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Friday Afternoon Storm Analysis

My apologies for the delay this afternoon. Definitely a busy day in the weather office! We will start with a few hours of snow during the late-morning hours of Saturday. Perhaps 1-3 inches, especially north of US20. Temperatures are expected to remain below freezing all day long. However warm air will begin to move in at 5,000 feet bringing a change to our precipitation type.

By midday and especially through the afternoon freezing rain will be the main concern. Our Microcast computer model is hinting at 1/2 to 3/4 inch accumulations. On top of that, winds in excess of 30mph would cause trees and powerlines to snap. The power grid could be compromised if this worst-case scenario does indeed take place.

By the time we get into late Saturday night, the temperature profile will be above freezing from the ground up bringing us plain-old rain. In fact, there could be a few lightning strikes as well. Please use this time to prepare, just in case!

Winter Storm Checklist

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

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.

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

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.)

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...

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

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.

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

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

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!

Coolest pictures you'll see all week!

Click here for spectacular pictures of Shuttle Endeavor's visit to the International Space Station. If you had the chance, would you go to space? I, for one, don't even have to think about that question (especially when I look at these pictures).

Model Madness!

Here are a series of graphics using the latest GFS data in our Microcast computer model. This model doesn't distinguish between rain and snow. It's all green here. You have to look closely at the 32° line that is labelled as a white line. You can see the variations that we have to take into account when forecasting rain and snow. The first graphic is giving us no precipitation for Wednesday (but the others are fairly moist. We'll keep a chance of light rain or snow in the picture for Wednesday afternoon).


The second graphic shows our next little blip for Friday morning. With the 32° line to the south, we are expecting this to come in the form of light snow...a dusting at most.






Now we're onto the bigger system for the Saturday night/Sunday timeframe. Notice how far the 32° line goes during the overnight hours! If this model should verify the axis of heavy snow (probably in the order of 6") would stripe the ground from Kansas City through Quincy and into Central Indiana. We're still highlighted in the 0.50" accumulated precip however. Should that all come in the form of snow, we'd see around 5 inches.

Deja Vu?

Before reading, please refer to December 1, 2006.

9:00pm Update: I just ran our in-house model and it appears that if anything it's trending a little further southward with a snow-bullseye going from Kansas City to Bloomington, IL to South Bend, IN. Will post graphically when the model is complete.

6:45pm Update: Accuweather.com Meteorologist Henry Margusity has a great analysis of this system on his weather blog. Click here for more.

6:14pm Update: Everyone must be snowlovers on here! Check out the poll question to the right.

4:30pm Update: Here's a look at the AM GFS model run valid for Midday Sunday. It indicates a potential for significant snow from Rockford up into Wisconsin. The rain/snow line is suspect however...I feel the models right now are under-doing the amount of cold air already present.

It's only 3pm and I am just beginning to put together the forecast. It's pretty cut and dry for days one through three. There are some signals now that a winter storm may develop over the Midwest for Saturday/Sunday (exactly one year from last year's record-breaking snow).

Here's an excerpt from the techincal discussion from the National Weather Service in Davenport:

SATURDAY AND SUNDAY...SIGNIFICANT AND PROBABLY MAJOR STORM TO PASS
NEAR IDEAL TRACK WITH SFC LOW PASSING ROUGHLY ALONG A MCI-GBG-CHI
AXIS. UKMET/GFS/ECMWF SIMILAR ON TRACK EXCEPT TIMING DISCREPANCIES
DUE HOW QUICKLY SYSTEM INTENSIFIES.  ECMWF IS STRONGEST WITH INTENSE
SYSTEM...GFS...VERY STRONG AND UKMET JUST STRONG.  UPDATED HWO FOR
CERTAINTY OF SIGNIFICANT WINTER WEATHER WITH GREATEST RISK NW OF A
SQI TO OTM LINE.  CONCERN IS COLD AIR WILL BE IN PLACE OF ARCTIC
ORIGIN FOR ICE AS STRONG WAA KICKS IN.  THIS RISK SHOULD BE CLARIFIED
NEXT 24-36 HOURS.  HAVE UPPED POPS TO LIKELY TO HIGH CHANCE WITH SNOW
NORTH OF HIGHWAY 30 AND A MIX SOUTH.  PROBABLY A LARGE TEMP GRADIENT
WITH STORM SYSTEM FOR LATER SHIFTS TO ADDRESS OF 20 DEGREES OR MORE
AND HAVE ONLY TRENDED ATTM.  INSPECTION OF ANOMALIES SHOWS 2 UPWARDS
TO NEAR 4 SIGMA.../90 TO 99 PERCENT STRENGTH/ OVER FORECAST REGION
WHICH SUPPORTS STRONG TO NEAR RECORD STRENGTH SYSTEM.

