MESOSCALE PRECIPITATION DISCUSSION 0617
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
205 AM EDT MON OCT 26 2015
 
AREAS AFFECTED...EXT E TEXAS...CENT/SE LOUISIANA...S MISSISSIPPI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 260600Z - 261200Z
 
SUMMARY...HIGH MOISTURE...MODERATE RATES AND SLOW MOTIONS LIKELY
TO COMPOUND FLOODING CONDITIONS

DISCUSSION...PLEASE SEE RECENT 0506Z SPENES THAT EXCELLENTLY
DESCRIBES THE SYNOPTIC ENVIRONMENT.  TWO FOCI WILL REMAIN FOR VERY
HIGH TOTALS THOUGH PROGRESSION OF THESE AREAS ARE MOVING OUT OF
LOWER FFG VALUES EXCEPT OVER SW MS WHERE A FEW MORE HOURS WILL
EXIST OF SSEO MEAN FFG EXCEEDANCE PROBABILITIES OVER 90% REMAIN. 

THE WESTERN FOCI AT THE APEX OF THE WRAP BACK OF THE WARM CONVEYOR
BELT WHERE THE NARROWING CHANNEL/CONFLUENCE REMAINS TO AID SOME
CONVECTIVE DEVELOPMENT DUE TO REMAINING SLANTWISE INSTABILITIES
WITHIN THE HIGHLY DIFFLUENT OUTFLOW CHANNEL ALOFT.  THIS AREA ALSO
REMAINS ON THE NE SIDE OF THE UPPER LOW THAT IS DRIFTING SE JUST E
OF HOUSTON ATTM.  THIS WILL CONTINUE TO SUPPORT THE LOCATION OF
THIS SLANTWISE CONVECTION TO REMAIN PIVOTED OVER SABINE/N NEWTON/N
JASPER COUNTIES IN TX AND SABINE PARISH IN LA...WITH RATES
NEAR/EXCESS OF 1-1.25"/HR WITH HIGH DENSITY OF VERY SMALL DROPLETS
ALLOWING FOR INCREASED RAINFALL EFFICIENCY WITHOUT HIGH RADAR
RETURN...FOR POTENTIAL TOTALS EXCEEDING 6HR FFG VALUES. 

NE/SE LA AND SW/S MS...SWIR INDICATES SURFACE LOW NEARING MARSH
ISLAND ELONGATING THE LOW NW-SE WITH A SUBTLE SURFACE WAVE LIFTING
NORTH ON SLOWLY ADVANCING COLD FRONT JUST WEST OF LAKE
PONTCHARTRAIN...THIS IS CONTINUING TO STRENGTHEN NEARLY
UNIDIRECTIONAL SOUTHERLY CLOUD BARING FLOW WITH NUMEROUS SHALLOW
CONVECTION THAT WILL TRAIN OVER E LA TOWARD THE SOUTHERN MS
COASTLINE WITH SLOW EASTWARD ADVANCEMENT.  CONVECTION WILL THEN
CROSS AND LIFT ACROSS STEEP WARM FRONT OVER SW MS...AND EXPAND NW
TO NE UNDER INCREASINGLY DIVERGENT FLOW ALLOWING FOR HIGHER MORE
EFFICIENT RATES UP TO 1.5"/HR.  SOME OF THE CELLS MAY ALSO BECOME
ROOTED ALONG THE WARM FRONT MOMENTARILY STALLING WITH HIGHER
SEVERE POTENTIALLY BUT ALSO THE HIGHER PROBABILITY OF COMPOUNDED
TOTALS...WITH THE HIGHEST FLASH FLOOD LIKELY HOOD GIVEN THE
ANTECEDENT CONDITIONS FOR EARLIER TOTALS THIS AFTERNOON.  IN
GENERAL HI-RES CAMS ARE IN FAIRLY GOOD AGREEMENT WITH THE GEM
REGIONAL/HRRR/ARW PERFORMING WELL WITH A 2-4" ZONE JUST MAXIMIZING
JUST NORTH OF THE WARM FRONT...ISOLATED TOTALS EXCEEDING THIS ARE
POSSIBLE IN STALLED/RIGHT TURNING MESO ENHANCED CONVECTIVE
CELLS...SUCH AS THAT RECENTLY OVER S MARION COUNTY MS.  

GALLINA

ATTN...WFO...HGX...JAN...LCH...LIX...MOB...SHV...

ATTN...RFC...LMRFC...WGRFC...

LAT...LON   32809235 32689006 31418848 29508835 29058840 
            28718897 28848976 29949044 30929118 31159265 
            31119325 30309401 30839463 31869417