textproduct: Reno

KEY MESSAGES

* Seasonably warm and dry today with typical afternoon zephyr breezes prevailing.

* A dry cold front will provide gusty winds and low humidity on Tuesday with elevated to critical fire weather concerns for northeast CA and parts of western NV.

* Cooler and breezy conditions are expected through the remainder of this week, with rain shower chances mainly in northeast CA and northwest NV Thursday and Friday.

DISCUSSION

The week begins with typical late-August weather, including near- average temperatures, dry conditions, and typical afternoon breezes. Conditions then shift by Tuesday as an approaching trough and dry cold front bring stronger southwesterly winds and critical fire weather concerns. See the Fire Discussion below. Gusty winds will develop along N. Sierra ridgetops Monday night with gusts near 50 mph overnight increasing to near 70 mph by Tuesday evening.

The strongest lower valley winds are expected Tuesday afternoon and evening, mainly northward of US-50, where gusts could reach 30-40 mph. These winds may produce mountain wave turbulence and wind shear for aviation, hazardous boating conditions on area lakes, crosswind hazards for high-profile vehicles, and locally reduced visibility from blowing dust on the desert playas.

Behind the front, the weeks coolest temperatures arrive Wednesday, with highs falling 10-15 degrees from Monday. Expect mid-70s for W.Nevada valleys and low to mid-60s in Sierra valleys. Low temperatures for colder Sierra valleys may dip below freezing each morning from Wednesday through the start of the weekend.

Although Tuesday will be the windiest day, breezy conditions will persist through much of the week as moisture gradually increases and helps ease fire weather concerns. Light showers become possible Thursday across northeast California, with generally 20-50% chances across W.Lassen and far N.Washoe counties. Shower chances of 10-20% could extend into the Tahoe Basin by Friday with decreased potential overall on Saturday.

The better potential for precipitation currently favors Sunday into early next week, as ensemble guidance shows a possibility that moisture from a tropical system could be drawn north into the Sierra and western Nevada. Confidence remains very low at this time, however, and will depend on how the tropical system develops and interacts with an offshore low. Fuentes

AVIATION

* VFR conditions today with typical afternoon wind gusts of around 20 kts expected for Sierra and W.Nevada terminals.

* A dry cold front on Tuesday will begin to increase areas of mountain wave turbulence with N.Sierra ridgetops winds (FL100) gusting near 40-45 kts after 06z this evening.

* For Tuesday, ridgetop gusts increase near 70 kts late afternoon, with Sierra and W.Nevada terminal gusts around 30-35 kts. Expect increased mountain wave turbulence and periods of LLWS.

* Areas of reduced visibility from blowing dust may impact KLOL, KNFL, KHTH and aviation operations on the Black Rock desert on Tuesday afternoon/evening. Fuentes

FIRE WEATHER

* Elevated to critical fire weather conditions return early this week with Tuesday being the main concern with a dry cold frontal passage expected to provide gusty winds and dry conditions.

* Monday brings very low humidity, near 10% in parts of northeast California and northwest Nevada, with southwest to west wind gusts around 25 mph and isolated gusts near 30 mph.

* Tuesday poses the greatest concern. Fire Weather Watches cover parts of NE California, NW Nevada, and the N.Sierra Front, including Reno and Carson City. Southwest gusts may reach 30 to 40 mph from midday into the evening.

* Winds remain gusty Wednesday, around 25 to 35 mph, though humidity improves. Brief near-critical conditions are possible near and east of US-95. Breezy to windy weather continues through Friday, but cooler temperatures, higher humidity, and possible showers mainly north of Susanville to Gerlach should reduce fire weather concerns. Fuentes

REV Watches/Warnings/Advisories

NV...Fire Weather Watch from Tuesday morning through Tuesday evening NVZ420-458.

CA...Fire Weather Watch from Tuesday morning through Tuesday evening CAZ270-278.