April has been quite a rainy month so far with 1.75 inches falling at the Chicago/Rockford Int’l Airport through 3pm Wednesday. That amount is 160% of normal! While 2/3 of an inch of rain falling as a surplus is a good thing to bring our drought to an end, the forecast is not.

The forecast from the National Weather Service’s GFS model shows 2.41″ of rainfall coming in the next 16 days. That amount is more than we should receive in a typical April, 135% of normal.

Of concern is this pattern of repeated rainfall. With our rivers now flooding in Northern Illinois and Southern Wisconsin, we need this pattern to change in order to get the river levels to level off.

Meteorologists refer to this type of situation as ”high evaporative feedback.” Because our ground is saturated, it will lead to increased evaporation in the days and weeks to come. This will cause storm systems to be wetter than normal, with our models possibly underdoing the rain forecast for the next few weeks. Signals show this pattern will persist for a few weeks, possibly well into May.

With a barrage of storm systems coming through the center part of the United States over the next 1-2 weeks, prepare for rising river levels and increased flooding. Below are a few of the river gauges from this afternoon. You can see all of the levels on the National Weather Service’s Rivers and Lakes Page here.  

Posted under climate/climate change, flooding, rain, record weather, safety, science, weather geek

Today, March 11th, marks the two year anniversary of the worst earthquake and worst tsunami to ever impact Japan. The earthquake occurred 43 miles of the northeast coast of Japan and was 20 miles deep. This produced a 133ft tsunami that traveled 6 miles inland. Monumental property damage was sustained from both the quake and the tsunami, with thousands of lives lost. Despite Japan’s amazing response to the detection of the earthquake with prompted a tsunami alert live on TV within minutes of the quake, given the short distance it still wasn’t enough time. Here is a look at the tsunami alert which had estimated wave heights on screen within minutes of the first tremor. -Greg http://www.youtube.com/watch?v=24KfBwkMw_M

Posted under earthquake/tsunami, science, weather geek

If you were an observant driver on any rural Winnebago County roads today, you may have noticed these signs along the shoulders. Each year roads are posted with lower weight restrictions due to melting snow and soft ground.

This afternoon, I spoke with Joe Vanderwirth with the Winnebago County Highway Department. He said that due to the warmer weather on the horizon these restrictions are put into place in order to prevent any damage to the roads. But these signs will only pop up on certain roads. Not affected are roads and highways with a good, solid sub-structure. Concrete and asphalt roads are built on a stronger sub-structure which can take more weight. The roads most susceptible to problems are those that are tar and gravel. Joe said the surface of these roads is like the icing on a cake. If the cake isn’t firm enough, the icing will push right down, causing the road to sink and crack.

That means large trucks, fully-loaded garbage trucks, farm implements, and some buses are now prohibited from some roads until the ground firms up again. The restrictions on area roads usually last 4-6 weeks, depending on the weather.

I asked Joe about the inconvenience these pose to drivers. He said it beats the costly repairs and road closures down the road if the weight limits weren’t posted. -Eric

Posted under news, safety, science, snow, statistics, weather geek

Check out this amazing NASA video of a solar flare that occurred in July 2012. Accompanying the flare was a phenomenon known as coronal rain. Coronal rain is actually hot plasma, which cools and condenses in the strong magnetic fields produced by solar flares. The plasma is eventually pulled back toward the surface of the sun. The magnetic fields help create a visual illusion that allows the plasma to appear in patterns similar to rain, fountains, or even fireworks. -Joe

Posted under science, space, sunlight, weather geek

We’re leaving the end of the meteorological winter AND it looks like most of the snow is behind us.
As you can probably guess, February has been the snowiest month of the season, bringing us a total of 20.9 inches! If you’re ready for a break from the snow, you’ll be happy to hear that the models aren’t showing any precipitation for quite awhile.
The trend is looking drier and warmer as we head into March. Two of our more reliable models, the ECMWF and the GFS, aren’t giving us much precip all the way through March 10th! Sorry snow-lovers, but enjoy the snow that’s on the ground now. Even after this 10 day dry spell coming up, the warmer tempertures pushing through are looking to make the next moisture coming to Northern Illinois be more of a rain event than a snow event.
While all the models are agreeing on the lack of moisture and warmer temps, they are also showing the “Montana Clipper” diving south of us, keeping the precip out of our area Monday and Tuesday.
So what does this mean? Look forward to dry, relatively warmer weather while the first signs of spring are peaking through!

Posted under rain, science, snow, weather, winter weather

There is a strong low pressure system over the Gulf of Alaska on Sunday, and it is expected to be just north of the Texas panhandle by Wednesday evening. We are tracking this system with many different forecast models, including the DGEX, Euro, GFS, and the GEM. As of right now, these four models are giving us very different outcomes.

Following the DGEX, the system is forecast to track just west of us, through Iowa and up toward Lake Superior by Friday evening. Temperatures will rise in Northern Illinois with  light snow through Thursday night, and possible freezing drizzle into early Friday morning.
The Euro is tracking this system a little further south, through the Plains into Iowa, and continuing through northwest Wisconsin. The Euro is showing Northern Illinois to have below freezing temperatures Thursday evening, still holding on to the possibility of freezing drizzle early Friday morning as temperatures slightly rise.

The GFS presents a similar track as the Euro, however it’s targeting the low to be right over Northern Illinois late Friday evening. There is less moisture being forecast with this system, and it’s being maximized around midnight on Thursday. Temperatures are led to be below freezing, making snow the most reliable outcome. Precipitation minimizes as the system heads northeast over Lake Michigan.

