MESOSCALE PRECIPITATION DISCUSSION 0109
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
109 AM EDT SAT MAY 23 2015
 
AREAS AFFECTED...PORTIONS OF EASTERN NM & NORTHWEST TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 230505Z - 231000Z
 
SUMMARY...ISOLATED THUNDERSTORMS HAVE BEGUN TO FORM IN EASTERN NM,
WHICH ARE EXPECTED TO EXPAND IN COVERAGE INTO NORTHWEST TX.  WITH
HOURLY RAIN RATES UP TO 1.75", FLASH FLOODING IS POSSIBLE INTO THE
MORNING HOURS DUE TO CELL TRAINING.

DISCUSSION...A STATIONARY FRONT STRETCHES WEST TO EAST ACROSS THE
WESTERN TX HIGH PLAINS.  INFLOW AT 850 HPA HAS RISEN TO 50 KTS OUT
OF THE SOUTH- SOUTHEAST, SLIGHTLY EXCEEDING THE MEAN 850-400 HPA
WIND, AS PRECIPITABLE WATER VALUES (PWS) HAVE INCREASED TO
1-1.25".  MOST UNSTABLE CAPE VALUES OF 1000-2000 J/KG ARE SEEN
NEAR AND SOUTH OF THE FRONT.  THE STAGE IS BEING SET FOR HEAVY
RAINFALL.

THE CAPE GRADIENT, THE 1000-500 HPA THICKNESS PATTERN, AND THE
DIRECTIONAL WIND SHEAR WITH HEIGHT SUGGEST EASTWARD PROPAGATION,
WITH FORWARD PROPAGATING CORFIDI VECTORS SUGGESTING A MOTION OF
25-30 KTS.  INCREASING MOISTURE ALONG THE FRONT IS EXPECTED TO
POOL FROM WEST TO EAST WITH TIME, WHICH COULD LEAD TO A BROADENING
CONVECTIVE BAND WITH TIME -- CELL TRAINING IS THE MAIN CONCERN
HERE.  FLASH FLOOD GUIDANCE VALUES IN THIS REGION ARE RELATIVELY
LOW DUE TO THE PAST THREE WEEKS OF RAINFALL.  MOST OF THE
MESOSCALE QPF GUIDANCE SUGGESTS LOCAL AMOUNTS OF 2-3" OVER THE
NEXT SEVERAL HOURS.  IT APPEARS THE 00Z ARW, 00Z SPCWRF, 00Z
WRF4NSSL, RECENT RAP RUNS, 00Z NAM CONEST, AND 03Z HRRR HAVE THE
BEST SIGNAL FOR THE EXPECTED CONVECTIVE EVOLUTION.  HOURLY RAIN
RATES UP TO 1.75" COULD LEAD TO FLASH FLOODING OVER SATURATED
SOILS.

ROTH

ATTN...WFO...ABQ...AMA...LUB...MAF...OUN...SJT...

ATTN...RFC...ABRFC...WGRFC...

LAT...LON   35160130 35079980 34699922 33749911 33269956 
            33190008 33030209 33000421 33030491 33270529 
            34100517 34910408