textproduct: Reno

KEY MESSAGES

* Periods of rain and mountain snow are expected through tonight with isolated thunderstorms this afternoon.

* Showery weather continues Sunday into early next week with another round of afternoon thunderstorms possible.

* Drier and warmer weather favored late next week.

DISCUSSION

According to the latest RAP upper air analysis, an upper trough resides over the NW CONUS this afternoon with a weak Pacific low just off the coast of CA. Current radar and satellite imagery report showers having already developed in Lassen, Mineral and N. Washoe counties this afternoon. While the entire region sees some chances for precipitation today and tonight, forecast models are highlighting two general areas for better chances (60-90%) for showers today: NE CA and far NW NV as well as portions of the CWA along and south of US-50. When looking at the latest HRRR run convective parameters, there is between 100-300 J/kg of SBCAPE in NE CA and N. Washoe County, which will support a 15-30% chance for isolated thunderstorms this afternoon. Areas along and south of US-50 will also see up to around a 15% chance for an isolated thunderstorm or two this afternoon. Thunderstorms do look to stay sub-severe, but will be capable of producing erratic, gusty outflow wind gusts up to around 40 mph as well as brief periods of moderate to heavy rainfall. Please keep this in mind if you have outdoor plans today.

As for Sierra snow potential today and tonight, snow levels look to be around 8000 ft this afternoon, but will decrease to around 5500-6000 by Sunday morning following a cold front passage this evening. When looking at the latest NBM snowfall probabilities, the Sierra crest sees around a 40-60% chance of 6 inches or more of snow by Sunday morning. Snow-prone portions of US-395 in Mono County have a 20-50% chance for 2 inches or more while I-80 at Donner Pass has a 10-20% chance of exceeding 1 inch of snow. While the latest Winter Storm Severity Index (WSSI) shows only pockets of minor impacts through tomorrow morning, please use caution if traveling through the Sierra tonight and tomorrow as roads may be slick. The NBM still shows the White Mountains with the highest potential snowfall amounts as there is a 20-40% chance that they see 10+ inches of snow.

For tomorrow, more rain and mountain snow showers are expected within the region as the upper trough reorients itself over the CWA. The forecast also calls for a 10-30% chance for isolated thunderstorms in the afternoon with the higher end chances seen in the eastern portions of Pershing and Churchill Counties. Thunderstorms are anticipated to not be severe again tomorrow, but will be monitoring conditions in case this changes. Daytime high temperatures cool behind the cold front with highs in W NV and NE CA valleys being between the middle 50s and the lower 60s while the Sierra communities will see high temperatures in the 40s.

Precipitation chances (~15-45%) will linger going into Monday, but begin to taper off on Monday night. Beyond Monday, the forecast for the rest of the work week shows dry conditions. Temperatures also look to go on a warming trend next week to where portions of W NV including the Reno-Sparks area currently see around a 30-60% NBM probability of reaching or exceeding 80 degrees by next Saturday. -078

AVIATION

Rain and mountain snow showers continues to be the main weather concern for the region today and going through the night. The area forecast also has around a 10-30% chance for isolated thunderstorms within the region. There is currently low confidence on whether storms will impact TAF sites (KTVL-KMMH-KMEV having a 10-20% chance between 25/22Z-26/03Z), but will continue to monitor conditions and amend TAFs as needed. However, showers today may bring temporary MVFR conditions to area terminal through 26/03Z. KTRK may see the risk of morning fog causing sub-VFR visibilities between 26/12-18Z, but low confidence at this time as winds could inhibit fog formation. More rain and mountain snow chances are expected on Sunday. -078

REV Watches/Warnings/Advisories

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