MESOSCALE PRECIPITATION DISCUSSION 0369
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
601 PM EDT THU JUN 22 2017

AREAS AFFECTED...NORTHERN & CENTRAL GA...EXT EASTERN AL

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

VALID 222200Z - 230200Z

SUMMARY...HIGHLY EFFICIENT RAINFALL ENVIRONMENT WITHIN WARM
CONVEYOR BELT ALSO SUPPORTS LOCALIZED TRAINING AND CELL MERGERS
THAT MAY POSE LOCALIZED FLASH FLOODING CONDITIONS OVER THE NEXT
FEW HOURS.

DISCUSSION...A SUBTLE SHORTWAVE WITHIN THE WARM CONVEYOR BELT
CONTINUES TO LIFT NORTHEAST THROUGH N CENTRAL AL PROVIDING MODEST
DPVA ASCENT ALONG THE ATTENDANT TROUGH EXTENDING SSE.  RAP
ANALYSIS SHOWS VERY DEEP WELL OF MLCPAES OF 2500 J/KG ALONG THE
UPPER CHATTAHOOCHEE RIVER VALLEY AS WELL AS INTO CENTRAL GA
(PLEASE NOTE VERY POOR 60 TD AT EMZ IS LEADING TO INCORRECT
ASSESSMENT OF INSTABILITY/MST FLUX IN AT VICINITY).  THE NATURE OF
WARM CONVEYOR HAS BEEN FOR NARROW TRANSVERSE BANDS OF CONVERGENCE
THAT SPROUT CONVECTION WITH NARROW UPDRAFT/DOWNDRAFT CORES
LIMITING THE OVERALL COVERAGE. STILL GIVEN THE UNIDIRECTIONAL
NATURE OF THE WIND PROFILE...CELLS ARE ALSO ABLE HAVE GREATER
VERTICAL DEPTH (NOT LOST TO SHEARING OF THE UPDRAFT) AND THEREFORE
DEEPER RAINFALL GENERATION TAPPING GREATER MOISTURE DEPTH
SUPPORTING RATES OF 2-2.5"/HR.  ADDITIONAL UPSTREAM DEVELOPMENT ON
THE NARROW BANDS WILL ALLOW FOR THE GREATEST RAINFALL TOTAL
STREAKS AND NEAR LOCAL FFG VALUE IN THE VICINITY WITH SOME
LOCALIZED FF POSSIBLE.

THE MAIN WARM CONVEYOR BELT FROM THE MS COAST TO ONGOING
CONVECTION IN E CENTRAL AL IS MAIN SOURCE/CHANNEL FOR MOISTURE
FLUX...GOES-16 VIS CONUS LOOP SHOWS SECONDARY STREAM FROM SLY
CHANNEL FROM EASTERN APALACHEE BAY PROVIDING ADDITIONAL LOW LEVEL
MST CONVERGENCE TO AID FURTHER DEVELOPMENT. THESE CELLS ALSO HAVE
A MORE NORTHERLY CELL MOTION COMPARED TO CELLS IN THE WARM
CONVEYOR (MORE NE).  AS SUCH THERE IS GOOD PROBABILITY FOR CELL
MERGERS INTO WEST CENTRAL AND N GA OVER THE NEXT FEW HOURS FURTHER
INCREASING FLASH FLOODING CHANCES.

GALLINA

ATTN...WFO...BMX...FFC...

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

LAT...LON   34968418 34758385 33588355 32538388 32298435
            32448485 33028534 34138569 34958523