Waterspouts possible this weekend

Waterspouts aren't a weather topic that we frequently talk about here in northern Illinois. 

However, this is typically the time of the year (late-summer/early-autumn) where they become very common across the Great Lakes.

Why? Well, waterspout formation all begins with water temperatures. It's at this point in the year where the lakes are at their warmest levels. The combination of that along with the insertion of a frigidly cold airmass aloft spells a conducive environment for lake effect showers and storms. Add some rotation and you get the potential for waterspouts.

Believe it or not, waterspouts fall into two categories, fair weather and tornadic. Waterspouts that are tornadic may begin as a tornado and then move onto a body of water. They also can form as severe storms roam over a body of water. Fair weather waterspouts on the other hand usually form along a flat base of a line of maturing cumulus clouds and are generally not associated with thunderstorms. While tornadic waterspouts develop downward from a thunderstorm's base, fair weather waterspouts develop on the surface and work its way up towards the base.

Sunshine to dominate our skies for a fifth straight day

Each of September's first three days have been nothing but 10 out of 10s, all featuring plenty of sun and very comfortable temperatures.

Despite this "big bubble, no trouble" high pressure system pushing further east, it will still have enough influence on our atmosphere to keep the perfect weather around for our Wednesday. Sunshine will dominate our skies from start to finish. 

That along with winds becoming more organized out of the south will allow afternoon highs to reach the low 80s. Thankfully, humidity will not be a concern this afternoon. The night kicks off with mostly clear skies, though a few clouds will drift into the region just before sunrise. This will make for a warmer and more seasonable start, leaving low temperatures in the upper 50s.

Cloud cover will gradually increase as Thursday progresses as our next cold front approaches from the northwest. With this front will come the chance for scattered showers and an isolated thunderstorm or two, especially during the Thursday evening and early Thursday night time frame. In the end, rainfall totals will end up at or below .25".

 

Behind the cold front, afternoon highs drop back into the low 70s for Friday. Cloud cover hangs tight, leaving skies partly to mostly cloudy. With Friday's cloud cover does come a slight chance for spotty afternoon shower or two. Overnight, temperatures will fall into the mid to upper 40s. Forecast models show the coldest air arriving on Saturday as an upper-level trough moves into the Great Lakes. This will leave highs in the low to mid 60s Saturday afternoon and overnight lows in the low 40s.

Below average precipitation expected through mid-September

Rain has been lacking as of late and the drier than normal conditions are anticipated to continue for at least the next week, if not longer. The latest long-range outlook from the Climate Prediction Center shows a higher probability for the drier than normal conditions through the middle of September. This, as temperatures are expected to warm back up.

September 1st marked the end of Meteorological Summer (June, July, August) and beginning of Meteorological Fall (September, October, November). Astronomical Fall begins later this month. But looking back over the last three months Rockford averaged 14.48 inches of precipitation, which is just over 1.2 inches above normal. Rainfall was down during the months of June and August, but up nearly four inches in July!

While this did help with the dry conditions that were beginning to develop in early Summer, we are beginning to see those drier than normal conditions develop once again across northern Illinois and southern Wisconsin.

The latest drought monitor from the National Drought Mitigation Center shows some counties in northern Illinois and southern Wisconsin as drier than normal. And while not officially in drought conditions just yet, the below average precipitation expected likely won't help much.

We do see some rain showers late Thursday evening with a cold front, but rain totals are only expected to be around 0.10-0.20 inches.

Tuesday morning weather update

Last week's stretch of intense summer heat feels like a thing of the past with how comfortable it has been over the past couple of days. 

For the third straight day, afternoon temperatures at the Rockford Airport registered cooler than average in the upper 70s. With high pressure locked over the Great Lakes, we can expect a 4th straight day in the 70s before our next warm up commences.

If you're getting back into that daily routine, know that Tuesday will be no different. Fair-weather cumulus clouds will mix with sunshine throughout the day, leaving afternoon highs in the upper 70s. Skies turn mostly clear overnight, allowing radiational cooling to once again be more effective. This will leave temperatures pleasant and cool near the 50° mark by Wednesday's sunrise.

