textproduct: Reno

KEY MESSAGES

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

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

DISCUSSION

While low pressure spins over the Eastern Pacific off the coast of BC today, the axis of the upper ridge has progressed east of the region allowing for a west-southwesterly flow over the CWA. Also within the upper air pattern, a weak shortwave trough is seen over WA/OR this afternoon. With this pattern aloft, dry conditions continue across the region for today. Winds are expected to decrease going into the evening hours across the region for the areas seeing gustier winds this afternoon (Sierra ridges, NE CA, and Northern Washoe County). Area low temperatures tonight expect to be in the 20s to lower 30s with the highest elevations of the Sierra seeing the upper teens. With lesser winds overnight, area wind chills expect to stay above zero.

Dry conditions are expected going for most of Monday with temperatures steadily climbing. Daytime high temperatures are forecast to be in the 50s to lower 60s in W NV while the Sierra communities have the 40s and 50s on tap. Chances for precipitation then begin to creep into the Sierra and NE CA late Monday night as the next system approaches. Forecast guidance depicts the aforementioned low splitting into a closed low that moves more into the Pacific and a shortwave trough that will pass through the PacNW on Tuesday into Wednesday. Looking at the CW3E AR Landfall tool, the probabilities for IVT values of 250 kg/ms continue to be very high signaling a weak atmospheric river event Tuesday into Wednesday. Precipitation chances look to be at their peak on Tuesday with 70-90% chances in the Sierra and NE CA, 40-60% in the Sierra Front, and 10-30% in the NV Basin and Range. Precipitation chances will taper off in the region on Wednesday.

The latest forecast guidance also shows the increased influx of AR moisture is taking a more northerly track across CA with less of an easterly component with the early week system. As such, the higher amounts of QPF expected for the system late Monday through Wednesday expect to stay west of the crest. However, the Sierra crest portions of the Tahoe region still do see some good QPF possible with a 15-25% NBM probability of getting 2+ inches by Wednesday night with the Eastern Sierra crest seeing a <10% probability for 2+ inches as well. The remainder of the Tahoe Basin as well as the Eastern Sierra and portions of Lassen County west of US-395 see a 20-50% chance of 0.5 inches of QPF during this system. The Sierra Front looks to see around a few tenths of an inch while the NV Basin and Range will have around 0.1 inches or less with the potential showers in its portion. See the Hydrology section for some potential impacts from the precipitation as well as snowmelt during this system. Snow levels climb to above 9-10 kft on Tuesday when the bulk of the precipitation is expected, allowing most of the region to see a p-type of rain. The highest elevations of the Sierra though will see heavy wet snow with SLRs of 2-6:1. The highest peaks of the Sierra in Mono County see a ~20-40% NBM snowfall probability of 4 inches or greater by Wednesday night.

Another concern with this system is the strong winds it will bring to the region particularly on Tuesday. The Sierra crest may experience gusts over 100 mph, while wind prone areas may have winds gusting up to 35-45 mph. Winds will decrease on Wednesday as the system moves out with an upper ridge moving over the area.

Drier and warmer conditions are expected from Thursday into the weekend. Long term guidance shows another potential system to begin March with signs of a trough moving into the area, but there's good uncertainty in timing and details this far out. -078

AVIATION

VFR conditions continue for the rest of today and going through the night. Light and variable winds are expected for a majority of the region TAF sites. KTRK and KTVL see southerly winds gusting up to around 20 kts through 23/02Z. Dry conditions are anticipated to persist into tomorrow. The next weather system arrives late Monday going through Wednesday which may cause sub-VFR conditions due to reduced visibilities with precipitation and potential fog. -078

AVALANCHE

No snow is forecast through Monday with mostly sunny skies and occasional high clouds.

Wind and Wind chills today: Gusty winds will decrease tonight allowing for wind chills to stay above zero.

Monday night through Wednesday: The next storm arrives on Monday night and peaks on Tuesday with rain and more high mountain snow above 9 to 10 kft as well as gusty winds up to 90-110 mph at the highest peaks. Snow levels start to come down on Wednesday, when precipitation chances taper off. However, there may be some lingering low shower chances going into early Thursday. Liquid amounts have come down a little bit with recent model runs showing less of an easterly component to the weak AR event. In the latest NBM probabilities, there is a 15-25% chance of 2+ inches of QPF at the Sierra crest from the Tahoe Basin northward between Monday night and Wednesday with the Eastern Sierra having a <10% chance. 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 include 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.