MESOSCALE PRECIPITATION DISCUSSION 0292
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
314 PM EST SAT DEC 21 2013
 
AREAS AFFECTED...NE TX...NRN LA...SRN AND ERN AR...WRN TN AND
MS...SE MO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 212014Z - 220114Z
 
SUMMARY...THE FLASH FLOOD THREAT WILL BECOME FOCUSED THROUGH 01Z.
SEVERITY OF FLOODING ON THE LOCAL LEVEL HAS POTENTIAL TO
INCREASE...ESPECIALLY OVER PARTS OF EASTERN ARKANSAS AND ADJACENT
AREAS THAT HAD ALREADY RECEIVED 3 TO 5 INCHES OF RAIN. STORM
TOTALS WILL LIKELY APPROACH 7 TO 8 INCHES IN ISOLATED SPOTS BY
THIS EVENING.

DISCUSSION...TRAINING OF QUASI-LINEAR CELLS WITH MODERATE TO HEAVY
RAIN HAD YIELDED A BROAD SWATH OF CLOSE TO 3 INCHES OF RAIN WITH
LOCAL OBSERVATIONS OF MORE THAN 5 INCHES IN EASTERN ARKANSAS AND
AJACENT AREAS OF MO/TN/KY...GENERALLY WEST OF MEMPHIS AND PADUCAH.
LESSER AMOUNTS HAD BEEN OBSERVED ACROSS NORTHERN LOUISIANA...BUT
CONVECTION WAS INTENSIFYING THERE AT 20Z.

WELL DEFINED LARGE SCALE ASCENT WAS APPROACHING AND WAS IN PHASE
WITH THE DIURNAL ENHANCEMENT OF INSTABILITY AND CONVECTIVE
INTENSITY. CELLS WILL LIKELY CONTINUE TO TRAIN UNTIL A BACK EDGE
SWEEPS THROUGH THIS REGION WITH A DEVELOPING MID LEVEL DRY SLOT.
12Z HIGH RESOLUTION MODELS SHOW A GOOD DEAL OF AGREEMENT...MEANING
THE SSEO IS FAIRLY REPRSENTATIVE...AND FORECASTS SWATHS OF AT
LEAST ANOTHER 1-2 INCHES ACROSS THE OUTLINED AREA THROUGH MID
EVENING.

THE GREATEST CONCERN FOR FLASH FLOODING IS OVER THE AREAS THAT
ALREADY RECEIVED HEAVY RAIN...WHERE STORM TOTALS WILL APPROACH 8
INCHES IN ISOLATED SPOTS. IN LOUISIANA...LOW LEVEL WINDS WILL
BEGIN TO VEER EARLY ON...WHICH MAY ALLOW MORE FORWARD
PROGRESSION...BUT INTENSE RAIN RATES COULD LOCALLY MEET THE 2 OR
2.5 INCHES SEEN IN 1 TO 3 HOUR FLASH FLOOD GUIDANCE. WITH TIME THE
HRRR SUGGESTS UPSCALE GROWTH AND QUICKER EASTWARD
PROGRESSION...WHICH WILL LIMIT RAINFALL TOTALS DEEPER INTO
TN/KY/MS. BUT WITH THE ENVIRONMENT SUPPORT OF 1.5-2 INCH PER HOUR
RAIN RATES...LOCAL FLASH FLOODING IS LIKELY.

BURKE

ATTN...WFO...OHX...PAH...MEG...JAN...LZK...SHV...

ATTN...RFC...ABRFC...LMRFC...NCRFC...OHRFC...

LAT...LON   37558818 37598948 36799058 35469158 33999259 32899353
            32399351 32169241 32439102 33618950 35388832 36778790
            37558818