Area Forecast Discussion
Issued by NWS Las Vegas, NV
Issued by NWS Las Vegas, NV
279 FXUS65 KVEF 161700 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 1000 AM PDT Mon Sep 16 2024 .SYNOPSIS...A large low pressure system will slowly move across California and Nevada bringing widespread gusty south to southwest winds to the region today along with a significant cooling trend. A second trough of low pressure will move across the area midweek bringing a reinforcing shot of cool air along with scattered showers. && .UPDATE...Satellite imagery showed a a deep trough spinning in northern California this morning. Ahead of the trough, strong forcing allowed for precipitation to blossom in western Nevada, with rain and isolated thunderstorms noted on radar in Esmeralda County and isolated showers in the northern White Mountains of Inyo County. Area webcams showed rain shafts that became more impressive through the morning in Emeralda County as the low levels saturated and rain became more efficient. Through rest of the day, will need to watch for rainfall impact in Esmeralda County as bands of rain continue to stream through the county. HREF 3hr PMMs for greater than 1.00 inch of rain in northern portions of Esmeralda County shows 10%-30% probabilities, mainly through the morning. WPC continues to highlight the region with a slight risk for excessive rainfall and flash flooding, which given the dynamics but short duration of precipitation potential and drier low levels makes sense. As the low shifts east, precipitation will be possible in parts of the Southern Great Basin. However, each model run backs of how much is able to develop, mainly focusing on the terrain in northern Lincoln County later today. With dry low levels and the rapid transition eastward of the system, it will be hard to get much precipitation to develop and then reach the surface. Probabilities for impactful precipitation outside of Esmeralda County are low to none, so no concerned with afternoon precipitation causing any flash flooding or other impacts. Wind advisories continue for much of the region today. So far through the morning, the strongest winds were reported in Nye County where south winds were gusting 35-45 MPH. Gusts over 60 MPH were also reported in the terrain of the Southern Great Basin, including Angel Peak. Widespread gusts of 35-45 MPH are likely this afternoon with the strongest winds expected in Lincoln and Mohave counties where the strongest pressure gradient will set up and probability for wind gusts over 40 MPH is 80% or higher. NO changes were made to the wind headlines, will need to consider if the wind advisory in the western Mojave Desert will need to be extended as HREF probabilities for over 40 MPH gusts remains over 70% overnight. High temperatures today will be noticeably cooler than yesterday. With cooler air pushing into the region with the upper level system, high temperatures will be 10-15 degrees cooler than yesterday. -Nickerson- && .PREVIOUS DISCUSSION...157 AM PDT Mon Sep 16 2024 .SHORT TERM...Today through Tuesday night. Gusty winds and cooler temperatures will be the most notable weather for most of the area today associated with the closed low currently centered over central California. No changes needed to the going wind advisory headlines. Widespread gusts of 35 to 45 mph are likely across much of the region today. The slow movement of the upper low will keep this a low-end wind event with occasional gusts over 40 mph at the more wind-prone sites, but impacts will be minor. Wind speeds will ramp up late morning through the afternoon then decrease this evening. Gusts around 40 mph may persist over parts of northern Bernardino County late this evening and overnight and we may have to evaluate the need to extend the advisory for those zones once we see how winds materialize through the day. A localized concern primarily for Esmeralda County is the potential for bands of training showers and thunderstorms driven by favorable dynamic forcing near the northeast quadrant of the upper low. The latest HREF and other high res models indicate the potential for 6 hour localized rainfall amounts of 0.50-0.75 inches over northern Esmeralda County between 12Z and 18Z this morning. It will be something to monitor, but the threat is not widespread enough to warrant a Flash Flood Watch. Upward forcing fades for training storms this afternoon and scattered showers with isolated thunderstorms will develop over northern Inyo County into this evening under the low center`s cold pool. This will lead to light snowfall above 9000 feet in the Sierra and White Mountains, but accumulations are not expected to cause any travel impacts in our zones. The center of the closed low is forecast to be over northeast Nevada at 12Z Tuesday and will lift over the Northern Intermountain Region which will result in fairly light winds with temperatures in the 50s and lower 60s to start the day then topping out in the 80s across the Mojave Desert zones...which is about 10-15 degrees below normal. .LONG TERM...Wednesday through Sunday. The next low pressure system drops south from the Pacific Northwest into California/Nevada on Wednesday, pushing east on Thursday. One impact from this system will be elevated southerly to southwesterly winds as a tight pressure gradient passes overhead. There is not a strong signal for widespread gusts over 40 mph at this time, but will continue to monitor trends. A modest increase in moisture associated with the low may bring another opportunity for precipitation, particularly over the southern Great Basin where forcing under the center of the low should be strongest. Lastly, it should help maintain temperatures 10 to 15 degrees below average through the rest of the workweek. One the trough exits to the east, a ridge over the Pacific Ocean will expand into the western United States, bringing rising heights and closer to average temperatures over the weekend. && .AVIATION...For Harry Reid...Occasional southwesterly gusts between 15 and 20 kts continue through the overnight and early morning period before speeds increase to 25 to 35 kts around sunrise and continue through sunset. Isolated gusts to 40 kts cannot be ruled out in the late-afternoon with a 10 percent chance of occurrence. Gust speed and frequency will gradually decrease overnight into Tuesday with winds returning to typical diurnal trends early Tuesday morning. FEW-SCT aoa 20 kft will increase through the latter part of the overnight period and will clear out before sunrise this morning. For the rest of southern Nevada, southeastern California, and northwestern Arizona...Occasional gusty south-southwest winds will continue overnight into the early-morning across the forecast area with speed and frequency increasing with sunrise. Gust speeds this afternoon will range from 25 to 35 kts with up to 40 kts possible (30 percent chance) at KDAG this afternoon. BKN-OVC aoa 10 kft and light rain possible at KBIH this morning and afternoon before clearing out through the day. Las Vegas Valley TAF sites will experience increasing cloud cover (FEW-SCT aoa 20 kft) this morning that is expected to clear out before sunrise. No operationally significant cloud cover elsewhere through the TAF period. The risk of reduced slantwise visibility continues due to hazy skies from the southern California wildfires. Visibility is expected to remain above 6 SM. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ SHORT TERM...Adair LONG TERM...Meltzer AVIATION...Soulat For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter