Update 8:00pm: Raining pretty good here in Winnebago... and temperatures continue to fall. Rockford is at 38°, Freeport is 33°, Monroe is 30°, and Dubuque is already down to 16°. Roads are probably going to be bad overnight.
Update 5:56pm: Feels like the front's passed here in Winnebago. Temperatures will quickly decline over the next few hours, with rain changing over to freezing rain and sleet, then snow. For those interested in technical discussions, the Storm Prediction Center has issued one. (FYI, I know the guy who wrote it.)
(4:13:25 PM) iembot: LOT issues Winter Weather Advisory valid at Dec 14, 6:00 PM CST for Boone, DeKalb, Kane, La Salle, Lee, McHenry, Ogle, Winnebago [IL] till Dec 15, 1:00 AM CST
Update 4:05pm: Dubuque has fallen 15° in two hours. That's the kind of change we'll experience in Rockford in the next hour or so as the cold front plows eastward. A period of rain will quickly change over to freezing rain and sleet, then snow. Accumulations look to be fairly low, although any glaze of ice is enough to cause substantial travel difficulties. Any wet or slushy surfaces, including pavement, will rapidly freeze this evening. Black ice is going to be a concern through the overnight. If you intend to drive anywhere this evening, please do so with great care.
For what it's worth, the Quad Cities NWS mentioned in their forecast discussion that this is "one of the strongest arctic fronts in years."
(3:20:30 PM) iembot: DVN issues Winter Weather Advisory for Jackson, Cedar, Clinton, Muscatine, Scott, Washington, Louisa, Jefferson, Henry, Des Moines, Van Buren, Lee [IA] and Clark, Scotland [MO] and Jo Daviess, Rock Island, Mercer, Henderson, Hancock [IL] till 12:00 AM CST
(3:20:30 PM) iembot: DVN issues Winter Weather Advisory valid at Dec 14, 7:00 PM CST for Bureau, Carroll, Henry, McDonough, Putnam, Stephenson, Warren, Whiteside [IL] till Dec 15, 2:00 AM CST
(2:58:59 PM) iembot: MKX issues Wind Chill Advisory valid at Dec 15, 3:00 AM CST for Columbia, Dane, Dodge, Fond Du Lac, Green, Green Lake, Iowa, Lafayette, Marquette, Sauk [WI] till Dec 15, 12:00 PM CST
Update 2:03pm: Let's play "Find the Cold Front!"Temperature spread across Iowa... 62° to -1°.
Original post: The very strong cold front is continuing to plow eastward. To show just how strong this front is, I have a temperature trace from the SchoolNet8 (KCCI-TV and the Iowa Environmental Mesonet) weather station in Carroll, Iowa. Notice that at 7 a.m., the temperature quickly rose to around 50° (due to compression of air immediately ahead of the cold front). Can you tell when the cold front passed?The temperature fell extremely quickly with the passage of the front, and in an hour had fallen 25°. This location is now in the single digits... a nearly 50° drop through the morning hours.
This cold front will actually be somewhat dangerous. Those who are outside later this evening and aren't prepared for a sharp change in temperature, as well as drastically falling windchills, will be at some risk. Even more hazardous will be an almost flash-freeze of any moisture or slush that's on roadways, sidewalks, etc. as it will rapidly turn to ice later this evening.
Edit: Was alerted to an even faster drop - Corning, Iowa. Just insane. Looks like about a 20° drop over just a few minutes.Also, one of the Des Moines NWS meteorologists commented that the cold front passage at their office was "one of the most abrupt" he's witnessed.
36 comments:
Hey justin, 2 questions, first if we were standing outside and the front passes would we notice the temp drop right away, and second if this had been the middle of summer and we had this type of front, would this be conducive for explosive violent thunderstorms.
This winter (and last winter) seem more like the "Old Fashioned Winters" that I remember from when I was a kid.
