Graphic for MPD #0267
MESOSCALE PRECIPITATION DISCUSSION 0267
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
921 AM EDT WED MAY 24 2017

AREAS AFFECTED...SOUTHERN GA...NORTHERN FL

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

VALID 241320Z - 241820Z

SUMMARY...INITIAL HEAVY RAINFALL CONVECTION SETTING THE STAGE FOR
POTENTIAL TRAINING CONVECTION THAT WILL INCREASE IN RAINFALL
EFFICIENCY IN THE EARLY AFTERNOON AND  POSE A THREAT FOR LOCALIZED
FLASH FLOODING.

DISCUSSION...EXPERIMENTAL GOES-16 AND GOES-E WV LOOPS DEPICT A
MATURE/DEEP CYCLONE OVER THE CENTRAL MS RIVER VALLEY LIFTING INTO
THE LOWER TN RIVER VALLEY WITH UNDERCUTTING DRY SLOT/SWLY UPPER
LEVEL JET STREAK CROSSING CENTRAL MS/AL ATTM.  A FAIRLY FLAT
SUBTROPICAL JET EXISTS AS WELL OVER THE CENTRAL GULF...ALL
APPROACHING AN INCREASINGLY DIFFLUENT UPPER LEVEL REGION ACROSS
THE SOUTHEAST.  THIS COMBINATION IS CURRENTLY PROVIDING A LARGE
AREA OF STRONG DIVERGENCE/UPPER LEVEL EVACUATION SUPPORTING UVV.

IN THE LOWER LEVELS THE FORCING IS QUITE STRONG AND EXPECTED TO
INCREASE WITH THE SWLY LLJ REACHING 50-60KTS AROUND 14Z TOWARD THE
CEDAR KEY REGION....ADDITIONALLY THE LOW LEVEL FLOW IS QUITE
CONFLUENT THROUGH THE REGION AS WELL SUPPORTING MST FLUX
CONVERGENCE STEADILY INCREASING TPW OVER 2.0 TO 2.25" TOWARD 17Z
PROVIDING AMPLE INSTABILITY (OVER 2000 J/KG) FOR CONTINUED
CONVECTIVE GROWTH AND INCREASED RAINFALL EFFICIENCY...POTENTIALLY
SUPPORTING RAIN RATES OVER 3"/HR TOWARD 18Z.

CURRENTLY FOCUSING MECHANISMS ARE ALSO PLENTY WITH A WEAK SURFACE
WAVE AT THE BASE OF SFC TROF NE OF VPS WITH A COLD FRONT EXTENDING
WSW FROM IT.  A LINGERING SFC TROF THAT HAS PROVIDED ACTIVATION OF
MORE DISCRETE CELLS EXTENDS ACROSS THE NORTHERN FL PENINSULA FROM
SGJ TO S OF CTY INTERSECTING WITH THE APPROACHING COLD FRONT SOUTH
OF CAPE ST. GEORGE ISLAND; CONVECTION ALONG THIS BAND CONTINUES TO
DEVELOP/COOL UNDER THE UPPER LEVEL EVACUATION BUT IS ALSO STARTING
TO LIFT NORTHWARD UNDER THE INFLUENCE OF THE APPROACHING HEIGHT
FALLS.  TO EXACERBATE THE DEVELOPMENT...STRONG SWLY SURFACE FLOW
ALONG THE NORTHEAST GULF COASTLINE LEADS TO FRICTIONAL CONVERGENCE
ACTIVATING SHALLOWER CELLS WITH CONTINUED REDEVELOPMENT GIVEN
STATIONARY FORCING AT THE COAST...ALLOWING RAINFALL TOTALS TO
SLIGHTLY ENHANCED THERE AS WELL. 

SO THE ENVIRONMENT PARAMETERS ARE IDEAL FOR CONVECTION AND
EFFICIENT RAINFALL THOUGH LIMITING FACTOR WILL BE THE DURATION OF
THE HEAVY RAINFALL.  DUE TO STRONG FLOW...INDIVIDUAL CELL MOTIONS
WILL BE QUICK AT 40-50KTS LIMITING TOTALS WELL BELOW THE VERY HIGH
(OVER 3"/1HR AND 4"/3HR) FFG VALUES IN THE VICINITY.  THOUGH WITH
INCREASING UNIDIRECTIONAL FLOW AS THE MAIN UPPER LEVEL FORCING
DPVA/JET LIFTS PARALLEL TO THE ORIENTATION OF CELL MOTION. THIS
WILL FAVOR THE POTENTIAL FOR SOLID UPSTREAM REDEVELOPMENT
PARTICULARLY FROM APALACHEE BAY AND I-10 NORTHWARD ACROSS S
GA...SUPPORTED BY RECENT HRRR, 06Z NAM-CONEST AND RECENT RAP
SOLUTIONS WITH TRAINING CONVECTION AND WITH RATES UP TO 3"/HR
ISOLATED FLOODING CONCERN CANNOT BE RULED OUT (PARTICULARLY AFTER
18Z).  STILL  CANNOT RULE OUT SOME COLD POOL GENERATION AND WITH
DEEPER MOISTURE/INSTABILITY SOUTH...FOCUS TRAINING BOUNDARY
FURTHER SOUTH TOWARD CEDAR KEY.

GALLINA

ATTN...WFO...CHS...JAX...TAE...TBW...

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

LAT...LON   32298175 32238127 31808092 31318113 30678130
            29718115 29328211 29048313 29568346 29748361
            29928387 30078410 30448413 30988394 31508283
            31888214


Last Updated: 921 AM EDT WED MAY 24 2017