textproduct: Reno

KEY MESSAGES

* Dry conditions persist through the rest of today with gusty winds this afternoon. * The next impactful storm arrives tonight with rain and high elevation mountain snow through Wednesday. Flooding potential persists with this weak atmospheric river event, but flooding confidence remains low.

* Warmer and drier conditions return late this week into the weekend. Although, there are hints of a weak system this weekend into early next week.

DISCUSSION

Low pressure system in the Eastern Pacific continues to pull a weak atmospheric river towards northern California and Nevada as observed in water vapor satellite imagery. In the meantime, partly to mostly cloudy skies will continue along with warmer temperatures as warmer and wetter air is pushed towards us. However, the rain is expected to start tonight after 12 AM when the HREF and REFS show rain at the western edges of our region.

Snow levels continue to be around 10-11 kft resulting in snow showers limited to those elevations and above. Therefore, the best chances for snow will be at the highest peaks, and in the highest portions of the Eastern Sierra in Mono Co. Amounts of 1 to 4 inches are likely in said area with a 10-40% chance of exceeding 4 inches with isolated locations getting up to 6-8 inches. However, the character of the snow will be very wet.

Rain over snow will be the main concern across the region, mainly over the Sierra and NE CA. Western NV will have some rain showers, but not much spillover is expected, with up to 0.25 inches of rain over the Sierra Front through Wednesday afternoon and a 20-45% chance of exceeding that amount. The Basin and Range and Mineral Co. could see up to 0.10 inches. Now, the mountains in CA will see upwards of an inch from western Lassen down to Mono with the highest amounts likely near the crest with 1.5 to 2.5 inches possible and a 15-35% chance of seeing more than 2 inches. Sierra communities are likely to see around 0.5 to 1 inch of rain with this system, and some locations seeing a bit more.

Winds will be a concern Tuesday into Wednesday. While the QPF/rain has come down, the winds have been on an upward trend. Sierra ridges are likely to see gusts over 100 mph on Tuesday before they decrease on Wednesday. Gusty winds (30-45 mph) are likely at lake level and over US 395. Wind-prone areas in western NV are also likely to blow with gusts greater than 40 mph with a 40-70% chance of exceeding that value.

Wednesday morning and beyond rain chances will steadily come down with just lingering light showers likely by the Wed. afternoon. At the same time, snow levels will start to come down to 7.5-9 kft which will lead to a dusting of snow in higher elevations. Afterwards, drier and warmer conditions are expected late week into the weekend. However, there are indications of an upper trough affecting the region again this Sunday into Monday.

-HC

AVIATION

VFR conditions are expected through this evening. Areas of MVFR to IFR conditions along with mountain obscurations are likely tonight after 03-06Z as rain showers begin from west to east with the next system. Light and VRB winds are expected at the valleys this morning, becoming from the southwest after 18-20Z areawide with speeds 10-15 kts and gusts up to 15-25 kts at TAF sites. LLWS and turbulence returns after 00-03Z this evening due to FL100 winds increasing to 40-55 kts.

-HC

AVALANCHE

No snow is forecasted for today with partly to mostly cloudy skies.

The next storm arrives tonight and peaks on Tuesday with more rain and high mountain snow above 9 to 10 kft, as well as gusty winds up to 90-110 mph at the highest peaks.

Snow levels come down on Wednesday afternoon to 7.5-9 kft for the Tahoe Basin, and for Mono county on Wednesday evening, when precipitation chances taper off. However, there may be some lingering low shower chances going into early Thursday.

Liquid amounts continue to fluctuate with this weak AR event. In the latest NBM probabilities, there is a 15-35% chance of 2+ inches of liquid at the Sierra crest from the Tahoe Basin northward between Monday night and Wednesday morning with the Eastern Sierra having a <10% chance. Current storm totals are around 1.5-2.5" in the Sierra crest around the Tahoe Basin, 1-1.5" below the crest. For Mono, 1-2" near the crest from Mono Lake and northwards, and 0.5-1.5" south of Mono Lake near the crest. Below 8 kft in Mono 0.5-1.0" of liquid.

SLR will be 2-5:1 above 9-10 kft with snow accumulations of 1-6" with isolated higher accumulations from Mono Lake southwards.

Ridgetop winds decrease on Wednesday to 50 to 80 mph.

-078/HC

HYDROLOGY

While flooding from the upcoming precipitation is possible, there is low confidence at this time. Currently, the WPC gives the Sierra portions of the region a marginal risk (at least 5%) for excessive rainfall on Tuesday. However, the rain over snow will lead to quicker runoff especially in urban areas. Please clear drains now if you can to help prevent possible ponding. Also, rivers and streams within the area are forecast to see rises leading to some potential flooding concerns this week. In particular, the Woodfords river gage for the West Fork Carson River has a 5-25% chance of reaching minor flooding stage on Wednesday. Other rivers that have a 5% probability for minor flooding including the Susan, Middle Fork of the Feather and the Pit River. Will continue to monitor in case flood products are needed. -078

REV Watches/Warnings/Advisories

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