Severe Thunderstorm Warning 14, NWS Las Vegas, NV

MOJAVE DESERT/SOUTHERN GREAT BASIN AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
405 PM AM PDT MON JUL 28 2003

.SYNOPSIS...THE THREAT OF AFTERNOON AND EVENING THUNDERSTORMS WILL
CONTINUE THROUGH AT LEAST MID-WEEK AS A MOIST UNSTABLE AIRMASS
CIRCULATES AROUND HIGH PRESSURE CENTERED OVER NORTHERN NEVADA.
DISTURBANCES ALOFT WILL FAVOR THUNDERSTORM DEVELOPMENT ACROSS
NORTHWEST ARIZONA AND SOUTHEAST CALIFORNIA THIS EVENING AND AGAIN
TUESDAY AFTERNOON.

.DISCUSSION...CONVECTION WAS FIRING OVER SOUTHERN MOHAVE AND
SOUTHEAST SAN BERNARDINO COUNTIES THIS AFTERNOON AS EXPECTED. THE
CIRCULATION OBSERVED THIS MORNING OVER ARIZONA APPEARS TO BE A
DRIVING FACTOR AND SHOULD CONTINUE TO FAVOR THESE AREAS AS IT MOVES
TO THE SOUTHWEST THROUGH THE EVENING. SHEER PROFILES...AVAILABLE
MOISTURE AND POTENTIAL INSTABILITY FAVOR ORGANIZED EFFICIENT RAIN
PRODUCING STORMS. MOVEMENT IS QUITE FAST BUT REDEVELOPMENT OVER
FAVORABLE AREAS COULD BE A PROBLEM. THE 18Z GFS ACTUALLY INDICATES
ANOTHER DISTURBANCE COMING OUT OF THE FOUR CORNERS AND INTO SOUTHERN
MOHAVE COUNTY BY TUESDAY AFTERNOON SO A SIMILAR AREA COULD BE ACTIVE
AGAIN TOMORROW. MOIST SOUTHEAST FLOW ACROSS THE SOUTHERN HALF OF THE
AREA REMAINS IN PLACE WEDNESDAY BUT NO APPARENT CONVECTION TRIGGER
SO WILL KEEP HIGHER POPS OVER THE MOUNTIANS. DID NOT CHANGE TEMPS
MUCH SINCE THEY LOOKED IN THE BALL PARK AND PATTERN CONTINUES TO
MAKE PINPOINTING HIGHS AND LOWS DIFFICULT.

DAY 3...POSSIBLY AN INTERESTING DAY SETTING UP FOR THURSDAY. THE GFS
SHIFTS THE HIGH PRESSURE CENTER ALOFT TO CENTRAL UTAH WITH A CLOSED
UPPER LOW LOCATED OFF THE SOUTHWEST COAST. BY 18Z...THE MOISTURE
PARAMETERS AND DYNAMICS ARE PROGGED TO BE FAIRLY IMPRESSIVE OVER
CLARK COUNTY. THE GFS FORECASTS 65 F DEWPOINTS...11 G/KG MIXING
RATIO ...35-40 K-INDEXES AND 1.6 PW FOR LAS VEGAS. THERE IS ALSO IN
AN AREA OF LOW-LEVEL CONVERGENCE AND UPPER DIVERGENCE FORECAST AS A
50 KT 250MB JET STREAK MOVES AROUND THE LOW. IN ADDITION...A WEAK
VORT MAX IS PROGGED TO MOVE AROUND THE HIGH AND THROUGH SOUTHERN
NEVADA. WITH THIS...I DID INCREASE THE POPS SLIGHTLY FOR THE VALLEY
AREA FOR THURSDAY BUT THE NEXT FEW MODEL RUNS WILL NEED TO BE
ANALYZED FOR THE POSSIBILITY OF HEAVY RAIN AND FLASH FLOODING.

EXTENDED...THE UPPER LOW BEGINS TO PULL NORTH AND EAST AS THE UPPER
HIGH MIGRATES FURTHER EAST AND THEN SOUTH TO CENTRAL TEXAS BY
SUNDAY. THIS WOULD KEEP THE MAIN MOISTURE FLOW WELL EAST OF THE AREA
WITH A SOUTHWEST FLOW OVER THE FORECAST AREA. LOWER POPS EXPECTED
WITH THE DRIER AIR. WITH LOWER HEIGHTS/THICKNESSES FORECAST...TEMPS
EXPECTED TO REMAIN AT OR BELOW NORMAL THROUGH THE EXTENDED.

.LAS...NONE

ADAIR/SALMEN

AZZ001>003-036-CAZ026>029-NVZ013>022-291400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LAS VEGAS NV
500 AM PDT MON JUL 28 2003

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

.DAY ONE...TODAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. SCATTERED
THUNDERSTORMS WILL DEVELOP ACROSS THE REGION THIS AFTERNOON...WITH
THE GREATEST COVERAGE EXPECTED ALONG AND SOUTHEAST OF INTERSTATE 15.
ALTHOUGH SOME STORMS MAY PRODUCE BRIEFLY HEAVY RAINFALL AND GUSTY
WINDS...CONDITIONS DO NOT FAVOR WIDESPREAD FLASH FLOODING OR SEVERE
THUNDERSTORMS.

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

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. MOISTURE
WILL CONTINUE TO CIRCULATE AROUND AN AREA OF HIGH PRESSURE OVER
THE WESTERN STATES THROUGH FRIDAY. THIS WILL CONTINUE TO BRING
ISOLATED TO SCATTERED THUNDERSTORMS EACH AFTERNOON. SOME DRYING OF
THE AIRMASS IS EXPECTED OVER THE WEEKEND...RESULTING IN LOWER
CHANCES OF THUNDERSTORMS.