MESOSCALE PRECIPITATION DISCUSSION 0394
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
706 AM EDT SUN SEP 21 2014
 
AREAS AFFECTED...WEST-CENTRAL TX & SOUTHEAST NM 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 211106Z - 211531Z
 
SUMMARY...CONVECTION IS INCREASING IN COVERAGE NEAR THE TX/NM
BORDER IN ASSOCIATION WITH A SURFACE TROUGH.  CONSIDERING THE
SATURATED SOILS IN THIS REGION, FLASH FLOODING IS CONSIDERED
POSSIBLE.

DISCUSSION...A SLOWLY RETROGRADING SURFACE TROUGH/LOW-LEVEL
CONVERGENCE ZONE IS MOVING SLOWLY THROUGH WESTERN TX INTO
SOUTHEASTERN NM.  IT IS ACTING AS A FOCUS FOR INCREASED SCATTERED
THUNDERSTORM DEVELOPMENT, AS 850 HPA INFLOW OF 25 KTS INTERSECTS
THE BOUNDARY ORTHOGONALLY, WHICH WELL EXCEEDS THE MEAN WINDS IN
THIS REGION, ALLOWING FOR EFFICIENT RAIN RATES.  PRECIPITABLE
WATER VALUES ARE IN THE 1.75-2" RANGE PER GPS PRECIPITABLE WATER
VALUES, WHICH COULD SUPPORT HOURLY RAIN RATES UP TO 2". MOST
UNSTABLE CAPES UPSTREAM ARE BETWEEN 1000-1500 J/KG PER THE LATEST
SPC MESOANALYSIS.  THE STAGE HAS BEEN SET FOR THE WET MULTICELL
ENVIRONMENT, WHICH SHOULD LEAD TO INCREASED ORGANIZATION IN THE
SHORT TERM.

THE EXPECTATION IS FOR THIS ACTIVITY TO SLOWLY SHIFT WESTWARD AND
WEAKEN AROUND 1530Z AS LOW-LEVEL INFLOW WEAKENS INTO THIS REGION
-- INSTABILITY SHOULD REMAIN SUFFICIENT INTO THE MORNING HOURS. 
WHILE 850 HPA INFLOW WEAKENS AFTER 13Z PER RECENT RAP GUIDANCE,
700 HPA INFLOW ISN'T FORECAST TO WEAKEN UNTIL 18Z, SO USED AN
INTERMEDIATE TIME FOR THE HORIZON OF THIS MPD.  THERE IS A SIGNAL
FOR LOCAL 2-4" AMOUNTS WITHIN THE MESOSCALE QPF GUIDANCE, WHICH
SHOULD CAUSE FLASH FLOODING CONSIDERING THE SATURATED SOILS IN
THIS REGION.  AS CONVECTION REMAINS SCATTERED, USED THE POSSIBLE
CATEGORY OVER LIKELY.  

ROTH

ATTN...WFO...ABQ...EPZ...LUB...MAF...SJT...

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

LAT...LON   33520270 33130184 32330154 31170175 30590277 
            30740395 31380475 32510486 33470390