Mount Wilson, NV Weather

Key messages

* Precipitation chances and cooler temperatures continue through the weekend. Heavy rain and thunderstorms may result in flash flooding at times.

* Cool and dry conditions for early next week.

Discussion: through Thursday

An unsettled weather pattern continues through the weekend as an upper level trough interacts with anomalous moisture associated with the remnants of Tropical Storm Vance. This afternoon, scattered showers and thunderstorms have been very efficient in the moist environment, dropping a quick 0.50 inches or more as they move over and flash flooding has been reported. Instability has also been impressive early this afternoon which has allowed for strong to severe thunderstorms with hail to develop in portions of Clark County. Scattered showers and thunderstorms will continue in southern Nevada and Mohave County which could lead to additional impacts such as heavy rain, flash flooding, and hail. By early tonight, this round will have waned as showers become more isolated in eastern Lincoln, northeast Clark, and northern Mohave County tonight through much of Saturday. This lull in activity will end Saturday evening though as the trough approaches. Forcing and moisture will increase with the incoming trough, however there continues to be uncertainty in how much moisture will advent northward into the area. The difference between the HRRR and RRFS/REFS is vast, especially on Sunday. Favored the RRFS/REFS solution as anomalous moisture is expected to be in place for most areas, but low confidence in how much will fall. The highest confidence for rainfall that could be moderate to heavy at times is in Mohave County where NBM has a 70%-80% probability for over 1 inch of rainfall from Saturday night through Sunday night. This is also where there is some agreement for at least 200% of normal PWATs (with higher anomalies possible). Given this signal for heavy rain along with saturated soils from recent rainfall today- issued a Flash Flood Watch for Saturday night through Sunday night in Mohave County outside the Colorado River Valley. Heavy rain and flash flooding is possible outside of this area, and if the ECMWF solution with higher PWATs further north and west verifies- later shifts may need to expand this flood watch. Precipitation will be possible areawide. , snow levels will remain high (generally above 9,0009,500 feet). The peaks of the Sierra and Spring Mountains could pick up several inches of snow, but recreational areas like Lee Canyon should see little to no accumulation.

As the trough exits early next week, a tightening surface gradient along its western flank will drive breezy to gusty winds Monday, particularly across the southern Great Basin. Most gusts will subside Monday evening, though terrain-channeled winds through the Colorado River Valley could linger into Tuesday. Cooler air will settle in behind the system despite shortwave ridging building overhead, keeping highs roughly 5 degrees below seasonal normals through Tuesday under dry conditions.

Aviation

For Harry Reid: For the 06Z Forecast Package:

Most of the shower activity has ended for the overnight period; however, a stray shower or two can't be ruled out, but confidence is too low to include in the TAF. CIGs will generally remain above 5kft, but some lower CIGs down to 2kft will be possible through 08Z. Winds will generally be light and variable. Southeast winds will increase after 21Z with gusts up to 18kts. Rain chances will increase late Saturday evening with lowering CIGs and low chances of visibility restrictions.

For the rest of southern Nevada, northwest Arizona and southeast California: For the 06Z Forecast Package: Most of the shower activity has ended, but some lower CIGs will remain across the Las Vegas Valley through at least 08z. Elsewhere, generally light winds and CIGs 10kft or higher. Rain chances will increase late afternoon areawide with lowering CIGs and slight chances of visibility restrictions. The greatest threat of rain and low CIGs will be during the overnight period.

Spotter information statement

Spotters are encouraged to report any significant weather or impacts according to standard operating procedures.