textproduct: Reno

KEY MESSAGES

* Freezing fog in the Sierra and NE California may pose impacts to this morning's commute.

* Low pressure will bring gusty winds and increased shower chances on Tuesday.

* Dry and mild weather prevails after Tuesday with signs of a more unsettled weather pattern around Veterans Day.

DISCUSSION

Current imagery from the GOES-18 satellite night fog product as well as from area cameras such as the runway camera at the Truckee Tahoe Airport shows a good amount of freezing fog in areas around both the Boca and Stampede Reservoirs this morning. Due to the yesterday's precipitation and clear skies tonight: the conditions are right for this hazard continue in this particular area, with the potential for localized areas of freezing fog in other Sierra and NE CA valleys through around 10-11 AM PDT today. Please use caution if traveling through these areas such as on I-80 as visibility could become limited and roads may be slick.

Going through the rest of today, forecast guidance shows an upper ridge moving over the region sandwiched between two low pressure troughs. This pattern aloft allows for dry conditions today with warmer daytime high temperatures (compared to Sunday's highs) in the upper 40s to upper 50s. Cloud coverage does look to increase this afternoon and evening with models showing a good amount of moisture at 500mb level moving over the region. These clouds will help the decrease the amount overnight cooling a bit, leading to the overnight low temperatures being warmer (by 5-10 degrees in the Sierra and by up to 5 degrees in W NV) than those experienced on the previous night.

On Tuesday, model guidance shows the trailing low pressure behind the departing ridge moving across N CA and then into N NV by the overnight hours. This upper pattern will cause increasing winds and rain/mountain snow shower chances within the region during the day. Forecast model cross sections are showing a downslope wind signature present on Tuesday as well with this system. Sierra ridgetop winds will begin to increase in the morning as the low approaches and gust up to around 60-80 mph generally out of the south-southwest. These increased winds may mix down in the Eastern Sierra valleys and adjacent W NV, causing surface winds to gust up to 25-35 mph (45 mph in wind-prone areas). As for precipitation on Tuesday: the 06Z run of the RRFS model shows a line of light showers moving west into the Sierra and NE CA around 11 AM-12 PM PST, into the Sierra Front around 2-3 PM, then into the NV Basin and Range around 5-6 PM, and finally out of the region by 8-9 PM. Will continue to monitor this going forward to see if the timing changes. The latest chances for precipitation look to be around 30-60% in NE CA and the Tahoe region with the remainder of the region seeing generally ~20% or less on Tuesday. Models continue to show the showers being shadowed out and keeping accumulations light. The latest QPF values for Tuesday range between a trace and 0.05 inches with the higher end amounts at the Sierra crest. The latest NBM probabilities show a 40-60% chance of 1+ inches of new snow at the Sierra crest by Tuesday evening, so there may be some minor travel impacts if you are traveling across the Sierra. Ensemble guidance then shows the upper low departing on Wednesday with a flattened upper ridge moving over region behind it. This ridge strengthens a bit going into next weekend, signaling temperatures taking a warming trend with dry conditions prevailing during the latter half of the week. Longer term guidance has mild and dry weather continuing into the following week, but also still shows signals of a possible return of wetter weather around Veterans Day. Please continue to watch the forecast as this potential system draws closer as there is still some good uncertainty this far out. -078

AVIATION

VFR conditions are expected for most area TAF sites today. The exception is at KTRK which currently sees FZFG dropping visibilities through around 02/17Z. Otherwise, relatively light winds are expected with high cloud coverage increasing through the day. This cloud cover may inhibit fog reformation near KTRK later tonight, but will continue to monitor conditions and amend TAFs as needed.

Increased winds and rain/mountain snow shower chances are expected in the region on Tuesday, with Sierra ridgetops gusting up to around 60-70 kts causing potential mountain wave turbulence. -078

REV Watches/Warnings/Advisories

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