textproduct: Reno

KEY MESSAGES

* Cool, showery and breezy conditions prevail today with isolated afternoon thunder and minor snow impacts for Sierra passes.

* Shower and thunder chances slowly decrease Monday and Tuesday, with a gradual warming trend.

* Expect drier and warmer weather for mid-late week, then shower chances may return by late next weekend.

DISCUSSION

An upper trough continues to reside over the W CONUS today in a positively tilted fashion. Model guidance shows this feature in the same position through the day with a PacNW shortwave moving down through the flow along the west coast. Current radar returns report ongoing showers in Lassen, Washoe, Pershing, and Churchill Counties with the remainder of the region being mostly dry at the time of this analysis. Going through the day, precipitation chances (~50- 80%) spread through the remainder of the CWA by the late afternoon with the Quad County area seeing lesser chances (25-35%). While most of the CWA sees around a 10% chance for an isolated thunderstorm within today's showers, chances increase to around 20-30% for areas along and north of a line from Susanville-Pyramid Lake- Fallon this afternoon where the HREF shows around 100-200 J/kg of SBCAPE. Thunderstorms that occur today look to be sub-severe though small hail and ice pellets can be possible with the cooler temperatures today along with gusty outflow winds. In the Sierra, snow levels look to be between 6-7 kft this afternoon allowing precipitation type to be snow in higher elevation. The Sierra crest has around a 50-70% of seeing at least one inch of additional snowfall by tomorrow morning with little to no accumulation expected elsewhere. Breezy west-northwest winds gusting up to around 30 mph in some locations continue into the evening before decreasing overnight. Cooler low temperatures are expected tonight with the NE CA and W NV valleys being in the mid 30s to low 40s range while Sierra communities have middle to upper 20s in the forecast.

For Monday, models have the aforementioned shortwave reinvigorating the trough a bit while having the trough progress eastward. With this pattern aloft, the region looks to see another day of showers though chances decrease to ~20-60%. The Sierra as well as Central NV portions of the CWA expect to see the higher end precipitation chances in the afternoon. Thunderstorm chances will be lower tomorrow compared to today though most of the region sees around a 10% chance. An exception to this will be in eastern Pershing and Churchill Counties which may see up to a ~20% chance for isolated thunderstorms. Snow levels look to be around 6.5-7 kft during the afternoon, so snow showers still remain on the table for the Sierra. However, not anticipating impacts with new snow at pass level. The latest run of the NBM shows there is a 10-20% chance that the Sierra crest sees one inch of snow or more as well. Area temperatures are forecast to only be a few degrees warmer compared to those experienced on the previous day.

For Tuesday, afternoon shower chances expect to decline quite bit to around 15-25% and be mostly in the Sierra portions of the region. Temperatures will warm up a bit with the forecast showing W NV valley highs in the middle to upper 60s and Sierra communities in the 50s. As for the rest of the week, an upper ridge moves over the CWA allowing for the warming trend to continue and dry conditions to prevail. By Friday, the W NV valleys have a 30-50% chance of hitting 80 degrees. Over the weekend, extended guidance is still showing a PacNW upper trough breaking into a closed low that moves into the region. While forecast details are still pretty uncertain this far out, this pattern may bring back precipitation and storm chances as well as halt the warming trend. -078

AVIATION

Rain and mountain snow shower chances expect to continue today within the region with a majority of the region's TAF sites staying with VFR conditions. KTRK and KTVL look to be the exception as MVFR ceilings are possible through 27/03-04Z. Area winds today generally gust up to around 20-25 kts through at least 27/05Z before becoming light overnight. There is an area wide 10-30% chance for isolated thunderstorms this afternoon within the region with higher end chances in NE CA and far NW NV as well as Pershing and Churchill Counties. Shower chances look to return again on Monday. -078

REV Watches/Warnings/Advisories

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