textproduct: Reno

KEY MESSAGES

* Showers and thunderstorms expected each afternoon through the holiday weekend, posing impacts to outdoor activities.

* Warmer than normal temperatures persist through Monday, but area waterways continue to run dangerously cold and swift.

* Gusty winds will pose aviation, recreation, and fire impacts Monday with cooler, showery weather Tuesday and Wednesday.

DISCUSSION

Showers and thunderstorms are expected to increase in coverage through the afternoon from Lassen County into the E Sierra as surface heating increases beneath weak instability aloft (~200 J/kg of MUCAPE sampled in the 12Z REV sounding). Weak N-NW steering flow will direct showers and storms into far W Nevada, increasing the potential for storm impacts as the afternoon progresses. Additional shower/storm development is expected along the zephyr breeze in the late afternoon. The more robust showers and storms will be capable of strong outflow winds up to 50 mph, small hail, brief heavy rain and sudden temperature drops, and occasional lightning. If you're getting an early start on outdoor recreation for the holiday weekend, make sure you have ways to receive weather alerts today!

Weak low pressure near the West Coast will introduce dry, southwesterly flow across the region this weekend, shifting moisture eastward into west-central Nevada. As such, best chances for showers and thunderstorms Saturday afternoon will reside east of US-95 and in southern Mono County. Shower and thunderstorms will also be possible (10-30%) near the Oregon border Saturday, but will be dependent on how far north moisture is displaced. Sunday may feature an uptick in thunderstorm activity as weak low pressure pivots into southern California. The other notable item to keep in mind is that temperatures this holiday weekend will be warm (daytime highs in the mid to upper 70s/80s), but lakes, rivers, and creeks are still running dangerously cold and swift so avoid cooling off in them.

A compact Pacific low and attendant cold front will move through the region early next week, increasing the likelihood of strong/gusty winds, showers and storms, and a sharp cooldown between Monday and Wednesday. Wind impacts seem to be of highest concern with this storm, making flights bumpy and lakes choppy. Critical fire weather conditions are also possible Monday afternoon in parts of NE California and NW Nevada (more details below). Sharply cooler temperatures and increased shower chances arrive Tuesday and Wednesday as the cold front sweeps through the region.

-Salas

AVIATION

The main concern today will be scattered showers and thunderstorms this afternoon with greatest chances (20-40%) in the eastern Sierra. While showers/t-storms may begin as early as 18-19Z, the 20-00Z timeframe is favored for greatest thunderstorm coverage and impacts to terminals -- especially at KTRK-KTVL-KMMH. With time, showers and storms may drift into KRNO-KCXP-KMEV. Stronger showers and storms will be capable of brief heavy rain/flight reductions to MVFR, small hail, sudden/strong wind shifts, and lightning.

Elsewhere, VFR conditions will prevail with typical west breezes in the afternoon. Shower and thunderstorm potential decreases Saturday as moisture is displaced eastward into west-central Nevada.

-Salas

FIRE WEATHER

A critical fire weather environment remains on track to unfold Monday afternoon across eastern Lassen Co, the Surprise Valley, and much of NW Nevada where gusty winds overlap low humidities. Duration of critical wind/RH is trending towards 4-8 hours in Lassen and far N Washoe County with 2-5 hours in Pershing County.

Fuels are the limiting factor in this case as there is uncertainty in the continuity of receptive fuel beds, but local intel from dispatch centers/GACC suggests the cured grasses and sagebrush will be capable of carrying fire in valleys/midslopes of far NW Nevada. Farther south, elevated fire weather conditions will be possible, but fuel conditions aren't as dry per local units.

Cooler temperatures, higher humidity, and increasing shower chances follow a cold frontal passage Tuesday and Wednesday. However, winds will shift from SW to NW behind the front Tuesday.

-Salas

REV Watches/Warnings/Advisories

NV...None. CA...None.