FRI 11:30PM - models still shifting Saturday PM round around but keeping southeast WI in the crosshairs. At this stage I won't be making any changes to the forecast maps and will use storm updates/raw output. Ready for this storm to be over with as it's been a nightmare keeping up with/contemplating all the constant changing...and the impostors. The weather pattern will stay busy into next week so keep your shovels handy! Little time to think. Also noticing a few improvements that can be made to the website in this new workflow so please be patient. It's going to take quiet weather to get this thing really humming...but it takes busy times like this to identify the issues. Thanks for reading! Stay tuned!
FRI 1:30 PM - Overnight/morning runs did a number on the overall confidence of this forecast. Went from pretty solid to more fluid and that's never good. For this forecast I used the GFS/EC framework with a nice blend of short range model trends. In my experience short range models will outperform the medium range regarding snow amounts in this forecast hour...they shouldn't be taken 100% literally...but elements of the short rangers should be applied.
Looking at current radar trends across Iowa, Kansas, Missouri...I don't think short range models are that far off. EC just not detailed enough to capture it. Short range models do really well in this regime with banding running over the same areas and there's some good looking bands in there. Looks really healthy. The other thing is momentum of the activity will probably carry northeast-ward into Wisconsin. If you look at the warning/watch situation it's almost like it bends abruptly heading into WI. I lined up the snowfall forecast with current trends. I think we're in good shape.
1:50PM FRI - healthy radar trends coming out of the southwest.
What makes this forecast complicated are the following factors:
1. Narrow band of heavy snow likely tonight across southern Wisconsin, perhaps edging into central WI. Several days ago models showed this...then backed off...and then brought it back again last night. This feature is here to stay but goes to show the volatility of the forecast this weekend. 2-6" possible overnight.
2. Uncertainty over Saturday night trowal...will it be weaker/further south per GFS, bigger deal for southern WI on the EC, or much further north like the NAM? In this situation I like the EC framework...noting that the 10:1 is probably too low. If you take the NAM amounts as high range next to EC (consideration for 10:1) then you get probably 4-8" Saturday night. This feature will make or break the forecast and honestly have to trust more in medium range models at that forecast hour and at the time of writing. Will note that EC has been most consistent on this aspect.
FREEZING RAIN - The main period for freezing rain will be Saturday morning. I thought it was interesting how forecast for freezing rain were more impressive yesterday...i.e amounts at or above 1.0" ice accretion. No doubt that would have been a huge deal. TODAY, not as world ending but still significant...also further north in the WI/IL border region. I forecast 0.25-0.5" of ice is possible from Iowa City to Maquoketa to Freeport IL up through Janesville and even over to Milwaukee area. I wouldn't be surprised to see greater than 0.5" of ice accumulation in that region(probably not Milwaukee but further southwest). Because the NAM specifically was backtracking in general and I didn't want to stick out too much I highlighted that zone with a "Target". But you have to wonder...if it's wishy washy going into it...how confident can you be in the highest of high ice accumulation amounts? Worst case scenario is really bad for that region. Prepare now for possiblity of power outage and impassible roads come Saturday morning.
More information can be found on the official forecast found on the home page. Thanks!