Source: 12z European Computer model (ECMWF)
One of the big unknowns this afternoon is how far north does the above freezing (0C) 850mb temperature line make it before it gets pinched off while moving back to the S/SE. This will be important because locations that have 850mb temps at or above 0C will see the snow mix with or switch over to freezing rain, sleet or rain on Thursday. Some models show the 0C H85 temperature contour making it as far north as Duluth and Two Harbors for a few hours on Thursday, while other models keep that 0C H85 temp contour a little farther south. Again, where 850mb temps are below 0C, all snow can be expected, but where the 850mb temps climb to 0C or a few degrees above, then a mixture of precipitation types will occur on Thursday.
Note: One thing that could off-set this warming would be if the lift in the atmosphere remains strong enough which would likely keep precipitation in the form of snow, this would be especially true in eastern Minnesota, not so much for most of northwest Wisconsin where it looks pretty likely that temps warm enough causing the snow to mix or switch to other precip types on Thursday.
12z RGEM model 12-26-18
This particular model looks pretty good to me in where they are showing the rain-snow line setting up for Thursday, look how close it gets to Duluth, wow!
Radar loop ending at 12:45 PM CST, Wednesday, December 26, 2018.
Still several hours away before the snow moves into the Twin Ports. Thinking after 10 PM tonight (more in the 11 PM to 1 AM time frame for when the snow arrives in Duluth and Superior)
Goes-16 mid level water vapor satellite loop from Wednesday, December 26, 2018.
Our storm is beginning to move out onto the southern Plains at midday Wednesday with a steady stream of gulf moisture in place ahead of the low, stretching from Texas to the northern Plains.
Winter Storm Warning in pink
Winter Weather Advisory in purple
Note: No changes to my snowfall map as of early Wednesday afternoon, although I do have some concerns that temperatures aloft warm up enough where the snow mixes with or changes to freezing rain or sleet at times on Thursday over eastern Minnesota, north to Duluth and Two Harbors. A greater chance for the snow to mix with or change to freezing rain, sleet or rain exists over most of northwest Wisconsin on Thursday.
…What has changed since Tuesday evening…
Start time to the winter weather headlines
-Winter Storm Warning now in effect from 9 PM this evening to Noon Friday.
-Winter Storm Watch which was in effect for Burnett, Washburn, Sawyer, Ashland and Iron Counties in northwest Wisconsin has been changed to a Winter Weather Advisory — This advisory is in effect from late this evening until Noon Friday.
Storm Timeline for Duluth and Superior
Winter Storm Warning from 9 PM this evening until Noon CST Friday
•Scattered flurries or a little light snow this afternoon and this evening
•Steadier/heavier snow arrives between 11 PM and 1 AM tonight with snow during the overnight hours.
•Snowfall of 2 to 4 inches expected by 7 AM Thursday
•Snow continues through the day Thursday and into Thursday night with some lingering light snow and flurries on Friday, especially during the morning.
•Bursts of heavy snow are possible Thursday into Thursday evening.
•A chance that the snow mixes with or changes to freezing rain or sleet on Thursday if temperatures aloft warm up enough. Computer models disagree on the extent of warming on Thursday with the NAM and German-Icon models showing enough warm air moving in at 850mb causing the snow to mix with or change to freezing rain or sleet, while the GFS, FV3-GFS and Euro models keep us cold enough for the precipitation to fall purely as snow through this event.
•Snowfall storm total accumulations through Friday morning of 8 to 12 inches for the south side of Duluth and for Superior with potential for 12 to 15 inches of snow on the north side of Duluth or on top of the hill. Note: These snowfall amounts could end up lower if we get more of a mix of precipitation on Thursday.
More updates later today