CLIPPER SNOWS TO SPLIT THE AREA...
The weekend got off to a frigid start Friday morning with sub-zero cold covering many parts of the Midwest, especially those locations with several inches of snow on the ground. You can see we weren't the only ones chattering as the sub-zero cold was widespread from Missouri and Illinois to the North Pole.
In my area Waterloo had 18 below and Cedar Rapids fell to -15. Ames bottomed out at -20. Here in the Quad Cities the mercury held at -5. Again, you can see how the worst cold correlates to the deeper snow pack.
One thing is for sure, if it's going to get bitter cold this is the time of year it's climatologically most likely. In the graphic below you can see that the coldest day of the year on average in my area usually occurs between January 21-25th.
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CLIPPER SNOW BACK IN THE FORECAST
Saturday starts quiet, but for some it ends with snow as a fast moving clipper streaks southeast Saturday night. Currently the track cuts across SE Iowa which means the snow band sets up northeast of the center. There will be a sharp NW SE cut-off to the snow just northeast of the storms path. You can see that line will run close to Iowa City, to the Quad Cities, and on to Kewanee. In that area its a very tough forecast as a 25 mile wide change in track could make a difference between a dusting to 1-2" accumulations. The snow begins in the late evening Saturday where it falls and ends by daybreak Sunday in most locations.
Currently the Weather Prediction Center shows shows these probabilities of an inch or more of snow.
The winter storm severity index is depicting only minimal impacts resulting in minor inconveniences. Personally, I think it will be more than that especially, in the NE third of my area where 2-4" totals (perhaps 5 in spots) look likely. I do expect winter weather advisories will be posted by Saturday morning for much of the area near and NE of the Quad Cities.
The big take-away for me late Friday night is that the EURO has moved just a bit NE on the snow band and now resembles the GFS. The one inch line now is just NE of the Quad City metro. Near and especially SW of a line extending from Iowa City to Davenport, to near Princeton little if and snow will fall.
I've included the latest snowfall output from the various models and they all show the hard cut-off to the southern extent of the snow in the SW half of my area. They also indicate how close the Quad Cities is to missing the whole event. It looks very tight and if the trends continue to inch the track any further north in the next 18 hours it will largely be a miss for the QCA. As it appears to me late Friday night, amounts in the 0.5" to 1.5" range (say 1") is what the average of all the guidance depicts across the metro. With that, here are what a bunch of models are showing for snowfall. These all vary to some degree and are not official forecasts. However, they will be used as input to determine what the official NWS forecast looks like when it's issued early Saturday. Overall, there is excellent consistency in model solutions.
The 3K NAM
The 12K NAM
However this plays out, the damage is done by early Sunday as the system races SE taking any snow with it. That leaves us with a cold but dry day Sunday with readings ranging from the low to mid teens in the fresh snow over of the north, to the low to mid 20s south of I-80.
Another clipper zips southeast Sunday night bringing the chance of some additional light snow to mainly the northern third of the region (HWY 30 north). Some amounts up to an inch or two are possible, especially closer to HWY 20. For now, this event is on the back burner and will get resolved later Saturday with fresh data. Temperatures though will rise Sunday night and early Monday in advance of the system. Highs should be close to freezing in the north Monday morning and might even reach the low 40s in the south by early afternoon. However, another wicked punch of Arctic air follows the passage of the clipper and its cold front. Temperatures will fall in all areas as Monday lengthens and by Tuesday morning the NW half of the area will likely be below zero. The is part of a bitterly cold stretch of weather that includes nasty wind chills through Wednesday.
I'll be keeping a close eye on the development of the clipper Saturday and if there's something new to report I'll push a Facebook live at you in the afternoon. With that, I say make it a good one and roll weather...TS