JUST A BIT TRICKY...
The expected intrusion of Arctic air did not fail to disappoint recipients iMidwest Wednesday. Gusty winds and falling temperatures had wind chills below zero by the time the sun had set. (At 2:00am Wednesday night the temperature at my place in Dubuque is +1 with a wind chill of 19 below). Along with that, scattered snow showers whipped through the region earlier in the day, creating some slick driving conditions, especially in the south between I-80 and HWY 34. A small pocket of heavier snow developed south of the Quad Cities where early Wednesday 1.2 inches fell just NE of Muscatine, 1.3 near Aledo, with 1 inch noted in Cambridge. Most places ended up with little more than a dusting.
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A CHALLENGING FORECAST AHEAD
During the overnight, fair skies and bitter wind chills prevailed. Readings in the single digits combined with brisk winds to create wind chills around 20 below in the north. At 6:00 a.m. Thursday, the GFS is still projecting wind chills to be around 6 to 12 below north of I-80.
Eventually, highs should inch into the 11-17 degree range from north to south. Wind chills will get into positive numbers, but not by much in the north. While the south is a bit more tolerable, the threat of some light snow remains on the table in that part of my area. This event is nothing to write home about, but a dry powdery snow could accumulate up to an inch, mainly during the late morning to mid-afternoon hours. The most likely area for snow is from about HWY 34 south. Here's what models are showing for potential amounts.
The EURO
The GFS
This minor impulse is a fast mover and exits by Thursday evening, with the next disturbance already in the queue for late Friday night and Saturday. This system is stronger with greater precipitation potential. On the other hand, it draws in much warmer air and brings into question precipitation type. Models today are somewhat slower with its arrival and while the GFS is quite wet, the EURO and 10k GEM are much lighter in my northern and eastern counties. Not only that, the track has shifted a bit more southerly, so much so on the 10k GEM that it even shows snow accumulations in parts of the north. To start with, here's what's indicated for precipitation from the event.
The GFS, heaviest and furthest north.
The EURO and 10K GEM are noticeably further south and west. This does make sense with a track further south. I suspect the GFS is having some sort of feedback issue, as it is clearly in another camp with its heavier and more easterly QPF. Compare the 2 solutions with the GFS above.
The EURO
The 10k GEM
Wintry precipitation is a major wild card right now, as both the GFS and EURO have 850 temperatures above freezing most of the event. That is a big negative for snow, but the shallow Arctic air that remains from this current surge could be enough for a period of mixed precipitation in the north that would primarily be freezing rain before transitioning to all rain. Certainly enough to cause some issues on roads in the north late Friday night or early Saturday.
Another possible outcome is that the 10k GEM keeps the depth of the cold air at 850 sufficient enough to get snowflakes down to the ground in the north. Right now the GEM is the outlier in this respect and I imagine it is biased on the cold side. A degree or two could make a big difference, and for that reason the forecast continues to hold a high degree of uncertainty. Right now the consensus is that if there is going to be wintry weather, it's mainly a period of freezing rain changing to rain late in the north Friday night or early Saturday, before readings area wide climb above freezing Saturday, ending the concern. The GFS indicates this for freezing rain amounts before the transition to rain.
If there is any further southward adjustments in modeling, snow and ice could be more of a factor, but the overall lack of cold air is a huge detriment to overcome, and I doubt that will happen. I will give it another day to simmer and hopefully feel better about a more precise outcome in my next post. I will be surprised to see much in the way of snow but do feel the freezing rain threat is a potential issue for the north.
Meantime, we've got a cold day on tap, with some snow of a light nature expected in the south. Send it my way, please! Roll weather...TS
