Graphic for MPD #0597

MESOSCALE PRECIPITATION DISCUSSION 0597
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
950 PM EDT SAT JUL 29 2017

AREAS AFFECTED...WESTERN AZ

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

VALID 300150Z - 300450Z

SUMMARY...CONVECTION TRAINING IN AN AXIS OF DEEP MOISTURE COULD
RESULT IN A SHORT TERM FLASH FLOOD THREAT THROUGH LATE THIS
EVENING.

DISCUSSION...THE EXPERIMENTAL GOES-16 CLEAN IR LOOP SHOWED COOLING
CLOUD TOPS OVER WESTERN AZ...ON THE WEST SIDE OF A MID LEVEL RIDGE
OVER THE SOUTHWEST STATES. THE CONVECTION IS FORMING IN AN AXIS OF
1000-1500 J/KG OF SBCAPE (BASED ON THE 30/00Z KFGZ SOUNDING). THE
AXIS OF INSTABILITY IS COINCIDENT WITH A NARROW RIBBON OF
1.25/1.50 INCH PRECIPITABLE WATER AIR EXTENDING FROM SOUTHWEST AZ
INTO SOUTHERNMOST NV.

HOURLY RAINFALL RATES IN THE DEEP MOISTURE RIBBON ARE AS HIGH AS
1.50 INCHES (PER THE KFSX RADAR)...AND AS THE CONVECTION MOVES
SOUTHWARD WITH THE MEAN 850-300 MB WIND...TRAINING IS EXPECTED.
MUCH OF THE HIGH RESOLUTION GUIDANCE IS NOT DEPICTING THE FLASH
FLOOD THREAT WELL...WITH ONLY THE MOST RECENT HRRR SHOWING ANY
REFLECTION OF THE CONVECTION IN THE DEEP MOISTURE CHANNEL.

BASED ON RADAR TRENDS AND THE POTENTIAL FOR TRAINING...LOCAL 2.00
TO 3.00 INCH RAINFALL AMOUNTS ARE POSSIBLE ACROSS PORTIONS OF
WESTERN AZ. ONE AND THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE AS
LOW AS AN INCH OVER THIS AREA...SO ANY TRAINING COULD RESULT IN A
FLASH FLOOD THREAT THROUGH LATE EVENING.

HAYES

ATTN...WFO...FGZ...PSR...VEF...

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

LAT...LON   35241374 35051301 34371278 32771332 32891383
            33431410 34891393


Last Updated: 950 PM EDT SAT JUL 29 2017