textproduct: Reno

KEY MESSAGES

* Monsoonal moisture continues to fuel widespread showers and thunderstorms today, with a focus on heavy rain and localized flooding potential.

* Convective activity becomes isolated and shifts south on Wednesday as drier air moves into the region.

* Hot, dry and breezy conditions prevail late-week, with monsoonal moisture bringing renewed chances for showers and thunderstorms this weekend.

DISCUSSION

As of the time of this writing, radar and surface obs indicate light to moderate rain showers, particularly across the eastern Sierra and western Nevada. The latest sounding 00Z sounding showed a moist and unstable atmosphere with PWs of 1.04 inches, MUCAPE of 851 J/kg, 0-6km shear of 39 kts, which was favorable for convection to continue overnight.

For today, monsoonal moisture remains across the region, with PWs expected to remain around or above 1.00 inch. Diurnal heating, combined with the lingering moisture, and instability, will lead to widespread showers and thunderstorms per the HREF, particularly during the mid-afternoon and early evening. Heavy rain and localized flooding remains the primary threat, especially near Lyon, Storey, Douglas, Mineral and Mono counties. DCAPE values around 700-1000 J/kg suggest the potential for gusty outflow winds to 40-45 mph, although wouldn't be surprised if there was an isolated stronger gust. Temperatures will be slightly cooler due to cloud cover and precipitation, generally in the 70s and 80s.

By Wednesday, a drier airmass filters into the northern Sierra and western Nevada as an upper-level ridge builds to our east and a trough persists from the northwest leading to southwest flow. This will lead to a decrease in shower and thunderstorm coverage, with activity becoming isolated over Mono, Mineral, and far eastern Churchill counties. Temperatures begin a warming trend, with highs climbing into the upper 80s and 90s for lower valleys. Winds are expected to increase, particularly over NE CA, with gusts to 30 mph possible over mountain ridges.

For Thursday, the upper-level ridge continues to build over the Four Corners region, keeping the monsoonal moisture south and east. This will result in predominantly hot and dry conditions. Isolated shower and thunderstorm chances will be confined mainly to Mono and Mineral counties. High temperatures will be well above normal, reaching the mid-90s to around 100 in the lower valleys. Winds will peak on Thursday and Friday afternoon, especially over NE CA and mountain ridges as we continue to keep a 20-50% chance of gusts exceeding 35 mph.

Over the weekend and the upcoming week, model guidance indicates a return of monsoonal moisture. This pattern is expected to bring renewed chances for diurnally driven scattered showers and thunderstorms, particularly over the Sierra and western NV with a 10-25% chance. While the exact timing and coverage remain uncertain due to model divergence, the overall trend supports a convective pattern. Temperatures will remain hot through the period, with highs generally in the 90s for lower valleys, and warm for Sierra communities in the 80s.

-HC

AVIATION

Light to moderate SHRA continues with a 30-50% chance of TSRA this afternoon for all TAF sites. Gusty winds up to 40 kts are possible near TSRA. Otherwise, winds will be south to southwest 7-12 kts with gusts to 20 kts. Convective activity will diminish by sunset with cloud obscurations continuing through 12Z Wednesday.

-HC

FIRE WEATHER

Storms will be slower and wetter today limiting the fire risk only to areas near the OR border. Gusty and erratic outflow winds up to 45 mph could also accompany thunderstorms. Moreover, an increasingly unstable environment this afternoon will be more favorable for deeper vertical plume growth/more active plume behavior on any fires that become intense.

Winds will increase midweek with the approach of an upper trough to our northwest leading to brief periods of elevated to critical conditions over portions of NE CA, especially over mountain ridges due to gusts of 30-35 mph, and a 20-50% chance of exceeding 35 mph.

-HRICH/Salas/HC

REV Watches/Warnings/Advisories

NV...None. CA...None.