Graphic for MPD #0132

MESOSCALE PRECIPITATION DISCUSSION 0132
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
150 AM EDT SAT APR 22 2017

AREAS AFFECTED...SOUTHERN AR, NORTHERN MS, AND SOUTHWEST TN

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 220549Z - 221149Z

SUMMARY...CLUSTERS OF STRONG THUNDERSTORMS WITH HOURLY RAIN RATES
TO 2" COULD DROP LOCAL AMOUNTS OF 3-5", WHICH COULD LEAD TO FLASH
FLOODING.

DISCUSSION...A 05Z MESOSCALE ANALYSIS REVEALS A WAVY FRONTAL
BOUNDARY ACROSS NORTHEAST TX AND SOUTHWEST AR.  THE PRIMARY/MOST
IMPORTANT WAVE APPEARS TO BE NEAR SULPHUR SPRINGS TX.  DIVERGENCE
ALOFT IS BEING FOSTERED BY AN UPPER LOW IN SOUTHEAST KS. 
CONVECTION DOWNSTREAM OF THE WAVE APPEARS TO BE TRYING TO
BRIDGE/TRAIN ACROSS SOUTHWEST AR AS OF LATE.  CIN IS MINIMAL IN
THIS REGION, SO THE CONVECTION IS NOT ALL THAT ELEVATED OVER
NEARBY BOUNDARIES.  PRECIPITABLE WATER VALUES OF 1.3-1.7" HAVE
BEEN SEEN IN RECENT GPS DATA.  INFLOW AT 850 HPA IS WEST-SOUTHWEST
AT 35-40 KTS, NEAR THE MAGNITUDE OF THE MEAN 850-400 HPA WIND. 
BULK SHEAR IN THE 0-6 KM LAYER IS CLOSE TO 40 KTS PER THE SPC
MESOANALYSIS PAGE.  THE WIND FLOW IS NEARLY UNIDIRECTIONAL WITH
HEIGHT.  MUCAPES OF 1000-2000 J/KG LIE ACROSS NORTHEAST TX AND IN
SOUTHERNMOST AR.

WITH LOW-LEVEL INFLOW EXPECTED TO STRENGTHEN ANOTHER 5-10 KTS,
BACKBUILDING CONVECTION IS POSSIBLE.  THE PRIMARY ISSUE IS
EXPECTED TO BE CELL TRAINING, THOUGH EMBEDDED MESOCYCLONES IN THIS
ENVIRONMENT, AS SEEN RECENTLY IN SOUTHWEST AR, COULD AUGMENT THE
HEAVY RAIN RISK.  PROPAGATION SHOULD BE PARALLEL TO THE MUCAPE
GRADIENT, EAST-SOUTHEAST AT ~30 KTS.  HOURLY RAIN RATES UP TO 2",
WITH LOCAL AMOUNTS OF 3-5", APPEAR TO BE IN THE CARDS.  THE
GUIDANCE THAT SEEMS TO HAVE THE EXPECTED CONVECTIVE PATTERN
CAPTURED THE BEST IS THE 00Z SPCWRF, 00Z WRF4NSSL, 00Z NAM CONEST,
THE 00Z CANADIAN REGIONAL, AND TO SOME DEGREE THE 00Z GFS, THOUGH
THEY DON'T SEEM TO HAVE HANDLED THE POSSIBLE EASTWARD EXTENT VERY
WELL BASED ON RAP MASS FIELDS.  FLASH FLOODING IS CONSIDERED
POSSIBLE.

ROTH

ATTN...WFO...JAN...LZK...MEG...SHV...

ATTN...RFC...ABRFC...LMRFC...SERFC...

LAT...LON   35329139 35218967 34488825 33348894 32859032
            32979217 33429388 33689443 34099498 34659350
           


Last Updated: 150 AM EDT SAT APR 22 2017