Flash Flood Guidance
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
000
AWUS01 KWNH 271921
FFGMPD
AZZ000-UTZ000-NVZ000-CAZ000-280100-

MESOSCALE PRECIPITATION DISCUSSION 0612
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
320 PM EDT SAT AUG 27 2016

AREAS AFFECTED...ERN CA...SRN NV...CNTRL/NRN AZ

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

VALID 271919Z - 280100Z

SUMMARY...HEAVY RAINFALL RATES OF 1 TO 1.5 IN/HR WILL POSE A FLASH
FLOOD THREAT FOR PORTIONS OF SRN NV/ERN CA/WRN AZ OVER THE NEXT
FEW HOURS. FARTHER EAST ACROSS CNTRL TO NRN AZ...SCATTERED
THUNDERSTORMS NEAR A LOW-MID LEVEL TROUGH WILL HAVE THE POTENTIAL
TO PRODUCE A FEW RUNOFF ISSUES LATER THIS AFTERNOON.

19Z SATELLITE IMAGERY SHOWED A SLOW MOVING UPPER LOW OVER SRN
NEVADA WITH STRONG DIFFLUENCE NOTED IN N-CNTRL AZ. VISIBLE
SATELLITE CONFIRMED THE PRESENCE OF A DEVELOPING SHOWER IN WRN
CLARK COUNTY WITH ESTIMATED MLCAPE OF 500-1000 J/KG AND
PRECIPITABLE WATER VALUES VIA 17Z GPS SITES SHOWING 1.2 TO 1.45
INCHES. STORM MOTIONS ON THE SW SIDE OF THE 500 MB LOW CENTER ARE
FORECAST TO BE LESS THAN 10 KTS UNTIL THE UPPER LOW EDGES EWD AND
STRONGER NLY FLOW DEVELOPS ACROSS THE AREA. UNTIL THEN
HOWEVER...22Z PERHAPS...SLOW STORM MOTIONS WITH ADDITIONAL STORMS
PRODUCED FROM ADDED DAYTIME HEATING MAY CAUSE A FEW RUNOFF ISSUES
WITH RAINFALL RATES OF 1 TO 1.5 IN/HR.

FARTHER EAST...A 700 MB LOW WAS NOTED ALONG THE CNTRL UT/AZ BORDER
WITH A TROUGH AXIS EXTENDING SW TOWARD THE COLORADO RIVER
VALLEY...NOTED VIA VAD WIND PLOTS AND RAP ANALYSES. A CONCENTRATED
ZONE OF SWLY 700 MB FLOW CONTAINING 20-30 KTS IS EXPECTED TO
PERSIST ON THE SE SIDE OF THE UPPER LOW...PARALLELING MEAN STORM
MOTIONS. SOME BREAKS SHOWN IN VISIBLE SATELLITE IMAGERY NOTED OVER
NRN AZ MAY ALLOW WEAK INSTABILITY TO DEVELOP IN THE PRESENCE OF
NEUTRAL TO WEAKLY ANOMALOUS PRECIPITABLE WATER VALUES. GIVEN ADDED
UPPER DIFFLUENCE AHEAD OF THE AFOREMENTIONED MID-UPPER LEVEL
LOW...WEAK INSTABILITY MAY BE COUNTER-BALANCED BY STRONGER
DYNAMICS LEADING TO A FLASH FLOOD THREAT IN CNTRL TO NRN ARIZONA
LATER THIS AFTERNOON INTO THE EVENING.

OTTO

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

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

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

LAT...LON   37691247 37651161 37481105 37051025 36271000
            35371027 35001103 34751219 34291313 33931414
            33901488 34291543 34821588 35811598 36181584
            36521556 36791450 37411322



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.