Update 12:34am: Yes, I’m blogging even after work. I made it back to my apartment just fine; Bypass 20 was cleared sufficiently that it’s very drivable if you drive appropriately. However, country roads out in open areas will likely not be as good tonight. At the station, we were experiencing blowing and even some minor drifting. This will impact rural roads that aren’t cleared as often. I can tell you from experience (i.e. my parking lot) that the slush is very, very slick! In addition, slush will likely freeze in some spots tonight, leading to very hazardous conditions. Please plan for extra time for your morning commute!

LIVE CHAT – For your username, please use your first name and the town where you live. Thanks! [The chat has ended for the night... thanks for joining us and reporting your snowfall totals!]

Update 6:48pm: Road conditions areawide are classified as patchy to completely covered in snow. We have about 1.5″ here at the station north of Winnebago. The highest snowfall total reported thus far is 3.0″ in DeKalb; there is still a fairly heavy band of snow located over DeKalb County right now.

Update 5:54pm: The Storm Prediction Center has issued a local technical discussion regarding snowfall trends through about midnight. Click here to read it. Snowfall totals in the Rockford metro are now around 1.5″ to 2″.

Update 4:35pm: Winter Storm Warnings continue. We have about an inch right now at the station, although Franklin Grove has 2.5″. I would suspect that other locations not far east and south of Rockford are somewhere in the 2-3″ range at this time.

When I was out measuring snow here, I could hear a car’s tires lose traction. The wet pavement that is now collecting a slushy accumulation will turn to icy pavement later this evening if it’s untreated. Bridges and overpasses will be the first to be susceptible to ice.

The heaviest snowfall will continue to fall along and east of Interstate 39.

Update 2:43pm: The snow has become heavier and more steady here at the station… and it appears the same way in downtown Rockford based on our skycam shot. Now that the snow has gotten going, it will become easier for it to accumulate both on the ground and on roadways. The snow will vary in intensity this afternoon and evening, but I don’t foresee any breaks in snowfall.

Update 1:42pm: What should be some heavy snow in/near Rockford is only light snow. It appears that temperatures are still a tad too warm (both at the ground and aloft) for good snow production. Still manageable road conditions for the time being, although I wouldn’t be surprised if bridges/overpasses have snow on them.

Update 12:52pm: Can you tell I like updating? Anyway, the image at left shows the change in barometric pressure over the past three hours. Once a weather system is pretty well developed, the surface low will tend to move toward wherever the greatest fall in pressure is located. At noon, the greatest pressure fall was in eastern Michigan. Since the low is now located in east-central Illinois, it should take a general northeast track. As the low pulls away, we will remain in the favored area for snowfall.

Update 12:33pm: A band of heavier snow is developing roughly along I-39 and moving westward. This trend of occasional bands of moderate to heavy snow will continue. In addition, winds will increase to around 15-25mph this evening, creating a blowing snow hazard, especially overnight.

Snowfall reports to weather@wrex.com are appreciated.

Original post: The entire WREX viewing area is under a WINTER STORM WARNING.

Hazardous winter weather will overspread the area today and tonight. The snow has taken a while to get going north of US20, but snow will eventually envelope the entire Stateline.

The latest data suggests the possibility of snowfall in excess of 6″ in some locations. In addition, strong winds late this afternoon will cause blowing snow.

IF YOU MUST TRAVEL TODAY, BE EXTREMELY CAUTIOUS!

Posted under Uncategorized

Update (8:53pm): Walworth County to be upgraded to WINTER STORM WARNING.

Update (7:22pm): Milwaukee NWS is discussing the possibility of upgrading portions of southeastern Wisconsin to a Winter Storm Warning. I’ll post as soon as I know.

Original Post: There are a few things that we look at for snowmakers around here. The track of the surface low pressure is the one that people are most familiar with. A surface low is pretty easy to find when it’s a well developed system.

Another thing we look for is something called “phasing.” That’s when the lower levels of the atmosphere and the upper levels of the atmosphere work in tandem to create a stronger weather system. Tomorrow’s system looks like it will phase pretty well. The included image is of water vapor imagery from this evening. Satellites don’t just take pictures of clouds; they also can detect water vapor high in the atmosphere. The swirl located in Kansas is where the upper-level low pressure system is located (and is the cause of the snow in Iowa right now). To the south, a large plume of moisture is being pulled into the eastern U.S. That’s also in the area where the surface low pressure is developing. All of those things will start to work together tonight, allowing for the evolution of a pretty decent winter storm.

That winter storm will move through the Ohio River Valley over the next 36 hours, bringing us our first widespread snow of the season. At this time, I-39 looks to be the general dividing line between the greater and lesser snow amounts. I have Rockford in the 1-3″ range, although I believe we’ll be closer to 3″ than 1″. Our far eastern communities (Walworth, McHenry, DeKalb Counties) are in the 3-6″ range. I doubt there will be too many reports above 4″ or 5″ in those locations.

