609 FXUS65 KVEF 050227 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 727 PM PDT Wed Jun 4 2025 .SYNOPSIS...Another round of scattered showers and isolated thunderstorms will form over the mountains today across our forecast area before gradually shifting into the valleys. Expect a reduction in coverage and severity today compared to yesterday. Another round expected on Thursday, with best chances pushing further north - across the Mojave Desert and southern Great Basin. Conditions dry out and heat up for the end of the work week into the weekend. && .UPDATE... The most notable update this evening was the cancellation of the Flash Flood Watch that was originally in effect through late evening. Storm coverage this afternoon and evening has been sparse compared to the last few days, and while rainfall rates with the stronger cells have at times approached 1 inch per hour and localized flooding may result, impactful widespread flash flooding is not expected. Convection currently percolating across portions of Inyo, San Bernardino, Clark, and Mohave Counties is largely expected to weaken after sunset with the loss of insolation and increasing stabilization, though another round of storms is progged to develop over the Southern Great Basin late tonight through early Thursday morning ahead of more widespread convection Thursday afternoon. Aside from minor changes to PoPs and Sky grids to capture near term trends, the forecast remains on track this evening. && .SHORT TERM...Today and Thursday. A cut off low will weaken into an open wave as it pushes through Sonora today. In addition to this wave, a shortwave will push into the southwestern Great Basin as it rides along our northwesterly flow aloft. Both of these systems will team up with the anomalous moisture over our forecast area (PWATs over 200 percent of normal) and with the lift associated with daytime heating to return scattered shower and isolated thunderstorm chances to the region today. At present, we`re seeing convection start up on the Spring Mountains of Clark County as well as Mt. Trumbull in the Arizona Strip. This convection will then gradually meander into nearby valleys through the remainder of the afternoon and evening. CAPE values are greatest around southern Nevada and northwestern Arizona, but are notably lower than yesterday - at about 500 J/kg. With PWATs hovering around 1.00", we continue to see a prolonged flash flood threat in these areas, which is noted by our Flash Flood Watch. The current Flash Flood Watch is in effect for northeastern San Bernardino County, Clark County, and Mohave County including the Colorado River Valley and is in effect until 11 PM PDT this evening. These are the same locations that the Weather Prediction Center has highlighted with a "slight" Excessive Rainfall Outlook. That said, the latest hi-resolution Convective Allowing Models continue to show a much quieter day compared to yesterday (in both coverage and severity), so it`s possible that we will be able to cancel the Flash Flood Watch early. In addition to an increased flash flood chances today, DCAPE over southeastern California ranges between 1200 and 1500 J/kg - similar as yesterday. As such, with some of the stronger storms, you can expect gusty outflow winds between 50 and 60 mph in addition to frequent lightning. An elongated trough will gradually set up across the Desert Southwest tonight into Thursday, which will allow additional vorticity advection into the Mojave Desert. These dynamics will again team up with anomalous moisture (PWATs 150-200 percent of normal) and heating of the day to return scattered showers and thunderstorms to the forecast area. Once again, convection will start in the mountains before gradually shifting into the valleys, with best chances of convection in southern Nevada. .LONG TERM...Friday through Tuesday. After an unsettled week, a substantial warming and drying trend will be underway on Friday. Persistent troughing that has allowed multiple systems to impact the region will give way to ridging, with both ensemble guidance and cluster analyses indicating a strengthening ridge over the weekend and into early next week, with at least some semblance of ridging lingering through at least midweek. Increasing thicknesses and associated subsidence will result in PWATs gradually returning to near and below-normal, with a return to well-above normal temperatures. Fairly widespread highs in the 90s and lower 100s are expected Sunday through Tuesday, with Monday currently looking to be the hottest day of the forecast. Along with the warming temperatures will be increasing HeatRisk, with "Major" HeatRisk returning to Death Valley and the Lower Colorado River Valley on Saturday, gradually expanding across other lower elevations through early next week. As to be expected in this pattern, aside from some lingering precipitation chances over far northeastern Lincoln County Friday afternoon, dry conditions are expected. && .AVIATION...For Harry Reid...For the 00Z Forecast Package...Shower and thunderstorm activity over the Clark County mountains will continue to push into the valley this afternoon. Best chances of thunderstorm activity over area terminals exists until 02Z this afternoon (30-40%). With thunderstorm activity, expect moderate-to- heavy rainfall, erratic, gusty winds from their direction, and CIGs down to 8 kft. Without thunderstorm influence, winds will favor the south-southeast between 6 and 8 kts this afternoon... becoming southwesterly after sunset. Thursday afternoon, shower and thunderstorm activity return, favoring the mountains early-afternoon once again. For the rest of southern Nevada, northwest Arizona and southeast California...For the 00Z Forecast Package...Shower and thunderstorm activity over the mountains will gradually push into the valleys this afternoon and evening. Best chances for precipitation at Las Vegas Valley terminals as well as KBIH exist until 02Z. With thunderstorm activity, expect moderate-to-heavy rainfall, erratic, gusty winds from their direction, and CIGs down to 8 kft... down to 6 kft at KBIH. Without thunderstorm influence, expect breezy south winds between 5 and 10 kts, with the exception of KDAG where gusty west winds will pick up after sunset between 20 and 25 kts. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Phillipson SHORT TERM...Soulat LONG TERM...Phillipson AVIATION...Soulat For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter