Las Vegas, NV 89153 Weather

Key Messages

* An incoming trough brings widespread rain and mountain snow chances, gusty winds, and below normal temperatures midweek.

* Increasing confidence for a dry conditions and warming temperatures this weekend.

Discussion

Through the Weekend.

An upper level trough, currently centered off the coast of Oregon, will bring significant chances in the weather pattern this week as it plunges south and east. Precipitation chances start to appear over high terrain on Tuesday afternoon due to increasing moisture and difluence aloft. However, more widespread precipitation is expected on Wednesday and Thursday as the trough moves into Southern California. Moisture advection brings PWATS into the 0.5 to 1.0 inch range, which is 200 to 300 percent of normal for late October. Elevated moisture combined with instability driven by strong winds aloft and cold air under the low may prompt particularly efficient rain rates on Wednesday and Thursday. Forecast soundings show 500- 1000 J/kg MUCAPE and 40+ knots of shear starting Wednesday afternoon in southern Nevada and northwestern Arizona. Snow levels remain above 10,000 feet on Wednesday and fall to around 8,500 feet on Thursday. Although the trough moves east by Friday, lingering moisture and instability may support additional showers over high terrain. Forecast confidence in timing for specific locations should increase with additional high resolution guidance.

Another notable impact will be increased winds starting Tuesday. 850 mb wind speeds increase to 25 to 30 knots. For Tuesday, the strongest surface winds will be in the Owens Valley and southern Great Basin. Peak gusts will generally be in the 25 to 35 mph range, with a low probability (10-20%) of wind gusts reaching 40 mph in the afternoon. Southerly winds spread to most of the remainder of the forecast area on Wednesday as the low tracks southeast. Lingering southwesterly breezes remain across the Mojave Desert on Thursday before the system moves out.

A ridge should develop this weekend as the trough moves off into the Four Corners. Moisture will scour out and dry conditions are expected. Temperatures remain several degrees below normal for this time of year, but will increase a degree or two compared to temperatures midweek.

Aviation

For Harry Reid...For the 00Z Forecast Package... Fairly quiet and benign conditions expected for the next 24-30 hours. Light winds favoring an E to NE direction under 8KT continue into the evening. Around 04z, light winds shift to a more WSW direction and remain light and variable throughout the night. Similar pattern expected Tuesday with light E-NE winds developing after 17-18z, becoming SE during the afternoon around and under 8 kt. VFR conditions will continue with a few passing clouds around 10- 12kft. Isolated convection possible in higher terrain tomorrow but no impacts to KLAS are currently expected.

For the rest of southern Nevada, northwest Arizona and southeast California...For the 00Z Forecast Package...Quiet and benign conditions to persist through the TAF period for most sites. Winds follow typical daily directional patterns and remain around 8KT or less the next 24 hours. The only exception will be KBIH, where southeasterly up-valley winds gusting to 15-25KT continue this evening, then redevelop again after 18z tomorrow gusting up to 30 kt. Elevated southerly winds may persist a few hours after sunset at KBIH before becoming light and northerly after 06z. VFR conditions prevail with no operationally significant cloud cover. Isolated convection possible in higher terrain tomorrow but no impacts to terminals are currently expected.

Spotter Information Statement

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