Obviously, this poses a significant travel problem, especially to those heading east. Planning for extra time and driving carefully and defensively will be important tomorrow.

With this being a fairly high-impact snowfall, I’ll be checking the blog pretty frequently. If you have any questions, feel free to leave a comment! Also, if you have any snowfall reports, send them to us at weather@wrex.com.

Posted under Uncategorized

Update 3:10pm: Entire viewing area now under a Winter Weather Advisory.
(3:09:24 PM) iembot: LOT issues Winter Weather Advisory valid at Nov 30, 6:00 AM CST for Winnebago, Boone, Ogle, Lee, DeKalb, La Salle, Grundy, Livingston, Iroquois, Ford [IL] and Benton [IN] till Dec 01, 9:00 AM CST
(3:09:24 PM) iembot: LOT issues Winter Weather Advisory valid at Nov 30, 9:00 AM CST for McHenry, Lake, Kane, DuPage, Cook, Kendall, Will, Kankakee [IL] and Jasper, Lake, Newton, Porter [IN] till Dec 01, 9:00 AM CST

Update 2:44pm: As expected, additional counties added. Advisory now includes Wisconsin viewers.
(2:44:10 PM) iembot: MKX issues Winter Weather Advisory valid at Nov 30, 12:00 PM CST for Dodge, Green, Jefferson, Kenosha, Milwaukee, Ozaukee, Racine, Rock, Sheboygan, Walworth, Washington, Waukesha [WI] till Dec 01, 6:00 AM CST

—-

(11/29/2008 1:50:28 PM) iembot: DVN issues Winter Weather Advisory valid at Nov 30, 12:00 AM CST for Jones, Jackson, Cedar, Clinton, Muscatine, Scott, Louisa, Des Moines [IA] and Bureau, Carroll, Hancock, Henderson, Henry, Jo Daviess, McDonough, Mercer, Putnam, Rock Island, Stephenson, Warren, Whiteside [IL] till Dec 01, 6:00 AM CST

I would expect this to be expanded into our other counties later this afternoon or evening.

Posted under Uncategorized

This afternoon I decided to check the current snow cover across the United States and Canada. Surprisingly you don’t have to go too far to the north to see a blanket of snow. On Sunday much of Iowa, southern Wisconsin, northern Illinois, Indiana and Ohio will get another 1-3 inches of snow on the ground. This will mean that the cool, northwest orientation of the jet stream will get colder and colder over the next week or two. There’s no sign that this pattern will switch around and with little bare ground northwest of here it’s almost a sure bet it will feel more like winter around here!

Posted under Uncategorized

Undoubtedly, a pronounced area of low pressure will develop and move into the Ohio Valley region by Sunday. There should be plenty of cold air wrapped into this system to keep it all as snow across the Stateline. At this point, the intensity of the snow bands is undetermined, but the forecast of 1-3″ that Eric raised last night seems reasonable. The heaviest snow should fall closer to the low which should setup near Cincinnati, Ohio. The higher totals over our area will be tallied near Dekalb, Sycamore, and Rochelle with the lower totals being witnessed around Galena, Freeport, and Monroe.

We’ve seen optimal driving conditions for the majority of this holiday weekend, but it appears the tail end of the festivities may be hampered by this snowmaker. If you have travel plans on Sunday, you should keep close tabs on the Weather Blog as this situation becomes clearer on Saturday. -ADAM

Posted under Uncategorized

Turkeys will thaw out in the morning and then warm in the oven to a high of 350°. The kitchen will be hot and humid. If you bother the cook there may be a squall or two. Later in the afternoon the cold front of a knife will slice through the turkey and cause accumulations of 1-3 inches on plates. Isolated 5 inch amounts will be possible on Dad’s plate.

Cranberry sauce will create slippery spots on one side of the plate as mashed potatoes drift across the other. Butter will spread across some sections of rolls.

A weight watch and indigestion warning will remain in effect for the rest of the day. Late in the evening clean up operations will begin. The turkey will diminish to sandwiches which will become colder during the night in the refrigerator.

As for the weekend forecast? The turkey will taper off into left-overs but in some sections there will be a warming trend as soup develops.

Posted under Uncategorized

We’ve pored over the data, run tests, used many beakers and test tubes… okay, maybe not quite that extreme.

We won’t soon forget last winter when more than 70 inches of snow fell in the Rock River Valley. There will not be a repeat of that this season. However, we are expecting slightly above average precipitation. As far as temperatures go, it appears the cold weather from November will be carried on into December and possibly January. Because we’ll be starting the season in a deficit (temperature-wise), we feel compelled to continue with a slightly below-average temperature pattern through winter 2008/2009.

Summary:
Last winter, we were in a strong La Nina pattern. That has since subsided this fall into a near-neutral pattern, perhaps a weak La Nina. Generally, La Nina leads to temperatures that are cooler than average in the Midwest. Other large-scale signals indicate the potential for a similar situation in which cold air is able to build up in Alaska/northern Canada, then spill southward into the central United States.

