300 FXUS65 KVEF 201624 AFDVEFArea Forecast Discussion National Weather Service Las Vegas NV 920 AM PDT Sat Sep 20 2025
.KEY MESSAGES...
* Slight chances for showers and thunderstorms will linger through the weekend and into the upcoming week.
* Humid conditions will continue, and additional tropical moisture could get pulled northward around the middle of the week. &&
.DISCUSSION...through Friday. Early morning satellite loop showed much quieter conditions than 24 hours ago with only scattered mid level clouds. Surface obs showed humid conditions, light winds, and mild temperatures. The humid conditions left over from Mario`s passage will be one driver of thunderstorm chances, which will be the primary forecast concern. Another driver will be the cutoff low near 32N 129W early this morning. Unfortunately, as is often the case with cutoff lows, there is still a lot of model disagreement regarding its eventual eastward track - when will it kick inland, and how far north or south will it be when it does so? These factors will drive when and where the best thunderstorm chances will occur, so low confidence in these details means a low confidence thunderstorm forecast. What can be said with moderate to high confidence is that another slug of tropical moisture southwest of the Baja will track northward over the weekend, and IF the cutoff low does not move north, this moisture will get directed onshore on the southeast side of the low. This could lead to enhanced rain chances southeast of I-15 as early as Sunday and Sunday night. Around midweek, IF the low begins to move inland as most of the clusters suggest, there could be another round of enhanced thunderstorm chances, but exactly where this occurs would be highly dependent on how far north or south the low is when it moves inland. Clusters suggest anywhere from San Francisco to Ensenada, so confidence is low. Slightly less than half of the clusters show a Gulf of Alaska low bringing southwest flow to our area next weekend, possibly flushing out the lingering moisture, but this is a long way away. &&
.AVIATION...For Harry Reid...For the 18Z Forecast Package...Winds will be light and diurnal today, with speeds generally 8 kts or less. Cannot rule out an occasional gust to 15 kts from the southeast this afternoon. SCT aoa 12 kft expected over area mountains this afternoon, but will clear out after sunset. Isolated thunderstorms are possible this afternoon along the Peach Springs corridor in northwest Arizona.
For the rest of southern Nevada, northwestern Arizona and southeastern California...For the 18Z Forecast Package...Winds will be light today following typical diurnal directional trends, with speeds generally 8 kts or less. The exceptions will be KBIH, with gusty south-southeast winds to 20 kts this afternoon and KDAG, with breezy westerly winds after sunset between 8 and 12 kts. SCT aoa 12 kft on area mountains this afternoon, but will clear out after sunset. Isolated thunderstorms are possible in northwest Arizona this afternoon. &&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. &&
$$
DISCUSSION...Morgan AVIATION...Gorelow
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NWS VEF Office Area Forecast Discussion