textproduct: Reno

KEY MESSAGES

* Isolated showers and thunderstorms are possible this afternoon and evening in Northeastern California and Western Nevada, with a threat of gusty winds and dry lightning.

* Smoke from the Hawk Fire will continue to impact air quality and visibility, especially near the Reno/Sparks metro area today.

* Increased winds will bring elevated to locally critical fire weather conditions and potential recreational impacts by midweek.

DISCUSSION

The synoptic pattern for today features a broad upper-level ridge over the southwestern US, with a shortwave disturbance tracking through the southwesterly flow aloft over northern California and into Oregon. This setup, combined with available instability and moisture, will support isolated showers and thunderstorms this afternoon and evening across portions of Northeastern California and Western Nevada. The rest of this week will be dominated by a persistent upper ridge over the Southwest US. However, it'll begin to flatten later this week as upper-level troughing strengthens over the Pacific NW. This pattern will maintain generally warm and dry conditions across the region, with a return of slight chances for monsoon-driven convection on the western periphery of the ridge around Friday.

With the storms this afternoon, there's a threat for strong, gusty outflow winds of 45-55 mph with any developing storms. PWAT values are around 0.60-0.80 inches, indicating some moisture, but a dry sub-cloud layer remains a concern for dry lightning, especially in areas closer to the Oregon border. PoPs today range from 15-20% across the Sierra Front and western NV. The Greater Lake Tahoe Area and Mammoth Lakes are expected to remain dry. Storm motions are expected to be quicker today, further increasing the dry lightning potential. Storms are expected to return Tuesday and Wednesday afternoon as well, with 20% chances south of US-50, especially S. Churchill and Mineral counties.

Smoke from the Hawk Fire continues to be a concern today, particularly for the Reno/Sparks metro area. Lighter morning winds will allow smoke to settle, reducing visibility and degrading air quality. Southwest-west afternoon breezes should aid in dispersion, but smoke will likely settle again overnight.

Afternoon winds are expected to increase Tuesday afternoon and each afternoon through Saturday, with gusts potentially reaching 25-40 mph, especially in wind-prone areas of the Sierra Front and Northeast California. These elevated winds, combined with low relative humidity, will contribute to elevated to locally critical fire weather conditions.

Precipitation chances remain low for Thursday, but NBM guidance shows a slight increase in shower chances (10%) for portions of the Sierra and Western Nevada on Friday and Saturday. Monsoonal moisture will stream northward on the periphery of the upper ridge, fueling scattered, diurnally driven convection. While widespread significant rainfall is not anticipated, isolated cells could produce brief, heavier downpours. Conditions are expected to become mostly clear and dry again by Sunday and next Monday as the pattern shifts.

-Justin

AVIATION

VFR conditions will prevail for the area TAF sites today and tonight with winds gusting up to 20-25 kts. Smoke from the Hawk Fire may continue to reduce visibilities at KRTS and in the vicinity of KRNO through the day, but the latest forecast is not calling for sub-VFR conditions at area terminals. Will continue to monitor this situation and amend TAFs if needed. The increased winds will aid in smoke dispersion this afternoon, but depending on fire activity today, smoke could to settle in portions of W NV going through the night when winds decrease.

As for precipitation chances today, there looks to be around a 15- 20% chance for isolated showers and thunderstorms in NE CA and W NV beginning around 21Z with portions closer to the the OR border seeing the higher end chances. By tonight at 03-04Z, precipitation chances look to fizzle out. Otherwise, conditions look to be mostly dry through the middle of the week with afternoon wind gusts increasing to around 30 kts.

-078/Justin

FIRE WEATHER

Breezy W/SW winds with gusts up to around 25 mph and RH reductions of 20-25% will support elevated fire weather conditions again this afternoon across the Sierra Front and NE CA, including the Hawk Fire. Slightly better overnight RH recoveries are forecast around the 40-50% range near the Hawk Fire.

Another concern today is that there is potential for dry thunderstorms this afternoon, with areas along the OR border under a 15-20% chance for showers and thunderstorms generally between 1-9 PM today. The latest HRRR shows CAPE values up to 500 J/kg signaling an unstable environment that can support vertical plume growth with the moist mid-level seen in forecast soundings. Precip chances around the Hawk Fire remain low (<10%), however, if storms do form over or close to the fire, there is a chance of gusty outflow winds that could push over the fire and cause a sudden wind shift.

Going through the rest of the week, increased winds with gusts upwards of 35 mph (40 mph in wind prone areas) are expected Tuesday through possibly Saturday, mainly for the Sierra Front and NE CA. The SPC's Fire Weather Outlook for these days also highlights these areas with 40% chance of critical fire weather conditions due to increased winds and low RH. Currently, days with the most widespread critical fire weather conditions in these areas looks to be Wednesday through Saturday. Please continue to watch for further updates in case fire products need to be issued.

-078/Justin

REV Watches/Warnings/Advisories

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