Graphic for MPD #0082
MESOSCALE PRECIPITATION DISCUSSION 0082
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
845 PM EDT MON MAR 27 2017

AREAS AFFECTED...SOUTH CENTRAL TN...NORTHERN AL

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

VALID 280044Z - 280359Z

SUMMARY...SHORT-TERM FLASH FLOODING CONCERN AS PROGRESSIVE LINE
FLATTENS TO THE MEAN FLOW SUPPORTING SOME TRAINING NEARING AREAS
AFFECTED BY EARLIER CONVECTION TODAY.

DISCUSSION...GOES-E/16 AND RADAR MOSAIC DENOTES CONSOLIDATED
CONVECTIVE LINE AT THE BASE OF ENHANCED SURFACE TROF SOUTH OF
CONTINUING TO SHEAR SURFACE LOW CROSSING NORTH CENTRAL TN. 
UPSTREAM HEIGHT FALLS HAS STALLED SOUTHWARD PUSH OF FRONTAL ZONE
MAKING IT STATIONARY ACROSS CENTRAL AR INTO N MS.  YET 925-85H
CONFLUENT MILD FLOW ALONG THE BOUNDARY WILL CONTINUE TO FEED
MODERATE MOISTURE WITH TPWS OF JUST ABOVE 1.0"/AND SFC TDS IN THE
LOWER 60S.  ADDITIONALLY WEAK SOUTHERLY FLOW IN ADVANCE OF THE
LINE WITH SIMILAR MOISTURE ENVIRONMENT WILL CONTINUE TO MAINTAIN
SUFFICIENT MST FLUX TO THE LINE.

THE GREATER CONCERN IS THE ORIENTATION OF THE STEERING FLOW TO THE
LINE BECOMING MORE PARALLEL AS IT DROPS SOUTH ACROSS THE SOUTHERN
MOST LINE OF COUNTIES IN TN INTO N AL...WITH SOME TRAINING OF
CELLS BECOMING MORE PROBABLE.  THOUGH MAGNITUDE OF RAINFALL WAS
NOT SIGNIFICANT WITH SOME MINOR EXCEPTIONS (FRANKLIN COUNTY AL AOA
1.0" - LIKELY TO BE MISSED BASED ON TRENDS) EARLIER TODAY...THE
WETTING OF THE GROUNDS OVER FFG VALUES IN THE 1.5-2.5" RANGE FOR
1HR-3HR TIME PERIODS MAY HAVE LOCALLY LOWERED THESE VALUES A BIT
SETTING THE STAGE FOR THIS NEXT ROUND.  RATES UP TO 1.5"/HR ARE
EXPECTED BUT WITH FAIRLY PROGRESSIVE CELL MOTIONS OVERALL THERE IS
LIKELY A LIMITED WINDOW FOR TOTALS TO COMPOUND LEADING ONLY TO
LOCALIZED AREAS TO EXCEED FFG VALUES LEADING TO FLASH FLOODING
POSSIBLE.  WITH LOSS OF DAYTIME HEATING INSTABILITY VALUES ARE
ALREADY REDUCING LIMITING THE THREAT IN TIME WITH CELLS LIKELY TO
BE WANING AS THEY CROSS INTO N GA.

GALLINA

ATTN...WFO...FFC...HUN...MEG...MRX...OHX...

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

LAT...LON   35388667 35308552 34928520 34578564 34568689
            34718781 35058822 35338798


Last Updated: 845 PM EDT MON MAR 27 2017