textproduct: Reno

KEY MESSAGES

* Cooler temperatures with periods of rain and high elevation snow will begin this morning and last through Thursday.

* Strong, downslope winds Wednesday evening into Thursday morning will deliver impacts to fire weather, road/air travel, and recreation.

* Warmer and drier weather with gusty NE ridgetop winds return on Friday followed by lighter winds Saturday.

DISCUSSION

Our first round of showers are starting to work their way into the Sierra this morning. Showers will work their way into the Tahoe Basin throughout the morning and eventually reaching Mono County by midday. Snow levels will range from 7000-8000' today, with snow amounts above 8000' ranging from 6-12" through tonight. High elevation snow and valley rain will be mainly focused from I-80 southward today. Because of this, we have issued a Winter Weather Advisory above 8000' from 5 AM this morning through 5 AM Wednesday. The Sierra Front and eastern Sierra also have a 10-50% chance to see 0.10+ inches of rain. Lightning chances will be low today, but Mono and Mineral counties will have a 15-20% chance. Temperatures will also take another hit today, dropping down to the low 60s across W NV valleys and upper 40s in Sierra valleys. Winds will stay breezy too, with gusts up to 25 mph. Though relatively light gusts, we may see some blowing dust today across western NV downwind of dry lake beds. However, the rain this morning may dampen the chances for blowing dust.

By early morning Wednesday, our next storm will arrive in the Sierra and NE CA. A larger and deeper upper level trough will move in, bringing additional Sierra snow and valley rain. Snow levels will start off around 7500' and then drop below 5000' after 10 PM due to a cold front racing southward Wednesday night. Snow amounts above 7000' along the Sierra crest from Alpine County northward have a 60-80% chance of at least 6", and 20-40% chance of at least 12" through Thursday afternoon. Over Mono County, there is currently a 20-50% chance of at least 2" through Thursday morning. Lower valleys in NE CA, W NV, and the eastern Sierra have a 50-70% chance of at least 0.10" of rain, and 20-50% chance of at least 0.20" of rain through Thursday afternoon. Lightning chances will hover in that same range as today, around 15-20% along the Sierra crest.

So, precip aside, another very impactful hazard on Wednesday will be strong downslope winds Wednesday evening through Thursday morning. CAM sounding data are checking all the boxes for strong west- southwest winds in the Sierra and along the Sierra Front and eastern Sierra. A 700mb jet maxing out at 70-75kt is going to be the driving factor behind these winds. Temperature profiles from multiple CAMs show a critical inversion layer above ridgetop level (~650-700mb) which acts like a cap, and beneath it, a well-mixed temperature profile that will easily allow the higher momentum air aloft to mix down to the surface. Sustained winds will likely top out around 30-35 mph with gusts up to 70+ mph (50-70% chance) across wind prone locations along Hwy 395. Other valley locations along the Sierra Front and NE CA will have gusts 50-60 mph. Impacts from these winds may include blowing dust, mountain turbulence and LLWS, and the risk of high profile vehicles tipping over.

By Thursday evening, all of this looks to wrap up, leaving behind chilly northeasterly breezes and mostly clear skies. Friday onward, a ridge builds in and hangs out over our CWA through this upcoming weekend and into early next week. Our temperatures will rebound back up to 10-15 degrees above average.

-Justin

AVIATION

Periods of SHRA are expected today through midday Thursday. MVFR- IFR conditions will be possible in these rain showers. Rain has already reached the Tahoe Basin this morning, and will expand in coverage down through Mono County as the afternoon goes on. Given high snow levels of 7000'+, Sierra terminals will likely (60-80% chance) only see rain as the dominant p-type until Wednesday night, when snow levels start to crash and a quick shot of snow becomes more likely (>90% chance). All other terminals will see intermittent rain showers this morning and afternoon, but amounts will be light(<0.15").

Some early morning LLWS and turbulence will be possible today, then weakening after 18Z. Afternoon winds today will be breezy out of the west/southwest with gusts up to 20-25kt.

Strong, impactful westerly winds Wednesday night through Thursday morning will cause mountain wave turbulence and LLWS. FL100 winds peak around 70-75kt, which will yield a 50-70% chance for Sierra and Sierra Front terminals to exceed gusts of 40kt.

-Justin

FIRE WEATHER

There is increasing potential for strong to locally damaging winds Wednesday evening into Thursday morning as a downslope mountain wave signature develops along the Sierra Front and Eastern Sierra.

A High Wind Watch remains in effect for the Sierra Front and Eastern Sierra during this time frame, with gusts of 50-60 mph likely along the US-395 corridor and 70-80 mph possible in wind- prone locations such as Washoe Valley and wind aligned canyons in Mono County. While the strongest winds are expected overnight, downsloping winds may limit RH recoveries to below 40% in these areas, maintaining poor overnight humidity recovery.

Considering the record March warmth and poor snowpack, any exposed and receptive fuels could experience elevated fire weather conditions with this potential high wind event despite ongoing green-up in lower elevations. Fuentes

REV Watches/Warnings/Advisories

NV...Wind Advisory from 2 PM Wednesday to 5 AM PDT Thursday NVZ005.

Winter Weather Advisory from 5 AM Wednesday to 8 AM PDT Thursday NVZ002.

High Wind Watch from Wednesday afternoon through Thursday morning NVZ003.

Wind Advisory from 2 PM Wednesday to 11 AM PDT Thursday NVZ004.

CA...Wind Advisory from 2 PM Wednesday to 5 AM PDT Thursday CAZ070.

High Wind Watch from Wednesday afternoon through Thursday morning CAZ071.

Winter Weather Advisory from 5 AM Wednesday to 8 AM PDT Thursday CAZ072.

Winter Weather Advisory until 5 AM PDT Wednesday CAZ073.

High Wind Watch from Wednesday afternoon through Thursday morning CAZ073.