There is a chance that Salt Lake City will have its sixth white Christmas in a row. There also is a chance that the storm forecast for Dec. 24 and 25 could be northern Utah’s next big chance to break up the building inversion.
According to the National Weather Service, valley inversion will “persist through at least the end of the week” and “fog and haze” will increase. And the air doesn’t just look bad, it is bad. By Thursday morning, Salt Lake, Davis, Tooele and Weber Counties all had PM 2.5 (fine particulate) levels high enough to prompt yellow (or moderate) warnings, according to the Utah Division of Environmental Quality.
The levels in those counties and other areas of the state are expected to get worse before they get better — possibly this weekend.
The NWS is forecasting an increase in the “southwesterly flow aloft” on Saturday, so “some mixing of the higher valleys will be possible, but inversions will likely remain in place in the lower valleys.” That flow will increase on Sunday, creating conditions “more favorable” to clearing out the smog in the lower valleys.
As for that Christmas snow/potential inversion buster, it’s not a sure thing, either. There is a “slight chance of snow” Monday after 11 a.m., and a “chance of snow” Tuesday and Wednesday. When the storm arrives in Utah on Monday, it won’t be carrying much moisture, and the possibility of precipitation will be “focused in southern Utah” on Monday into Tuesday.
Will there be a white Christmas? Maybe, according to the NWS. There is a stronger chance in southern Utah, where “guidance is pointing to a ... snow event Tuesday into Wednesday." However, the question is whether it will be cold enough to change rain to snow. That “looks likely.”
Temperatures are expected to warm up a bit in the Salt Lake area over the weekend, with highs near 37 on Friday and 41 on Saturday and Sunday. And then they’ll head in the opposite direction — the forecast high in near 38 on Monday, 33 on Tuesday and 30 on Christmas Day.