Area Forecast Discussion
Issued by NWS Las Vegas, NV
Issued by NWS Las Vegas, NV
138 FXUS65 KVEF 181649 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 949 AM PDT Wed Sep 18 2024 .SYNOPSIS...A trough of low pressure will swing across the western US during the second half of the week, bringing a slight chance of precipitation to the southern Great Basin and reinforcing the below- normal temperatures. Drier and warmer conditions will return over the weekend as a high-pressure ridge builds over the region. && .UPDATE...Clouds increased in northern Inyo County through the Southern Great BAsin this morning as mid-level moisture streamed into the region ahead o the incoming upper level low. Satellite imagery showed a negatively tilted trough with the center of the low strenghtening in off northern California Coast. In southern portions of the area, skies remained sunny. Temperatures at this hour were a bit warmer than yesterday at this time as heights rose slightly and southwest flow slowed for slightly warmer air to stream into the area. No significant changes were made to the afternoon forecast. The upper level system will continue to dig southeast through the day, shifting closer to the area as it does so. Forcing will increase in northern and central California as diffluence aloft sets up over the region, however moisture is limited with PWATs sitting around 0.3- 0.5 inches today. A few showers may be able to develop this afternoon in the Sierra and Whites which may shift into the Owens Valley and northern Esmeralda late this afternoon and this evening. HREF probabilities for any precipitation (over 0.01 inches) falling in the 6 hour period this afternoon is highest in the Sierra and the northwest corner of Esmeralda County, with chances under 20% elsewhere. So no significant impacts are expected as any precipitation will be in the terrain and even there, the probability for over 0.1 inch through this afternoon of rain to fall is 20% or less. Clouds will increase in Inyo, Esmeralda, and central Nye counties through the afternoon with mostly sunny7 skies prevail for areas further southeast. Winds will remain light. High temperatures this afternoon will run about 3-5 degrees warmer than yesterday, but even that will be about 10 degrees below normal for this time of the year. -Nickerson- && .PREVIOUS DISCUSSION...115 AM PDT Wed Sep 18 2024 .SHORT TERM...Today through Friday. A trough of low pressure currently off the Oregon coast will continue to move south today along the California Coast. Dry weather is expected area-wide through this afternoon. However, by this evening, the approaching trough will result in enough difluence aloft to produce a few showers over Esmeralda and northern Inyo counties. Moisture will still be limited with PWATs of .50" to .60", so no significant precipitation is expected to fall. The trough will continue to move south on Thursday before moving inland over southern California Thursday night and across the CWA on Friday. This timing is a bit slower than the previous forecast, with the best chance of precipitation now expected Thursday night and Friday. Given the cold-core nature of this system, there is the potential for weak convection to develop as the center of the low passes Friday. Right now, the best chances for this are across southern Inyo, Nye, Clark, and northern Mohave counties, where CAPE values of 200-400 J/kg are forecast. However, moisture will continue to be limited over the area, with most of it being intercepted by the Sierra. The probability of impactful precipitation amounts of 0.50 inches is less than 30 percent, mainly over the higher elevations of Inyo and Esmeralda Counties Thursday night and northern Lincoln County on Friday. The chance of seeing 1.00 inch or more for the entire event is near zero area-wide. Snow levels will be 9000ft or higher through Friday, so any snow that does fall will be confined to high elevations of the Sierra and White Mountains where a few inches will be possible. It is also not out of the question that the highest peaks in the Spring Mountains could see their first dusting with this system. No impactful winds are forecasted through the end of the week. Temperatures will warm slightly today when compared to Tuesday but still remain about 10 degrees below normal for this time of year. Readings will then fall a few degrees by Friday as the base of the trough swings across the region. .LONG TERM...Saturday through Tuesday. Picking up Saturday morning, model consensus is for the low to be exiting stage right, with any lingering precip chances limited to the eastern fringes of our CWA. As the low departs, the warming trend will begin, and high temps should be five to 10 degrees warmer Saturday than Friday, except in the far eastern CWA where clouds and precip chances will hold temps down one more day. Dry weather then takes hold for the rest of the period as high pressure builds in from the west, and highs rise another four to eight degrees from Saturday to Monday before plateauing on Tuesday. No significant winds are expected through the period. && .AVIATION...For Harry Reid...Generally light winds favoring diurnal trends are expected through mid afternoon with just a few clouds AOA 20kft. There is a brief window for southeasterly winds of 8 to 12 knots between 23z-4z before the winds transition back to the southwest after sunset. For the rest of southern Nevada, northwest Arizona and southeast California...Most areas across the Mojave Desert and Colorado River Valley will observe another day of fairly light winds with mostly sunny skies. Exception will be near the Sierra and Owens Valley with breezy southeast winds expected near KBIH this afternoon that will ease after dark. Increasing clouds and shower activity are also expected near KBIH, mainly after 23z and persisting into Thursday. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ SHORT TERM...Planz LONG TERM...Morgan AVIATION...Outler For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter