Expires:No;;327299 FXUS65 KVEF 170452 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 952 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 06Z Forecast Package...Winds will follow typical daily directional patterns with speeds of less than 10 knots throughout the forecast period. FEW to SCT mid and high clouds remain in the area with bases at or above 10kft. Temperatures increase to 100 degrees or greater between 19Z Monday morning and 04Z in the evening. For the rest of southern Nevada, northwest Arizona and southeast California...For the 06Z Forecast Package...Winds follow typical daily directional patterns with speeds of less than 10 knots for most terminals over the next 24 hours. Exceptions include KBIH where gusty southeasterly winds pick up in the afternoon, and KDAG where gusty westerly winds persist tonight and return tomorrow evening. FEW to SCT mid and high clouds remain in the area, with bases at or above 10kft. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ DISCUSSION...Phillipson AVIATION...Meltzer For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter