textproduct: Reno

KEY MESSAGES

* Dry weather prevails this week with daytime temperatures warming slowly to above average from midweek onward.

* Light winds and valley inversions will keep hazy skies and air quality reductions this week, with patchy freezing fog in some Sierra valleys.

* Sierra ridges can expect periodic breezy to gusty east winds this week, with the best chances tonight into Wednesday, and again by late Thursday.

DISCUSSION

Expect little change in our dry weather pattern for the next several days. Our resident high pressure ridge centered over northern CA/NV will stay put through midweek, then retreat to off the Pacific NW coast by late week but return inland by the weekend.

In general, the weather that has been occurring for the past few days will be stuck on repeat for the remainder of this week, with valley inversions keeping hazy conditions with some reductions in air quality especially around urban areas. The dry air mass and limited cloud cover will keep typically chilly nights for mid- January. For areas not affected by freezing fog, temperatures managed to edge upward a few degrees Monday, and another modest rise is expected today through Wednesday. Then for the remainder of the week into the start of the weekend, highs stabilize with most western NV and Sierra valleys settling in the lower-mid 50s, although a few sites above the inversion-trapped valley floors could have a peek at 60 degrees. Unfortunately for those more persistent foggy areas, most notably around Mono Lake, highs are unlikely to reach 30 degrees with the fog producing poor visibility and patchy slick conditions on paved surfaces. Some shores of Mono Lake may see a short period of clearing each afternoon, followed by fog returning after sunset. Smaller scale shallow fog could also develop near other lakes and sources of standing water each night/morning this week.

Winds remain light for lower elevations, while for Sierra ridges, a steady east flow will keep gusts in the 20-35 mph range for the next few days. A slight tightening of the 700 mb gradient could bring short periods of 40+ mph ridge gusts tonight-Wednesday and again around Thursday night.

For the late weekend into early next week, the high pressure ridge shows some potential weakening which may help reduce the strength of the valley inversions. This could bring highs near 60 degrees to more sites around the region, and possibly help disperse some of the freezing fog around Mono Lake, although there remains some questions as to whether enough mixing will occur. As for when we might see precip return to the region, longer range guidance brings signals of more storm activity after January 21st. MJD

AVIATION

Patchy FZFG will continue through this morning at KTRK with IFR/LIFR conditions at times until around 17Z, and likely return between 08-17Z for tonight/Wednesday AM. Some of this fog could be shallow and only partially obscure the airport's runways.

Otherwise, VFR conditions and light surface breezes prevail today and through much of this week at the main terminals, with minor slantwise visibility reductions due to haze around the W NV terminals.

E/NE FL100 wind gusts will ease back to below 30 kt for much of today, but then increase to 30-40 kt again over the Sierra crest tonight through Wednesday morning, leading to areas of turbulence for flights crossing the Sierra. MJD

REV Watches/Warnings/Advisories

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