The GEM is the outlier of the four models, and is tracking the system further south. Temperatures are forecast to remain below freezing with enough moisture to give us snowfall and no freezing drizzle. The low is then forecast to fizzle out as it pushes across Southern Illinois and heads into West Virginia by Friday night.

So, what does all of this mean? Although all the models are tracking this system through different parts of the Midwest, they’re all agreeing on two things: snowfall on Thursday and a weakening system as it moves east. Just how much snow we will get will be tricky to forecast until the system moves into California on Tuesday. Right now, it does look like a few inches are possible.

Posted under FutureTrack, science, snow, weather, weather geek, winter storm, winter weather

Persistent clouds are the reason temperatures struggled to get to 30 degrees today. Clouds have a huge influence on our daily temperatures this time of year. Their presence could make the difference between a 45 and 30 degree day! We’re going to talk degrees for a moment, but not the typical degrees…degrees above the horizon. 90° is straight above you and on the winter solstice (December 21st), the highest the sun was in the sky was only 24.3° above the horizon. As the season progresses, the sun’s elevation rises. Today, the sun’s angle was 34.2° and in one month it will raise to 44.7°. The more direct the sunlight, the warmer our temperatures will be. That’s the reason we will go from winter to spring in just a little over a month.

So, what was going on today with all the clouds?

During the winter, the low sun angle forces the sun’s rays to spread out, weakening them. If there’s a cloud deck around, these weaker rays take longer to break up the clouds. This is exactly why we had a stratus deck today, which can be directly related to our temperatures. Having these clouds blocked the sun from heating the surface, keeping things cool.

Unfortunately, the low sun angle is here to stay for a while and clouds will linger throughout the week!

*An earlier version of this blog post incorrectly stated the sun altitude angles.  The data has since been corrected.

Posted under 13 Climate Authority, science, statistics, sunlight, weather, weather geek

The freeze-thaw cycle we’ve seen in the past 4 days has really taken a toll on area roads.

And with heavy rainfall Saturday night into Sunday, things will unfortunately get worse before they get better. Above is an infographic that explains how potholes form. Click on the images to enlarge. 

The recipe of freezing temperatures, followed by rain, and then a cold night is literally causing the pavement to break up in many locations.

First, rainwater and road chemicals find their way into tiny cracks which can go deep into the sub-pavement surface. As the liquid freezes, it expands, literally pushing the pavement apart. This isn’t when the pothole forms though. It’s not until we get above-freezing temperatures once again that the liquid that caused the crack flows away. Now, we’ve gone from a crack to a small hole. Repeat this process a few times and you may get a crater! Because the melting process causes the cracks to become more pronounced, February is primetime for the worst holes to show up.

So, while drivers may be steaming mad that the city isn’t doing anything to prevent them, just know there’s not much anyone can do to prevent potholes (except repave roads every few years (which is mighty expensive)).  Hopefully, area road crews are able to patch the biggest holes before you get any wheel or tire damage. In the meantime, drive slow and cautiously.  On our 7 Day, there are plenty of freeze-thaws coming from night to day which means more potholes will pop up!

You can also report a pothole on your computer or mobile device by clicking here or by calling 815-987-5771. -Eric

Posted under safety, science, weather geek

Yesterday brought the area a considerable amount of accumulating ice as freezing rain/rain immediately froze on impact with the super chilled ground. However, many of the main roads never became iced over, even during the peak of the system. We can attribute this to the copious amounts of salt that were put down prior to the deep freeze. We all know that salt helps to melt ice, but have you ever wondered why it is so effective sometimes, and other times it just doesn’t seem to get the job done? Wonder no more! It has to do with salt’s freezing point. Salt lowers the freezing point of water/ice. Water freezes at 32°F… unless there is salt mixed in with the water. In a 10% salt solution of water, the freezing point drops from 32° to 20°, and a 20% salt solution of water drops the freezing point all the way down to 2°. This means that when you sprinkle salt on sidewalks or roadways it can melt the ice it is applied to. This is a very effective process when temps are above 20°. When they are lower, they reach the new freezing point that the salt gives to the ice therefore canceling it out. -Greg

Posted under ice, science, winter weather

Winter temperatures tend to be colder when a fresh snow pack is on the ground. A snow covered ground in January, our coldest month, tends to make the air even more frigid. Snow impacts temperatures in a few ways, the first being its affect on solar radiation. We all know that when the sun is out it heats up the Earth. It’s incoming rays are captured by the ground, vegetation, pavement, and any other objects they come in contact with. This absorbtion of the sun’s rays is how are temperatures climb during the morning and afternoon hours. However, snow doesn’t absorb the sun’s rays. It actually reflects part of them back into the atmosphere, and uses part of them to melt itself. The term to describe how good an object is at absorbing the sun’s radition is referred to as albedo. Albedo numbers are given to objects that are key players in radiation absorbtion. Values for albedo range from 0-1 with higher numbers being less effective absorbers. For example, man-made asphalt has an albedo of 0.05-0.20 meaning it is an amazing absorber (which I’m sure you could tell if you have ever walked barefoot across a parking lot in the summer. On the flip side, snow has an albedo of 0.8-0.95 meaning virtually all sunlight is reflected thus allowing for less captured heat.

Snow cover in January is also a culprit because it is one of our shortest months in terms of daylight per day. Meaning there is a shorter time frame to gain heat to begin with, much less when snow is hampering the process. Night time temperatures are also impacted by snow because at night the snow easily gives off heat allowing for quick temperature drops. -Greg

Posted under science, snow, winter weather