textproduct: Reno

KEY MESSAGES

* A prolonged period of triple-digit heat across western NV and eastern CA valleys prevails through this weekend.

* Smoke and haze from regional wildfires could bring impacts to air quality at times through this week.

* Dry conditions persist in most areas this week, but low-end isolated shower and thunder chances may return Friday into this weekend for parts of the eastern Sierra and western NV.

DISCUSSION

After a short break yesterday, temperatures resume their climb to near 100 degrees for lower elevations this afternoon, then push above the century mark from Wednesday through this weekend. The latest guidance is a touch lower on the high end of the temperature range, with peak forecast highs of 104 degrees for US-95 sites in west central NV and 100-103 degrees for other valleys across western NV/eastern CA from Thursday-Saturday. Overnight temperatures will generally fall to the 60s, except around 70 degrees for typically warmer sites such as Fernley and Hawthorne. Given the long duration of this event, we will extend the current Heat Advisory through Sunday morning. However, we are not expecting extreme heat (highs typically near or above 105 degrees and/or more widespread lows above 70 degrees for our area) so the Extreme Heat Watch will drop out and be replaced with this Advisory. As mentioned frequently in the past week, be safe and smart if planning outdoor activities for the rest of this week and weekend, and consider alternatives that avoid the peak afternoon temps/sun exposure, especially if more sensitive to heat. For those heading to higher elevations above 6000 feet including the Sierra, it will still be quite warm with highs near or above 90 degrees.

Smoke and haze from Pacific NW fires will linger through tonight and then recede Wednesday as afternoon SW-W winds return with typical zephyr-type gusts near 25 mph and brief gusts to 30 mph, and continuing at similar speeds daily through Saturday. However, a new active fire in the foothills east of Stockton CA (Gann Fire) is projected to push smoke toward the Sierra later today. The latest high-res guidance is indicating a larger area of smoke/haze from this fire affecting more of the Sierra and western NV Wednesday as southwest flow increases. This keeps the risk of reduced air quality in place, although the magnitude of air quality impacts will depend on how active the Gann fire burns in upcoming days.

Overall dry conditions remain with us this week, although afternoon cumulus buildups are projected to return mainly south of US-50 Thursday. However, by Friday afternoon there are hints of increasing moisture (PW values rising to 0.6-0.8") and early runs of higher resolution guidance are hinting at isolated convection. While forcing may not very evident, abundant daytime heating and convergence from terrain features and the afternoon zephyr could lead to a few stray showers/t-storms (up to 10% chance) forming near/east of the Sierra crest and extending northward into parts of western NV east of Reno/Carson City. A further increase in moisture is showing up Saturday leading to more cloud cover especially south of US-50 and into west central NV, but isolated showers and t-storms can't be ruled out again.

For Sunday, highs could still top 100 degrees as the high pressure over the Great Basin only shows a slight retreat/weakening trend. Then from Monday onward, a low pressure trough reaching the Pacific NW coast is more likely to push the ridge farther away from western NV. This should bring temperatures down but afternoon winds could trend upward, leading to increased fire weather concerns. MJD

AVIATION

* For the rest of today, W-NW wind gusts 15-20 kt mainly between 23-03Z at the western NV terminals, around 20 kt for KMMH between 21-03Z, and lighter winds at KTRK/KTVL. For Wednesday, SW-W wind gusts increase to 20-25 kt for the main terminals starting 20-22Z and diminishing between 03-05Z, with similar wind conditions continuing through late this week.

* VFR conditions prevail through this week, although smoke and haze from fires across the western US may bring periods of reduced slantwise visibility to area terminals through at least Wednesday. Prolonged heat Wednesday through Saturday will result in increased density altitude concerns areawide. MJD

REV Watches/Warnings/Advisories

NV...Heat Advisory from 8 AM Wednesday to 8 AM PDT Sunday NVZ001- 003>005.

CA...Heat Advisory from 8 AM Wednesday to 8 AM PDT Sunday CAZ070-071.