Graphic for MPD #0067
MESOSCALE PRECIPITATION DISCUSSION 0067
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
257 AM EST THU MAR 10 2016
 
AREAS AFFECTED...NE LOUISIANA...W MISSISSIPPI...EXT SW TENNESSEE 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 100757Z - 101357Z
 
SUMMARY...MEAN FLOW PARALLEL TO FRONTAL ZONE/SFC MST
CONVERGENCE...ALLOWING FOR TRAINING CONVECTION WITHIN WARM
CONVEYOR BELT.

DISCUSSION...IR SHOWS INCREASED DEEP CONVECTION COOLING TO JUST
BELOW -70C AT THE INFLECTION POINT WHERE THE SURFACE FRONTAL
BOUNDARY CURVES FROM NEAR N-S ORIENTATION TO MORE OF W-E
ORIENTATION NEAR LASALLE/AVOYELLES PARISHES IN E LA.  ADDITIONAL
DEEP CONVECTION NORTH OF THE INTERSECTION DUE TO SSELY LOW LEVEL
INFLOW TO THE FRONTAL BOUNDARY/WEAK SURFACE PRESSURE TROF/SQUALL
LINE CONTINUES TO EXPAND AS WELL WITH MEAN DEEP LAYERED FLOW
GENERALLY PARALLEL TO THE FRONTAL BOUNDARY SUPPORTING TRAINING
CELL TRACKS WITH A VERY SLOW EASTWARD ADVANCEMENT.  THIS SLOW
EASTWARD ADVANCEMENT IS A NET POSITIVE GIVEN IT CELLS ARE MOVING
INTO AN AREA THAT AS BEEN AFFECTED MUCH LESS BY PRIOR ROUNDS OF
CONVECTION.  STILL THE DEEP LAYERED FLOW IS GENERALLY SATURATED
THROUGH A LARGE PORTION OF THE LOWER ATMOSPHERE AS IT RESIDES AT
THE CONFLUENCE OF THE SOUTHEASTERLY FLOW OUT OF THE CARIBBEAN AND
FLORIDA STRAITS AS WELL AS THE DEEP SOUTHERLY FLOW OUT OF THE BAY
OF CAMPECHE/EASTERN TROPICAL PACIFIC.  THIS ALLOWS FOR TPWS OVER
1.75" AND RAINFALL EFFICIENCY TO BE FAIRLY EFFECTIVE WITH VERY
LITTLE INSTABILITY TO WORK WITH AS PROFILES ARE VERY SKINNY
(100-300 J/KG) AND MOIST ADIABATIC PER 00Z SOUNDINGS AND RECENT
RAP SOUNDINGS.  INSTABILITY WILL BE INCREASE PARTICULARLY NEAR THE
INFLECTION POINT WITH RECENT HRRR VALUES TRICKLING UP TO 1000 J/KG
BY 13Z ALONG WITH INCREASING LOW LEVEL FLOW/MST CONVERGENCE TO
SUPPORT A CONTINUATION/REDEVELOPMENT IN THIS AREA OVER THE COMING
HOURS...THIS COULD LEAD TO A CONCENTRATED AREA OF VERY HIGH TOTALS
AND SIGNIFICANT FLASH FLOODING ACROSS LASALLE/AVOYELLES PARISHES. 

HI-RES CAMS DO NOT HAVE A GOOD HANDLE ON THE INITIAL CONDITIONS
FOR THIS LINE AS MOST ARE GENERALLY TO FAR WEST WITH THE FRONTAL
ZONE.  WITH CONTINUED HEIGHT FALLS TO THE SOUTHWEST AND LIMITED
DRY AIR CURRENTLY IN PLACE ...COLD POOL PROPAGATION SHOULD BE
LIMITED UNTIL SHORTWAVE OVER S TX ADVANCES NORTH INTO LA/S AR
TOWARD 12-13Z. 

GALLINA

ATTN...WFO...JAN...LCH...LIX...LZK...MEG...SHV...

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

LAT...LON   35498959 34968867 32978998 31419108 30919141 
            30919231 31599249 33139179 35119070 


Last Updated: 257 AM EST THU MAR 10 2016