MESO: Nws Weather Prediction Center College Park Md

AWUS01 KWNH 270101
FFGMPD
COZ000-NMZ000-UTZ000-AZZ000-270400-

MESOSCALE PRECIPITATION DISCUSSION 0226
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
900 PM EDT MON AUG 26 2013

AREAS AFFECTED...NORTHERN AZ...SOUTHERN UT...SOUTHWESTERN CO

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

VALID 270100Z - 270400Z

SUMMARY...SCATTERED THUNDERSTORMS CONTINUE GROWING IN COVERAGE AS
THEY MOVE ACROSS PORTIONS OF UT AND SOUTHWESTERN CO. REGIONAL
FLASH FLOODING IS POSSIBLE IN AREAS WHERE CELLS TRAIN THROUGH 04Z.

DISCUSSION...SCATTERED THUNDERSTORMS ARE SPREADING ACROSS SOUTHERN
UT, AND SOUTHWEST CO, PER RECENT RADAR AND SATELLITE IMAGERY. THE
REGION HAS CAPE VALUES AROUND 2000 J/KG DUE TO SOLAR INSOLATION TO
THE EAST OF A BAND OF CLOUDS EXTENDING FROM THE CYCLONE ONCE KNOWN
AS IVO -- LOCATED WEST OF BAJA CALIFORNIA. DIVERGENCE ALOFT IS
BEING CAUSED PRIMARILY BY AN UPPER-LEVEL TROUGH ACROSS THE PACIFIC
NORTHWEST. PRECIPITABLE WATER VALUES ARE IN THE 1.25-1.75 INCH
RANGE ACROSS THIS REGION, WHICH IS NEAR THE 90TH PERCENTILE FOR
LATE AUGUST AND
SHOULD ALLOW FOR ABOVE AVERAGE PRECIPITATION EFFICIENCY FOR THE
REGION. THE STRONGER CELLS ARE EXPECTED TO HAVE RAINFALL RATES OF
1-2" PER HOUR.

LOW-LEVEL WIND SHEAR VALUES DO NOT APPEAR TO BE SUFFICIENT TO
ORGANIZE CONVECTION A GREAT DEAL. CELL TRAINING IS POSSIBLE, WHICH
COULD LEAD TO LOCAL RAINFALL AMOUNTS OF 2-4 INCHES. REGIONAL
FLASH FLOODING IS CONSIDERED POSSIBLE UNTIL 04Z, WHEN THE LATEST
HRRR/RAP GUIDANCE INDICATES PRECIPITATION ACTIVITY SHOULD BE ON
THE DOWNTURN DUE TO EXHAUSTING CAPE. THIS ISSUANCE ACCOUNTING FOR
RECENT RADAR AND SATELLITE TRENDS WHICH SHOW THUNDERSTORMS EXITING
THE MPD #0225 AREA INTO THIS REGION.

ROTH

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

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

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

LAT...LON 37060797 36180857 35641009 36631138 36991345 37781342
38521285 39531160 39851020 39780874 39450808 38410778
37480790 37060797

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