MESOSCALE PRECIPITATION DISCUSSION 0595
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
845 PM EDT SAT JUL 29 2017

AREAS AFFECTED...SOUTHWEST NM...SOUTHERN AZ

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 300045Z - 300415Z

SUMMARY...SLOW MOVING CELLS IN THE MONSOONAL FLOW WILL POSE A
CONTINUED FLASH FLOOD THREAT THROUGH THE EVENING HOURS.

DISCUSSION...THE EXPERIMENTAL GOES-16 CLEAN IR LOOP SHOWED COOLING
TOPS WITH CONVECTION OVER FAR SOUTHWEST NM INTO SOUTHERN AZ. THE
COVERAGE OF CELLS HAS DIMINISHED TO A DEGREE IN THE PAST TWO
HOURS...DUE PRIMARILY TO THE EXHAUSTION OF AVAILABILITY
INSTABILITY...AS THE MOST RECENT RAP ANALYSIS SHOWED A GROWING
AREA OF CIN ACROSS SOUTHWEST NM AND SOUTHEAST AZ

DESPITE THE SCATTERED NATURE OF THE CONVECTION...SLOW MOVING CELLS
(DUE TO 850-300 MB MEAN WINDS GENERALLY LESS THAN 10 KNOTS) IN THE
DEEP MONSOONAL MOISTURE (WITH THE AXIS OF THE 1.50/1.75 INCH
PRECIPITABLE WATER AIR POINTED TOWARD SOUTHWEST AZ) WERE STILL
PRODUCING HOURLY RAINFALL RATES NEAR 1.50 INCHES...WHICH WAS
RESULTING IN FLASH FLOODING IS PORTIONS OF FAR WESTERN NM.

THE MAIN FLASH FLOOD THREAT SHIFTS TOWARD SOUTHEAST AND SOUTH
CENTRAL AZ DURING THE NEXT 4 HOURS...AS LIFT ASSOCIATED WITH THE
OLD MCV OVER SOUTH CENTRAL AZ PROVIDES A FOCUS FOR LIFT. BASED ON
WHAT HAS OCCURRED THIS AFTERNOON IN THE AIRMASS...HOURLY RAINFALL
RATES NEAR 1.50 INCHES COULD RESULT IN LOCAL 2.00 TO 3.00 INCH
RAINFALL AMOUNTS...ESPECIALLY OVER SOUTH CENTRAL AZ.
THESE AMOUNTS ARE SIMILAR TO THOSE DEPICTED BY THE MOST RECENT
HRRR.

AS THE INSTABILITY IS EXHAUSTED FURTHER... THE EXTENT OF THE
SCATTERED CONVECTION SHOULD CONTINUING SHRINKING...AND THE FLASH
FLOOD THREAT SHOULD WANE AROUND 04Z.

HAYES

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

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

LAT...LON   33720975 33720893 31980796 31490862 31231010
            31461130 31921255 32571315 33441295 33441184
            33161077