textproduct: Reno

KEY MESSAGES

* Strong winds with rain and high elevation mountain snow continues through Wednesday.

* High flows on rivers and stream with the potential for nuisance flooding in poor drainage areas and possible minor flooding along the Susan River near Susanville.

* Warmer and drier conditions return by late this week though another system could arrive by late this weekend into early next week.

DISCUSSION

Wind, rain, and (high elevation) snow, oh my! Let's step through this one by one, shall we? It is very windy out there today, with current observations around the ridges of the Sierra topping out around 100 mph while wind prone locations along Washoe Valley have gusts exceeding 75 mph. Travel, both air and ground, have already seen impacts with increased turbulence, delays, and difficult travel for high profile vehicles. Strong gusts may also displace unsuspecting trash cans and light patio furniture.

What about the rain? Latest radar shows showers just now pushing into our forecast area in NE CA, though showers have been stagnant along much of the Sierra around the Tahoe Basin. As seen by the wind, we're relatively shadowed out here in W NV. That is mostly expected to continue, though a few light showers might be able to make it over this afternoon/evening. Otherwise, rain is expected to continue along the Sierra through late tonight, with lingering showers expected to wrap up Wednesday afternoon. The concern with these rain showers though comes with the increased snowmelt and runoff. Expect ponding on roadways as well as poor drainage for low-lying areas. For details on the extent of river rises and flooding potential, please see the Hydrology section below.

Snow, you said? I hate to be the bearer of bad news, but only so much snow. Current forecast has 1-6" of snow, mainly along the Sierra crest of Mono county. The warmer nature of this storm system has let snow levels skyrocket to 9,500-10,500 feet today, meaning only the tippy tops of the Sierra will see snow. For more details on SWE and SLRs, please see the Avalanche section below.

High pressure returns for the later half of this week, bringing temperatures 10-15 degrees above normal by Friday. This translates to highs in the upper 50s and 60s for Sierra communities and W NV valleys, respectively. While it'll be quite pleasant for late February standards, a sneaky hazard we could see here is increased snowmelt. Just because it isn't raining doesn't mean there won't be concerns for lingering hydrology impacts. We could see another glancing blow of precip late this weekend (Sunday) from the Tahoe Basin and northward, associated with a cutoff low off the coast of central California. For details related to that system, we'll have to hold off until later in the week when models can resolve said system better.

-Giralte

AVIATION

Periods of MVFR/IFR conditions for Sierra terminals today with mountain obscurations expected for both Sierra and Sierra Front terminals. SHRA will continue through tonight, dwindling by Wednesday afternoon. The highest rain rates for Sierra terminals will be through 06Z this evening, with lighter, more isolated showers afterwards.

LLWS and mountain wave turbulence will prevail today for all terminals today. 700mb (FL100) winds will peak around 70-75kt out of the WSW through at least 03Z today with terminals experiencing gusts up to 40kt. For more information regarding turbulence, LLWS, and more, please visit aviationweather.gov.

-Giralte/Justin

AVALANCHE

Rain and high elevation snow is expected to continue across all avalanche center terrain through Wednesday afternoon.

* Snow levels, totals, and rates: Snow levels will range from 9,500-10,500 feet today with the Tahoe Basin on the lower side of that range and Mono county on the higher side. Totals will range from 1-6", primarily for parts of BAC and northern ESAC terrain. Rates aren't expected to surpass 0.5"/hr.

* SWE and SLRs: SWE will be locally higher in the Tahoe Basin with 1-1.5" expected. SWE decreases as you move south with 0.4-0.6" around BAC terrain and up to 0.25" for ESAC terrain. SLRs will be very low at 2-6:1.

* Ridgetop gusts: Localized WSW gusts up to 100 mph today, decreasing overnight to 50-60 mph, otherwise gusts of 80-90 mph. Typical ridge gusts up to 35 mph are expected to return by Wednesday afternoon.

-Giralte

HYDROLOGY

High winds, warm temperatures, and moderate rain are already taking a toll on the snowpack and resulting in rises in area rivers and streams. Raw hourly SNOTEL data indicate rain water moving through the snowpack at many locations, even at some elevations above 7000 feet. As of this writing, only a few lower elevation shallow snow sites have indicated any loss of snow water equivalent.

So far stream rises have been moderate, but an indicator of how reactive the snowpack and wet soils are to rain and snowmelt.

Our primary flooding concerns remain focused on foothill and mountain urban areas where deep snow large plow berms may block drainage systems and funnel runoff into unexpected areas along with ponding in poor drainage areas.

While flows are expected to be high along many rivers and streams throughout the area, flooding concerns are limited to the Susan River near Susanville where the river is expected to crest near minor flood stage tonight. It is also worth keeping a close eye on the West fork of the Carson near Woodfords which is expected to approach, but not exceed, minor flood stage.

Check for River forecast updates this afternoon and evening at: www.cnrfc.noaa.gov.

-TB

REV Watches/Warnings/Advisories

NV...Wind Advisory until 7 PM PST this evening NVZ002-003.

CA...Wind Advisory until 7 PM PST this evening CAZ072-073.