Polar Front Moving Through

The two graphics above are readings as of 9am across the Upper Midwest. Lows this morning in Fargo, North Dakota fell to -7°F! Yes, that is a minus sign ahead of that number. A big push of much colder air is pushing south as indicated by the 24 hour temperature change. Right now this cold front stretches from Milwaukee to Rockford to the Quad Cities and continues to move to the southeast. Winds out of the northwest have increased dramatically in the past three hours as gusts are now as high as 30 mph. You can expect the blustery conditions to continue into this afternoon. Despite all of the sunshine today, don't expect temperatures to get much higher than the mid-30s. Dress warm on this Tuesday! -ADAM

Sunday's spontaneous snow

Candice Hill of DeKalb caught the burst of heavy snow over DeKalb Sunday afternoon with her digital camera. She says "The pictures don't really do it justice, and it really only lasted about 30 minutes."

A dusting of snow was recorded at the DeKalb Taylor Airport on Sunday. Scenes like these will become more common in the next few weeks. -ERIC

December to start on a frigid note

Get ready for the cold! 13WREX is forecasting the first major winter chill to take place just as we switch the calendar from November to December. There are some indications that we may stay below freezing for many days starting this weekend, lingering into the following week.

Our average high temperature for today is 40°. We are expecting the next few days to be in the 35-45° range. A cold front will then tug down the cold air beginning on Wednesday. Secondary reinforcements will step the temperatures down progressively during the weekend. During the Sunday-Tuesday time frame (12/2-12/4) we are expecting temperatures to be around 15° below average which would yield highs in the middle 20s. Lows could be dip into the single digits in some locations which would be near record cold.

As far as precipitation, we are expecting a few bouts of wintry weather during the next week or so. Right now none of these look to be prolific snow generators. However, I am expecting the ground to whiten up later this week into early next week (which will only promote the development of the cold). -ERIC

Sun Slipping Away

I was going to post this a few weeks ago, but we were in the middle of unveiling the Winter Forecast. Sunrise today was at 6:59am and sunset will be at 4:27pm. Our days will continue to get shorter for another four weeks. We will lose another 23 minutes of daylight before we start slowly gaining back some sunshine.

The earliest sunset is at 4:24pm, which occurs during the first two weeks of December. The latest sunrise is at 7:25am, and that occurs during the first week of January. The shortest day happens in the middle of these two time frames. Winter officially begins in the wee hours of December 22nd this year. On that day sunrise is at 7:22am and sunset is at 4:27pm. This means we will see only 9 hours and 5 minutes of sunlight... and that is only if the skies aren't overcast!

P.S. If you haven't seen this picture of a human holding the sun in its hands before it is pretty neat. It was obviously taken by a creative photographer near sunset. -ADAM

Could Snow Arrive Early?

I got this picture off Accuweather. Tomorrow's temperature fall right before 40 degrees and there is a chance of scattered rain throughout the day mixed with snow.
Temperatures remain mild for Monday thru Wednesday but the cold fronts moving in from Canada with the wall of snow and flurries from the north will move south by Wednesday bringing snow to the Great Lakes.
So while the Chicago area might get snow...the stateline might recieve another dose of the rain and snow mix since temperatures are suposed to remain around 40 degrees for Wednesday.
This coming week will feel like deja vu for Northern Illinois. Last week we saw similiar temperatures with mid week snow and rain mix with sun by Friday.
The same is similar this week. By Sunday the temperatures will be cold enough that the precipitation should fall in the form of snow instead of rain.
Enjoy the more mild temps at the beginning of the week while you can because by the end of it lows will dip down into the teens.
Welcome to the winter preview.

