textproduct: Reno

KEY MESSAGES

* Chances of light rain and mountain snow continue through the day mainly for the Sierra and vicinity areas.

* A storm system on Saturday and Sunday brings colder temperatures along with light valley rain, and mountain snow above 7000 ft.

* Drier and warmer conditions return by Sunday afternoon through mid-week next week.

DISCUSSION

Current radar imagery shows a band of light rain and light mountain snow over Central CA and the western slopes of the Sierra. Most of it is being blocked at the crest with a few light showers spilling over to the eastern slopes of the Sierra and western NV. Rain amounts are very light or none at all. This is expected to continue through the morning hours per the HREF and REFS. Although more spillover is expected later this morning especially for the Sierra and Sierra Front. Rain also develops in areas east of US-95, especially closer to far eastern Churchill/Pershing counties today. Activity will be more spotty this afternoon and evening, so expect breaks with the light rain in western NV, and the rain snow mix in the Sierra. Snow levels will be around 7000-7500 feet, above those elevations a trace to 3 inches of snow are possible through the evening hours today. Chances of exceeding 3 inches are 10-50%+ above 10 kft south of US-50, and a 10-40% of exceeding one inch above 7 kft.

The models are finally starting to align with better consistency for a clearer scenario on Saturday and Sunday. The broad upper low off the PacNW generates a secondary low in the Eastern Pacific and pulling a plume of warm and moist air which, merges with the colder and drier air from the northern system over California and Nevada. This scenario has led to an increase in precipitation with snow levels starting around 7-8 kft Saturday and potentially dropping to 5 kft or lower by Sunday morning. The main area of concern will be in the Sierra above 7000 ft, where snow amounts of 3-6 inches are likely with a 10-40% chance of exceeding 6 inches north of US-50 and 30-60% to the south of US-50 by Sunday afternoon. At Lake Tahoe level and US-395 in Mono county, there is a 10-50% chance of reaching 2 inches of snow by Sunday afternoon too. A Winter Weather Advisory remains in effect for the Sierra for the above reasons. Checking with CalTrans and NDOT (for Mt. Rose Highway) for the latest road conditions is recommended as travel through these areas, especially the passes will be hazardous.

Western NV and NE CA valleys will see mostly rain with a low (5-15%) chance of a wintry mix making it to valley floors on Sunday morning. The moisture is mostly leaving as the really cold air makes it in. So, a few snow showers amounting up to a trace or a dusting of snow are possible by Sunday morning in the valleys.

By Sunday evening through Tuesday or Wednesday next week warmer and drier conditions are expected with an upper ridge developing in the region. Model uncertainty continues with the ending of the precipitation on Sunday as some ensemble members keep showers in the area through Sunday night, albeit light. Then again with the approach of the next system sometime between Tuesday evening and Thursday, and a potentially subsequent system for the following weekend. However, based on how guidance has behaved this week, I wouldn't put much trust in them until at least early next week.

-HC

AVIATION

VFR conditions with brief periods of MVFR are expected through Saturday morning over western NV and northeast CA. The periods of MVFR will be due to -RA primarily reducing CIGs. VIS reductions should be minimal, except near the strongest showers. Rain chances are 5-30% through Saturday morning. For KTRK, KTVL and KMMH, expect periods of VFR and MVFR due to low clouds and 30%+ chances of -RA/-SN. Snow chances will be higher in the early morning hours, especially around sunrise. Little to no snow accumulations are expected. Mountain obscurations prevail through the weekend. Periods of turbulence and LLWS are expected through this morning, then return again late this evening.

More valley rain and mountain snow is expected on Saturday and Sunday with the next system.

-HC

REV Watches/Warnings/Advisories

NV...Winter Weather Advisory from 8 AM Saturday to 7 AM PDT Sunday NVZ002.

CA...Winter Weather Advisory from 8 AM Saturday to 7 AM PDT Sunday CAZ072-073.