MESOSCALE PRECIPITATION DISCUSSION 0093
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
842 PM EDT MON APR 09 2018

AREAS AFFECTED...NORTH-CENTRAL FL PENINSULA

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

VALID 100041Z - 100641Z

SUMMARY...A BAND OF TRAINING THUNDERSTORMS COULD HANG UP ACROSS
THE NORTH-CENTRAL PENINSULA ONCE CIN SETS IN THIS EVENING AND DUE
TO MINIMAL EXPECTED SOUTHWARD SAG TO THE SURFACE BOUNDARY.  HOURLY
RAIN TOTALS TO 2" WITH LOCAL AMOUNTS TO 3-5" ARE ANTICIPATED
THROUGH 06Z.

DISCUSSION...A COLD POOL-REINFORCED STATIONARY FRONT SNAKES ITS
WAY FROM NEAR CEDAR KEY FL THROUGH THE ORLANDO METROPOLITAN AREA
TO NEAR MELBOURNE, WITH THE PARENT CYCLONE SHOWING UP AT THE BACK
EDGE OF ACTIVE CONVECTION SOUTH-SOUTHWEST OF APALACHICOLA.  A DEW
POINT GRADIENT EXISTS FROM NORTH OF OCALA EASTWARD TOWARDS DAYTONA
BEACH.  ALOFT, A SHORTWAVE APPEARS TO BE MOVING QUICKLY THROUGH
THE NORTHWEST GULF OF MEXICO AIDING DIVERGENCE ALOFT. 
PRECIPITABLE WATER VALUES OF 1.5-1.75" EXIST IN THE REGION PER 00Z
SOUNDINGS.  ML AND MU CAPE VALUES OF NEAR 2000 J/KG LIE JUST AHEAD
OF THE BOUNDARY, WITH CIN DEVELOPING NEAR EASTERN FL.  EFFECTIVE
BULK SHEAR OF 30-40 KTS EXISTS IN THE AREA WHICH IS ORGANIZING THE
CONVECTION INTO A BAND.

THE CONCERNS ARE THAT PORTIONS OF THIS TRAINING BAND WITH EMBEDDED
CELL MERGERS, PARTICULARLY THE WESTERN PART, COULD SEE CONVECTION
HELD UP BY TWO FACTORS -- GREATER INSTABILITY IN THE GULF OF
MEXICO AND CIN SETTING IN DURING THE NEXT COUPLE HOURS WHICH COULD
HOLD UP FURTHER SOUTHWARD CONVECTIVE PROGRESSION.  THE RAP
INDICATES THAT THE SURFACE BOUNDARY REMAINS MOTIONLESS DURING THE
NEXT SEVERAL HOURS (THOUGH IT COULD BE TOO SLOW) ADDING TO
CONCERNS ABOUT PERSISTENT HEAVY RAINFALL.  THE EASTERN PORTION OF
THE BAND SHOWS THE MOST PROMISE TOWARDS SOME SOUTHWARD
PROPAGATION, AS THE 1000-500 HPA THICKNESS PATTERN IS ORIENTED
WNW-ESE WHICH WITH TIME SHOULD MATCH THE INSTABILITY GRADIENT AS
THE CONVECTION LOWERS MU CAPE VALUES.  HOURLY RAIN TOTALS TO 2"
ARE SUPPORTED BY AVAILABLE MOISTURE/INSTABILITY WHILE MESOSCALE
GUIDANCE HAS A SIGNAL FOR LOCAL 3-5", WHICH WOULD BE MOST
PROBLEMATIC IN URBAN AREAS.

ROTH

ATTN...WFO...JAX...MLB...TAE...TBW...

ATTN...RFC...SERFC...

LAT...LON   29938202 29648112 28478046 28448114 28568180
            28888275 29438343 29758357 29928308