MESOSCALE PRECIPITATION DISCUSSION 0518
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
344 PM EDT THU JUL 20 2017

AREAS AFFECTED...EXTREME NORTHWEST AZ...UT...WESTERN/CENTRAL
CO...NORTHWEST NM

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

VALID 201940Z - 210140Z

SUMMARY...SCATTERED SHOWERS AND THUNDERSTORMS WITH LOCALLY INTENSE
RAINFALL RATES WILL EXPAND IN COVERAGE THIS AFTERNOON. HEAVY
RAINFALL RATES AND SLOW CELL MOTION WILL SUPPORT SOME FLASH
FLOODING CONCERNS.

DISCUSSION...DIURNALLY ENHANCED AND OROGRAPHICALLY FOCUSED SHOWERS
AND THUNDERSTORMS WILL BE THE THEME ONCE AGAIN THIS AFTERNOON AND
INTO THE EARLY EVENING HOURS OVER ESPECIALLY CENTRAL/EASTERN UT
AND ACROSS WESTERN/CENTRAL CO. ADJACENT AREAS OF NORTHWEST NM WILL
BE IMPACTED TO AN EXTENT...AND LATER IN THE DAY...NORTHWEST AZ MAY
SEE AN UPTICK IN CONVECTIVE ACTIVITY DEPENDING ON HOW WELL
CONVECTION ORGANIZES OVER THE MOGOLLON RIM. A VERY WELL-DEFINED
MCV SEEN IN GOES-15 VISIBLE SATELLITE IMAGERY OVER FAR SOUTHERN NV
ALSO WILL NEED TO BE MONITORED AS A FORCING MECHANISM.

THESE AREAS CONTINUE TO BE LOCATED WITHIN AN AREA OF CONCENTRATED
MONSOONAL MOISTURE AS EVIDENCED BY THE 15Z CIRA-LPW AND GOES-15
SOUNDER DATA WHICH SHOW TPW VALUES UP AROUND 1 INCH. OVERALL...THE
COLUMN IS A BIT MORE MOIST OVER CENTRAL/EASTERN UT...AND SO THE
RAINFALL RATES HERE WILL TEND TO BE A BIT HIGHER COMPARED TO
WESTERN CO. HOWEVER...THE EFFECTS OF OROGRAPHIC FORCING AND SLOW
CELL MOTION GIVEN WEAK MID LEVEL FLOW OVER THE REGION WILL BE
CAPABLE OF ALLOWING ANY OF THE THUNDERSTORMS TO PRODUCE LOCALLY
ENHANCED RAINFALL.

A CONSENSUS OF THE HIRES MODEL CONSENSUS SUPPORTS RAINFALL RATES
OF UP TO 1.5 INCHES/HR WITH SOME STORM TOTALS OF AS MUCH AS 2 TO 3
INCHES LOCALLY. THIS AGAIN WILL LIKELY BE ENOUGH TO CAUSE SOME
FLASH FLOODING CONCERNS OVER THE HIGHER TERRAIN AND NEAR ANY
CANYON AREAS MORE SUSCEPTIBLE TO ENHANCED CHANNELING OF RUNOFF.

ORRISON

ATTN...WFO...ABQ...BOU...CYS...FGZ...GJT...PUB...RIW...SLC...
VEF...

ATTN...RFC...ABRFC...CBRFC...MBRFC...WGRFC...

LAT...LON   41030724 40740601 40470553 39800531 39380509
            38950487 38360504 37790500 37350520 36750576
            36220657 35830748 36180832 36620884 36980970
            37091095 37051221 36841306 36421385 37471407
            38911362 40131256 40841101 40990932