Monday AM update:
An end to the dry weather and inversions now looks all but definite. Warm advection moisture will bring a slight chance of snow to the area tonight and tomorrow but the real storm that will drop good amounts of fresh snow and clear out the inversions is coming in on Thursday. Another system could follow this one on Sunday, although there is still uncertainty with regard to the second system. Conservative first estimates for snowfall totals for the high Wasatch on Thursday and Friday is 6-16″. Might have to go higher as we approach the storm. It is a cold storm so valleys will see snow as well and ratios will be high so it will pile up quickly. Full update tonight . . .
1 PM: 12z ECMWF (Euro) came in closer to the GFS for the late-week system. Good news! Hopefully that trend will continue.
Not too much new to talk about… Our next chance for snowfall will start on Tuesday as warm advection moisture begins to stream into far northern Utah. This should generate enough lift for at least light snow showers in the mountains north of I-80 and perhaps the Cottonwoods. Not expecting much in the way of accumulation. Next system should move into the area on Thursday or Friday. Euro continues to be much slower and more split with this system than the GFS which leads to low forecaster confidence. If the GFS solution wins out, we’ll have a shot at a decent snow storm. The Euro would still bring snow but the amounts would be significantly lower. Euro has been out-performing the GFS lately so might be wise to side with that model, though we hope the GFS is correct. Both systems bring in plenty of cold air. Over the next 24-48 hours, the models should start to align and provide us some answers.
The other good news is that this storm should be strong enough to scour out most of the inversions in Utah. This will clear the pollution but I wouldn’t expect too much of a warm-up as this is a very cold storm system. The upper elevations, which have been warmer lately, will see a significant drop in temperature behind the front this weekend.
There is a secondary system that should affect the area on Sunday or Monday, depending on the model. Again, the Euro wants to split this system much more than the GFS. GEM is taking the middle ground again. Not going to worry about it too much for now but we’ll have potential for a little more snow.
After that we might ridge up again for the third week of the month. CFSv2 has finally come around to the idea of wet weather returning to the entire west for the last week of the month. Not surprised as the teleconnections are starting to trend in our favor and most of these support west coast troughing within the next couple weeks. Models usually have to play catch up so hopefully we’ll start to see those trend toward wet weather in the long-range soon.
Previous . . .
We’ve been pointing toward the 10th or 11th of January as a possible end to the dry weather for the past 7-10 days and it is looking like that will be the case. The other day the GFS gave us some slim hope for an even earlier ending with the phantom Monday system but the more consistent ECMWF won out and the system will split and bring Utah little if anything.
Attention then turns to the next system which is timing its frontal passage for late Thursday/early Friday. We may start to see warm advection precip falling primarily in the high elevations ahead of the system as early as Tuesday. Accumulations should be light on Tuesday and Wednesday until the main system approaches on Thursday. As of right now this system is looking very solid on both the GFS and Euro. It doesn’t have the most moisture in the world, but it has a strong front, lots of cold air and instability behind the front, and relatively slow movement. Not comfortable at this point guessing exact amounts but at least a moderate storm is likely.
GFS and Euro both show a secondary system dropping into the area sometime around Sunday. This system will likely not be quite as strong but will bring in another shot of cold air and snow.
The other effect this system on Thursday/Friday will have on Utah weather will be to scour out the inversions. Don’t think we’ll get enough air flow to do much damage to the cold pools on Tuesday and Wednesday, but by Thursday we should see the cold air and pollution start to blow out. Again, this system is of a cold nature, so don’t expect the valleys to warm up too much, but at least we’ll be able to see across the valleys again by Friday. More details on this system as the week progresses . . .
CFSv2 and long-range GFS and Euro point to possibility of us returning to ridging during the third week of January (15-21). Uber-long range models are hinting at this ridging breaking down during the last week of the month with the storm door possibly opening. Now this is all very speculative but it’s always worth noting. December long-range forecasts turned out to be pretty accurate so . . . who knows!