29. Light snow overnight, more snow tonight, another cool down to follow.
Here is a screenshot (to the right) at 22:35 last night. A band of light snow moved east across the region overnight, bringing less than an inch of new snow, but this morning is sunny!! I measured 0.2" of snow with a snow cover of 14.6" still on the ground. This was a weak clipper system located north of the Canadian border that is sliding northeast.
A new low pressure moving this way.
At 6:00 there was a clipper system sitting along the Montana/Canadian border and will be moving this way today and tonight.
This map (to the left) is from the HPC and shows the forecast track of low pressures across the country. What is interesting to note is that the current pressure of the low in Montana is 992 mb (29.30 'Hg), while the computer models show it as 999 mb (29.50 "Hg) now. This indicates that the models are already over-estimating the pressure of the low, and if they is doing this they may be underestimating the strength of the system.
What is this clipper bringing for us?
Several things are against a large snow-maker.
1) there isn't much moisture. 2) it's moving pretty fast 3) it's a relatively weak system
The map (to the right) shows the forecast map at 6:00 tomorrow (Thursday), where the low pressure will be approaching La Crosse. The snow shield will be north of the stationary front, across northern Wisconsin, while another high pressure of cold air slides toward us.
Watches and Advisories have been posted by the NWS.
The map (to the right) is from USWX.com and shows which counties have watches and advisories.
Both the NWS Duluth and Minneapolis have posted Snow Advisories for their forecast areas for expected amounts to range between 3 and 5 inches of snow by Thursday afternoon.
NWS Green Bay and La Crosse have posted Winter Storm Watches for sections of their forecast areas. In these locations the exact snowfall totals are still unclear, but over 6 inches of snow is possible. These NWS offices will update the Watch as soon as the outcome is clear.
Clipper then arctic air, clipper then arctic air.
Tonight's clipper will be followed by a shot of arctic air and then a warm-up, followed by another clipper and shot of arctic air.
The chart (to the right) show forecast temperatures for my location during the next five days. The red line is high temperatures, the blue is low, and the dashed lines are average high/low temperatures.
Sunday the next clipper will pass through.
The weekend's clipper looks a little stronger and better organized than tonight's, it also looks like it may have more moisture to work with. It's still four days away so things will change between now and then, but it may be worth watching since it may give us some measurable snow amounts.
The map (to the left) is the 06 UTC GFS model at 90 hours, showing Saturday evening at 18:00. More model maps can be found at NCEP's Model and Analysis page.