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Sacramento Weather Discussion For Monday, December 30, 2024 At 12:50 pm PST Synopsis….. It's been quite a while since the last Sacramento weather discussion due to some service restrictions and time budgeting issues. But since I am going to be on a better schedule I'm hoping to have at least four to six of these out a week. Otherwise, the forecast remains on track for dry weather to continue through at least Thursday night with patchy morning fog and very cold overnight temperatures. ………Discussion………. The latest GOES 16 satellite imagery over the Sacramento area shows clear skies and a developing Northwest wind as synoptic ridging builds in from the West. And current temperatures are in the low to mid 50s as of this writing. The expectation is that temperatures will continue to warm into the upper 50s to near 60° by the 2:00 to 3:00 hour as sunny skies and a light northwest wind continue over our region. ……….Tuesday-Wednesday [SHORT-TERM]……… The weather pattern in the short-term for New Year's Eve and New Year's Day looks pretty tranquil, although Tuesday and Wednesday will have temperatures in the low 50s as cold air advection continues at the 850mb level, this combined with low 30s for Tuesday morning and a low Sun angle will make temperatures to struggle to get into the 50s for these two days so if headed out early in the morning both for Tuesday morning and Wednesday morning expect To wear a heavy coat and perhaps some mittens as again overnight lows will dip into the lower 30s with some of the coldest locations possibly getting down to as low as 28 or 29°. But because of low confidence in the forecast Frost advisories and freeze warnings are not currently anticipated at this time, although we may also have to watch for the possibility of dense Valley fog formation south of the San Joaquin Valley tonight but if any forms it will likely be patchy and rather shallow and will burn off pretty quickly tomorrow (around 8 am). Now as we go into Wednesday morning dense valley fog could be more of an issue as it becomes more widespread since low level wind fields will switch more out of the zonal wind direction and not much of a north wind component. This will also aid in higher PWAT’s values too witch typically increase the overall moisture boundary layer. This is why Wednesday could be the coldest daytime high of the week since more extensive fog this time of the year with a fairly shallow Sun angle does not allow the fog to burn off as it did in mid-December, where we had a total of six fog days in a row. So expect a partly to mostly cloudy New Year's Day with cool temperatures. ………..Thursday-Friday [MID-TERM]………. Now, while we do have foggy morning,s the overall weather pattern remains virtually the same under the influence of subtropical Ridge to our South aiming any storms just north of us into Northwestern California, although passing high clouds on Thursday could limit fog formation for Thursday morning. Now after we get past Thursday is when the pattern gets a little bit on the complicated side with another system sliding far enough South where the majority of the Sacramento Valley and San Joaquin Valley are likely to get some rain chances on Friday with the latest ecmwf Ensemble still indicating at least a 40 to 60% chance of rain amounts exceeding a tenth of an inch areas south of I-80 With a 20 to 40% chance for one scene rainfall amounts exceeding a half an inch but mainly north of I-80 and across the foothills of the Sierra and the Coastal Range. Therefore, Friday looks like a soggy day with daytime highs in the upper 50s with rain shower chances throughout the day, But like the systems we had previously this system looks to be fairly warm since it's going to be hopping over the ridge access; therefore, snow levels will likely be around 6000 to 7000 ft in the Sierra, with maybe three to six inches of snow above past level. ……….EXTENDED January 4th - January 11th………[LONG TERM] While there is some disagreement in the deterministic model runs from the GFS and the ecmwf it seems clear that East Coast troughing will help to amplify the Ridge across the West, bringing an end to any rain and windy weather over our area and Welcoming an extended period of dry and Mild weather with near to above average temperatures now where exactly does the axis of this Ridge develop will be very important in terms of the development of any Tule Central Valley fog on Days end. If the ridge builds just to our last where we get northwesterly flow this would bring dryer air across the region but if the ridge build just to our East over the Great Basin we would get more Westerly and southwesterly flow in the mid-levels and get more Westerly and southerly flow at the surface that is very light helping to stagnate the air mass further. So therefore while dry weather resumes by Saturday and Beyond synoptic weather pattern Futures like thulee fog are hard to predict but one thing's for sure we should have daytime highs warming into the low to mid 60s with overnight lows also warming up into the low to mid 40s. Stay tuned for more updates. I'm conducting daily weather discussions as we figure out the timing and strength of the upcoming wet weather pattern change. Forecaster……….David Schlotthauer