Winter Storm Checklist

Should the power grid become compromised because of ice/sleet/snow, be prepared!

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This post was written by Eric Sorensen on November 30, 2007

Winter Storm Warnings in Effect

Winter Storm Warnings have been posted for the entire 13News viewing area. A Winter Storm Warning is issued when severe winter weather is expected within the next 24 hours.

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This post was written by Eric Sorensen on November 30, 2007

Waiting for its Arrival

We’ve been talking about this weekend’s storm system all week long. The models have come together quite well this morning as the different pieces of data are coming up with a fairly uniform solution. The forecast hasn’t changed much in the past 24 hours as we are still expecting a wintry mix with sleet and freezing rain causing the most problems.

WREX was the only station in Rockford that participated in a special conference call with the National Weather Service in Chicago today. Their forecast is quite similar to what we have been talking about the past day or two. It still appears as though the precipitation will start early Saturday afternoon in the form of snow, but quickly switch over to a blend of sleet and freezing rain by mid to late afternoon. This outcome will cause the worst driving conditions between 4pm and midnight Saturday evening. They spoke about the possibility of an ICE STORM WARNING being issued later today or early tomorrow morning, but said they would hold off until the event got closer. They also spoke about the “worst case scenario”. In the “worst case scenario”, a half an inch of frozen precipitation would cover the WREX viewing area. This ice coupled with gusty southeast winds could create widespread power outages. Granted, this is the “worst case scenario”, but it is important to know that the potential does exist.

The graphic above is of estimated precipitation totals from 6am Saturday through 6am Sunday morning. As you can see the bullseye for heaviest precipitation is very close to the Rockford area. As we teeter along the freezing mark near the ground and higher up in the atmosphere our precipitation will be changing its form frequently this weekend.

If you are trying to find something to do for Saturday night, I would say you should hold a “get to know your neighbor night”. Invite your neighbors over for dinner, cards, or stimulating conversation because you are not going to want to travel too far from home. -ADAM

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This post was written by Eric Sorensen on November 30, 2007

Snow potential for Saturday afternoon

10:53pm – The going forecast looks good. We will start with a brief, but moderate, round of snow for Saturday afternoon before changing to freezing rain/sleet and rain. If anything, the evening models are decreasing our chance of freezing rain in favor of sleet. That would be a blessing! Sleet (ice pellets) are much easier to drive on versus rain freezing into ice. Adam will have coverage on Friday. Winter Storm Watch won’t be upgraded to a warning until Friday evening.

The main threat with this winter storm will be in the form of freezing rain Saturday night. However, the precipitation will likely begin as snow in the mid-morning.

Snow could accumulate 1-3 inches across Northern Illinois with 3-4 possible in our Southern Wisconsin counties during the day on Saturday. Snow should changeover to freezing rain/sleet during the 3-7pm timeframe from south to north ending the snow accumulation. (Snow may be highly sought after if the freezing rain comes down for more than an hour or two.)

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This post was written by Eric Sorensen on November 29, 2007

Winter Storm Watches Hoisted Areawide

6:20pm – Winter Storm Watches in effect from Milwaukee all the way down near Tucson! This storm will affect millions of people this weekend.

3:40pm – Chicago and Davenport will be issuing Winter Storm Watches for the entire area within the next 30 minutes. This storm is expected to bring the worst weather to the area on Saturday with a round of snow changing to freezing rain and then to rain. Additional details will follow…

2:10pm – The National Weather Service in Milwaukee has put out a Winter Storm Watch. Snow will begin to overspread the area during the morning hours of Saturday. NWS Milwaukee: “By Saturday evening, the snow will change to freezing rain/sleet with accumulations of ice up to 1/2″ on top of a few inches of snow.” Travel may be impacted in these areas Saturday into Sunday. More to come…

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This post was written by Eric Sorensen on November 29, 2007

The Setup for Freezing Rain

With the storm track appearing to likely go through Nebraska, central Iowa, and into Wisconsin we could be in for some nasty travel this weekend. The precipitation type will likely change several times Saturday and Sunday as our temperatures at the surface and overhead teeter along the freezing mark. Late in the day Saturday could be a scenario that is worse than receiving heavy snow.

