MESOSCALE PRECIPITATION DISCUSSION 0250
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
449 PM EDT TUE AUG 05 2014
 
AREAS AFFECTED...SRN ID...NRN UT...WRN WY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 052048Z - 060048Z
 
SUMMARY...THUNDERSTORMS WITHIN A VERY ANOMALOUS MOIST AIRMASS WILL
PRODUCE LOCAL INTENSE DOWNPOURS. LACK OF SUSTAINED INFLOW WILL
LIMIT THE BREADTH OF THESE STORMS AND THEIR DURATION OVER ANY
GIVEN POINT...BUT VERY SMALL SCALE ACCUMULATIONS OF 1 TO 1.5
INCHES IN AN HOUR ARE POSSIBLE...AND WOULD LIKELY LEAD TO FLASH
FLOODING.

DISCUSSION...AT 2030Z A CONVECTIVE HEAVY RAIN EVENT WAS MID
STREAM...WITH REPORTS OF WATER BEGINNING TO AFFECT SOME ROADS IN
IDAHO...AND RADAR/SATELLITE DEPICTING THE GROWTH OF
ORGANIZED...SHEARED LOOKING CONVECTION IN WESTERN WYOMING. THIS
FAR INTO THE CONTINENTAL INTERIOR THE 1.2 INCH PRECIPITABLE WATER
VALUES IN PLACE WERE AT LEAST 3.5 STANDARD DEVIATIONS FROM
CLIMATOLOGY...AND WERE SUPPORTING RAIN RATES OF AT LEAST 1 TO 1.5
INCHES IN AN HOUR. EARLY IN THE EVENT SOME TRAINING OCCURRED AT
CLOSE PROXIMITY TO KSFX...WHERE THE DUAL POL ESTIMATES OF 1.5 TO
NEAR 2 INCHES OR MORE OF RAIN APPEAR BELIEVABLE.

DESPITE WEAK STEERING FLOW...STORMS HAD SHOWN SOME ORGANIZATION
BEYOND THAT OF ORDINARY CELLS...POSSIBLY OWING TO ENHANCED CLOUD
LAYER FLOW AROUND A SMALL MCV IN SRN ID. THE NAM WAS FORECASTING
THIS FEATURE TO STALL ITS NORTHWARD PROGRESS AND COME BACK SE
TOWARD NRN UT THIS EVENING. AS THIS OCCURS...THE BETTER INFLOW
CAPABLE OF YIELDING BRIEF TRAINING EPISODES WILL SPREAD INTO FAR
NE NV AND NRN UT. BY 01Z...HOWEVER...SIMULATED REFLECTIVITY OUTPUT
FROM THE HRRR AND NAM CONEST SUGGEST CELLS WILL BE LOSING
INTENSITY OWING TO WIDESPREAD OVERTURNING AND GENERALLY WEAK UPPER
LEVEL SUPPORT.

BURKE

ATTN...WFO...RIW...GJT...TFX...SLC...PIH...BOI...LKN...

ATTN...RFC...CBRFC...CNRFC...MBRFC...NWRFC...

LAT...LON   40811273 40821382 40731487 40801591 41461653 42321589
            42971436 43631291 44451116 44810992 44470872 43390865
            41980908 40630956 40110975 39621015 39351059 39601141
            40281224 40811273