Flash Flood Warning 17, NWS Las Vegas, NV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
250 PM PDT THU AUG 14 2003

.SYNOPSIS...MOISTURE CIRCULATING AROUND AN AREA OF HIGH PRESSURE
OVER WYOMING WILL CONTINUE TO BRING A CHANCE FOR SHOWERS AND
THUNDERSTORMS TO PORTIONS OF THE MOJAVE DESERT AND SOUTHERN GREAT
BASIN TONIGHT. A LOW PRESSURE SYSTEM WILL MOVE WEST INTO ARIZONA ON
FRIDAY...INCREASING PRECIPITATION CHANCES AND COOLING TEMPERATURES
FOR THE END OF THE WEEK.

&&

.SHORT TERM...AREA OF CLOUDS WITH LIGHT SHOWER ACTIVITY CONTINUES TO
MOVE ACROSS THE SOUTHERN PORTION OF THE FORECAST AREA THIS
AFTERNOON. SUSPECT THAT VERY LITTLE OF THIS WILL ACTUALLY REACH THE
GROUND IN THE FORM OF RAIN. WATER VAPOR IMAGERY SHOWS SOMEWHAT DRIER
AIR MOVING IN FROM THE NORTHEAST BUT THUNDERSTORMS ARE FIRING IN
THIS AREA WHERE MORE SUNSHINE HAS HEATED THE SURFACE. EXPECT THE
DEBRIS FROM THIS ACTIVITY TO MOVE OVER OUR FORECAST TONIGHT
RESULTING IN A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS FOR
SOUTHEAST ZONES. CLOSED LOW IS EXPECTED TO MOVE WEST INTO ARIZONA
FRIDAY WHICH WILL HELP INCREASE MOISTURE AND INSTABILITY AND WILL
PROVIDE SOME DYNAMIC LIFT. HAVE GONE WITH AN INCREASING CHANCE OF
THUNDERSTORMS BUT MOST OF INYO AND NYE COUNTIES SHOULD STILL REMAIN
DRY. THE CLOSED LOW THEN LINGERS OVER ARIZONA FRIDAY NIGHT SO WILL
KEEP CHANCE OF SHOWERS AND THUNDERSTORMS OVERNIGHT PRETTY MUCH IN
THE SAME AREAS. UPPER TROUGH WHICH HAS BEEN STATIONARY OFF THE COAST
MOVES EAST ACROSS THE PACIFIC NORTHWEST ON SATURDAY. THE MODELS
TENDING TO BRING SLIGHTLY DRIER AIR INTO OUR FORECAST AREA FROM THE
WEST AS A RESULT. THEREFORE EXPECT WESTERN PORTION OF FORECAST AREA
TO REMAIN DRY WITH SLIGHTLY LOWER POPS EAST. UPPER LOW OVER ARIZONA
CONTINUES TO WEAKEN AND MOVE SLIGHTLY NORTHEAST ON SUNDAY WHICH
FURTHER REDUCES PRECIPITATION CHANCES. WHILE SOME COOLING IS
EXPECTED WITH THE CLOSED LOW MOVING INTO ARIZONA AND THE ASSOCIATED
CLOUD COVER...MODELS GUIDANCE HAS SOME WIDELY VARYING NUMBERS FOR
SATURDAY. WILL LEAN TOWARD A MORE CONSERVATIVE COOLING TREND AS
INDICATED BY THE NGM AND ETA GUIDANCE.

.LONG TERM...FORECAST IS A COMPROMISE AMONG VARIOUS MODELS AND
INCONSISTENCIES BETWEEN RUNS. OUT OF THIS A GENERAL TREND CAN BE
GLEAMED AND LEANED HEAVILY TOWARDS 12Z GFS AND OLD ECMWF RUN. FOR
MONDAY THE LOW THAT PLAGUED THE AREA OVER THE WEEKEND WILL START TO
EJECT INTO UTAH. MOISTURE WILL BE WRAPPED AROUND IT AND EXTENDED
BACK INTO THE NORTHERN AND EASTERN PARTS OF THE CWA. THIS ALONG WITH
PROGGED LI BEING ZERO TO MINUS 1 WILL ENSURE SOME THUNDERSTORM
ACTIVITY THERE.  TUESDAY WILL SEE THE LOW STILL IN UTAH BUT WEAKER.
RESIDUAL MOISTURE WILL STILL BE AVAILABLE FOR MORE DIURNAL
THUNDERSTORMS IN THE NORTH. WEDNESDAY AND THURSDAY WILL SEE WEAK
RIDGING OVER THE AREA ALONG WITH TROUGHING OFF THE COAST TO BRING IN
SOUTHWEST FLOW TO DRY THE AREA OUT SOMEWHAT. LEFT LOW POPS IN GRIDS
TO MATCH NEIGHBOR OFFICES BUT WILL TAKE MENTION OUT IN ZONE VERBIAGE.

&&

.LAS...NONE.

&&

HARRISON/JACQUES

AZZ001>003-036-CAZ026>029-NVZ013>022-150102-

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE LAS VEGAS NV
600 AM PDT THU AUG 14 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST CALIFORNIA/SOUTHERN
NEVADA/NORTHWEST ARIZONA

.DAY ONE...TODAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.