961 FXUS65 KVEF 011526 AAA AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 820 AM PDT Sun Jun 1 2025 .SYNOPSIS...Showers and thunderstorms are expected across much of the forecast area starting today as low pressure pulls remnant tropical moisture into the region. The greatest rainfall amounts will likely be in northwestern Arizona tonight into tomorrow. Cooler temperatures can also be expected areawide before they begin to climb again midweek. && .UPDATE... Upper low currently spinning off the southern CA coast will continue to help draw remnant moisture northward from tropical storm Alvin. We have already seen some big jumps in dew points this morning with areas around Las Vegas and the lower Colorado River Valley seeing readings about 10-15 degrees higher than 24 hours ago. This moisture will continue to increase this afternoon leading to a few isolated showers and thunderstorms. The greatest threat for showers and storms will likely be late this evening and overnight as the upper low off the coast begins shifting east and allowing additional moisture and instability to be drawn into the area. The best chances will occur south and east of I-15, but a few storms could also develop further north. Another area of showers and storms today will be across Inyo, Esmeralda, central Nye, and northern Lincoln Counties where residual moisture remains in place. Another concern will be the increasing southerly winds this afternoon. Winds 20-30 mph with some gusts around 40 mph are expected over Clark, Mohave, and eastern San Bernardino Counties. This will have the greatest impact on the area lakes and lower the Colorado River with boaters needing to take some extra precautions as the winds increase. && .SHORT TERM...Today through Tuesday. A low pressure system that is currently centered to the west of Baja California will be the main driver of weather over the next few days as it sends remnant moisture left over from Alvin towards the forecast area. Isolated high based showers are already beginning to form south of Interstate 40 this morning. However, air near the surface is very dry and most droplets will evaporate before they reach the ground. These virga showers should continue through at least midday in the Mojave Desert. Instability-based convection should begin over the southern Great Basin and eastern Sierra with 250 to 500 J/kg CAPE to work with, but any totals from these should remain light. Given the high bases, strong outflow winds are a possibility with any showers that form. Greater moisture arrives with a push of 20 to 30 mph southerly winds later today and tonight as the low drifts northeastward into Arizona. This will send PWATs to the 1.2 to 1.6 inch range, or 250 to 300 percent of normal for early June. The greatest potential for rainfall at this time will be along and south of Interstate 15. Forecast soundings show the atmospheric column moistening in the low levels, indicating that more rainfall should reach the surface and flooding will become the primary threat rather than wind. The heaviest precipitation should occur late tonight and into Monday morning in northwestern Arizona. A Marginal Excessive Rainfall Outlook is in place for southern Mohave County to reflect the flood threat. Rainfall chances continue through the day on Monday as the center of the low moves into northern Arizona. Instability from the low should sustain shower and thunderstorm activity in northwest Arizona and in the southern Great Basin. As the low tracks east into the Four Corners on Tuesday, another low will become positioned over northern Baja, similar to the first low. By this time, over an inch of PWAT remains over the forecast area, mainly in areas around the Colorado River, and potential for isolated to scattered showers continues over northwestern Arizona. Today`s temperatures will be 5 to 10 degrees cooler than yesterday as moisture and cloud cover increase and heights aloft decrease with the approaching low. Temperatures will decrease another 5 to 10 degrees tomorrow, primarily north of Interstate 40 due to cloud cover. By Monday, most areas should be in the Minor (Level 1) HeatRisk category with a spot of Moderate (Level 2) in Death Valley. .LONG TERM...Wednesday through Sunday. A northwest flow will set up over the region mid-to-late week. Along this northwest flow, a series of shortwaves will glide down into the southern Great Basin and Mojave Desert. With no mechanism to shove remnant moisture out of the forecast area from the early- week systems, these shortwaves will tap into the leftover moisture, resulting in at least slight PoPs existing through Thursday. Best chances will exist in the southeastern Great Basin and eastern Mojave Desert on Wednesday and Thursday with breezy south-southwest winds elsewhere (20-30 mph). Despite these shortwaves, a growing ridge of high pressure over the eastern Pacific as well as over northern Mexico will result in increased 500 mb heights across the Desert Southwest. As such, temperatures will continue to climb back to 4 to 6 degrees above seasonal normals heading into the weekend, with temperatures approaching 10 degrees above-normal heading into the next work week. This will result in desert valleys reading high temperatures in the 100s once again, with widespread "Moderate" HeatRisk. && .AVIATION...For Harry Reid...For the 12Z Forecast Package...South southwest winds should persist this morning, with spotty gusts of 15 to 20 knots not out of the question. Gusts of around 25 knots will become more common by late morning and persist through the afternoon. Late this evening, chances for showers and thunderstorms will move in from the south, and the main threat will be erratic gusty winds. Chances for showers and thunderstorms will decrease, but not go away entirely, early Monday morning. For the rest of southern Nevada, northwest Arizona and southeast California...For the 12Z Forecast Package...South to southwest winds gusting 20 to 30 knots will be common across the region today, especially from late morning through the evening. Chances for showers and thunderstorms will begin over the Sierra crest around midday and spread northeastward across the southern Great Basin through tonight. Another area of thunderstorm chances will begin along and south of Interstate 40 this afternoon and spread northeastward to areas along and southeast of Interstate 15 through tonight. The main threat with thunderstorms will be erratic gusty winds, and a few of the storms over northwest Arizona could produce locally heavy rain and low ceilings with terrain obscuration. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Gorelow SHORT TERM...Meltzer LONG TERM...Soulat AVIATION...Morgan For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter