Flash Flood Guidance
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000
AWUS01 KWNH 301304
FFGMPD
COZ000-NEZ000-WYZ000-301902-

MESOSCALE PRECIPITATION DISCUSSION 0234
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
903 AM EDT WED JUL 30 2014

AREAS AFFECTED...SOUTHEAST WY AND NORTHEAST CO

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

VALID 301302Z - 301902Z

SUMMARY...BUILDING INSTABILITY COMBINED WITH UPSLOPE FLOW AND
AVAILABLE MOISTURE COULD LEAD TO FLASH FLOODING OVER SATURATED
SOILS.

DISCUSSION...RADAR IMAGERY OVER THE PAST HOUR HAS INDICATED AN
UPTICK IN PRECIPITATION INTENSITY ACROSS SOUTHEAST WY AND
NORTHEAST CO.  UPSLOPE FLOW OF 10-20 KTS IS SEEN IN THE 850-700
HPA LAYER, WITH PRECIPITABLE WATER VALUES IN THE REGION ~1.25",
WHICH REMAINS 1.5-2 STANDARD DEVIATIONS ABOVE NORMAL OR NEAR THE
90TH PERCENTILE FOR LATE JULY.  THE BOULDER CO SOUNDING IS QUITE
MOIST WITH NO DRY LAYERS NEAR THE SURFACE, SO NO ADDITIONAL COLD
POOLS ARE EXPECTED TO FORM WITH ONGOING LOW-TOPPED CONVECTION.
THE MEAN 850-400 HPA WIND FLOW IS EXTREMELY WEAK IN THIS AREA --
THE MAGNITUDE OF THE LOW-LEVEL INFLOW DOES EXCEED THE MEAN FLOW
WHICH SHOULD ALLOW FOR GOOD PRECIPITATION EFFICIENCY.  DIVERGENCE
ALOFT IS BEING AIDED BY A DISTURBANCE ENTERING SOUTHWEST WY, AN
UPPER LEVEL LOW LEAVING EASTERN CO, AND A CURVED -- ALBEIT WEAK --
200 HPA JET STREAK TO THEIR SOUTH.

WITH CAPE VALUES INCREASING -- NOW PAST 500 J/KG PER THE SPC
MESOANALYSIS PAGE -- BELIEVE MODERATE TO HEAVY RAINFALL, UP TO AN
1" AN HOUR, IS POSSIBLE OVER THE NEXT SEVERAL HOURS BEFORE
MOISTURE IN THE REGION FADES THIS AFTERNOON.    PROPAGATION
VECTORS ARE FAIRLY LIGHT, INDICATING LESS THAN 10 KTS OF FORWARD
PROPAGATION IS POSSIBLE.  ADDITIONAL ACTIVITY COULD FORM FURTHER
DOWN THE FRONT RANGE OF THE ROCKIES INTO THE PUB FORECAST OFFICE`S
AREA.  THERE WAS A MODEST SIGNAL FOR HEAVY RAINFALL IN THE MOST
RECENT MESOSCALE QPF GUIDANCE, WITH LOCAL AMOUNTS OF CLOSE TO 2"
INDICATED.  CONSIDERING THE SATURATED SOILS IN THE REGION, FLASH
FLOODING IS CONSIDERED POSSIBLE.

ROTH

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

ATTN...WFO...PUB...BOU...CYS...GJT...

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

LAT...LON   38620561 40090602 41090696 41630562 41470418 40210347
            39170364 38740429 38620561



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