MESOSCALE PRECIPITATION DISCUSSION 0415
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1028 PM EDT MON AUG 03 2015
 
AREAS AFFECTED...EASTERN KY & VICINITY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 040227Z - 040727Z
 
SUMMARY...A CONVECTIVE SYSTEM IS MATURING ACROSS EASTERN KY AT
THIS HOUR.  HOURLY RAIN RATES UP TO 2" THROUGH 07Z COULD CONTINUE
FLASH FLOODING.

DISCUSSION...A CONVECTIVE SYSTEM WHICH MOVED OUT OF EASTERN IN
EARLY THIS AFTERNOON INTO NORTHEAST KY HAS SHOWN BACKBUILDING
CHARACTERISTICS, WHICH CAN BE ASCRIBED TO THE INSTABILITY PATTERN
ACROSS THE REGION.  MLCAPES OF 2500-3000 J/KG LIE UPSTREAM ACROSS
MUCH OF KY, WITH 850 HPA INFLOW OF 20-25 KTS PROVIDING ENOUGH
CLOUD BASE INFLOW FOR CONVECTIVE ORGANIZATION.  PRECIPITABLE WATER
VALUES ARE NEAR 1.50", PER GPS VALUES.  A MESOSCALE SURFACE WAVE
ACROSS NORTHERN KY APPEARS TO BE PROVIDING AS AN ANCHOR ALONG THE
BOUNDARY, WITH OUTFLOW BOUNDARIES FROM ONGOING CONVECTION
REINFORCING THE MESOSCALE FRONT ACROSS EASTERN KY WHICH IS
BEGINNING TO SHOW UP IN THE TEMPERATURE AND WIND PATTERN.  STORMS
HAVE BEEN MOVING EAST-SOUTHEAST AT ~25 KTS, CLOSE TO THE MAGNITUDE
OF THE FORWARD PROPAGATING CORFIDI VECTORS.

SATELLITE TRENDS SHOW A STEADY STATE SYSTEM AS OF LATE, IMPLYING
IT HAS ANOTHER 3-4 HOURS OF LIFE.  HOWEVER, INSTABILITY UPSTREAM
SUGGESTS ANOTHER FIVE HOURS OF PRODUCTIVITY, WHILE STEADY 850 HPA
INFLOW THROUGH 10Z SUGGESTS ANOTHER EIGHT HOURS OF ISSUES.  CIN
SHOULD DEVELOP ALONG THE BOUNDARY OVERNIGHT, WHICH MAY LEAD TO A
MINIMAL SOUTHWARD CONVECTIVE ADJUSTMENT WITH TIME.  OVERALL, AN
EAST-SOUTHEAST PROPAGATION OF 25 KTS ALONG WITH CELL BACKBUILDING
SHOULD PERSIST UNTIL MOISTURE AND INSTABILITY RUNS OUT.  RAP
GUIDANCE SUGGESTS MOISTURE ACROSS THE REGION BEGINS TO LESSEN
OVERNIGHT, FALLING DOWN TO A NARROW CORRIDOR OF 1.25" VALUES BY
09Z (SIX HOURS OF POTENTIAL ISSUES).  WILL HEDGE TOWARDS THE
AVAILABLE INSTABILITY AND SATELLITE TRENDS AND USE A FIVE HOUR MPD
HORIZON.  HOURLY RAIN RATES UP TO 2" COULD CAUSE PROBLEMS MAINLY
OVER EASTERN KY THROUGH 07Z.  THE MESOSCALE GUIDANCE HAS
ESSENTIALLY NO IDEA THIS COMPLEX EXISTS, WHICH INCREASES
UNCERTAINTY.  THIS SYNOPTIC SITUATION BEARS SOME RESEMBLANCE TO
THAT OF NORTHWEST MO LAST NIGHT, WHERE LOCAL AMOUNTS OF 5"
OCCURRED, THOUGH CLOUD BASE INFLOW SHOULD BE STRONGER.  BELIEVE
LOCAL AMOUNTS OF 3-5" ARE POSSIBLE DUE TO EXPECTED HOURLY RAIN
RATES AND CELL TRAINING.

ROTH

ATTN...WFO...ILN...JKL...LMK...MRX...RLX...

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

LAT...LON   38468398 38428295 37498196 36818209 36668278 
            36918362 37578428 37998440