textproduct: Reno

KEY MESSAGES

* Warm and dry conditions continue through Friday, with highs 10 to 15 degrees above normal and areas of Moderate HeatRisk across lower valleys.

* Southwest to west breezes increase Friday with brief elevated fire concerns. Stronger winds and higher fire risk is expected Saturday.

* Some cooling returns this weekend, with temperatures near or slightly below early June averages Sunday through much of next week. Gusty winds and shower chances may also return next week.

DISCUSSION

The synoptic pattern across the western US remains dominated by low-amplitude ridging through Friday, maintaining a warm and dry air mass. A change in the pattern begins on Friday as the next Pacific storm system approaches the region. This will tighten the pressure gradient leading to increasing southwest to west winds, especially on Saturday. A significant shift to cooler, wetter and unsettled weather occurs next week due to the aforementioned trough descending into the Great Basin. Rain and isolated thunderstorm chances return to the forecast.

* Temperatures: Friday remains with well above seasonal averages around 10-15 degrees above normal. Western NV valleys can expect afternoon highs in the upper 80s to mid 90s, while Sierra communities reach the upper 70s to low 80s. This prolonged warm period combined with very dry air, will lead to widespread Moderate HeatRisk across lower valleys. Overnight lows remain in the 50s-60s for valleys, and 40s for Sierra communities. A cooling trend begins this weekend through much of next week. By Sunday, high temperatures drop to below seasonal averages. This cooler trend continues through Tuesday with the NBM showing highs in the mid 70s for Reno, and low 60s for South Lake Tahoe.

* Winds: Winds will be relatively light today as the region sits between systems. Afternoon W-NW breezes are expected, with gusts generally below 20 mph. Afternoon gusts of 25-35 mph are expected across much of the region on Friday, with some areas seeing gusts up to 30-35 mph, particularly in wind-prone corridors and along the eastern Sierra slopes by Friday evening. The strongest winds are anticipated on Saturday. Southwest to west wind gusts of 35-40 mph are likely across much of western NV and eastern CA, with localized higher gusts up to 50 mph possible over exposed ridges, particularly in the Greater Lake Tahoe and Mono County areas. These strong winds, combined with very low relative humidity (minimum RH generally 8-15% in lower valleys), will lead to elevated to locally critical fire weather conditions across much NV. Periods of gusty winds will continue into early next week. NBM guidance suggests sustained winds and gusts will remain elevated, with gusts potentially reaching 30+ mph on Monday and Tuesday, particularly across exposed terrain and valleys.

* Precipitation: Dry conditions will prevail through Sunday. Increased shower chances are forecast from Monday afternoon through Wednesday, especially for areas near and north of I-80 and the Tahoe region. The latest ensemble guidance, including the NBM, leans slightly wetter for these northern areas, with 10-35% for showers on Monday and Tuesday in the Tahoe/Truckee area, and a 5-15% chance for storms. Elsewhere across western Nevada and Mono County, chances for measurable rain remain lower, typically in the 5-10% range. While confidence in widespread significant precipitation remains low, isolated light showers cannot be ruled out.

-HC

AVIATION

VFR conditions prevail with only KTRK having 10% chance for patchy FG. Winds will be generally from the west between 20-03Z with gusts up to 15 kts today and 25 kts tomorrow. However, Sierra Front terminals have a 40-50% chance of brief periods exceeding 30 kts.

Saturday keeps the higher impacts with SW-W gusts of 25-35 kt at the main terminals. FL100 fo 30-40 kts will likely result in areas of turbulence, crosswinds, and LLWS over and east of the Sierra.

-HC

FIRE WEATHER

Warm and very dry conditions through Friday will maintain very large afternoon vapor pressure deficits (40-50 hPa), especially across western NV lower valleys, where RH falls into the single digits and low teens. This will continue to dry fine fuels, with localized elevated fire weather concerns today. Elevated to brief periods of near critical are expected on Friday, where SW-W gusts of 25-35 mph overlap receptive grasses and brush over western NV and portions of eastern Lassen/Plumas counties.

Saturday remains the primary concern as the strongest winds arrive after several days of drying. Southwest-west gusts over 35 mph are likely across much of western NV and portions of eastern CA, with minimum RH generally 8-18% in lower valleys. Longer critical wind/RH overlap supports elevated to critical fire weather conditions, where fuels are sufficiently cured. For the aforementioned reasons a fire weather watch is in effect for Saturday from 11AM to 11PM.

HC

REV Watches/Warnings/Advisories

NV...Fire Weather Watch from Saturday morning through Saturday evening NVZ420-423-429-458.

CA...Fire Weather Watch from Saturday morning through Saturday evening CAZ278.