Our winters had seemed awfully mild for quite a long time, and I was starting to wonder if my mind was just exaggerating what I remembered from kid-hood.
Much as I HATE this vicious weather, at least it makes me feel like I'm not nuts, and we really do get the kind of winter weather I thought I remembered after all.
Tony - It wouldn't be immediate, but you'd start feeling it in a matter of minutes. This is definitely one of the sharpest fronts I've ever seen. As far as your thunderstorm question... depends if all the other stuff came together correctly. Having a 40-degree drop would certainly help with the potential explosiveness... fortunately, those sorts of contrasts are rare in the summertime.
Ok, that's what I thought with the thunderstorm one. I didn't think it was likely in the summer, but I thought of it yesterday and thinking with this kind of drop, it would be possible if everything came together. I might step outside around 7 tonight barring it isnt raining and then see how sharply colder it gets.
Based on that map, I would say the front is near cedar rapids, and just west of dubuque.
Is this a type of situation that could cause roads to freeze over rapidly and cause travel problems... Possibly lasting through early tomorrow morning?
Hopefully the roads will be treated in the evening and early overnight. With temperatures free-falling, road treatments will be almost useless as temperatures drop into the single digits.
Assume road conditions will be hazardous.
What time do you think the front will push through here. I have been reading about 5pm. Also, how much snow do you think we will get with tuesdays snow.
Interesting ... I just talked to someone in Oklahoma who said that the weather there is almost exactly like the weather here ... except about 20 degrees warmer. They said it was windy and "close to 70" today but they were forecasting almost a 50 degree drop in temps...down into the 20s, which is expected to come barreling through any moment now.
Temperature has fallen from 52 degrees around 1:00PM, to 29 degrees at the moment.
It has been three and a half hours, and the temperature has fallen 23 degrees. Roughly falling seven degrees per hour.
At 4:25pm, the front had not yet passed Freeport... although I'd wager it's done so by now.
Dubuque reporting freezing rain right now. Cedar Rapids has collected 0.1" of ice.
Justin, how much ice do you think for DBQ, if CR already has a tenth of an inch?
It looks like it is pretty much over?
And, one more question, are they factoring in the rain that has fallen today and (is currently freezing, here) into the "up to a quarter inch of ice accumulation" expected?
Thanks!
Periods of ice then snow over the next few hours in Dubuque, I'd say.
As far as the "up to 1/4 inch" they mean what is expected to fall this evening... does not count any liquid rain that fell earlier today.
Thank you for updating us justin. About how long before the front passes rockford.
Salt and sand and deicer trucks won't be able to keep up. Just went out to the car to spray some deicer before it was too late-- it might be a little too late. Ice accumulation of E.05-.1" on the windshield, with sidewalk and driveway turning very icy. The temperature is 25 degrees, and the wind is very strong-- such a contrast from the beautiful 52 degrees this afternoon!
Do you agree with the NWS, Justin, when they say "up to one quarter inch?" Thanks for continuing to update us. I don't think that anyone was expecting this cold front to be so potent. :)
Remember that "up to 1/4 inch" doesn't mean "you're going to get 1/4 inch." That's just the upper bound that they think could occur within the advisory area. I don't foresee Dubuque getting an amount that high.
Tony - front will pass in the next hour or so.
Ya know.... I wonder if this could cause enough difficulties for school cancellations tomorrow... Hmmm
Don't get your hopes up. :)
I just stepped outside my house in loves park, and it feels like it has chilled down a little, but not too much. The wind is still out of the south and there is no rain here yet.
Pouring down rain in Pecatonica right now. 41 degrees. The morning should be interesting, my road doesn't usually get any attention till later in the day. ugh
Wonder how the bypass to rockford will be.
Raining pretty good here W. of Beloit also. That brisk breeze that was blowing out of the south all day has died down to just about nothing.
There are a lot of puddles that are going to be ice skating rinks tomorrow morning.
