textproduct: Reno

KEY MESSAGES

* Cooler and breezy conditions persist through Thursday, with widespread gusts up to 30-40 mph.

* Rain chances increase for NE CA and the Tahoe Basin late tonight into Thursday, with the highest probabilities Thursday afternoon and evening.

* Uncertainty remains high regarding the trajectory of TS Marie, but an increase in tropical moisture could bring shower and thunderstorm chances to the region Sunday into early next week.

DISCUSSION

The synoptic pattern for the short term is dominated by an upper-level low digging south from the Gulf of Alaska into the Pac NW. This troughing over the West Coast will continue to usher in cooler air and increasing moisture into the region, particularly for northeast CA and far northwest NV. Persistent troughing and a slow-moving upper low over the West Coast and Pacific Northwest will be the main pattern through early next week. This pattern will maintain cooler than normal temperatures across the Northwest US, while stout ridging across the central U.S. will lead to southwesterly flow ushering in tropical moisture across parts of the Southwest and Intermountain West.

For today, breezy conditions continue with southwest winds generally 15-25 mph gusting up to 30-45 mph, especially in wind- prone areas along US-395 and across lake surfaces. Areas of blowing dust are possible in western Nevada basins, including near the Black Rock Playa and Carson Sink. High temperatures will remain below seasonal norms, generally in the low to mid 60s for Sierra communities and low to mid 70s for lower valleys.

Tonight, showers are expected to develop across western Lassen County and northern Washoe County. NBM guidance shows PoPs increasing to 30-60% over those areas overnight. Winds will remain breezy, especially over ridges, with gusts up to 40-45 mph possible in the Tahoe Basin and Lassen/E Plumas/E Sierra. Overnight lows will be cool, ranging from the low 30s in the Sierra to mid-40s and low 50s in lower valleys, with some Sierra communities flirting with near-freezing temperatures.

Thursday will be the main period for precipitation. Showers are expected to move farther east Thursday afternoon, into the Tahoe Basin and Sierra Front with PoPs peaking at 80-90% for Lassen County and NW NV, 30-60% for the Tahoe Basin, and 15% along the Sierra Front. Based on the trajectory of the system, the Sierra Front looks to be heavily shadowed, so any rain that makes it over the Sierra crest will be light. Precipitation amounts range from a trace along the Sierra Front, 0.10" around the Tahoe Basin, 0.40-0.50" around Portola and Susanville, and upwards of an inch along the Sierra crest. Isolated thunder cannot be ruled out, though instability is expected to be limited. Breezy conditions will continue with SW winds 15-25 mph and gusts 30-40 mph, especially in the afternoon. The Lake Wind Advisory continues through 11 PM PDT Thursday.

By Friday, lingering showers are possible in the northern Sierra and NE CA early Friday morning, then conditions will quickly dry out as the trough moves east. Mostly clear skies and milder temperatures are expected. Winds will diminish compared to previous days, generally 10-15 mph with gusts up to 30 mph. Highs will be similar to Thursday.

Looking ahead to Sunday, increasing moisture from the south, potentially linked to Tropical Storm Marie, will begin to impact the region. The exact track of Tropical Storm Marie remains highly uncertain, with models gravitating towards two solutions: one keeping the storm offshore, and another bringing it north towards northern California. Even if the low stays offshore, southwesterly flow may pull a decent amount of moisture inland. While confidence in significant rainfall remains low, the potential for isolated showers exists for Sunday and Labor Day. Conditions are expected to dry out and warm up further by Tuesday as the tropical moisture influence wanes and ridging strengthens.

-Justin

AVIATION

VFR conditions continue today, although increased winds are expected again today. Gusts up to 35kt this afternoon and evening, with LLWS and mountain wave turbulence likely. BLDU may be seen across western NV today too, especially for airfield operations at the Black Rock Desert.

Rain showers will start to move into far northeast CA and far northwest NV tonight into Thursday morning, keeping all terminals VFR. But by 19Z Thursday, the showers will have moved well into the Sierra crest and Tahoe Basin, potentially pushing flight rules into MVFR-IFR for TRK and TVL. RNO/CXP/MEV will be heavily shadowed Thursday, maintaining VFR, though a stray light shower cannot be ruled out.

-Justin

REV Watches/Warnings/Advisories

NV...Lake Wind Advisory until 11 PM PDT Thursday NVZ002>004.

CA...Lake Wind Advisory until 11 PM PDT Thursday CAZ071>073.