textproduct: Reno

KEY MESSAGES

* Light rain with a low chance of afternoon thunderstorms persists near the Oregon border today. Dry and breezy elsewhere. * Smoke may lead to periods of degraded air quality across the Reno area, Tahoe Basin, and eastern Sierra today and Friday.

* Warm and dry weather prevails Friday into the weekend. Rain and thunderstorm chances may return to the Sierra south of Tahoe early next week.

DISCUSSION

A compact upper low churning in northern California is noted on latest moisture-channel imagery, with attendant shower and thunderstorm activity near the OR-CA border. An area of focused synoptic lift should allow narrow bands of light rain to persist overnight from Modoc County south into Lassen and northern Washoe counties. Forecast soundings even suggest there may be enough instability aloft to support occasional lightning embedded in these rain bands. Farther south, weak instability ahead of an impinging shortwave may produce isolated showers near and west of the Tahoe Basin, but odds of this are only 15% or less.

The upper low finally dislodges and lifts northeast towards the northern Rockies as the day progresses. As it does, colder air aloft will overspread warming surface temperatures in Lassen County/the Surprise Valley and far N Washoe County this afternoon. Resultant weak instability will support a 10-30% chance of rain showers and isolated thunderstorms during the afternoon in this area before activity tapers in the evening. Elsewhere, areas of smoke and haze from the Floriston and Dome fires are forecast to filter into far western NV roughly along I-80, and into portions of Mono and Mineral counties this afternoon as W/SW wind gusts of 25-30 mph return. This may lead to periods of degraded air quality over the next couple of days -- including the Greater Reno/Sparks area -- but severity will depend on fire activity.

Breezy E/NE winds will develop along and west of the Sierra crest Friday into Saturday morning in the wake of a dry frontal passage. As such, those recreating in the high Sierra elevations may be greeted by brisk temperatures Saturday morning. Assuming the Floriston and Dome fires are still actively burning, this change in wind direction will alleviate smoke impacts across the Reno area but shift smoke into Tahoe communities on Friday. Meanwhile, smoke from the Dome Fire will be directed away from Mono and Mineral counties, helping to improve air quality.

Transient high pressure will provide a dry weekend with warmer, more seasonable temperatures. Weak low pressure will approach from the eastern Pacific and pass to our south between Sunday and Tuesday. The main response is a slight increase in rain and thunderstorm chances along the E Sierra south of Tahoe early next week. However, confidence on this remains low given uncertainty in how far south of a track the low assumes. Moreover, attendant moisture is unimpressive, so any shower/storm activity will tend to be more limited. The more likely outcome is a mild and dry week with cumulus build-ups in the afternoons.

-Salas

AVIATION

S/SW FL100 winds around 30 kts will maintain minor LLWS and mountain wave turbulence concerns in the Sierra through 12Z. Light morning winds will become W/SW gusts of 20-25 kts after 19Z this afternoon.

Smoke from the Floriston fire may reduce visibilities at KRNO this afternoon, but to what extent is dependent on fire activity. A wind shift may redirect smoke impacts/VIS reductions away from KRNO and toward KTRK-KTVL on Friday.

-Salas

REV Watches/Warnings/Advisories

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