This slow warm up continues into Wednesday as this  high pressure system pushes further east. This will land our afternoon highs back into the low 80s. Along with this temperature climb does come an slight uptick in humidity levels. 

Not to worry, I’m happy to report that levels won't be even close to the highly oppressive levels that were felt early last week. The highest our dew points look to get is the low 60s and that's ahead of the cold front slated for Thursday. Speaking of that front, showers and possibly a thunderstorm or two will develop along and behind it as it sweeps through the western Great Lakes Thursday night into early Friday morning. Severe weather is unlikely. 

The bigger weather headline with our next frontal passage is the fall-like air that filters in behind it. Rapid cooling just above the surface will translate to surface temperatures in the low 70s Friday, then in the low 60s for Saturday afternoon. Overnight lows Friday night will land in the upper 40s, then closer to the 40° mark Saturday night. After a few lingering showers Friday, dry conditions quickly settle in for the remainder of the weekend. 

Labor Day afternoon weather update

Skies have turned partly cloudy Monday afternoon as high pressure moves across the Great Lakes, warming temperatures into the low to mid 70s. It's been a very comfortable early September day!

As high pressure remains in control across the Great Lakes Monday night skies will clear after the sun sets, leaving mostly clear conditions overnight. This will allow temperatures to drop into the low 50s, with a few outlying areas possibly falling into the upper 40s.

By Tuesday afternoon high pressure will begin to drift further east, setting the stage for a slow warming trend through the middle of the week. Temperatures through Thursday will warm a few degrees each day, with the low to mid 80s expected Wednesday and Thursday. A cold front will pass Thursday night bringing a chance for a few showers, perhaps an isolated thunderstorm, but no severe weather is expected. Spotty showers will continue Friday as the wind picks up from the north. This will keep afternoon temperatures in the low to mid 70s under mostly cloudy skies. A much cooler air mass settles in for the weekend with afternoon highs likely not making it out of the 60s. But that chill is short-lived as we begin to see another warm-up heading into next week. 

Big bubble, no trouble; Sun-filled Labor Day ahead

As my weather director back at Millersville always liked to say, "big bubble, no trouble". In other words, if you loved Sunday's weather, you'll be a big fan of the forecast for the Labor Day holiday. 

High pressure sitting close by will make for another sun-filled and refreshing afternoon. Winds will shift from the northeast to the east, limiting afternoon highs to the mid 70s. All in all, a perfect 10 out of 10 for outdoor holiday activities.

In fact, to make a long story short, skies will remain quiet until this "big bubble, no trouble" high pressure drifts away sometime late Wednesday. This is when forecast models show our next disturbance taking shape. This will help sweep a cold front through the region late Thursday into Thursday night, bringing with it a wave of showers and possibly an isolated storm or two. Some of this activity may linger into Friday depending on the front's timing. 

Ahead of the frontal passage, highs sneak back into the low 80s Wednesday and Thursday. Once the front is to our east, winds will take a turn to the northeast, allowing yet an even cooler air-mass to spill into the western Great Lakes. Afternoon highs will end up rolling back into the low 70s for Friday, then into the upper 60s for the upcoming weekend. Overnight low get chilly, landing in the upper 40s Friday night, then down into the mid 40s Saturday night.

Clear skies and cool temperatures through Labor Day

 Sunny skies allowed for a pleasant Sunday in the Stateline, with highs reaching into the mid-70s for most. It will remain clear through the night following last night's cold front. This will allow for overnight lows to drop into the low 50s and upper 40s even for some.

Even more pleasant weather on the way for Labor Day, with temperatures starting out cool in the morning, but warming into the mid-70s again for the afternoon under mostly sunny skies. This is big change from last year, when we hit a high of 92° on Labor Day!

The trend of sunny and cool days continues into the middle of the week, with highs rising a bit day after day through Thursday when we see highs back in the low-80s. This comes with our next upper-level wave, bringing rain and isolated storm chances Thursday evening into Friday morning. This upper-level trough then looks to settle in over next weekend. It will be another seasonably cool stretch with highs back near 70° and lows in the 40s!