MESOSCALE PRECIPITATION DISCUSSION 0805
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
929 AM EST MON DEC 26 2016
 
AREAS AFFECTED...AR...BOOTHEEL OF MO...SOUTHERN IL...EXT WESTERN
KY...EXT SOUTHWEST IND...EXT NORTHEAST TN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 261430Z - 261930Z
 
SUMMARY...INCREASING RAIN RATES WITH SOME TRAINING MAY LEAD TO
SOME LOCALIZED FLASH FLOODING CONDITIONS PARTICULARLY IN AREAS OF
SATURATED SOILS.

DISCUSSION...GOES-E IR AND EARLY VISIBLE IMAGERY ALONG WITH RADAR
MOSAIC DEPICTS A LINE OF SCATTERED TO NUMEROUS CONVECTIVE CELLS
THAT IS FILLING IN WITH TIME JUST AHEAD OF WEAK LEAD COLD FRONT
THAT CROSSES SW-NE FROM NE TX/AR INTO S IL ATTM.  AHEAD OF THE
FRONT...12Z SOUNDINGS FROM SHV/LZK SUPPORT NEARLY UNIDIRECTIONAL
BOUNDARY LAYER TO 7H NEARLY SATURATED MOISTURE FROM THE WESTERN
GULF SUPPORTING TPWS OF 1.3-1.5" VALUES FROM NE TX/N LA INTO SE
IL/SW IND.  FAIRLY COINCIDENT THE ATMOSPHERE IS MILDLY UNSTABLE
WITH MLCAPES OF 500-1000 J/KG AS FAR NORTH AS THE MO BOOTHEEL WITH
SIMILAR 500 J/KG MUCAPES INTO S IL.  STRONG RIGHT ENTRANCE ASCENT
DYNAMICS FROM 120KT JET ACROSS THE CENTRAL PLAINS PROVIDES
ADDITIONAL MID-LEVEL ASCENT FOR DEEPER CONVECTIVE ELEMENTS. 
THOUGH THE MAIN RAINFALL GENERATION REGION BELOW 7H IS STRONGLY
UNIDIRECTIONAL TO ALLOW FOR TRAINING CONVECTIVE ELEMENTS AND WITH
LOCAL RADARS TICKLING 1HR RATES UP TO 1.25" MAY SUPPORT TOTALS OF
1.5-2" NEARING LOCAL FFG VALUES.  PROPAGATION VECTORS ARE A BIT
WEAK (E OR SE AT LESS THAN 5KTS)  WITH LIMITED NEAR SURFACE INFLOW
AND LIMITED COLD POOL/DOMINANT DOWNDRAFT SETUP IN THE NEAR TERM TO
SUPPORT SOME LOCALIZED HIGHER TOTALS AND FLASH FLOODING CONCERNS.
THIS IS PARTICULARLY THE CASE ACROSS SW AR TOWARD THE MEMPHIS
METRO (SOUTH OF LIT) WHERE GROUND CONDITIONS REMAIN A BIT MORE
SATURATED FROM THE LAST WEEK'S RAINFALL.  STILL WINTER GROUND
CONDITIONS SHOULD ALSO SUPPORT ADDITIONAL RUNOFF FOR INCREASED
LOCALIZED FF THREAT.

HI-RES GUIDANCE HAS BEEN A BIT SLOW TOWARD THE DEVELOPMENT AND
CONSOLIDATION OF THE CONVECTIVE LINE WITH LESS VIGOR OR
CONSOLIDATION OF THE CONVECTION.  THOUGH RECENT HRRR/HRRR EXP RUNS
HAVE SHOWN A TREND TOWARD CURRENT ACTIVITY BUT LIKELY UNDER DOING
THE OVERALL COVERAGE.  

GALLINA

ATTN...WFO...LZK...MEG...PAH...SHV...

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

LAT...LON   38178790 37658769 36608893 35629026 34239221 
            33769320 33669404 34239418 34629384 35789194 
            36899030 37908891