textproduct: Reno

KEY MESSAGES

* Warm with breezy afternoons through Thursday.

* Gusty winds with a strong cold front on Friday & Saturday. Elevated fire weather concerns for W.Nevada.

* Temperatures cooling 10-20 degrees below average over the weekend with light showers possible.

DISCUSSION

Temperatures dip 2-3 degrees today but will remain seasonably warm through Thursday with highs in the low-to-mid 90s across western Nevada with upper 70s to low 80s for Sierra valleys. Afternoon cumulus will once again develop across elevated terrain, some may be deep enough to pop a few light showers (15% chance) across N.Lassen/N.Washoe counties this afternoon. Otherwise very dry conditions with late afternoon zephyr winds will prevail with gusts of 20-25 mph this afternoon, increasing to 20-30 mph by Thursday afternoon.

A major pattern change is expected this weekend as an unusually strong cold front (by June standards) sweeps through much of the Great Basin. This front will take us from being about 10 degrees above average to around 20 degrees below average by Sunday which means we can expect strong winds in between. In general, we are looking at widespread 20-50% chances to see wind gusts over 40 mph across the E.Sierra and W.Nevada on Friday and Saturday with Saturday showing stronger sustained wind potential around 20-30 mph as surface gradients tighten with the arrival of the front.

Fire weather concerns will be at the forefront for western Nevada as these areas will see the best combination of strong winds, low humidity, and dry fuels. Fire Weather Watches remain in effect for Friday and Saturday. See the Fire Discussion below for additional details. In addition to fire weather concerns, winds could disrupt outdoor recreation, create hazardous boating conditions, and impact road and aviation travel. High profile vehicles could be impacted by strong crosswinds, and blowing dust may reduce visibility in areas downwind of desert sinks.

Precipitation will mainly concentrate along the cold front Saturday into early Sunday morning. Showers chances will largely remain northward of I-80 with a 10-20% chance of seeing up to 0.10" of rainfall with 30-50% odds for areas across N.Lassen County into the Surprise Valley/far N.Washoe County. Snow levels will fall to around 7000-8000' from the Tahoe Basin to the Oregon border which means light snow showers are not out of the question for higher elevations of the N.Sierra and Warner mountains.

The airmass behind the front has temperatures of around -4C at 700mb which is near observed minimums for the date. This means our temperatures will fall to around 15-20 degrees below late June averages Saturday and Sunday. While not cold so to speak, highs in the lower 70s for this time of year have a 75% chance of setting record cold high temperatures on Sunday. Sierra valleys by Sunday morning could see 60-70% odds of overnight lows falling below freezing. Even Carson Valley communities could see a 20-25% chance hitting the freezing. Fuentes

AVIATION

* VFR conditions with typical west/northwest breezes each afternoon with gusts around 20-25 knots, increasing to 25-30 knots by Thursday afternoon.

* A strong cold front Friday and Saturday will produce strong and gusty winds across the E.Sierra and W.Nevada terminals. Gusts of 30-40kts will be possible along with increased likelihood of mountain wave turbulence, LLWS, and areas of reduced visibility due to blowing dust mainly around KLOL, KNFL, and KHTH. Fuentes

FIRE WEATHER

* Unusually strong cold front for late June projected to bring areas of critical fire weather conditions Friday and Saturday. Fire Weather Watches remain in effect for the Sierra Front eastward into the Hwy 95 corridor.

* High confidence in seeing sustained winds 20-30 mph with gusts above 40 mph both days, W/SW direction on Friday and W/NW on Saturday. Saturday's winds may end up being more of a sustained wind concern versus just the gusts. Almost an April-like pattern in late June.

* For areas in the watch along and north of a Carson City to Lovelock line, including Reno, the humidity may be just above RFW criteria, around 15-25% for afternoon minimums. But with plenty of dry fuels/grasses and recent significant lightning event last Friday with holdover potential, winds of this magnitude may lessen the impact of slightly higher RH.

* E.Sierra fire weather zones are also expected to see these same strong winds with ridgetops seeing wind gust potential exceeding 80 mph. However, fuels have not been reported to be critical and minimum RH is expected to be around 30-40%. However, the exception could be along Hwy 6 and 395 below 7000' in Mono County where RH could dip into the teens.

* Humidity recoveries Friday night into Saturday morning look good (45-75%), but winds will remain breezy for mid-slopes and ridges.

-Chris/Fuentes

REV Watches/Warnings/Advisories

NV...Fire Weather Watch from Friday morning through Saturday evening NVZ420.

Fire Weather Watch from Friday morning through Saturday evening NVZ423-429.

CA...