178
FXUS65 KVEF 041147
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
447 AM PDT THU SEP 4 2025
KEY MESSAGES
* MONSOONAL MOISTURE REMAINS IN PLACE TODAY BEFORE SLOWLY RETREATING
EASTWARD OUT OF THE REGION, SHIFTING THE BEST PRECIPITATION
CHANCES FURTHER EAST EACH DAY THROUGH SATURDAY.
* DRY CONDITIONS AND RELATIVELY COOLER TEMPERATURES ARE EXPECTED
TO RETURN NEXT WEEK.
DISCUSSION
TODAY THROUGH WEDNESDAY.
THE POSITION OF HIGH PRESSURE OVER THE SOUTHWEST US AND A TROUGH OFF
OF THE PACIFIC COAST CONTINUES TO DRAW MOISTURE ASSOCIATED WITH
HURRICANE LORENA INTO ARIZONA, CALIFORNIA, AND NEVADA. MOISTURE AND
CLEAR SKIES WILL ALLOW FOR THUNDERSTORM DEVELOPMENT ACROSS MUCH OF
THE AREA THIS AFTERNOON, ESPECIALLY OVER HIGH TERRAIN WHERE
OROGRAPHIC LIFT WILL GIVE AN EXTRA BOOST FOR DEVELOPMENT. OUTFLOW
WINDS FROM INITIAL CONVECTION WILL SUPPORT ADDITIONAL THUNDERSTORM
DEVELOPMENT INTO THE EVENING. HIGH RESOLUTION GUIDANCE SHOWS THE
POTENTIAL FOR ANOTHER ROUND OF THUNDERSTORMS MOVING IN FROM THE
NORTHWEST OVERNIGHT, LIKELY DRIVEN BY A COMBINATION OF A SHORTWAVE
PASSAGE ALOFT AND OUTFLOW BOUNDARIES NEAR THE SURFACE. CONFIDENCE IN
THE OVERNIGHT ACTIVITY IS LOW AS IT HINGES ON THE POTENCY OF THE
SHORTWAVE AND STRENGTH OF THUNDERSTORM DEVELOPMENT EARLIER IN THE
DAY. AMPLE MOISTURE WITH PWATS BETWEEN 1 AND 1.5 INCHES AND
SATURATED FORECAST SOUNDINGS MEANS THAT FLASH FLOODING WILL ONCE
AGAIN BE ONE OF THE MAIN HAZARDS. DCAPE VALUES EXCEEDING 1000 J/KG
POINTS TOWARDS GUSTY OUTFLOW WINDS AS ANOTHER HAZARD WITH ANY STORMS
THAT FORM. THIS ENVIRONMENT WILL SUPPORT ADDITIONAL CONVECTION ON
FRIDAY AND SATURDAY. THE BEST CHANCES FOR STORMS ON FRIDAY AND
SATURDAY WILL BE IN LINCOLN, CLARK, AND MOHAVE COUNTIES.
DRIER AIR WILL BECOME DOMINANT BY SUNDAY AS THE PACIFIC TROUGH MOVES
EAST THROUGH THE WESTERN UNITED STATES. LOWERING HEIGHTS ALOFT WILL
RESULT IN A GRADUAL DECREASE IN TEMPERATURES THROUGH THE MIDDLE OF
NEXT WEEK. HIGHS SHOULD BE 5 TO 10 DEGREES BELOW AVERAGE BY
WEDNESDAY, WHICH MEANS HIGHS IN THE LOW 90S IN LAS VEGAS.
AVIATION...FOR HARRY REID...FOR THE 12Z FORECAST PACKAGE
THE
PRIMARY AVIATION CONCERN ARE THUNDERSTORMS EXPECTED TO DEVELOP
THIS AFTERNOON ACROSS THE HIGHER TERRAIN SURROUNDING THE LAS VEGAS
VALLEY, WITH POTENTIAL FOR OUTFLOW BOUNDARIES AND/OR ADDITIONAL
DEVELOPMENT IN CLOSER VICINITY TO THE TERMINAL (15-25% CHANCE).
ERRATIC GUSTY WINDS, LIGHTNING, AND BRIEF MVFR/IFR CONDITIONS IN
HEAVY RAIN CAN BE EXPECTED WITH STORMS TODAY. MUCH OF THIS
ACTIVITY WILL DIMINISH BY EARLY EVENING, WITH ADDITIONAL CONCERN
FOR SHOWERS/STORMS TO MOVE SOUTHWARD OUT OF THE GREAT BASIN AFTER
06Z. THESE WOULD RESULT IN A NORTHEASTERLY WIND SHIFT AT THE
TERMINAL, AND WHILE THERE IS UNCERTAINTY IN TIMING/MAGNITUDE,
THERE IS MODERATE CONFIDENCE IN ITS OCCURRENCE. OUTSIDE OF
CONVECTIVE INFLUENCES, WINDS GENERALLY REMAIN AROUND 8KT OR LESS
AND BE SOMEWHAT VARIABLE, WITH VFR CONDITIONS PREVAILING.
FOR THE REST OF SOUTHERN NEVADA, NORTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA...FOR THE 12Z FORECAST PACKAGE...THIS AFTERNOON,
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL DEVELOP ACROSS
SOUTHERN NEVADA AND PORTIONS OF SOUTHEASTERN CALIFORNIA AND
NORTHWESTERN ARIZONA, PERSISTING INTO EARLY EVENING. CONVECTION
WILL BEGIN OVER HIGHER TERRAIN BEFORE MOVING ACROSS LOWER
ELEVATIONS, WITH LOWER CONFIDENCE IN DEVELOPMENT ACROSS WESTERN
SAN BERNARDINO COUNTY, AND HIGHER CONFIDENCE FOR IMPACTS AT AREA
TERMINALS ACROSS THE LOWER COLORADO RIVER VALLEY. ERRATIC GUSTY
WINDS, LIGHTNING, AND BRIEF MVFR/IFR CONDITIONS IN HEAVY RAIN ARE
EXPECTED WITH STORMS THAT DEVELOP, WITH OUTFLOW WINDS POSSIBLE
AWAY FROM STORMS. AFTER 06Z, THERE IS MODERATE CONFIDENCE IN
STORMS MOVING SOUTHWARD OUT OF THE GREAT BASIN THAT COULD PRODUCE
GUSTY NORTHERLY TO NORTHEASTERLY WINDS FOR PORTIONS OF SOUTHERN
NEVADA AND NORTHWESTERN ARIZONA. OUTSIDE OF CONVECTIVE INFLUENCES,
WINDS WILL GENERALLY REMAIN 10KT OR LESS AND BE SOMEWHAT VARIABLE
THIS AFTERNOON ONWARD, WITH VFR CONDITIONS PREVAILING.
SPOTTER INFORMATION STATEMENT
SPOTTERS ARE ENCOURAGED TO REPORT
ANY SIGNIFICANT WEATHER OR IMPACTS ACCORDING TO STANDARD OPERATING
PROCEDURES.
DISCUSSION...MELTZER
AVIATION...PHILLIPSON
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