Area Forecast Discussion
Issued by NWS Las Vegas, NV
Issued by NWS Las Vegas, NV
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949 FXUS65 KVEF 162223 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 325 PM PDT Sun Aug 16 2026 .KEY MESSAGES... * Isolated showers and thunderstorms are expected this afternoon and early evening, mainly over the higher terrain of southern Nevada, southeastern California, and northwestern Arizona. * Temperatures will steadily increase throughout the week, with areas of Major HeatRisk expanding by midweek, especially across the Colorado River Valley, Death Valley, and portions of the Las Vegas Valley. An Extreme Heat Watch is in effect. && .DISCUSSION... Southwesterly flow aloft persists today, with latest water vapor imagery and 500 hPa RUC analysis indicating a weak perturbation and fetch of mid-level moisture associated with the remnants of Tropical Depression Hernan moving over the region. This will be enough to maintain afternoon and early evening storm chances despite decreased shear and instability, with convection focused mainly over the higher terrain of San Bernardino, Clark, and Mohave Counties. These storms will be capable of producing locally heavy rainfall, gusty winds, and lightning. Localized flooding also remains a concern, especially if storms develop and train over areas that received substantial rainfall the past several days. Any convective activity that develops this afternoon is expected to weaken quickly through early evening. After today, a drying trend is expected as broad mid-level ridging builds westward over the region, yielding increased subsidence and mainly dry conditions through midweek. While the warming trend has already started today, the aforementioned ridge and associated increasing thicknesses will yield a quick return to above normal temperatures for most locations by Tuesday. Given the climbing temperatures, widespread Moderate HeatRisk (level 2 of 4) is expected by Tuesday, with pockets of Major HeatRisk (level 3 of 4) concurrently developing through the Lower Colorado River Valley and Death Valley. These areas of Major HeatRisk will gradually expand midweek, with temperatures peaking Wednesday into Thursday. An Extreme Heat Watch has been issued for portions of southern Nevada, northwestern Arizona, and southeastern California Tuesday through Friday, with ensembles indicating possible relief from the heat in time for the weekend as we see another uptick in monsoonal moisture. While thunderstorm chances return to far eastern areas as early as Thursday and Friday, details are likely to change between now and then, thus all are encouraged to practice heat safety this week, and check back for the latest forecast. && .AVIATION...For Harry Reid...For the 00Z Forecast Package...Winds are expected to remain light and generally follow typical daily diurnal patterns through the TAF period. Shower activity remains possible along the edges of the Las Vegas Valley through sunset but is generally not expected within the airport vicinity. Similar conditions will resume tomorrow with shower coverage decreasing even further. Temperatures will remain near 100 through 02z tonight and climb above 100 again Monday from 19z through 3z. For the rest of southern Nevada, northwest Arizona and southeast California...For the 18Z Forecast Package...Isolated showers are possible through sunset across the higher terrain of southern Nevada and northwest Arizona. Showers will die off quickly around sunset. Winds across the region will remain light with the exception of the southern Great Basin and Owens Valley, where breezy south winds are forecast through the evening and again Monday. Cloud bases should remain AOA 10kft AGL through the TAF period. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ DISCUSSION...Phillipson AVIATION...Outler For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter