MESOSCALE PRECIPITATION DISCUSSION 0442
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
716 PM EDT TUE AUG 11 2015
 
AREAS AFFECTED...SOUTHEAST AZ 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 112316Z - 120346Z
 
SUMMARY...THUNDERSTORMS WITHIN AN UNSTABLE AIRMASS WITH STRONG
LOW-LEVEL INFLOW COULD CAUSE FLASH FLOODING AND DEBRIS FLOWS.

DISCUSSION...A MID-LEVEL SHORTWAVE IS ABOUT TO CROSS THE BORDER OF
MEXICO INTO SOUTHWEST AZ.  EAST OF THIS FEATURE, 15-30 KTS OF
CONVERGENT INFLOW AT 700 HPA IS BEING REPORTED BY VAD WIND
PROFILES, WHICH SHOULD PERSIST FOR THE NEXT SEVERAL HOURS. 
MLCAPES HAVE BUILT TO 1500-2500 J/KG IN SOUTHEAST AZ AND ADJACENT
PORTIONS OF MEXICO.  PRECIPITABLE WATER VALUES OF 1-2" EXIST
ACROSS THIS REGION PER GPS INFORMATION, WHICH ARE 1-2 SIGMAS ABOVE
THE MEAN FOR MID-AUGUST.  

AN OUTFLOW BOUNDARY OVER PORTIONS OF SOUTHERN AND EASTERN AZ COULD
ACT AS THE FOCUS FOR LATER CONVECTION, ALONG WITH TOPOGRAPHY IN
THE AREA.  STORMS ARE EXPECTED TO FORM AND EXPAND IN COVERAGE AND
INTENSITY ACROSS SOUTHEAST AZ, WHICH COULD SHIFT FROM EAST TO WEST
WITH TIME ALONG WITH THE MOISTURE CHANNEL.  ADDITIONAL
THUNDERSTORMS IN NORTHWEST MEXICO ARE ON PACE TO CROSS THE BORDER
IN THE NEXT 2-3 HOURS, EXACERBATING ISSUES.  THE CAM GUIDANCE IS
RELATIVELY UNIMPRESSED, SHOWING LOCAL AMOUNTS IN THE 1-1.5" RANGE.
 WITH THE AVAILABLE MOISTURE, INSTABILITY, AND CLOUD BASE INFLOW,
PRECIPITATION AMOUNTS COULD OUTPERFORM WHAT IS ADVERTISED.  HOURLY
RAIN RATES UP TO 1.5" WITH LOCAL AMOUNTS OF 2-3" ARE POSSIBLE IN
THIS REGIME. FLASH FLOODING AND ASSOCIATED DEBRIS FLOWS ARE
CONSIDERED POSSIBLE, MAINLY ASSOCIATED WITH CELL TRAINING AND CELL
MERGERS.

ROTH

ATTN...WFO...ABQ...EPZ...FGZ...PSR...TWC...

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

LAT...LON   34040972 33950918 33410876 32400868 31400869 
            31280897 31280978 31250990 31281104 31281104 
            31281104 31881157 32651186 32651186 33041110 
            33491044