH
OBSERVED RAIN RATES IN THE LEADING LINE AT 0.25 INCHES IN 5 TO 10
MINUTES.

DISCUSSION...AT 0315Z RADAR MOSAICS DEPICTED A WELL FORMED
QUASI-LINEAR CONVECTIVE SYSTEM FROM NORTHERN MISSISSIPPI TO NEAR
THE OHIO RIVER. THE SYSTEM WILL FOLLOW CORFIDI VECTORS FOR FORWARD
PROPAGATION...EAST TO NORTHEAST AT 35 TO 40 KNOTS. INSTABILITY WAS
SUFFICIENT HOWEVER...BOOSTED BY STRONG DEEP LAYER LIFT...TO
SUPPORT A FAIRLY BROAD LEADING LINE OF STRONG CONVECTION...MAKING
FOR A 5 TO 15 MINUTE DURATION OF INTENSE RAIN RATES AT ANY GIVEN
POINT. A SAMPLING OF EARLIER SURFACE OBSERVATIONS OVER WESTERN
KENTUCKY...KOWB...KEHR...INDICATED AROUND A QUARTER INCHES OF RAIN
IN 5 TO 10 MINUTES. DUAL POL RADAR ESTIMATES FROM KHPX AND
KOHX...ALONG WITH GAUGE OBSERVATIONS...SUGGEST QUICK TOTALS OF
1.10 TO 1.30 INCHES WILL BE COMMON ALONG THE LINE...AND WHEREVER
BRIEF TRAINING OCCURS RADAR ESTIMATES HAD TOPPED 1.50 INCHES.

THE MCS MAINTENANCE COMPOSITE INDEX PER THE SPC MESOANALYSIS WAS
RUNNING WITH VERY HIGH VALUES / LIKELIHOOD OF THE ACTIVITY BEING
MAINTAINED AS IT MOVES TOWARD EASTERN TN/KY AND ADJACENT PARTS OF
MS/AL AND WV. RECENT HRRR RUNS AND THE 00Z WRF-ARW WERE DOING A
DECENT JOB WITH SIMULATED REFLECTIVITY / EVOLUTION OF THE
LINE...BUT THE 12Z NSSL WRF PERHAPS OFFERED MORE REALISTIC
QPF...WITH A FEW STRIPES OF 1.50 INCH AMOUNTS THROUGH 09Z. FALLING
ON SATURATED GROUND...WITH 1-HR FFG 0.50 TO 1.50 INCHES THROUGHOUT
THIS REGION...THE NEW RAIN WILL ALMOST CERTAINLY CAUSE FLASH
FLOODING.

BURKE

ATTN...WFO...HUN...ILN...JKL...LMK...MEG...MRX...OHX...PAH...
RLX...

ATTN...RFC...LMRFC...OHRFC...SERFC...

LAT...LON   38498250 37938199 36328442 34898733 34398964
            34938969 36128861 37418765 38168646 38158543
            38148422