Icescrapers, Gloves, and Umbrellas.

Those are the items that you should handy this week. An umbrella might be needed as you head to work or any destination on Monday.
Wednesday the 30 degree temperatures return and bringing with them the rain and snow mix that we experienced last week.
With a chance of snow in the morning on Thursday temperatures at night will be getting pretty chilly in the 20's . So just like last night frost will be greet you on your car in the morning...so it is a good idea to have a ice scraper near by to clean off your car. Make sure you take a pair of gloves with you while you scrape.

First snow of the season!

Here are some snowy scenes from Thanksgiving morning. Taken by Juanita Hartle from Polo, Illinois. Great stuff! Did you enjoy the snow? -ERIC

Back End of the Holiday Traveling

Weatherwise, the traveling on the front end of the holiday weekend was problematic as a combination of rain, sleet, and snow fell on Wednesday. By late Wednesday night most of us had about an inch of snow on our backyards, creating a rare white Thanksgiving.

Most of the snow has already melted and it appears as though the driving conditions on the back end of this holiday weekend will be much better around here. On Saturday and Sunday, a strong storm system will impact some of the states in the southern tier of the country. Snow showers will blanket portions of Colorado, New Mexico, western Kansas, and western Texas. Rain showers will cover portions of east Texas, Oklahoma, Arkansas, Louisiana, and Mississippi. If you are flying into some of these locations you might run into some delays. Otherwise, if you are just doing some driving in the Midwest the trip should be smooth. This storm system is too far to the south to affect us this weekend, but it should bring us a chance for rain on Monday. -ADAM

Happy Thanksgiving!

Here are some Thanksgiving Temps from around the world:

Breckinridge, CO: 23 degrees and partly sunny

Toronto, Canada: 28 degrees and snowy

Caracas, Venezuela: 88 degrees and partly cloudy

London England: 49 degees and partly cloudy

Moscow, Russia: 22 degees and Mostly Clear

Taipei, Taiwan: 69 degrees and showers
Enjoy your Turkey Day!
And don't forget to watch the Macy's Thanksgiving Day Parade on NBC!!

My favorite float in the parade is Scooby Doo? What's your favorite float?

EXCLUSIVE WINTER WEATHER INFO

8:52pm - 0.70" of measured snow here at the WREX-TV studios. Snow falling heavily.

8:47pm - Band of snow now working into western Winnebago County is the storm's last gasp. Snow tapering off in Freeport now with at or less than 1" received. NWS "Snow Advisories will likely be pulled before the scheduled expiration time."

8:30pm - Would love to have a viewer/blogger report from the Freeport area. How much snow has fallen? Intensity? E-mail esorensen@wrex.com. Thank you!

8:23pm - Galena [Jo Daviess Co, IL] co-op observer reports SNOW of M0.8 INCH at 08:17 PM CST -- still snowing lightly.

8:22pm - Doppler radar continues to show a band of heavy snowfall that will move into the Rockford metro shortly after 9pm. Spotter reports confirm up to 2 inches of accumulation with this band. Visibilities will also be reduced to near zero for those travelling.

8:15pm - [Dubuque Co, IA] trained spotter reports SNOW of M1.8 INCH at 08:12 PM CST -- light snow still falling.

7:16pm - NWS Quad Cities: Spotter in Pearl City in Stephenson County /west of Freeport/ reports the light rain changed to snow prior to 7 pm and some decent flakes attim with grassy/elevated surfaces starting to whiten up

6:44pm - NWS Milwaukee: Recent snow reports as of 630 pm. Baraboo/Dells 1.4 inches...Westfield in Marquette County a trace...Markesan in Green Lake 2 inches...Rio in Columbia County 1/4 inch. Waunakee in Dane County 1 inch.

6:17pm - Heaviest snow extending from Galena through Darlington into Madison. Visibilities will diminish along the US20 corridor from Stockton to Freeport by 7:30pm.

6:14PM - 2.3 inches in Cedar Rapids at KGAN-TV Studios

5:49pm - 1.5 inches in Cedar Rapids at KGAN-TV Studios

5:45pm - Snow falling at the WREX-TV studios.