textproduct: Reno

KEY MESSAGES

* A weather system brings showers, thunderstorms, and cooler temperatures this weekend. Be prepared for recreation and travel impacts due to gusty winds, rain, hail, and mountain snow.

* Cool, showery weather continues Monday and Tuesday. Snow may impact travel over mountain passes above 8000 feet Monday.

* Warm weather returns late next week.

DISCUSSION

According to the latest RAP analysis of the upper air pattern, a Pacific upper low is off the coast near the CA/OR border this afternoon giving the CWA a south-southwesterly flow aloft. The latest satellite imagery and radar returns report a good amount of cloud cover over most of the region with showers and thunderstorms occurring this afternoon. Going through the rest of today, models project the low creeping south along the coast allowing for shower chances of 25-45% within the region. As for timing, the latest run of the HREF shows the window for precipitation being open through 9-10 PM PT tonight though there could be some lingering showers overnight. The forecast also has around a 15-25% chance for thunderstorms today though the aforementioned cloud cover may inhibit some convection within the region. When looking at severe weather potential today, severe thunderstorms cannot be ruled out completely as MUCAPE values for this afternoon still look to be between 500-800 J/kg. Potential hazards with thunderstorms today look to be gusty outflow winds, small hail or ice pellets, and brief moderate to heavy rainfall. Storms will be moving quickly today, so dry lightning ahead of the storms will be possible. Remember: when thunder roars, go indoors! Low temperatures for tonight will range between the middle 40s and the lower 50s in W NV valleys while Sierra communities will be in the 30s.

For tomorrow, forecast guidance shows the Pacific low making it to around the Central CA coast before beginning an east-southeasterly track across CA. With this pattern aloft, another day of showers and thunderstorms is to be expected on Sunday though the coverage expects to be a bit more compared to today. Also, Sunday's forecast contains better precipitation chances (increasing to around 40-80%) with thunderstorm chances raising to 15-35%. The latest HRRR model run is showing MUCAPE values again around 500-800 J/kg especially in the Sierra and NE CA portions of the region, signaling that storms on this side of the crest could become severe (capable of 60 mph wind gusts, hail up to one inch in diameter). Please keep this in mind if you have plans to recreate at Lake Tahoe as strong outflow storm winds could cause hazardous conditions on the water. Daytime highs for tomorrow look to be mostly similar to those seen Saturday with some locations being a degree or two warmer.

Models then show the low moving closer to the CWA on Monday though on a track to skirt to the south of the CWA. Due to this expected pattern, shower and thunderstorm chances will continue into Monday with precipitation chances further increasing to 60-90%. The latest RRFS run is showing CAPE values that would merit thunderstorm chances being 20-30% in the afternoon. Will continue to watch this in case a signal for stronger thunderstorms comes in future model runs. Daytime high temperatures on Monday will be cooler than those over the weekend with NE CA and W NV valleys being in the upper 50s to middle 60s range and Sierra communities being in the 40s. It is also worth mentioning that the forecast still has the snow levels around 8 kft on Monday, making accumulating snow probable in the higher elevations of the Sierra. The latest NBM probabilities are showing around a 40-60% chance of seeing 4+ inches of snow in the both the White Mountains and the Sierra crest of Mineral County. With this, there is some potential that Eastern Sierra Passes may see some impactful snowfall.

On Tuesday, a fourth day of showers and thunderstorms is in the forecast. However, models have the upper low moving through S CA making the better precipitation chances (30-60%) along and south of I-80 with portions to the the north being around 15-30%. On Wednesday and going through the rest of the week, a ridge looks to move in behind the departing low signaling drier conditions and warmer temperatures. W NV valleys currently have highs forecast in the lower to middle 80s Thursday through Saturday. -078

AVIATION

VFR conditions are anticipated today and tonight within the region. However, there is around a 25-45% chance for showers this afternoon and evening with around a 15-25% chance for lightning. South to southwest winds gusting up to around 20-25 kts are forecast through 03/02-04Z. There is low confidence in fog around KTRK overnight due to increased cloud cover, but will monitor in case this changes. Following a brief precipitation pause overnight, better shower chances (~40-80%) are expected on Sunday. Thunderstorm chances increase as well to around 15-35% with the higher end chances seen in the Sierra. Lower cloud heights are seen this weekend which may cause mountaintop obscurations. -078

REV Watches/Warnings/Advisories

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