The National Weather Service office in Detroit came up with a number of analogue years; that is, years in the past that were similar to what occurred this past year. They used years in which a La Nina was ongoing from winter through the summer, with a return to neutral conditions by fall. We used that technique in our Winter Outlook by looking back at what conditions Rockford experienced in the seven analogue years. While there was certainly variability in temperature and snowfall, we were able to identify a couple of general trends.

Temperature:
We can already get a glimpse into a good part of December using our ensemble computer models. What they suggest is a continuation of the cold. Aside from the first week of November, a significant long-term pattern has developed bringing us repeated bouts of cold weather. This trend is also very similar to one of the aforementioned trends from the analogue years. We found that December typically ended up with much below average temperatures – sometimes to the tune of 5°F below average. It also appeared that a significant cold wave would affect the Midwest after the middle of the month, sending Rockford’s temperatures below zero for several days. While we aren’t giving specifics within this Winter Outlook, it is hard to ignore such suggestions.

In any event, some moderation in temperature is expected into January (partially based on data from analogue years). Given that we are in a weak La Nina, or perhaps non-existent La Nina by February or March, we are given fewer signals of any deviation above or below. As a result, we are going to trend to near normal temperatures in January. For February, we are not seeing any notable indication for either above or below average temperatures, but data from analogue years points to the possibility for slightly warmer than average conditions. Even if February does end up warmer than average, we do not feel it will outdo the very cold December and near-average January.

In a nutshell, our Winter Outlook calls for below-average temperatures on the whole, particularly during the month of December.

Precipitation:
As with temperatures, a lack of a strong La Nina or El Nino doesn’t lend itself to making a precipitation outlook easy. Looking back at our analogue years, snowfall amounts had a high level of variability. A few years had vastly higher than average snowfall totals, while others had scarce amounts of snow. We are calling for average to slightly above average snowfall this winter, partly due to the fact that colder than average temperatures will favor snow.

Since cold air intrusions will be frequent for the first part of winter, we expect Alberta Clipper systems to be quite common. While these usually are starved for moisture and therefore produce relatively low snowfall totals, their frequency may mean more small snows more often. Recall only to last year when we had so many Alberta Clippers; the minor amounts of each one added up to a sizable portion of the 72.9 inch total for the season.

There is some indication that the dominant “Texas Hook” storm track may be a bit farther northwest this year than last year, putting the heavier snow bands northwest of Rockford. That doesn’t mean we won’t have any significant snowstorms; they just may become rarer into February and March of 2009.

Eric Sorensen
Adam Painter
Justin Gehrts

For additional reading:
NWS Detroit Winter Outlook – http://www.crh.noaa.gov/images/dtx/climate/winterout08.pdf [Note: keep in mind that the specifics pertain to Lower Michigan, not necessarily northern Illinois/southern Wisconsin]

WREX Winter Outlook Notes – http://www.justingehrts.com/files/winter_outlook_notes.pdf

Posted under Uncategorized

Thanksgiving 2008 will be a quiet holiday for Midwesterners. Sunshine will be plentiful for travelers on Wednesday. Residual lake effect snow will occur across eastern lower Michigan and northeastern Ohio. Otherwise, you’re good to go anywhere in the midwest. By Friday a clipper system will track from Minnesota into Michigan. There could be some minor accumulations in northeastern Wisconsin and northern lower Michigan. Rain will fall along the Ohio River valley as another system tracks across Dixie. Happy Thanksgiving!

Posted under Uncategorized

Today’s cool breeze takes on a bit of a different meaning. Northwest winds are currently ranging between 10-15 mph and should stay at that strength the rest of the day. Even though most of our snow from yesterday morning has already melted away, that is not the case in central and southern Wisconsin. They picked up quite a bit more snow from yesterday’s storm system. These winds are basically going to be cooled down by this layer of snow. Think about what happens when you put a large tray of ice cubes down in front of a fan. That blowing air is going to feel much cooler than it would without that cooling mechanism in front of it. In summary, we started the day off on a relatively mild note with a low of 28°. Even though we are going to see a lot of sunshine, temperatures are probably still going to stay at or below the average of 40° because of this cool breeze. -ADAM

Posted under Uncategorized

It appears as though we are going to continue to be stuck in this northwesterly flow. With our jet stream coming from this direction it is going to be quite difficult to register above average temperatures for more than a day or two. In this setup we are visited by a cold front about every third day. This will routinely knock our highs back into the 30s. These fronts originating in western Canada typically don’t have much moisture to work with, making for drier than normal conditions. The best part about this outcome is that there shouldn’t be too many travel headaches around Thanksgiving.

For what it’s worth, I measured 0.75″ of snow outside the WREX studios at 6:30am. The snowball I made this morning has sadly melted away. -ADAM

Posted under Uncategorized