Given that, according to the 7-day forecast, once it goes below freezing tonight we aren't going to see the air temp above freezing for the next week (brrr) ... but we will have a bunch of ice on the roads and sidewalks... (grrr) ...
Justin G, could you say something about solids turning into gases without first passing through the liquid state? I.e., I know that even when it is well below freezing, the snowpack does shrink and ice does seem to erode ...
So during an extended period below freezing with what appears to be not-so-much sun .... is any of this ice going to go away by any means other than physically chipping away at it? Or had we just better make friends with it because we're going to be skating on it for the next week or so one way or another?
Ah, solid straight to gas... a.k.a. sublimation.
We do lose snow depth partially from it settling and partially from sublimation, although I would assume the latter is a fairly small percentage. I'm having to think back to my physics and chemistry days (ugh) but I would think sublimation works better when the relative humidity is very low.
Regardless, the process is slow enough to not really be worth waiting ... it's best to just tackle the problem and patiently look forward to spring when the snow finally is gone for a while. :)
I have noticed that on the weather channel, right before the pink, there is enhanced orange and red, that isnt thunderstorms is it. I have to pick my friend up in one hour and I sure hope it isn't a glaze of ice.
I would imagine it's what's known as "bright banding." The radar beam is high enough in elevation that it's picking up water-covered sleet and snow... which the radar sees as being very reflective.
Oh ok, I thought for a moment I was going to hear thunder or something. I know it is raining pretty good here in loves park, I just pray the ice holds off til shortly after 9 so I can get back home safely.
It is 8:44pm and my husband and I are driving back from the Davenport, Ia area on I-88 and about 5 minutes ago we just saw lightning..and it is only 23 degrees out..I have never witnessed that before during the winter..please be safe all if anyone is on the roads tonight..they are slick..we just saw 2 cars in a ditch on the side of the road on I-88.
Yeah, I saw lightning around 5:30PM here in Dubuque, only one strike, and it was a "blink and miss it" phenomena.
Everything has a very heavy coating of ice, somewhere in between one and two tenths of an inch... Not including the rain that fell earlier today that froze over.
Roads are incredibly icy! Just had to go to the gas station to fill up the car- I was afraid the gas may freeze overnight with temperatures dipping well below 0 degrees anticipated here.
The grass is 90% covered in a icy/frozen slushy/dusting of snow, can't even feel the grass, and where you can feel the grass, it is very "crunchy." Haha :)
Temperature here continues to fall: 9.2 degrees right now.
Winds blowing continuously at about E30mph, with gusts of about 40mph+ every once in awhile.
Looks like Tuesday might be high-end advisory (low-end warning?) snowfall, and Thursday looks nasty?
Are we out of the woods with freezing rain now based on the radars. I was at walmart picking my friend up and we had a very heavy downpour of rain, but ended as fast as anything.
Just drove home here in Rockford, and the roads got VERY slick VERY fast. If anyone has to drive tonight... try not to.
I know you're just a meteorologist Justin, but have you heard any word if they will be sending salt trucks out? I didnt see one and I've been driving around most of the night.
Haven't heard about salt trucks. I certainly hope they head out, since this sudden cold was hardly a surprise to anybody who followed the forecast in the past day or two. With each passing hour, any road treatment will become less and less effective.
I am heading out now to pick someone up and when I come back home, I will let anyone know if I see any trucks out.
Hmm... school cancellations seem like a better and better possibility. Especially with the tempuratures so cold in the morning.
School? Can we just cancel this WEEK and start over again with next week?
Just drove North on I-90 up to Madison. WI DOT was listing the Interstate in "Good Winter Driving Condidion" but I was a tad skeptical given the rain/ice we were looking at last night.
Pleased to report that the Interstate is indeed clear and dry.
Main problem was the wind, which was obviously causing "high profile vehicles" to struggle at times to stay in their lanes.
I can vouch for WI Wx Buff, roadways are not too bad this morning. They are certainly manageable as long as your car starts in these frigid conditions!
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