Flash Flood Guidance
Issued by NWS

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000
AWUS01 KWNH 291703
FFGMPD
NEZ000-COZ000-WYZ000-UTZ000-IDZ000-292302-

MESOSCALE PRECIPITATION DISCUSSION 0230
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
103 PM EDT TUE JUL 29 2014

AREAS AFFECTED...PORTIONS OF THE CENTRAL ROCKIES

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

VALID 291702Z - 292302Z

SUMMARY...SHOWERS AND THUNDERSTORMS HAVE STARTED TO BUILD AS AN
UPPER LEVEL LOW APPROACHES THE REGION AND SOLAR INSOLATION
INCREASES INSTABILITY ACROSS THE REGION.  COUPLED WITH HIGHLY
ANOMALOUS MOISTURE VALUES, FLASH FLOODING IS POSSIBLE IN THIS
REGION.

DISCUSSION...PRECIPITABLE WATER VALUES ~1.25", 2-3 STANDARD
DEVIATIONS ABOVE NORMAL OR ABOVE THE 90TH PERCENTILE FOR LATE JULY
-- HAVE BEEN ESCORTED INTO THE REGION AHEAD OF AN UPPER LEVEL LOW
MOVING ACROSS UT.  THE SPC MESOANALYSIS PAGE INDICATES MIXED LAYER
CAPE VALUES OF 1000-2000 J/KG ACROSS WESTERN UT, WITH A GROWING
AREA OF 500-1500 J/KG CAPE ACROSS SOUTHEAST WY AND EASTERN CO.
WEAK UPSLOPE FLOW, ON THE ORDER OF 10-15 KTS, APPEAR TO BE FOCUSED
INTO THE CENTRAL CONTINENTAL DIVIDE FROM BOTH SIDES PER THE LATEST
RAP RUNS AND VAD WIND PROFILES.

THE THREE-HOUR 00Z SSEO ENSEMBLE- BASED FLASH FLOOD GUIDANCE
EXCEEDANCE OVER THE NEXT SEVERAL HOURS INDICATE THAT PORTIONS OF
CENTRAL CO, SOUTHEAST WY, AND FAR WESTERN WY HAVE A 50+% CHANCE OF
FLASH FLOODING THROUGH 23Z.  A FRONTAL ZONE ALONG WITH INFLOW INTO
THE TOPOGRAPHY SHOULD HELP FOCUS CONVECTION.  BOTH SETS OF
PROPAGATION VECTORS INDICATE 5-10 KT MOTION TO THE EAST IS
EXPECTED LATE THIS MORNING INTO THIS AFTERNOON, THOUGH SOME DRY
AIR ALOFT COULD SPEED UP ACTIVITY INTO THE 10-15 KT RANGE -- CELL
TRAINING IS POSSIBLE ONCE COLD POOLS DEVELOP.  HOURLY RAIN RATES
UP TO 1.5" ARE POSSIBLE WITHIN THIS RELATIVELY MOIST AIR MASS,
WITH A SIGNIFICANT PERCENTAGE OF THE MESOSCALE QPF GUIDANCE
INDICATING LOCAL AMOUNTS OF 2-3" POSSIBLE WITHIN A SHORT PERIOD OF
TIME.  FLASH FLOODING IS CONSIDERED POSSIBLE.

ROTH

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...UNR...PUB...BOU...CYS...RIW...GJT...SLC...PIH...

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

LAT...LON   37670698 38790830 39910951 40151136 40001255 39881324
            40401377 41681380 42731327 44001183 44451008 44470823
            43470568 41730418 39770374 38060451 37670698


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