MESOSCALE PRECIPITATION DISCUSSION 0244
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
357 PM EDT SAT AUG 02 2014
 
AREAS AFFECTED...WESTERN NM, MUCH OF AZ, FAR SOUTHEAST CA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 021956Z - 030156Z
 
SUMMARY...CONVECTION WITH HOURLY RAIN RATES UP TO 1.5" COULD LEAD
TO FLASH FLOODING/DEBRIS FLOWS ACROSS THE REGION DURING THE NEXT
SEVERAL HOURS.

DISCUSSION...MUCH OF AZ AND WESTERN NM HAVE BEEN DESTABILIZING DUE
TO DAYTIME HEATING OVER THE PAST SEVERAL HOURS.  THE SPC
MESOANALYSIS INDICATES MIXED LAYER CAPES OF 500-1500 J/KG ACROSS
SOUTHERN AND CENTRAL AZ, WHILE NESDIS/SAB OBJECTIVE ANALYSES SHOW
LOW-LEVEL CONVERGENCE MAXIMIZED ACROSS WESTERN NM AND PORTIONS OF
AZ.  PRECIPITABLE WATER VALUES RANGE FROM 1" ACROSS NORTHERN AZ
AND CENTRAL NM TO OVER 2" ACROSS THE LOWER CO RIVER VALLEY AND
DESERTS ACROSS SOUTHWEST AZ.

LOW-LEVEL FLOW AT THE 850 HPA AND 700 HPA LEVELS IS EXPECTED TO BE
10-15 KTS ACROSS THE REGION, WHICH COULD LEAD TO GREATER THAN
AVERAGE CONVECTIVE ORGANIZATION.  THE 12Z-BASED SSEO NEIGHBORHOOD
PROBABILITIES HAVE SPOTS OF >30% OF EXCEEDING FLASH FLOOD GUIDANCE
IN THE REGION, DESPITE THEIR LOW BIAS CONCERNING QPF IN THE
REGION, EXTENDING WELL INTO THE NIGHT.  HOURLY RAIN RATES UP TO
1.5" ARE POSSIBLE HERE, WITH LOCAL AMOUNTS OF 2-3" POSSIBLE PER
12Z SPC WRF, 12Z PARALLEL NAM CONEST, 12Z EXREF MEMBER NUMBER 7,
AND THE 12Z CANADIAN REGIONAL MODEL.

ROTH

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

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

LAT...LON   35531446 36111383 36091232 35811065 35080830 34470730
            33590684 32470783 31720964 31491104 31611192 32021321
            32361397 33301465 34301480 34901480 35531446