THE POLAR PLUNGE...

After a rather frigid start to December, a thaw of significant proportions took highs from the low 20s to the upper 50s in the blink of an eye. Since Sunday, the mild conditions have peaked and temperatures have been trending down, first gradually and now incrementally. Thanks to a potent but fast moving surge of Arctic air, readings will begin to slip Wednesday and free-fall Wednesday night. Here's a history of temperatures so far this month in the Quad Cities.

Another perspective of the temperature downfall that only intensifies the next 24 hours.

At the surface Wednesday, the packed isobars indicate rising NW winds that will drive the Arctic air mass into the Midwest.

By late morning and into the afternoon, gusts of 35 to 40 mph are expected.

The HRRR indicates 850 temperatures diving to -23 in Dubuque, which is near the SPC historical low for a sounding at 5,000 ft December 12th.

Lows Thursday morning will be in the single digits, with the HRRR indicating zero in Dubuque.

Below zero wind chills will be common to start the day Thursday, with some in the north close to 20 below. Ouch!

Afternoon highs should make it back into the low to mid-teens later Thursday as the crux of the cold passes to the northeast.

A final issue to address is the snow shower potential. The extremely cold air aloft is bound to generate steep lapse rates necessary for snow showers/squalls. These are most likely from daybreak into afternoon. They tend to be rather hit-and-miss in coverage, traveling in bands from NW to SE. Snow rates can be quite intense but for only brief periods of time. Therefore, most places should see little more than a dusting. However, some of the stronger banded squalls could end up capable of producing isolated pockets of 1/2 to 1" accumulations.

After a frigid but dry Wednesday night, a band of light warm advection snow is shown on most models streaking rapidly across my southern counties Thursday afternoon. Due to the cold air, any snow that develops will produce high snow ratios and fluff up nicely. However, water equivalent is projected to be .05 or less, which should keep any accumulations in the south to .5 to 1.0 inch. More of a nuisance than anything, but certainly enough to cause slick spots if current trends hold. Most of the snow should fall from I-80 south. Here's what models are suggesting for snow.

The EURO

The GFS

The 10K GEM

The 3k NAM

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A STRONGER SYSTEM TO START THE WEEKEND

Friday, the Arctic air that was in place Thursday beats a hasty retreat as strong warm air advection develops ahead of a wave crossing the Plains. The big question remains, how much cold air remains and will wintry precipitation develop. The latest guidance indicates respectable moisture but a slight shift north on the track. That implies the area north of HWY 30 may be glanced by a short period of snow, freezing rain, or even sleet before a transition to good old rain. The south is likely to avoid those issues if trends hold with just rain indicted.

As it stands snow, precipitation moves north across the area later Friday evening before the bulk of it departs from south to north Saturday midday. The EURO shows the mixed precipitation late Saturday night in the north, with rain south.

Whatever happens initially, it should not be a problem even in the north Saturday as temperatures quickly go above freezing and into the 30s. Again, the window for travel concerns would mainly be north of HWY 30 and especially focused on the area of HWY 20 north Friday night. It's just too early with too much uncertainty to get cute with precipitation types and accumulations. Even if there was any snow or ice, I doubt accumulations would amount to much. However, with ice, a little goes a long way. Stand by!

As for precipitation, that is something we could really use after another 3 plus weeks of dry weather. Here's what the EURO and GFS indicate for precipitation totals Friday night and Saturday. Just how much of it comes in a wintry form? Sadly, little if any falls as snow and what a shame as colder temperatures would have produced a nice 6-12" swath of snow.

The EURO

The GFS

Get ready for a quick return to the deep freeze tonight and Thursday. At least for 48 hours, it's back to winter. Have an outstanding day and roll weather...TS