MESOSCALE PRECIPITATION DISCUSSION 0705
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
345 PM EST SAT DEC 26 2015
 
AREAS AFFECTED...S MISSOURI... S ILLINOIS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 262044Z - 270244Z
 
SUMMARY...INCREASING COVERAGE AND ASCENT/STRENGTH OF UPDRAFTS FOR
OVERRUNNING CONVECTION AS WARM FRONT NEARS CAPABLE OF INDUCING
FLASH FLOODING CONDITIONS.

DISCUSSION...WARM FRONT LIFTING NORTH ACROSS ARKANSAS WITH
INCREASED PROXIMITY TO ONGOING SW STREAM OF MID-LEVEL SHOWERS WITH
ISOLATED CONVECTION.  WARM SECTOR MOISTURE WITH TDS IN THE MID TO
UPPER 60S WILL CONTINUE TO BE TRANSPORTED OVER THE FRONTAL ZONE IN
S MO WITH CONFLUENT LOW LEVEL FLOW FROM SSE 15-20 KTS AT THE
SURFACE OVER E AR TO SSW 45-50 KTS FROM E OK/W AR...INCREASING MST
FLUX AND DEEP MST CONVERGNCE FOR MODERATE ISENTROPIC ASCENT WHILE
UPPER LEVEL FLOW IS BECOMING MORE DIFFLUENT ABOVE 4H ACROSS THE
DISCUSSION AREA.  AS SUCH SOME MODERATE MUCAPES TO 500 J/KG ARE
AVAILABLE FOR SOME ELEVATED VETICAL CONVECTION WITHIN THE GENERAL
SLANTWISE ASCENT.  THIS WILL INCURE EMBEDDED RATES OF UP TO 1"/HR
WITHIN BROAD .5"/HR RATES.  WV LOOP AND RAP ANALYSIS INDICATE A
WEAK S/W NEAR STL MOVING NE...WITH SURFACE INFLECTION OVER S
IL...THIS SHOULD FLATTEN THE FRONT ACROSS S MO AND SLOW NORTHWARD
PROGRESS...AS WELL AS A MORE PERPENDICULAR ASCENT PLANE TO THE
FLOW...SHOULD KEEP AXIS OF CELL REGENERATION REALATIVELY STATIC
OVER THE NEXT 6HRS IN S AND CENTRAL MO 

NORTH OF THE BOUNDARY...FLOW IS GENERALLY DRIVEN SLIGHTLY NORTH OF
PARALLEL TOTHE BOUNDARY ALLOWING THESE MODERATE RAINFALL RATES TO
TRAIN FOR THE NEXT 6HRS WHILE ALSO RECIEVING INCREASED MST FLUX
OUT OF THE SOUTHWEST IN THE 7-5H LAYER PER CIRA LAYERED TPW PLUME
(WITH .3-.4" ANALYZED)...SO EFFICIENCY/MAGNITUDE SHOULD FAVOR
CELLS IN SW MO WITH 6HR TOTALS NEARING 3-4"...DECREASING TO 2-3"
OVER SE MO INTO SW IL.  THOUGH WITH LOWER FFG VALUES INTO SE MO/SW
IL.   

HI-RES CONVECTIVE ALLOWING MODELS PARTICUARLY THE 12Z ARW AND ESRL
EXPERIMENTAL HRRR SEEM TO HAVE A FAIRLY GOOD HANDLE ON THE AXIS
AND MAGNITUDES. 

GALLINA

ATTN...WFO...EAX...ILX...LSX...PAH...SGF...

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

LAT...LON   39568965 39358828 38488823 37918961 36809193 
            36719354 37449428 38099399 39159118