MESOSCALE PRECIPITATION DISCUSSION 0565
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 AM EDT THU OCT 08 2015
 
AREAS AFFECTED...PORTIONS OF WESTERN TX/SOUTHEAST NM 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 080559Z - 080859Z
 
SUMMARY...HEAVY RAINFALL IS BEGINNING TO DECREASE IN COVERAGE AND
INTENSITY.  THE FLASH FLOOD THREAT SHOULD FADE OVER THE NEXT FEW
HOURS.

DISCUSSION...AN UPPER LOW NEAR THE SOUTHERN BORDER OF AZ/NM IS
PROVIDING DIVERGENCE AND LIFT ACROSS WESTERN TX AND NORTHERNMOST
MEXICO OVER A PAIR OF THERMAL BOUNDARIES AND NEAR/DOWNWIND OF
TOPOGRAPHY.  PER THE 0516Z SPENES MESSAGE FROM SAB/NESDIS, CLOUD
TOPS HAVE UNDERGONE A SLOW PROCESS OF WARMING OVER THE PAST COUPLE
HOURS AS MUCAPE ACROSS THE REGION SLOWLY FADES, DOWN TO 500-1000
J/KG PER RECENT SPC MESOANALYSES.  CONVECTION HAS BECOME MORE
SCATTERED IN NATURE AS OF LATE PER RADAR IMAGERY.  PRECIPITABLE
WATER VALUES ARE BETWEEN 1-1.4" PER RECENT GPS INFORMATION. INFLOW
AT 850 HPA REMAINS FROM THE SOUTHEAST 25-35 KTS, SIMILAR IN
MAGNITUDE TO THE 850-400 HPA WIND BUT AT A RIGHT ANGLE. 
CONSIDERING THE ORIENTATION OF THE INSTABILITY AND THUNDERSTORM
DEVELOPMENT ACROSS THE TX BIG BEND, INSTABILITY APPEARS TO BE
ADVECTING IN WITHIN THE 500-700 HPA LAYER.

A MAJORITY OF THE GUIDANCE SUGGESTS THAT CELL COVERAGE SHOULD
BECOME ISOLATED BY 09Z, LIKELY DUE TO EXHAUSTING INSTABILITY.  THE
WRINKLE IN THE FORECAST IS A BUBBLE OF 500-1500 J/KG
MUCAPE/INSTABILITY MOVING UP THE RIO GRANDE VALLEY, WHICH NEEDS TO
BE WATCHED IN CASE IT LEADS TO A RENEWED UPTICK IN CONVECTIVE
DEVELOPMENT OVER THE NEXT SEVERAL HOURS.  HOURLY RAIN RATES WITHIN
THIS ENVIRONMENT HAVE THE POTENTIAL TO PEAK AT 1.5".  THE CAM
GUIDANCE ADVERTISES 1.5-3" OF RAINFALL OVER THE NEXT SEVERAL
HOURS, WHICH COULD FALL QUICKLY.  AMOUNTS OF 3" WOULD BE NEAR THE
10 YEAR RECURRENCE INTERVAL FOR SPOTS WITHIN THIS AREA AS WELL AS
THREE HOUR FLASH FLOOD GUIDANCE VALUES.  FLASH FLOODING REMAINS
POSSIBLE OVER THE NEXT FEW HOURS BEFORE CONVECTIVE COVERAGE
BECOMES ISOLATED.

ROTH

ATTN...WFO...EWX...MAF...SJT...

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

LAT...LON   32590244 32540167 32080133 30800105 29860129 
            29660152 29670154 29680160 29720229 29710241 
            29630262 29430280 29030298 28940320 28940342 
            29190389 29280405 29460443 29700467 30480488 
            31340413 31990349