textproduct: Reno

KEY MESSAGES

* Gusty to strong winds will pose impacts to travel and recreation through this afternoon.

* Rain and high Sierra light snow showers will continue through this morning.

* A break on winds and precipitation is expected Thursday before wet and windy weather resumes Friday into the weekend, with potential for more atmospheric river events through Christmas Day.

DISCUSSION

An upper shortwave trough continues to deliver light rain across northern NV/CA this morning per radar and surface observations. The higher chances of rain (60-90%) continue for the Tahoe Basin, NE CA, and the Sierra Front through the morning. Snow levels remain high, generally above 9 kft in the Sierra and 6-7.5 kft for the Surprise Valley and northern Washoe, limiting significant snow to the highest peaks. Precipitation will taper off by this afternoon.

Winds remain the main concern through this afternoon. A deepening surface low to our north, combined with robust 700 mb flow of 50-65 kts, will generate widespread gusty to strong winds. Wind Advisories remain in effect for much of the area. The strongest winds are anticipated in two periods: early Wednesday morning and again late morning to early afternoon. SW/W gusts of 35-50 mph across valleys, 50-70 mph in wind-prone areas, and 80-100 mph in Sierra ridges are expected today. These winds will pose impacts to travel and recreation, including aviation and crosswind hazards on north to south oriented highways. Winds begin to weaken by this evening.

Weak ridging returns on Thursday, resulting in mostly dry conditions and significantly lighter winds. However, another system approaches on Friday, bringing a return of gusty winds and increasing chances for rain and high-elevation snow. NBM guidance shows increasing precip chances for the Sierra and northern NV/CA, though snow levels are expected to remain high initially and decreasing by Saturday morning to 6-7.5 kft.

By Saturday, the deepening of an upper trough allows a westerly to southwesterly flow into the West Coast conducive to a series of atmospheric river (AR) events with rounds of precipitation to Northern CA/NV. NBM guidance indicates high chances for precipitation 60-90% across the Sierra and northern NV/CA through early next week. Valley locations will also see increased chances for rain 40-80%. While snow levels are expected to remain elevated through much of the weekend, there is increasing confidence in significant snowfall at higher elevations, above 7 kft, as colder air eventually filters in.

The days leading up to Christmas still look favorable for stronger winter storms, which may result in significant holiday travel disruptions across the Sierra and western Nevada. Confidence in the exact timing and intensity of these AR events remains moderate, but the overall trend points to an active pattern.

-HC

AVIATION

Mountain wave turbulence and LLWS impacts will be the primary concern for all terminals with light rain showers periodically lowering CIGS/VIS to MVFR conditions at Tahoe and Sierra Front terminals tonight through Wednesday morning.

SW/W FL100 winds continue at 40-60 kts through 18Z this morning. Surface wind gusts SW/W reach 25-35 kts at KTRK-KTVL-KMMH and 35-45 kts at KRNO-KCXP-KMEV around 12Z. Mountain wave turbulence and LLWS will likely be an issue to some extent through this evening, but will be most intense from 12Z-18Z along with the strongest winds.

Low clouds and occasional -RA/RA may obscure mountains for Sierra and western NV terminals. Rain showers may sneak into KRNO- KCXP- KMEV through 14Z.

-Salas/HC

REV Watches/Warnings/Advisories

NV...Wind Advisory until 4 PM PST Wednesday NVZ002>005.

CA...Wind Advisory until 4 PM PST Wednesday CAZ070>072.