textproduct: Reno

KEY MESSAGES

* Summer-like heat will maintain widespread moderate to areas of major HeatRisk through Thursday.

* Thunderstorm activity increases each day through Friday, peaking Friday. This will bring concerns for impacts to fire, recreation, and aviation.

* Cooler and drier weather is favored to return over the weekend.

DISCUSSION

Near triple digit heat again today for the lower valleys of W NV and NE CA, with the mid to upper 80s for our Sierra counterparts. Overnight lows in the mid to upper 60s will continue to provide limited heat relief. Thankfully, heat will subside by this weekend, with highs slinking back to the upper 80s and 70s for valleys and higher elevations, respectively.

Afternoon shower and thunderstorm chances will increase both in probability and areal coverage each day through Friday. As for today, best chances (15%) for shower and thunderstorm development will be along the Sierra of Mono and Alpine counties, extending into the Pine Nut Mountains. An emerging ridge breakdown pattern Thursday and Friday will increase chances further, with a 20-40% chance for showers Thursday across the entire Sierra through the Tahoe Basin with isolated chances for showers in Lassen county of NE CA, as well. Thunderstorm chances Thursday range from 15-20%. Model guidance hints at showers and storms lingering overnight Thursday into Friday as the upper level low tracks further towards the California coast. Model soundings across the area show inverted-V profiles; with thunderstorms that develop, there are increasing chances for new fire starts from lightning.

Friday will be the day of greatest concern, though, as shower and thunderstorm chances expand areawide; there is a 40-60% chance of showers with 15-20% chances for lightning. PWATs range from 0.6-0.8" with MUCAPE values ranging anywhere from 400-800 J/kg. Inverted-V profiles continue, so while some storms may produce brief, heavy rainfall, some may be drier in nature, which increases the risk for dry lightning. DCAPE values also range over 1000 J/kg, coinciding with outflow gusts over 50 mph. With the warm temperatures and healthy diffluence aloft, provided by the eastward track of the aforementioned low pressure, it will be quite easy for storms to develop. Make sure to check the forecast before you head outdoors and keep an eye and ear to the skies.

-Giralte

AVIATION

Near triple digit heat will pose density altitude concerns for western Nevada terminals. Typical afternoon wind gusts of 15-20 mph prevail with VFR conditions.

-Giralte

FIRE WEATHER

Hot and dry conditions continue through Thursday, with chances for showers and thunderstorms increasing each day through Friday. Overnight RH recoveries continue to be poor for much of the Basin and Range of western Nevada.

Storms that develop Thursday and Friday will be faster moving, but a mix of wet storms and dry storms (dry lightning threat). Outflow gusts up to 50+ mph are possible both days, which will help rapidly spread any fires that develop from lightning starts. As a reminder, lightning can strike up to 10 miles away from a storm. The preceding dry conditions from this week will promote receptive fuels. With the greatest concern for thunderstorms Friday, a Fire Weather Watch is in effect from 8am until 11pm.

-Giralte

REV Watches/Warnings/Advisories

NV...Fire Weather Watch from Friday morning through Friday evening NVZ458.

Heat Advisory until 5 AM PDT Friday NVZ004.

Fire Weather Watch from Friday morning through Friday evening NVZ423.

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