textproduct: Reno

KEY MESSAGES

* Pattern shift from strong morning inversions today to high elevation snow and freezing rain by tonight.

* Stronger storm brings heavy mountain snow, strong ridge winds, and rain showers to valleys Friday evening into Saturday and possibly Sunday. Some flooding concerns for the Susan and Feather Rivers.

* Shower chances continue through the weekend into early next week with another system as early as Monday.

DISCUSSION

Looks like cloud cover chose to not inhibit fog development this morning! So on that humbling note, let's discuss what we're expecting, starting this afternoon. The low from Baja is steadily pushing northward, and we'll start to see precip in the far reaches of Mono county as early as noon today. Snow levels will be very high, over 9000' with some Tahoe Basin locations over 10,000'. Based on the trajectory of this storm, it'll be a bit harder to get spillover into W NV but it's not out of the question. Showers will reach into the Tahoe Basin by the early evening, and NE CA after sunset.

Something we don't often deal with is the possibility for freezing rain in valleys of Mono county and NE CA tonight and into Thursday morning. Those aforementioned strong morning inversions? Keep those in mind. Since there's not much wind with this first system, that cold valley air will continue to sit there; there's no mechanism for that to mix out just yet. So, this means surfaces will be cold and rain that likely falls will freeze easily upon contact. This will make any travel late Wednesday night through Thursday morning for those locations very challenging and slick. Slow down and allow for extra time to get to your destination.

Showers will be on and off Thursday but look to clear out in the evening for much of the Sierra. Snow levels will drop through the day Thursday to about 7500' by sunset. Friday also looks to be relatively clear with a break between systems. The second big moisture push will move in Friday night, continuing through Sunday. This system will be colder in nature, with snow levels near or below 7000' by Saturday morning. As such, a Winter Storm Watch is in effect for the Tahoe Basin and Mono county. Please see the product for more details.

But wait, there's more! With low snow levels with this first system comes the threat for rain on snow and thus flooding concerns, mainly for NE CA. Areal flooding near and along the Susan River will be possible, with CNRFC forecasts hinting that the Susan could reach minor flood stage by Saturday. As previously mentioned, there won't be a huge threat associated with winds for this first system but ahead of the second system Friday, expect an uptick in winds. Gusts of 35 mph are expected across much of the area Friday and Saturday, with localized gusts up to 45 mph for wind prone locations.

Active weather stays on the menu through at least early next week with another system possible Monday into Tuesday. However, models are having difficulty deciding on the timing and placement of that system. Stay tuned!

-Giralte

AVIATION

VFR conditions expected through much of today for Sierra Front terminals. Isolated IFR/LIFR conditions will be possible for KTRK/KTVL today due to FZFG until about 16Z. MVFR conditions are expected for KMMH by this afternoon due to the incoming system. Similar conditions are likely for KTVL/KTRK today, but more so by the evening hours.

FZRA is possible for KMMH late tonight and into Thursday morning, leaving surfaces slick. Otherwise, expect -SHRA for Sierra terminals due to high snow levels. Winds will continue to be relatively light today.

-Giralte

AVALANCHE

Two storm systems will impact all avalanche center terrain starting today through at least Sunday.

* First system: Warm with snow levels above 9 kft through tonight before dropping to 8.5 kft by Thursday afternoon. Significant snowfall amounts will be isolated to the highest peaks in Mono county with 6-10 inches possible. Locations across the Tahoe Basin may see a couple inches at most. SLRs are low (6-8:1) with SWE up to 1.25" along the crest, otherwise 0.5-1".

* Second system: Colder with snow levels starting around 7 kft at the storm's onset late Friday night. There's a wide spread in snow levels, but are expected to drop to 6-6.5 kft by Saturday night. SLR's settle back to 8-10:1 with SWE along the highest peaks near 3" (Tahoe Basin) and 1.5-2" for Mono county. Otherwise, 1.5" for Tahoe and 1-1.5" for lower elevations of Mono county. As of now, heaviest snowfall with rates near 1"/hr expected Saturday afternoon. Expect westerly ridge winds of 60-80 mph.

-Giralte

REV Watches/Warnings/Advisories

NV...Winter Storm Watch from Friday afternoon through Sunday morning NVZ002.

CA...Winter Storm Watch from Friday afternoon through Sunday morning CAZ072-073.