With melting snow, falling rain, light wind, and dewpoint temperatures close to the air temperature, the atmosphere is saturated. As a result, dense fog has formed across the region and will continue for much of the afternoon and evening.  A DENSE FOG ADVISORY remains in effect for all of the 13 WREX viewing area though Sunday night. Visibilities will be at or near zero at times, so make sure you have your lights on and take caution while driving.

-Joe

Posted under fog, safety, travel, weather

While most of us picked up under a tenth of an inch of rain due to scattered showers on Saturday, heavier rain is on the horizon.  Overnight Saturday through early Sunday, a steady, heavy rain is expected to move east out of Iowa and into northern Illinois and southern Wisconsin.  There may be a break or two in the rain midday Sunday, but more scattered showers are likely into the evening and early Sunday night.  Areas of fog are likely, too.

Numerous locations in eastern Iowa have picked up over an inch of rain as of Saturday evening, thanks to the flow of moisture streaming north from the Gulf of Mexico.  Five of the six major models I’ve monitored this evening continue to paint our region with over 1 inch of rain.  On the lower end of the spectrum, the RPM model is projecting 0.80″ while the Canadian GEM model cranks out 2.45″ of heavy rain in Rockford.  On average, I believe most of us will pick up around 1 inch of rain.  The highest totals will be west of the Rock River.

There is a flooding concern.  With temperatures hovering near 40 degrees, our 6 to 10 inches of snow on the ground will continue to melt.  Also, with a frozen ground nearly 6 inches deep, most of the melting snow and falling rain will run off and not soak into the earth.  There will be some rises on area creeks and rivers as well as some minor urban street flooding.

-Joe

Posted under flooding, fog, FutureTrack, rain, weather

The forecast has remained fairly consistent over the past few days regarding Sunday.  However, there are better indications that the bulk of the precipitation will arrive in Rockford around noon.  A brief period of sleet mixed with freezing rain is possible at the onset, while the afternoon hours should be limited to just freezing rain.  As temperatures hover at or slightly below freezing, significant ice accumulations of 0.1″ to 0.3″ are possible.  However, if the warmer layer of air in the atmosphere is able to influence our surface temperatures, thus allowing temperatures to rise a degree or two, ice accumulations will be reduced.  There is a very thin line between freezing rain and liquid rain.  Regardless of how much ice accumulation we receive, area roads will be slippery and some power outages are possible.

By Sunday evening, our freezing rain will mix with liquid rain and eventually fall as just liquid rain by nighttime.  Temperatures will rise into the middle 30s by 10pm or so.  Patchy fog will form as ice begins to melt with the milder temperatures.

Posted under fog, ice, safety, travel, weather, winter weather

Dense Fog Advisories are up for Jo Daviess, Stephenson, Carroll, Green, and Rock Counties through late morning Friday. Melting snow and little wind will cause visibilities to dip less than 1/4 mile in many locations. Please allow extra time to get to your destination Friday morning! -Eric

Posted under fog

Last week we had our fair share of dense fog with a few nights with zero visibility. Luckily, Northern Illinois and Southern Wisconsin didn’t see many car accidents. However, that was a different story on Interstate 10 near Beaumont, Texas where more than one hundred vehicles were in a crash, killing at least two people.

Jon Erdman from The Weather Channelresearched statistics by the National Highway Safety Administration and NOAA and came up with some staggering statistics when it comes to driving in the fog. There are 36,000 crashes each year involving foggy weather with 15,600 people injured. 600 people die as a result of accidents due to fog. Compare that to just 37 people per year killed by lightning. Staggering statistics! (Click here to read the full article and watch video.)

Please remember to slow down. During foggy conditions, the speed limit is too fast for conditions. Do not outdrive your headlights in case there are stopped vehicles or wildlife in the roadway. Most importantly, allow extra time so you’re not rushed on the highways. -Eric

Posted under fog, safety

Visibilities are already dropping across Northern Illinois with Freeport down to a half mile. As the air remains saturated and dewpoints rise tonight, fog will become thicker. Late tonight, another disturbance will work northeast, possibly sparking off a few rain showers and thunderstorms. This may scour out some of the restrictive visibilities late.

Use caution if you’re heading out and remember to use the low beams and ease up on your speed. -Eric

Posted under fog

11pm Sunday visibilities

Patchy dense fog will develop overnight.  Some locations will see visibilities drop below a quarter of a mile.  The patchy fog will stick around for early Monday morning.

By afternoon, we’ll have mostly sunny conditions and temperatures in the upper 80s.
-Joe

Posted under fog, weather

The National Weather Service has issued Freeze Warnings for Jo Daviess, Stephenson, Boone, Carroll, Whiteside, Ogle, Lee, DeKalb, and Green County for early Saturday morning as temperatures dip into the 20s and 30s.

You may have heard us in recent weeks forecast cooler temperatures in rural valleys. Typically, they are the coolest spots at night around here. The reason is the air at higher elevations becomes heavier and sinks as night wears on, pooling in the lowest elevations. In Meteorology this is known as negative buoyancy. The cool air descends hills along the same terrain as rain or snow would run off. When the air reaches the valley floor, it will keep cooling due to continued radiational heat loss as the night wears on.  Cold air pools can be very deep in mountainous areas but can be as small as just a few feet around here. In short, cover your plants if you’re in a valley!

Interestingly, any obstruction the cold air encounters entering a valley causes the air to stop, much like water running into a dam. In this example, a stand of trees may block the wind, causing a frost pocket.The temperature may be several degrees colder in this shaded area than the valley floor itself.

In addition, valleys with ponds or rivers can provide fog. -ES

Posted under cold blast, fog, weather geek

With a light and variable wind (generally under 5mph) and breaks in the cloud cover, some patchy dense fog has developed over parts of northwestern Illinois.  All of us will see some reduced visibilities under 5 miles throughout the morning.  Some areas near Freeport and Dixon have reported under 1/2 mile visibilities at times.  Take it slow if you are driving through dense fog, and use your low beams!

-JA

Posted under fog, safety

Areas of dense fog have formed across Northern Illinois and Southern Wisconsin. For that reason, a Dense Fog Advisory has been posted for Rock and Walworth Counties until 4am Thursday morning. Use caution if you’re traveling late tonight! -ES

Posted under fog