textproduct: Reno

KEY MESSAGES

* Breezy and dry tonight with light showers possible late day Tuesday.

* Storm will bring wetting rains and high elevation snow to the region Wednesday and Thursday.

* Cool but mainly dry Friday into the weekend. Unsettled pattern could bring a storm or two next week.

DISCUSSION

* Confidence continues to grow in a widespread wetting rain Wednesday into Thursday, as banded precip sets up over the forecast area to the N/NE of slow moving upper low. This one definitely has more going for it than the "storm" a little over a week ago. While showers could develop as early as Tuesday afternoon/evening, the bulk of the rainfall looks to be Wednesday afternoon into Thursday with a 70-90% chance of at least 0.25" in both valleys and mountains. Orographics won't really be a big lifting factor given S/SW flow and most of the forcing being aloft.

* While this will by and large be a welcome & beneficial rainfall that will help quell fire potential and recharge the streams, some simulations show potential for 1-2" rain under any banding that develops. That could yield flooding in poor drainage areas or on recent burn scars including the Hawk and Bug fires near Reno. With autumn leaf and needle drop happening, gutters and drains should be checked beforehand. I'd also expect the commutes Wednesday & Thursday to be extra slow due to rain & ponding water.

* We also could be looking at some snow for the Sierra that may have an impact for the still-open passes such as Tioga, Sonora, and Mt Rose. Guidance indicating Wednesday night into Thursday as the best potential for that happening - 70% of 2-3" and 25% of 6" for these passes. It's that time of year to start thinking about preparing your vehicle for winter travel, e.g. good tire tread & wipers & battery, start carrying chains & check your survival kit.

* In general wind won't be a major issue with this system. The one exception is in the Eastern Sierra in the Owens/Chalfant Valleys up into the Hwy 95 communities in Mineral County. Southerly breezes look to channel up those valleys Tuesday & Wednesday, with gusts potentially peaking 40-45 MPH. This could produce some localized fire weather concerns Tuesday.

* Simulations kick this upper low out pretty quick on Friday, such that we're left with mainly dry and cool fall-like conditions through the upcoming weekend. Into next week, the pattern is pretty low-predictability as evidenced by the wide spreads in temperature and precip forecasts in the NBM. That being said, a number of the AI models, which show skill at long lead times, are showing a decent early season snow event for the Sierra around or just before Halloween. CPC has a slight risk for heavy snow in their 8-14 day hazards outlook.

-Chris

AVIATION

* Low pressure off the California coast will produce enhanced S/SW flow aloft (700mb flow 25-30 knots) over the Sierra and W Nevada, along with SCT to BKN mid and high level cloudiness, into Tuesday.

* Gusty winds are expected this afternoon/evening, generally 20-25 knots at most TAF sites. As surface winds subside overnight into Tuesday morning, low level wind shear will be likely given continued breezy flow at ridgetop levels. Mountain wave turbulence is likely especially from RNO/TVL northward.

* Showers are forecast to develop after 18z/Tues with roughly 15-30% probability for brief MVFR periods in rain and lower ceilings. Much wetter for Wednesday-Thursday with IFR or worse conditions in rain and mountain obscuration.

-Chris

REV Watches/Warnings/Advisories

NV...None. CA...None.