MESOSCALE PRECIPITATION DISCUSSION 0324
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1124 PM EDT TUE AUG 26 2014
 
AREAS AFFECTED...FAR NORTHERN AZ...SOUTHERN UT 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 270315Z - 270630Z
 
SUMMARY...ADDITIONAL HEAVY SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO EXACERBATE ONGOING FLASH FLOOD CONCERNS THE NEXT FEW HOURS.

DISCUSSION...AN UPR LOW MOVING SLOWLY EASTWARD THROUGH ERN NV WILL
BE MOVING GRADUALLY INTO CNTRL UT OVERNIGHT AND WILL CONTINUE TO
FOSTER AREAS OF HVY SHOWERS AND THUNDERSTORMS. THE LATEST WV
IMAGERY SUGGESTS IMPRESSIVE LARGE SCALE ASCENT WITH ROBUST
DYNAMICAL FORCING AND RESULTING DIV FLOW ALOFT OVER NORTHERN AZ
AND INTO CNTRL/SRN UT.

THE DYNAMICS ALOFT ARE INTERACTING WITH A NOSE OF MODEST
INSTABILITY EXTENDING FROM WRN AZ NWD INTO SRN UT...WITH MUCAPE
VALUES OF 500 J/KG TO 1000 J/KG. THE LATEST IR SAT IMAGERY ALREADY
SHOWS A CLUSTER OF RELATIVELY COLD-TOPPED CONVECTION OVER SWRN
UT...BUT THE CLOUD TOPS ARE STILL COOLING WHICH IS INDICATIVE OF
STRENGTHENING AND FURTHER CONFIRMS THE DEGREE OF LARGE SCALE
ASCENT OVER THE AREA.

THE CONVECTION IS ALREADY PRODUCING AREAS OF INTENSE FLASH
FLOODING AND ESP OVER AREAS OF HIGHER TERRAIN INVOLVING THE SRN
WASATCH MTNS. THIS IS EXPECTED TO CONTINUE OVER THE NEXT FEW HOURS
AS ADDITIONAL HVY SHOWERS AND THUNDERSTORMS DEVELOP OVER SWRN UT
AND ADVANCE SLOWLY EAST ACROSS FAR SRN UT AND POSSIBLY SINKING
SEWD SOMEWHAT THROUGH NRN AZ WHERE THE INSTABILITY IS SLIGHTLY
GREATER.

RAINFALL RATES OF UP TO 1.5 INCHES/HR ARE EXPECTED...WITH STORM
TOTAL AMTS OF LOCALLY 3 TO 5 INCHES ANTICIPATED. THESE RAINS COULD
CAUSE LIFE-THREATENING FLASH FLOODING AND MUDSLIDES...ALONG WITH
DAMAGING DEBRIS FLOWS. WILL CONTINUE TO MONITOR.

ORRISON

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

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

LAT...LON   37281043 36791119 36521225 36481315 36651374 37171405
            37631365 37951235 37991097 37281043