textproduct: Reno

KEY MESSAGES

* Rain and high elevation snow chances expected today into Monday with low chances for isolated thunderstorms.

* Following a precipitation pause on Tuesday, a mid-week system will bring back light rain and snow chances along with increased winds.

* Dry conditions and near-average temperatures are forecast toward the end of the week.

DISCUSSION

Current radar returns show some lingering isolated showers generally north of I-80 this morning with the remainder of the region staying dry. However, forecast guidance is showing low pressure (presently over the Pacific) tracking eastward over N CA by this evening and then opening up into an upper trough over the CWA by late morning Monday. With this pattern aloft, the region will see more shower chances today and tomorrow. Areas along and north of I-80 will have a 25-55% chance for precipitation today with the higher end amounts closer to the OR border. The Tahoe Basin and Quad Counties region down into Northern Mono County look to have similar chances with the higher end being at the Sierra crest. The precipitation chances for the remaining portions of the region expect to be around 15% or less today. Not ruling out an isolated thunderstorm or two today, but chances are low being around 10% or less. Shower chances lessen slightly going into the night, but will increase again on Monday morning especially in the NV Basin and Range which sees a 25-55% chance. By Monday evening, all precipitation chances will have exited the region.

QPF totals for the next two days look to range from a trace to just under a half of an inch (with the highest amounts along to the OR border). Area temperatures also trend downward to start this week after the last week's warmup. As such, snow levels will be around 8-8.5 kft this afternoon, and steadily drop to around 5.5-6.5 kft by Monday morning allowing for rain to transition to snow in some areas. However, this system does not yield much accumulating snow as the highest amounts are seen in the Sierra crest south of the Tahoe Basin (around an inch or 2 by Monday evening with a 10-30% of greater than 2 inches). It's also worth mentioning that gusty Sierra ridge winds are forecast this afternoon with gusts up to around 60+ mph possible.

An upper ridge then moves over the region on Tuesday allowing for dry conditions and a slight rebound in temperatures. However, this does not last long as a trough pushes into the region on Wednesday and departs to east on Thursday allowing for the cooling trend to resume. While light rain/snow chances return mostly on Wednesday, the main concern at this looks to be the increased winds associated with this system passing through. Forecast guidance has been showing a possible downslope wind signature in the last few runs particularly in the NV Basin and Range. The latest NBM probabilities show around a 40-60% of gusts of 45+ mph possible in these areas. Will continue to monitor this in case a wind product is needed in the middle of this week.

Going into the weekend, extended guidance is showing a low cutting off from the eastern trough on Friday and Saturday that moves into S CA and AZ. There is low confidence in forecast details this far out. But for now, dry conditions are in the forecast late this week with valley temperatures looking to climb back into the 60s over the weekend. -078

AVIATION

VFR conditions are forecast today for all area terminals. KTRK though may see some patchy fog before 01/16Z once again that could potentially cause sub-VFR visibilities (will amend TAF if confidence grows). Chances for light rain showers are expected today within the region, but currently not anticipating these showers to lower flight restrictions (generally 15-30% chance for an isolated shower this afternoon at the area TAF sites). FL100 winds look to increase to around 40-60 kts out of the SW in the Sierra allowing for LLWS after 01/18Z that could last at least until 01/06Z. -078

AVALANCHE

Light rain/snow showers will impact all avalanche center terrain mainly Sunday through Monday.

* Snow levels and amounts: Snow levels start out this morning around 8.5-9 kft, dropping steadily to 7-8 kft by late Sunday night. Levels will then plummet further to near or just below 6 kft by sunrise Monday before increasing to 6750-7500 ft (locally higher part of that range for southern Mono county) by mid afternoon. That secondary peak in snow levels coincides with when the showers are expected to exit the region. Snow amounts still look to be light and predominantly along the highest peaks, with a trace to 0.5 inches in the Tahoe Basin and 1-2.5 inches for central Mono county (up to an inch for ESAC terrain).

* SLR and SWE: SLRs will start out 5-6:1 Sunday, increasing to 8- 11:1 by Monday morning. SWE will be highest in the Tahoe Basin with 0.1-0.4 inches through Monday morning, with locally lower as you progress southward (up to around 0.3 inches for BAC terrain and up to around 0.2 inches for ESAC terrain).

* Wind gusts: Southwest ridgetop winds increase a bit more today, with gusts up to around 60-70 mph possible by this afternoon.

* Lightning: Thunderstorm chances still are generally <10%, peaking at 13% along the crest in the Tahoe Basin late this afternoon and evening. -078

HYDROLOGY

All rivers and streams in the area have crested last week, but flows remain elevated and may respond quickly to additional snowmelt with mild temperatures and isolated shower chances to start the week, especially smaller creeks and steams.

Use extra caution near rivers and creeks. Prolonged high flows may lead to unstable banks and erosion.

No new flooding is forecast, check for river forecasts and observations at www.cnrfc.noaa.gov

-TB/078

REV Watches/Warnings/Advisories

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