Fog Tonight into Sunday Morning, Warm, Dry Weather Thereafter

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If you picked up any rain from this weak storm so far today, Saturday, you’re pretty lucky, because a lot of locations in the coastal mountains, west side of the valley and along the central coast didn’t pick up anything due to the lack of lift. Lift was strong enough to bring a few bands of rain along the east side of the valley up into the foothills and west slope of the sierra, with snow above around 6000ft, but amounts haven’t been too much.

Cumulus/terrain enhances convection over the northern foothills and mountains around 2pm.

Cumulus/terrain enhances convection over the northern foothills and mountains around 2pm.

Up in the northwest corner of the state, post-frontal convective precipitation has kept them pretty wet through the morning and afternoon… and some clearing north of Yuba City has allowed some convection to develop in Tehama, Butte, Plumas, Lassen, and eastern Shasta counties with some CGs (cloud-to-ground lightning) embedded in the stronger storms. Showers and possibly some thunderstorms are expected to continue up in the north valley and adjacent mountains/foothills into the early evening, as post-frontal convection rolls over the northern coastal mountains.

Radar and visible satellite from the early afternoon.

Radar and visible satellite from the early afternoon.

Once clouds and precipitation clears out this evening and clouds start to slowly break up and/or push east, temperatures will drop off and likely meet surface dew points rather quick after around 8 – 10pm in areas with saturated low-levels due to the rain. Most short range/high resolution models are in decent agreement for fog development due to these conditions, which seems very plausible given the situation and relatively light winds.

January 11th Fog

Models indicate potentially widespread dense fog developing in the early morning hours of Saturday, with .1 mile visibility being modeled across a large part of the Sacramento valley. Wouldn’t doubt seeing some pockets of near zero visibility possible between around 2am and 9am Sunday.

It appears fog will likely develop from the north end of the valley to as far south as Merced… possibly even further south, and really they haven’t seen much precipitation that far south.

Since we haven’t seen much widespread fog this season, it may surprise quite a few people, and we all know fog can become dangerous overnight and morning drivers. So, please do take note of this if you have to drive overnight or Saturday morning, and take it slow if you do run into any fog.

Fog may not be able to develop Sunday night/Monday morning due to increased north winds, wiping out ground moisture.

12z NAM indicating some 30 - 35kt 850mb winds overhead Sunday afternoon, with some 20 - 30mph gusts probably making themselves to the surface.

12z NAM indicating some 30 – 35kt 850mb winds overhead Sunday afternoon, with some 20 – 30mph gusts probably making themselves to the surface.

Our large, strong ridge returns in force Sunday through most of the week next week with temperatures in the valley jumping into the mid to upper 60 on a widespread scale, however due to a thermal belt/inversion developing, low to mid 70s are possible in parts of the valley and foothills as well, which is exceptional for mid-January. We’ll have to see if any warmer locations try to work their way up to the mid 70s… but 80s don’t appear too likely at the moment.

Forecast surface temperatures via the 12z GFS on Tuesday afternoon.

Forecast surface temperatures via the 12z GFS on Tuesday afternoon.

There are not many indications of a pattern change in the extended, as opposed to earlier solutions of the GFS, which were indicating a rather significant pattern change between the 17th an 20th… but has since been trending towards a more ridge-dominated pattern with occasional weak systems. I’ll continue to monitor any potential for any break in the pattern and post an update when one presents itself, as always.

12z GFS's 500mb height anomalies valid for around the 26th/27th indicating our ridge extending very far north... perhaps at one point too far north to continue it's onslaught of blocking of the westerlies?

12z GFS’s 500mb height anomalies valid for around the 26th/27th indicating our ridge extending very far north… perhaps at one point too far north to continue it’s onslaught of blocking of the westerlies?

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