THE FROZEN TUNDRA...
Last Wednesday at 3:35pm the temperature in Dubuque was 35 degrees. By 4:53 the reading had fallen to 32 and has not reached freezing since. As of 6am Tuesday, that means the city has gone 124 consecutive hours at or below at 32 degrees. As it stands now, Dubuque should make it until 10am Wednesday before they inch above the 32 degree threshold. If the forecast holds, the sub-freezing streak would then end at 152 hours. The final tally will be just shy of a week (6 days and 18 hours). The frost depth went from essentially nothing to 3 inches during this period. I'm amazed at how much ice I'm seeing on the Mississippi outside the main channel.
The temperature meteogram in Dubuque since 12AM November 30th to 6pm December 2nd looks like this. Highs of 24, 25, and 24. Lows of 9, 9, AND 11. The average 3-day temperature comes out to 17 degrees, about 13 degrees below normal.
Making things extra wintry was the addition of some light snow late Sunday night into Monday morning. A weak clipper deposited 1–2 inches of snow in a southeast trajectory that ran from Fort Dodge, Iowa to Macomb in WC Illinois. Moisture content was very low (.07", generally less). However, snow ratios were greater than 20:1 allowing the powder to fluff up. Just enough to track a cat at my place in Dubuque.
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We've got another cold day on tap Tuesday with highs remaining in the upper 20s to low 30s. After a quick drop Tuesday evening, west, southwest winds will increase, allowing temperatures to turn steady or even rise a few degrees by Wednesday morning. Finally, highs break freezing Wednesday, reaching the upper 30s north to mid 40s far south. The heat wave remains brief as modified Arctic air surges back over the region Tuesday night. Rapidly rising pressure will cause winds to explosively increase along and behind the Arctic front later Wednesday and Wednesday night. Here you can see the front at 6pm Wednesday near I-80 with its howling north winds. Some brief but intense snow showers may accompany surge of cold air. A few spots in the north could see a dusting.
The EURO indicates 10 meter wind gusts approaching 50mph in my northern counties around HWY 20. 40-45 mph gusts are possible elsewhere.
Temperatures will drop nearly 30 degrees Wednesday night, reaching the range of 8-13 by daybreak Thursday.
The cold combined with powerful winds will have wind chills as low as 5-10 below Thursday morning before they ease into the low to mid-teens in the afternoon. Actual highs should remain in the 21-25 degree category.
With high pressure still in control, Friday remains rather fresh, with highs mainly in the upper 20s to low 30s.
WEEKEND WARM-UP
Over the weekend, the NW flow flattens for a time, allowing more of a zonal jet configuration (west to east). That enables Pacific air to find its way back into the pattern. As a result, highs Saturday should pop into the mid to upper 40s with some low 50s possible Sunday, especially south of I-80. Dry conditions are currently anticipated Thursday through the weekend and well into next week.
Long range, there is significant model variability in guidance, with the EURO showing a stormy period around December 17th thanks to a deep trough ejecting out of the west.
The GFS instead shows ridging over the west and no evidence of the trough or any weather of consequence.
By then, we are into phase 6 of the MJO, which does teleconnect to a trough ejecting out of the west as opposed to the ridge the GFS shows. That favors some version of the EURO solution. Plenty of time to figure it all out.
With that, I will call it a post. Get ready for some ups and downs going forward. Roll weather....TS
