MESOSCALE PRECIPITATION DISCUSSION 0359
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1245 PM EDT TUE SEP 09 2014
 
AREAS AFFECTED...SOUTHERN UT...NORTHWEST AZ...WESTERN CO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 091640Z - 092230Z
 
SUMMARY...MULTIPLE BANDS OF PERSISTENT CONVECTION WILL CONTINUE TO
FOSTER A THREAT OF FLASH FLOODING THROUGH THE AFTERNOON.

DISCUSSION...THE LATEST RADAR IMAGERY CONTINUES TO SHOW BANDS OF
CONVECTION OVER SRN UT THAT ARE TENDING TO BACKBUILD AND TRAIN
OVER THE SAME AREA. SOME ACTIVITY IS ALSO SEEN DEVELOPING OVER
PORTIONS OF NWRN AZ WITH LESSER INTENSITY. ALL OF THIS IS IN ASSOC
WITH A SHORTWAVE TROUGH THAT IS SEEN IN WV IMAGERY DIGGING ACROSS
SERN NV ATTM...AND OVER THE NEXT FEW HOURS THE ENERGY/DYNAMICS
ALOFT WILL BE SHIFTING FARTHER EAST ACROSS CNTRL/SRN UT AND
EVENTUALLY WILL MOVE INTO WRN CO.

THE SHORTWAVE TROUGH IS ALREADY INTERACTING WITH MODEST
INSTABILITY AND A PLUME OF RATHER DEEP MOISTURE...WITH THE LATEST
GOES-SOUNDER DATA INDICATING PWATS OF 1.2 TO 1.4 INCHES ACROSS
NWRN AZ AND EXTENDING NEWD INTO WRN CO. ALREADY THERE HAS BEEN
FLASH FLOODING AT LEAST LOCALLY...AND WITH THE INCREASE IN DIURNAL
HEATING/SFC-BASED INSTABILITY THROUGH THE MIDDAY AND AFTERNOON
HOURS...CONVECTION SHOULD TEND TO INTENSIFY AND EXPAND IN COVERAGE
WHICH WILL ELEVATE THE CONCERNS FOR ADDITIONAL FLASH FLOODING.

THE 12Z NAM-CONEST...12Z ARW AND 12Z NMMB ALL SUPPORT THE IDEA OF
SEEING MULTIPLE LINEARLY ORIENTED BANDS OF CONVECTION THROUGH THE
AFTERNOON THAT WILL HAVE THE CAPABILITY TO TRAIN OVER THE SAME
AREA. THIS COUPLED WITH INTENSE RAINFALL RATES THAT SHOULD EXCEED
1.5 INCHES/HR LOCALLY AND WITH MOUNTAINOUS TERRAIN...IT IS
EXPECTED THAT ADDITIONAL FLASH FLOODING WILL OCCUR.

ORRISON

ATTN...WFO...ABQ...FGZ...GJT...SLC...VEF...

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

LAT...LON   39630799 39500702 38820679 38270723 37570836 
            36801011 36051203 35781323 36151393 36981404 
            37591361 38321167 38931002