![National Oceanic and Atmospheric Administration](/build/images/header/noaa.d87e0251.png)
![National Weather Service](/build/images/header/nws.4e6585d8.png)
![United States Department of Commerce](/build/images/header/doc.b38ba91a.png)
Area Forecast Discussion
Issued by NWS Las Vegas, NV
Issued by NWS Las Vegas, NV
596 FXUS65 KVEF 170317 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 817 PM PDT Fri Aug 16 2024 .SYNOPSIS...Dry and breezy conditions can be expected across the Western Mojave Desert and Western Great Basin through the weekend. This will be contrasted with increasing moisture and thunderstorm activity across the eastern Mojave Desert and northwest Arizona, with locally heavy rainfall possible Saturday in northern Mohave County. Monsoon storms will tend to retreat into Arizona early next week before creeping back west midweek onward. Temperatures will remain a few degrees above normal through the period. && .UPDATE...High clouds and moisture continue to move in this evening as an inverted trough lifts north through SE California. This feature brings 20-40% rain chances to Clark, Mohave, and eastern Nye Counties early tomorrow morning, while Lincoln County has 30-60% chances throughout most of the morning hours. After this first wave, attention turns to eastern portions of our area in anticipation of afternoon redevelopment. Main area of concern is northern Mohave County, where a Flash Flood Watch is in effect through Saturday evening. In addition to the flood potential, anomalous vertical wind shear (~30-40 knots) will increase the likelihood of strong to severe storms, with damaging winds and small hail possible. Storm chances linger across SE Nevada and NW Arizona on Sunday, before getting pushed to the eastern fringes of our area next week as drier air moves in. && .SHORT TERM...through Sunday night. Interesting forecast pattern for the upcoming 24 to 36 hours as the remnants of a westerly propagating shortwave trough along the international border lifts north and becomes entrained in a broad south-southwesterly flow pattern across the Great Basin. As it does so, precipitable water anomalies of 150-200 percent of normal will spread north across mainly Clark, Lincoln, and Mohave Counties. This rich moisture will then be acted upon be favorable jet dynamics and upslope orographics. Overall, this is a weather pattern more typical of early fall transition events than your standard monsoon set up, but may lead to some locally strong storm development late tonight and into Saturday evening. While the latest few iterations of the HRRR fail to develop much nocturnal activity tonight, several members of the HREF suggest convection developing late tonight across southern Mohave and Clark Counties, and lifting north into Lincoln county prior to daybreak. While the risk is conditional on storm development, 30-40 knots of deep layer southerly shear would be conducive to some stronger updrafts capable of small hail and strong outflow wind gusts. Tend to believe the HRRR is underdone with overnight development, especially given the magnitude of Integrated Water Vapor Transport suggested by forecast guidance. Whatever does develop tonight, will tend to shift into Utah in the morning hours, though continued moist southerly flow will foster additional storm development during the afternoon, mainly across northern Mohave County. With a favorable unidirectional southerly flow pattern which would favor storm training, and HREF signal for excessive precip, went ahead and issued a Flash Flood Watch for northern Mohave County from 12z Saturday morning through 4z tomorrow evening. Afternoon storm development further west tomorrow closer to Las Vegas is uncertain, and may struggle due to post- short wave subsidence, but a few isolated storms may still develop with locally strong wind gusts and heavy rainfall possible. Further west across the Western Mojave Desert and Western edges of the Great Basin, dry and breezy conditions can be expected both Saturday and Sunday, with elevated fire danger the primary concern. A Red Flag Warning remains in effect for Saturday and Sunday in Esmeralda and Nye counties where fuels and conditions are at critical risk. Meanwhile, temperatures areawide will remain above normal, though clouds and precipitation may keep things fairly close to normal across northern Mohave County Saturday. Storm chances will persist across our eastern zones into Sunday, though storm coverage is not expected to be quite as widespread as on Saturday. Nonetheless, locally heavy rainfall and gusty winds will remain possible with the stronger storms that do form. .LONG TERM...Monday through Friday. Overall weather pattern will change little next week, with dry and breezy conditions persisting across our western zones and more moist, convective conditions across our eastern zones. Where exactly that boundary lies each day is less certain, though NBM pops do shift noticeably eastward into mainly just northwest Arizona Monday and Tuesday in response to the flow aloft shifting more southwesterly. By midweek onward, flow backs to more southerly again, opening the for for a westward creep of the monsoonal moisture. Otherwise, temperatures will remain above normal through the period. && .AVIATION...For Harry Reid...Breezy south to southwest winds will continue through the afternoon with over a 50% chance for gusts over 20KT through this evening. Winds will diminish tonight with gusts ending after 03Z then southwest winds around 8KT overnight through Saturday morning. Southeast winds around 150 degrees will set up after 15Z Saturday then another round of breezy south to southwest winds are expected Saturday afternoon. Winds saturday will be stronger than today with as high probability (80%) for gusts over 20KT and a low probability (20%) for gusts over 25KT. Most likely, it will be dry through the TAF period with no thunderstorm impacts at the terminals. There is a low chance for scattered precipitation to blossom after 09Z tonight through southern Nevada through early Saturday morning, then another low chance for thunderstorms to develop Saturday afternoon. Confidence is currently too low to add convection to the TAFs however will need to watch how things unfold. If convection does develop late tonight and/or Saturday afternoon, lightning, sudden gusty winds, and CIGs 10kft are possible. For the rest of southern Nevada, northwest Arizona and southeast California...South to southwest winds with gusts of 20-25KT will continue through the evening. Winds will diminish tonight with diurnal wind trends expected through Saturday morning. Breezy south to southwest winds will develop again Saturday with gusts 20-30KT expected Saturday afternoon in many locations. There is a low chance (20%-30%) for showers and thunderstorms to develop across Clark and Lincoln Counties that would push north into central Nevada through Saturday morning, then another round of convection may develop Saturday afternoon in northern Mohave County through southwest Utah and eastern Lincoln. Any thunderstorms that develop would bring the risk of sudden gusty winds, lightning, heavy rain, and CIGs to 8kft- 10kft. && .FIRE WEATHER...Dry and breezy conditions remain expected across our western forecast area, namely across Nye and Esmeralda Counties where a Red Flag Warning is in effect over the weekend. Elevated fire danger will exist in Inyo County as well, though fuels are not as critical. Points east across the Eastern Mojave Desert, Lincoln County, and Northwest Arizona will see increasing RH today and tonight as a weather disturbance moves through with chances for rain and thunderstorm activity. Similar conditions will continue into next week with dry and breezy conditions persisting across our western forecast area. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Woods DISCUSSION...Outler AVIATION...Nickerson For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter