Severe Thunderstorm Warning 25, NWS Las Vegas, NV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
300 PM PDT MON AUG 25 2003

.SYNOPSIS...A TROUGH OF LOW PRESSURE APPROACHING THE CALIFORNIA
COAST WILL PULL MONSOON MOISTURE FURTHER NORTH INTO NORTHERN NEVADA
TONIGHT. THE TROUGH WILL PROVIDE SOME ADDITIONAL LIFT RESULTING IN
SCATTERED SHOWERS AND THUNDERSTORMS TUESDAY. MONSOON MOISTURE
LINGERS ACROSS SOUTHEAST NEVADA...EASTERN CALIFORNIA AND NORTHWEST
ARIZONA WEDNESDAY AND THURSDAY FOR CONTINUED CHANCE OF MAINLY
AFTERNOON AND EVENING THUNDERSTORMS.
&&

.SHORT TERM...AS EXPECTED STORMS CLINGING TO THE HIGHER TERRAIN THIS
AFTERNOON WITH BEST COVERAGE ACROSS SOUTHERN MOHAVE COUNTY AND THE
MOJAVE NATIONAL PRESERVE. DRIER/STABLE NORTHERLY FLOW WORKING SOUTH
FROM UTAH LIMITED DEVELOPMENT ACROSS LINCOLN AND FAR NORTHERN MOHAVE
COUNTY. BEST COVERAGE THE REST OF THIS AFTERNOON AND EVENING WILL BE
ACROSS EASTERN SAN BERNARDINO...AND SOUTHERN MOHAVE COUNTIES AS
STORMS PROPAGATE SOUTHWARD INTO THE LOWER COLORADO RIVER VALLEY
WHERE MOIST/UNSTABLE AIR LIES. WATER VAPOR IMAGERY SHOWS UPPER
TROUGH APPROACHING THE CENTRAL CALIFORNIA COAST WITH MOISTURE PLUME
SHIFTING NORTH ALONG THE CALIFORNIA COAST. ETA/GFS SHOW SPEED MAX
(DIVERGENCE ALOFT) AND DYNAMICS INCREASING FROM BISHOP/TONOPAH
OVERNIGHT. WILL KEEP POPS HIGHER IN FAR WESTERN ZONES TONIGHT AND
TRIM BACK TO SLIGHT CHANCE ELSEWHERE AFTER MIDNIGHT.

FOR TUESDAY...ETA/GFS CONSISTENT WITH PREVIOUS RUNS SHIFTING UPPER
TROUGH INLAND WITH BROAD AREA OF DIVERGENCE ALOFT HELPING LIFT DEEP
MONSOON MOISTURE ACROSS THE REGION. FOR WEDNESDAY AND THURSDAY...GFS
SHOW MID LEVELS DRYING AS WESTERLY FLOW DEVELOPS...HOWEVER LOW LEVEL
WINDS TO WEAK TO SCOUR OUT MOISTURE. 30-40 KNOT SPEED MAX ACROSS THE
AREA WILL CONTINUE TO PROVIDE POCKETS OF DIVERGENCE ALOFT TO THE
REGION. HIGHER POPS STAY IN THE SOUTHEAST HALF OF THE FORECAST AREA
WITH LITTLE OR NO THREAT OF NORTHWEST ZONES.
&&

.LONG TERM...
STILL A LOT OF UNCERTAINTY IN THE EXTENDED...ESPECIALLY CONCERNING
IGNACIO REMNANTS. GLOBAL MODELS IN AGREEMENT WITH RIDGE BUILDING
OVER THE CWA FRIDAY AND SATURDAY...THEN BRINGING A TROUGH FROM THE
PACNW OVER NORTHERN CA/NV ON SUNDAY. GFS THEN LINGERS SOME
TROUGHINESS OVER THE WEST MONDAY...BUT EJECTS ENERGY ASSOCIATED WITH
MAIN AXIS EAST. PROBLEM IS WHAT TO DO WITH IGNACIO. LATEST NHC
FORECAST TRACKS HIM UP THE WEST COAST OF BAJA. MODELS BRING REMNANT
MOISTURE ACROSS MUCH OF THE CWA FRIDAY THROUGH MONDAY IN BETWEEN THE
RIDGE AND THE APPROACHING TROUGH...WHICH LOOKS GOOD IF IGNACIO TAKES
HIS FORECASTED TRACK. HOWEVER...HAVE LOW CONFIDENCE IN ANY SOLUTION
WHICH INVOLVES A HURRICANE. IN COORDINATION WITH NEIGHBORING OFFICES
HAVE DECIDED TO STAY DRY FOR NOW OVER MOST OF THE CWA...DID ADD POPS
TO SOUTHERNMOST ZONES AND INCREASED CLOUD COVER. POPS ARE LIKELY TO
BE TWEAKED/ADDED IN FUTURE SHIFTS.

&&

.LAS...NONE.
&&

PIERCE/OROW

AZZ001>003-036-CAZ026>029-NVZ013>022-261400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LAS VEGAS NV
550 AM PDT MON AUG 25 2003

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

.DAY ONE...TODAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. ISOLATED
THUNDERSTORMS WILL ONCE AGAIN FORM MAINLY THIS AFTERNOON ACROSS MUCH
OF THE AREA. CONDITIONS DO NOT FAVOR SEVERE STORMS...BUT BRIEF HEAVY
RAIN MAY BE SEEN.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

THUNDERSTORMS WILL BE POSSIBLE EACH DAY...WITH TUESDAY AND WEDNESDAY
SEEING THE BEST CHANCES AND MOST WIDESPREAD THUNDERSTORMS.
CONDITIONS ARE NOT EXPECTED TO FAVOR SEVERE STORMS...HOWEVER FLASH
FLOODING IS A POSSIBILITY...PARTICULARLY ON TUESDAY AND WEDNESDAY.