137
FXUS65 KVEF 172009
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
109 PM PDT WED SEP 17 2025
KEY MESSAGES
* INCREASING TROPICAL MOISTURE WILL MOVE INTO THE REGION THURSDAY
AND FRIDAY, BRINGING CHANCES FOR SHOWERS AND THUNDERSTORMS.
LOCALLY HEAVY RAIN AND HIGH RAINFALL RATES WILL LEAD TO AN
INCREASED RISK OF FLASH FLOODING.
DISCUSSION
THROUGH TUESDAY.
CURRENT SATELLITE IMAGERY SHOWS A BATCH OF TROPICAL MOISTURE MOVING
TOWARDS THE SOUTHERN CALIFORNIA COAST. THUNDERSTORMS ARE ONGOING IN
NORTHERN BAJA AND THE SAN GABRIEL MOUNTAINS IN CALIFORNIA. THIS
MOISTURE IS EXPECTED TO BE PUSHED INLAND BY AN EASTWARD MOVING
TROUGH OVER THE NEXT TWO DAYS, SENDING PWATS TO OVER 200 PERCENT OF
NORMAL FOR THIS TIME OF YEAR. MID AND HIGH CLOUD COVER WILL HINDER
WIDESPREAD CONVECTION ACROSS MUCH OF SOUTHERN NEVADA AND
NORTHWESTERN ARIZONA TOMORROW. HOWEVER, ENOUGH CLEARING BEHIND THE
CLOUD COVER COMBINED WITH AMPLE MOISTURE WILL CREATE A FAVORABLE
ENVIRONMENT FOR CONVECTION IN THE DESERTS OF SOUTHEASTERN
CALIFORNIA. STORM DEVELOPMENT BEGINS IN THE MORNING AFTER SUNRISE
AND WILL LAST THROUGHOUT THE DAY AND OVERNIGHT. MID AND UPPER
LEVEL SUPPORT AND SOME TRAINING POTENTIAL MEANS THAT RAIN RATES OF
1 TO 2 INCHES PER HOUR ARE POSSIBLE. THEREFORE, ISSUED A FLOOD
WATCH FOR SAN BERNARDINO COUNTY FROM 8 AM PDT THURSDAY TO 2 AM PDT
ON FRIDAY. FRIDAY SHOULD BE LESS ROBUST AS THE BEST FORCING EXITS
THE AREA, BUT LINGERING MOISTURE AND INSTABILITY WILL LEAVE AN
ACTIVE MONSOONAL ENVIRONMENT. THE AREA SHOULD GRADUALLY DRY OUT
OVER THE WEEKEND AND EARLY NEXT WEEK. TEMPERATURES WILL INCREASE
NEXT WEEK AND REACH ABOVE AVERAGE VALUES BY TUESDAY.
AVIATION...FOR HARRY REID...FOR THE 18Z FORECAST PACKAGE
LIGHT
AND DIURNAL WINDS WITH SPEEDS OF LESS THAN 10 KNOTS ARE EXPECTED
THROUGH THE REST OF THE DAY. CANNOT RULE OUT A STRAY GUST TO 15 KTS
THIS AFTERNOON FROM THE EAST. WINDS WILL BECOME SOUTHWESTERLY
OVERNIGHT, RETURNING TO THE EAST-NORTHEAST THURSDAY MORNING. FEW-SCT
AOA 25 KFT THROUGH THE DAY TODAY, INCREASING TO BKN-OVC OVERNIGHT.
SCT-BKN AOA 12 KFT PUSH INTO SOUTHERN NEVADA AFTER SUNSET AND
PERSIST THROUGH THE REMAINDER OF THE TAF PERIOD. BEST CHANCES OF 98-
100 DEGREES THIS AFTERNOON EXIST BETWEEN 23 AND 01Z.
FOR THE REST OF SOUTHERN NEVADA, NORTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA...FOR THE 18Z FORECAST PACKAGE...LIGHT AND DIURNAL
WINDS ARE EXPECTED TODAY, WITH SPEEDS GENERALLY LESS THAN 10
KNOTS. THE EXCEPTION WILL BE KDAG, WHERE GUSTY WEST WINDS BETWEEN
20 AND 25 KTS WILL PICK UP AFTER SUNSET AND LAST THROUGH THE
NIGHT. BKN- OVC HIGH CLOUDS WILL INCREASE SOUTH-TO-NORTH ACROSS
THE REGION TODAY, WITH SCT-BKN MID-LEVEL CLOUDS REACHING KDAG,
KBIH, KEED, AND KIFP THIS AFTERNOON AND KLAS, KVGT, KHND THIS
EVENING. PRECIPITATION CHANCES INCREASE AREAWIDE ON THURSDAY WITH
CONVECTION BEGINNING AS EARLY AS 15Z. HEAVY DOWNPOURS AND STRONG
OUTFLOW WINDS ARE THE MAIN CONCERNS.
SPOTTER INFORMATION STATEMENT
SPOTTERS ARE ENCOURAGED TO REPORT
ANY SIGNIFICANT WEATHER OR IMPACTS ACCORDING TO STANDARD OPERATING
PROCEDURES.
DISCUSSION/AVIATION...MELTZER
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