The ingredients are lining up for a freezing rain event during the afternoon and evening hours on Saturday. Temperatures Saturday morning will be cold in the teens. With cloudy skies it is going to take awhile for our temps to rebound. Warmer air (above the freezing mark) higher up in the atmosphere is set to stream into the area. It will be overrunning a shallow layer of colder air (below the freezing mark). When the precipitation starts from the cloud base it will come out in the form of rain and travel through the majority of the atmosphere in the liquid form. Once it makes contact with the ground it will freeze on contact and turn most roadways into skating rinks. If you are driving this weekend and notice the precipitation change into sleet or freezing rain, be extremely cautious! -ADAM

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This post was written by Eric Sorensen on November 29, 2007

Not all snow this weekend

We’ve been talking about the possible storm tracks for this weekend’s storm for days now. Today, the models are beginning to converge on a solution that may take the center of low pressure very near the area Saturday night into Sunday (not a recipe for heavy snow here). So, here’s what I’m thinking right now: Light snow will begin sometime on Saturday (and possibly accumulate a few inches) as temperatures are expected to be well below 32°. Snow will mix with sleet before changing to rain or freezing rain Saturday afternoon/evening. East of I-39 will be warmer than western sections so I’ve kind of put a cut-off along I-39 for FZRA west and RA east. The higher possibility of accumulating snow right now looks to stay west of the Mississippi River. As the entire system pushes northeast on Sunday we should be able to cool enough to change everything that’s left over to snow with an inch or two possible.

CAUTION: That’s how it looks right now. I know it’s easy to speculate on what we think we see in the models (and what we want to see) but this one is not a full-fledged snow event…not a total-rain event either. Precipitation type will be critical in determining the severity of the system and the impact it will have on travel.

I’ve probably gone through a hundred maps and models today and my confidence in this forecast is still only around 50%. Stay tuned.

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This post was written by Eric Sorensen on November 28, 2007

Models don’t agree when it comes to weekend storm

Here is a look at the morning run of the GFS and NAM computer models. Since the NAM only goes out to Saturday evening, I took a few screen shots of both computer models valid at that time. What is interesting is how the GFS model is developing a closed area of low pressure over northern Kansas with widespread overrunning rain over much of the Great Lakes. The NAM model is slower to develop the low and in turn keeping the Great Lakes cooler and drier through Saturday evening. (Keep in mind that the 540 line is usually the rain/snow line).

I am going to pay less attention to the GFS model in my afternoon analysis/forecast as I believe the GFS is developing this storm too soon and is bringing in too much warm air. Having said that, the NAM is getting a little warmer with each model run which would possibly lead to a more messy system versus a totally white one. Precipitation type (rain, sleet, freezing rain, and snow), timing, and intensity will be refined in later forecasts and discussions. Another day will provide us with better consensus, especially since the NAM will yield a complete look at this storm. More to come this afternoon! -ERIC

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This post was written by Eric Sorensen on November 28, 2007

No Snow? Let’s Make Some!

This morning I found an interesting article about snowmaking around the Midwest. This is the link to the article: artificial snow

It talks about how cold the air must be to start making snow, the physics behind the process, the different types of snowguns, and much more.

Skiing areas such as Alpine Valley, Tyrol Basin, and Chestnut Mountain will be completely open soon. Would you be interested in seeing a ski report? If so, please reply to this posting. If not, you can let us know your opinion as well! -ADAM

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This post was written by Eric Sorensen on November 28, 2007

Breathtaking sunset tonight

I hope you had the chance to see the beautiful sunset that we had over Northern Illinois on Tuesday. Both of these pictures were taken down in the Ogle/Lee County area. Special thanks to Scott Awalt and Sue and Bill Paulin for sharing!

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This post was written by Eric Sorensen on November 28, 2007