textproduct: Reno

KEY MESSAGES

* Well above average temperatures will persist through Friday. * A potent cold front is expected to produce gusty winds with enhanced fire weather concerns Friday and Saturday.

* Significant cooling is expected behind the front with below average temperatures returning, along with 50-70% chances for rain and mountain snow showers by Sunday into early next week.

DISCUSSION

Unseasonable warmth continues through Friday before a potent cold front brings a significant pattern change this weekend. Highs remain 10-15 degrees above average, reaching the upper 80s in W.Nevada and upper 70s to near 80 in Sierra valleys. Lows in W.Nevada valleys will dip only into the low 50s, potentially setting warm minimum records. Reno set a record high of 88 yesterday, but todays and Fridays low-90s records likely remain out of reach. Renos first week of October was its warmest on record, but much cooler conditions arrive by Sunday.

Southwest winds increase Friday, with afternoon gusts of 25-35 mph along the Sierra Front, NW Nevada, and NE California. Saturdays strong cold front brings widespread gusts of 35-45 mph, with a 20-30% chance of exceeding 50 mph. Ridgetop gusts may reach 70-80 mph Saturday morning through Sunday morning.

Increasing winds and prolonged dryness will bring critical fire weather Friday afternoon to NE California and NW Nevada, where Fire Weather Watches have been upgraded to Red Flag Warnings. Additional watches cover much of W.Nevada south into Mono County Saturday. Despite rising humidity with the front, strong winds could drive rapid fire growth where fuels remain critically dry. See the Fire Weather Discussion for details. Gusty winds may also create hazardous boating conditions and create impacts for travel in wind-prone areas of Nevada, E.Lassen County, and Mono County.

Highs drop 20-25 degrees from Friday to Sunday, reaching only the low 60s in W.Nevada and low 50s in E.Sierra communities, about 10-15 degrees below average. Lows Sunday through Tuesday nights fall well below freezing in Sierra valleys. W.Nevada valleys have a 20-30% chance of reaching freezing, with a 50-60% chance of subfreezing temperatures in more rural areas.

The main forecast challenge remains precipitation Sunday into early Tuesday as Tropical Storm Rachels moisture moves north into S.California and S.Nevada. Precipitation is favored Sunday into Monday (50-70% chance), but amounts remain uncertain, with some ensemble members showing heavier totals. Blended guidance favors the Sierra from Tahoe into Mono County and W.Nevada south of I-80, with a 20-50% chance of at least 0.50 inches of liquid. Snow levels remain variable, currently around 7,500-8,500 feet Sunday into Monday. Higher elevations from Tahoe south into Mono County have a 20-50% chance of at least 4 inches of snow. Fuentes

AVIATION

* VFR conditions will predominate. Light, terrain-driven winds continue today, with afternoon gusts below 20 kts.

* The first potent fall cold front will begin to increase winds Friday afternoon, with the strongest winds expected with the frontal passage on Saturday. This will result in an increased mountain wave turbulence potential along and east of the Sierra crest, with periods of LLWS possible. Surface wind impacts peak with Saturday's cold frontal passage.

* Shower chances become more widespread across the Sierra and W.Nevada Sunday into Sunday night, with the highest precipitation probabilities Sunday evening. Mountain obscuration and periods of MVFR conditions are possible, particularly at Sierra terminals. Fuentes/Johnston

FIRE WEATHER

The seasons first potent cold front will bring increasing southwest winds Friday afternoon, peaking Saturday as it moves through NE California and W.Nevada. Winds combined with low humidity may produce periods of critical fire weather conditions both days.

FRIDAY: Friday afternoon gusts will reach 25-35 mph as minimum RH falls to 10-17%. The strongest winds will favor areas near the Oregon border, though elevated fire weather concerns may extend along the Sierra Front. Fire Weather Watches have been be upgraded to Red Flag Warnings for Friday afternoon and evening for portions of NE CA and NW NV, including fire weather zones 270, 278, and 458.

SATURDAY: Winds peak Saturday afternoon and evening, with widespread gusts of 35-45 mph mainly south of I-80. Humidity will increase across NE California and far NW Nevada, while areas south of I-80 may see continued elevated concerns with a more marginal minimum RH of 15-20% on Saturday afternoon. Due to recent record warmth combined with prolonged dry conditions, additional Fire Weather Watches have been issued for portions of W.Nevada including the Sierra Front and the E.Sierra from E.Alpine County into Mono County.

SUNDAY ONWARD: Behind the front, highs will drop 20-25 degrees from Friday to Sunday, reaching the low 60s across W.Nevada and low 50s in E.Sierra communities. Wetting rain potential increases Sunday- Monday, mainly south of I-80, as remnant moisture from Tropical Storm Rachel moves northward. The moistures track and precipitation totals still show higher uncertainty, but the overall trend has been wetter. Areas south of I-80 have a 20-50% chance of receiving at least 0.50 inches of rainfall through early next week, with the highest chances farther south. Fuentes/McKellar

REV Watches/Warnings/Advisories

NV...Red Flag Warning from 1 PM to 9 PM PDT Friday NVZ458.

Fire Weather Watch from Saturday morning through Saturday evening NVZ420-421-423-429.

Lake Wind Advisory from 5 AM to 11 PM PDT Saturday NVZ002>004.

Lake Wind Advisory from 11 AM to 11 PM PDT Saturday NVZ001.

CA...Red Flag Warning from 1 PM to 9 PM PDT Friday CAZ270-278.

Fire Weather Watch from Saturday morning through Saturday evening CAZ274.

Lake Wind Advisory from 5 AM to 11 PM PDT Saturday CAZ072.

Lake Wind Advisory from 11 AM to 11 PM PDT Saturday CAZ073.