DISCUSSION

* THUNDERSTORMS: Confidence remains unchanged (medium) as HRRR showed a decrease in the 40 dBZ echo potential overnight, but maintains a convective signature for elevated and quick moving clouds/showers starting along and south of US-50 late this afternoon or early evening and lifting northward into the late evening and early morning hours Saturday. Latest satellite imagery showed cumulus development beginning over southern Mono County which may lead to a few cells through 5 PM before best focus shifts eastward into NV this evening. Gusty outflow winds to 35+ kts will be a threat with any shower or storm that develops with a 10-20% chance for seeing lightning. We maintained a 5-10% chance as far west as Hwy 395.

* WINDS: Gusty southwest winds will continue into this evening, especially along Hwy 395 and across NE CA/NW NV with most gusts 25-30 mph, but locally as high a 35 mph for a few hours. As a 70 kt 250 mb upper jet moves across the Sierra, winds will ramp up over the ridges and upper slopes with gusts 50+ mph (locally to 70 mph at the typical windiest spots). While winds will decrease at lower elevations, they may remain elevated on Lake Tahoe and across foothill locations overnight and Saturday AM behind the exiting shortwave.

* SMOKE: Satellite and Alert cams indicate smoke across parts of northeast CA and northwest NV from wildfires (primarily the Park and Stockade Canyon wildfires) this afternoon. As winds turn back to more west-southwest behind tonight's shortwave, HRRR indicates this smoke drifting farther south into western NV this weekend, possibly impacting areas as far south as Fallon and Reno by Sunday/Sunday night.

* NEXT WEEK: After seasonal temperatures through the end of July, there are indications that the ridge will build near the Four Corners and expand westward into the Great Basin per latest ensemble clusters. This pattern would likely return temperatures to 10 degrees above average with 100+ degrees across western NV as we go into August. Also, the high's position would bring a return southerly flow and increasing risk of thunderstorms.

Hohmann

AVIATION

* For late this afternoon/tonight, an upper level wave will bring a 10-20% chance of storms across W NV, focusing east and north of Reno. There is a 10-15% chance for storms at KMMH from 21Z to 00Z today with a 5% chance of storms at KRNO-KCXP-KMEV after 27/00Z. Storms may linger past midnight across NW NV as storms lift northward.

* SW-W winds with gusts 20-25 kt across most of the main terminals with gusts to 40 kt across the ridges through sundown. As a 70 kt 250 mb jet traverses the Sierra tonight/early Saturday, 700 mb winds will increase to 30-35 kts with gusts up to 60 kts at ridge level. This will lead to increasing LLWS along the eastern Sierra from the Tahoe Basin southward to Mammoth Lakes. Leeside turbulence may increase to moderate at times along the eastern Sierra into far western NV.

* Smoke and haze from local wildfires will produce areas of reduced slantwise visibilities from Susanville to Gerlach and points north, with high resolution models indicating this smoke slowly shifting south toward I-80 in W NV this weekend.

Hohmann

FIRE WEATHER

Afternoon west-southwest breezes to 25-30 mph and low daytime relative humidity will lead to elevated fire weather concerns areawide through this evening. Some areas across Lassen and northern Washoe counties may see a few hours of critical fire weather conditions, though this threat is too isolated spatially to warrant the issuance of a Red Flag Warning today.

There is a slight chance for shallow nocturnal convection tonight, roughly along and east of a line extending from eastern Mineral County into far northern Washoe County. Isolated showers look to initiate along this line following sunset before tracking northeast and out of our region overnight. Thunderstorm chances are low, but non-zero, with main concerns for gusty outflow winds given steep low-level lapse rates.

Fire weather concerns diminish this weekend as the cooling trend continues and overnight RH recoveries improve. For areas north of I- 80, dense smoke concentration from the Park Fire may further reduce daytime heating and thus limit fire activity for new or existing fires this weekend. Whitlam

REV Watches/Warnings/Advisories
NV...None.
CA...None.