MESOSCALE PRECIPITATION DISCUSSION 0521
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
746 PM EDT WED AUG 03 2016
 
AREAS AFFECTED...SOUTHWEST UT...NORTHWEST AZ 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 032345Z - 040530Z
 
SUMMARY...STORMS DEVELOPING OVER THE HIGHER TERRAIN OF SOUTHWEST
UT AND NORTHWESTERN AZ WILL HAVE BEEN MOVING OFF THE TERRAIN. 
THIS SHOULD CONTINUE INTO THE LATE EVENING HOURS...WITH THE TREAT
OF ADDITIONAL FLASH FLOODING. 

DISCUSSION...DEEP MONSOON MOISTURE IN PLACE OVER PARTS OF THE
DESERT SOUTHWEST U.S. COMBINED WITH WEAK SHORTWAVE TROUGHS
EMBEDDED WITHIN WEAK SYNOPTIC SCALE FLOW HAS SET THE STAGE FOR
HEAVY RAINFALL PRODUCING CONVECTION EXPECTED TO CONTINUE THROUGH
THE REMAINDER OF THE EVENING.  PRECIPITABLE WATER VALUES IN EXCESS
OF 1.5 INCHES ARCS FROM SOUTHERN AZ NORTHWESTWARD ALONG THE
WESTERN AZ BORDER.  CONVECTION HAD DEVELOPED EARLIER IN THE
AFTERNOON AND PROPAGATED OFF THE COMPLEX TERRAIN.  RECENT RADAR
TRENDS SHOW MANY OF THE CELLS HAVE BECOME SLOW MOVING TO NEARLY
STATIONARY.  WHILE THE STORM ANVIL CANOPY WILL LIMIT MUCH
ADDITIONAL INSOLATION...PLENTY OF INSTABILITY WILL BE IN PLACE TO
SUPPORT ADDITIONAL CONVECTION THROUGH MUCH OF THE EVENING.  

QPF FROM THE HRRR AND ARW APPEAR TO HAVE BEEN TOO LIGHT SO FAR BUT
THEY HAVE POINTED TOWARDS HEAVIEST RAINS MOVING OFF THE HIGHER
TERRAIN.  

GIVEN THE NATURE OF THE DESERT GROUND...PLUS GREATER THAN NORMAL
SOIL MOISTURE ALREADY BEING IN PLACE IN RESPONSE TO RAINFALL OVER
THE PREVIOUS DAYS..THINK THE THREAT FOR FLASH FLOODING WILL
CONTINUE UNTIL CONVECTION SETTLES DOWN LATER TONIGHT. 

BANN

ATTN...WFO...FGZ...PSR...SLC...TWC...VEF...

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

LAT...LON   38131235 37901143 36301211 34961212 32891093 
            32851259 34651403 36081432 37521402