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FXUS65 KREV 030944 AFDREV

Area Forecast Discussion National Weather Service Reno NV 244 AM PDT Fri May 3 2024

SYNOPSIS

Warmer temperatures continue today, with light winds. Active weather returns with a storm system bringing gusty winds along with valley rain and mountain snow, with conditions slowly improving Sunday. Early next week, a slow warming trend with low chances for precipitation remain in the forecast.

DISCUSSION

Enjoy the calm, warm weather today because it's all coming to a quick end by the weekend. High-resolution models and the HRRR are picking up some isolated showers is in Alpine, Mono, and into Mineral counties, where there is a slight 10-15% chance of precipitation during the early afternoon. Otherwise, we'll see mostly seasonal temperatures today with low to mid-60s for Sierra communities and northeast CA while upper 60s to low 70s are expected in western NV.

WEEKEND STORM: It seems like our spring weather pattern enjoys messing up our weekend plans by always returning us to winter! Near-term models all show an anomalously cold, dynamic low pressure system moving into northern CA by Saturday afternoon with a strong cold front moving through the area. This low then transits east into the central Great Basin by Sunday afternoon. As a reference, ensembles show 500mb temperatures of -28 to -30C, which falls into the lowest 1/10th percentile for the date and what we usually expect in January! Let's dive into the details of your ruined weekend below:

* Winds: As this system moves into the region, strong southwest winds will begin to increase by late Friday night through Saturday. Ensembles show an increasing 700mb jet upwards of 40-50kts dropping south, with the strongest gusts prior to frontal passage on Saturday afternoon. At this moment, gusts upwards of 80-100 mph are conceivable along the ridges throughout the eastern Sierra. Additionally, US-395 in Mono counties may see wind gusts upwards of 50-60 mph with stronger gusts to 70 mph in wind prone areas. Strong winds will also materialize for the rest of western NV on Saturday, where gusts of 45-55 mph are possible with stronger gusts upwards of 60-70 mph in wind prone areas such as US-395 from Reno to the CA/NV border and US-95 in Mineral County near Hawthorne. There is a 40-60% probability for damaging winds from south of I-80 into Douglas, Lyon, Mineral and Mono counties.

* Snow/Rain: Not a significant change to the latest QPF guidance.
When it's all said and done, western Lassen southward through Alpine County, as well as along the crests in Mono County have a likely 60-80% chance for at least 0.50". The highest crests in the Tahoe Basin have a 40-60% chance for at least 1.00", with only a 20-30% of 1.00" in Mono County. Snowfall totals as well as snow probabilities have increased compared to prior guidance.
There is a likely >80% chance for at least 2" of snow at lake level in the Tahoe Basin, with a likely (>70%) chance for at least 6" of snow along the Sierra crests from Mono County northward into western Lassen County. There is even a 40-60% chance for isolated amounts up to 12" along mountain passes (US-50). Lastly, Snow levels will start at around 6,000-7,000 feet in the Tahoe Basin northward, to around 8,000-9,000 feet in Mono County before falling to around 5,000 feet everywhere by Saturday evening. We might see some snow flurries into western NV Saturday night.

* Temperatures: It will be downright cold for May standards on Saturday and Sunday. High temperatures will be upwards of 15-20 degrees below average, as we struggle to hit 40 degrees for Sierra communities and low 50s in western NV. There is additionally the chance for sub-freezing temperatures in western NV and northeast CA on Sunday and Monday mornings.

* By Monday into next week, ensembles begin to diverge in solutions in either a long-wave trough pattern across the west, or a ridge building in from the eastern Pacific. At this time, we keep below average temperatures Monday into Wednesday as we warm back up from the weekend storm with near average by the end of next week. We'll hang on to low chances for additional showers on Monday, with drier conditions the remainder of the week.
- Mckellar

AVIATION

* Friday will feature pleasant flying conditions with light winds and clear skies though around 03z. There is a slight (10-15%)
chance for showers for KMMH Friday afternoon.

Weekend Storm: A strong, cold spring storm system is moving into the region Friday night into Saturday.

* Snow/Rain: Widespread mountain snow showers and valley rains are likely (>70%) late Friday night into Saturday evening throughout the eastern Sierra, northeast CA, and western NV. This is a colder airmass allowing snow levels to drop to 5000-5500 feet by Saturday night. Sierra terminals KTRK, KTVL, and KMMH could see between 2-4" of snowfall with a 80% chance for at least 2".
However, high sun angle in May may limit accumulations during the day. There is also a slight chance for snow flurries Saturday night into Sunday morning in western NV.

* Winds: Strong west to southwest winds will ramp up across the Sierra as early as Friday night and will continue through Saturday night. Sustained ridgetop winds in the Sierra of 30-50kts with gusts upwards of 60-80kts are are conceivable during this time period. Expect periods of mountain wave turbulence, as well as LLWS for all area terminals. Otherwise, strong west to southwest winds are possible for all western NV and Sierra terminal on Saturday.
-McKellar

REV Watches/Warnings/Advisories
NV...Wind Advisory from 8 AM to 5 PM PDT Saturday NVZ005.

Winter Weather Advisory from 11 AM Saturday to 8 AM PDT Sunday NVZ002.

High Wind Warning from 8 AM to 8 PM PDT Saturday NVZ001-003.

Lake Wind Advisory from 8 AM to 8 PM PDT Saturday NVZ004.

CA...Wind Advisory from 8 AM to 5 PM PDT Saturday CAZ070.

Winter Weather Advisory from 11 AM Saturday to 8 AM PDT Sunday CAZ071>073.

Sacramento %234, Sacramento River, California, Tide feet

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