Wednesday afternoon weather update

 

The locally dense fog from Wednesday morning was quick to clear as the sun came up, leaving skies mostly sunny for the afternoon. This allowed afternoon temperatures to warm into the mid and upper 70s.

The clouds that developed during the afternoon will fade away as the sun sets Wednesday night. Winds will turn light as high pressure builds in over the Midwest and Great Lakes. This will allow overnight lows to fall once again into the 40s in many locations. Locally dense fog will be possible once again heading into Thursday morning, but with a little less low-level moisture in place the dense fog may not be as widespread as Tuesday night.

Mostly sunny skies will carry over into Thursday as highs warm close to 80 degrees. Dry conditions will continue into Friday as cloud cover slowly increases. Winds will also increase from the east, at times gusting to 30 mph, through Friday evening. Breezy conditions will last into Saturday with only a slight chance for a few showers from the remnants of Hurricane Helene now in the southern Gulf of Mexico. 

Dense fog advisory issued for some

Moisture leftover from the recent rainfall has allowed our Wednesday to start on a foggy note.

Visibility for a few locales have fallen under a mile ahead of the morning commute. For that, the National Weather Service has placed Winnebago, Ogle, Boone, Lee, McHenry, and DeKalb County under a Dense Fog Advisory until 9AM. If you plan to travel, be sure to use your low beams, increase following distance between other vehicles, and remain alert for rapidly changing conditions on the road.

Once the fog lets up, high pressure settling in will make for a rather pleasant Wednesday. Sunshine will dominate our skies, with a few clouds mixing in during the afternoon. Highs will trend roughly 10° warmer than Tuesday, reaching the mid 70s. 

Clear skies overnight may result in another chance for patchy fog early Thursday. Otherwise, expect more sunshine with afternoon highs ending up in the upper 70s, close to the 80° mark. 

Locally dense fog develops Tuesday night

 

Locally dense fog has developed Tuesday evening with visibility falling under half a mile in a few locations. Low visibility may cause some impacts for the early morning commute Wednesday, so be sure to use your low beams, increase distance between vehicles, and remain alert for rapidly changing conditions on the road.

Temperatures Tuesday evening have fallen into the low to mid 50s as skies have cleared following the cloud cover, drizzle, and light showers through the afternoon. The clouds for some did hold temperatures in the 60s, with Rockford's high only reaching 65 degrees. This is the coolest temperature since September 7th when the high reached 67. Where the cloud cover cleared a little sooner during the afternoon temperatures were able to warm into the low 70s.

The fog Tuesday night has formed now that the skies have cleared, and winds have calmed. Temperatures are also cooling closer to the dew point temperature, which is currently in the low to mid 50s.

The fog shouldn't last too long into the morning Wednesday as skies turn partly cloudy and highs warm into the mid-70s. Fog may once again develop Wednesday night with overnight lows falling into the upper 40s in a few locations.  

The Fujiwhara Effect: What exactly is it?

What is soon to become tropical storm Helene is forecast to bring northern Illinois additional chances for rain this weekend. 

As of this morning, this tropical entity was centered south of western Cuba. The latest from the National Hurricane Center brings soon-to-be Helene into the warm waters of the Gulf, allowing it to be strengthen into a high end category 2, possibly reaching major hurricane status prior to landfall. 

The remnants of Helene are then expected to take an unusual turn to the northwest towards Illinois as they wrap around a separate upper-level low. This is a meteorological process known as the Fujiwhara effect. It's when two separate low pressure systems rotate around one another. 

 

Forecast models have been consistent over the past few days, "slingshotting" Helen's remnants into central Illinois Saturday morning. 

For the time being, a slight chance for showers in the forecast for Saturday with slightly higher chances in place Sunday into next Monday.

 

Monday evening weather update

 

Cloud cover continues to move in late Monday afternoon and evening as moisture from a low-pressure system to the southwest inches northeast. This low will move towards southern and central Illinois Monday night bringing with it a band of rain showers.

Parts of the viewing area will see rain, but not everyone, as the rain is a little more favored for areas south and southeast of Rockford. There, a few heavier downpours could occur from Whiteside County up through central DeKalb County.

Cooler temperatures were found all around the region, only warming into the upper 60s and low 70s. Rockford's high made it to 70 degrees. This cool down seemed to be right on cue with the transition over to Fall Sunday, going from a high of 92 Saturday afternoon to only a high of 71 Sunday.

Throughout the week temperatures will warm and remain above average (average high should be the low 70s). Tuesday may be just a bit cooler as the day starts off with a little cloud cover, but clearing conditions can be expected by the afternoon. Highs Tuesday will warm into the low 70s. High pressure is then expected to build in Wednesday and Thursday leaving us with mostly clear skies and temperatures warming through the upper 70s.  Friday is looking to be a dry day before the chance for at least a few showers move in for the weekend.

  

Next rain chance slides in overnight, heaviest to our south

Relief came in multiple ways on Sunday thanks to a cold front sweeping through early in the day. 

Not only did some locales witness much-needed rainfall, but also temperatures weren't as warm. Drier air filtering in behind Sunday's rainfall will keep us cool and dry for the start of the week. Afternoon highs will end up back in the low 70s. 

 

Forecast models then show a weak upper level trough slowly drifting into the western Great Lakes from the central plains. With it will be a plume of moisture that will result in further chances for showers across N. Illinois starting closer to the midnight hour. 

It does seem that the heaviest rainfall will occur to the south and southeast of Rockford, with rain tapering off around mid to late morning. Expect overnight lows to fall into the low 50s. 

Conditions dry out into Tuesday afternoon as the associated system pushes east, though an isolated shower or two cannot be ruled out. Afternoon highs for the 3rd straight day will land in the low 70s. An area of high pressure then settles into the midsection of the lower 48, allowing dry and pleasant weather to the second half of the week. Highs will be a little bit warmer landing in the upper 70s. 

Fall-like weather to continue the rest of the week

 Parts of the Stateline saw some much-needed rainfall in the form of scattered showers and a few isolated storms through early Sunday afternoon. While this wasn't the case for all, many locations especially in Southern Wisconsin received upwards of 1-2" of rainfall. The Rockford airport recorded 1.31" of rain since midnight, the first measurable rain in over 3 weeks!

Drier air filtering in tonight will keep us dry and cool through Monday evening, but Monday night may return some moisture and a few spotty showers. Higher coverage of steady rain may be possible Southeast of Rockford through midday before drier air again cuts off rain by evening.

 

It will be cool the next couple of days, with highs in the low 70s and lows in the 50s, very close to average for this time of year. We will stay dry Monday before scattered showers return into the first half or so of Tuesday.

Looking ahead into the week, the jet stream will develop a cutoff low pressure system to our Southwest, keeping similar weather day after day in place. We will stay dry for at least Wednesday and Thursday with highs into the mid and upper 70s. Rain chances may return by the end of the week as tropical moisture form the next tropical system may get caught in the cutoff low.

For now, those are just slim chances, and the 7-day forecast reflects that as temperatures return back above average by Wednesday into next weekend.