Windy and warm conditions could lead to elevated fire risk this weekend

 

The summer heat will carry over into the month of October as temperatures are forecast to remain in the 80s through at least the weekend, if not early next week. Tuesday's high made it to 86 in Rockford, 16 degrees above the average high of 70.

The average high temperature for the first of October should sit right around 69 degrees, but it looks like we'll warm right back into the low 80s for the afternoon. There will be more cloud cover thanks to a slight increase in gulf moisture late Tuesday night and Wednesday. Unfortunately, this won't bring us any rainfall, but it will help filter out some of the sunshine for the afternoon. That moisture slowly shifts away from the region Thursday as temperatures climb back into the mid-80s, then upper 80s Friday and Saturday.

The bump in temperatures will also come with an increase in a southwest breeze, which at times could gust as high as 20-25 mph - especially Saturday afternoon. The dry and warm conditions, when combined with the breeze, could elevated the fire risk this weekend. This could become a concern as harvest is in full swing, elevating the crop fire risk Friday, Saturday, and Sunday. Along with that, brush fires could also be an issue from any outdoor burning. Please use caution while harvesting, and it may be a good idea to limit any outdoor burning this weekend.

High pressure sticks around as tropical activity continues in the Atlantic

 

A major hurricane continues to churn well off the southeast coast Monday evening as a tropical storm continues to gain strength and is forecast to become a hurricane within the next 24 hours. Hurricane Humberto is a category 4 hurricane with maximum sustained winds of 140 mph. It is currently moving to the north/northwest around 13 mph but will eventually take a turn back to the northeast, moving it further out into the Atlantic by the middle to end of the week.

Tropical Storm Imelda is expected to strengthen, reaching category 1 hurricane strength Tuesday. It is currently off the east coast of Florida with maximum sustained winds of 65 mph and moving north at 9 mph. It, too, will begin to turn back to the northeast Tuesday afternoon - possibly strengthening into a category 2 hurricane Thursday - but not expected to make landfall along the southeast or east coast of the U.S. It will, however, impact Bermuda where Hurricane Watches have been issued as the storm nears by the middle of the week. Tropical storm conditions can be expected beginning Wednesday afternoon with heavy rainfall expected and potential flash flooding conditions. Heavy rain may also occur along the coastal Carolinas which could cause localized flash and urban flooding through Monday night.

High surf and swells from both Humberto and Imelda can be expected, producing dangers rip currents and marine conditions along the east coast over the next few days.

These two Atlantic tropical systems have created sort of a 'back up' in our atmosphere, helping to buckle the jet stream overhead with high pressure building across the Midwest and Great Lakes. Tropical systems are very efficient at releasing a lot of heat into the upper levels of the atmosphere which can cause periods of above average warmth.

Throughout the week the upper-level ridge will eventually begin to break down some, but we really won't see an influx of cooler air. In fact, some of the longer-range outlooks continue to highlight a higher probability for above average temperatures continuing through the middle of the month. A slightly wetter pattern may develop, but right now it looks like the highest chance for any significant rainfall may bypass us to the north. I did introduce just a small chance for precipitation Tuesday, but that at this point is only at 20 percent. 

 

Atlantic hurricane season starting to ramp up

 

There hasn't been much noise this season so far in terms of tropical weather so far however the Atlantic hurricane season seems to be ramping up a bit! There are now two named storms off United States Eastern coast with one impacting the Bahamas. The first of which has already made news headlines which is Hurricane Humberto as just a couple days ago it reached Category 5 strength! Thankfully this system is expected to stay over water and not affect the United States coast.

The most recently named storm is Hurricane Imelda which is at Tropical Storm intensity over the Bahamas. This storm is expected to move north and then eastward heading away from the United States, however, is expected to reach Hurricane status.

Both storms can clearly be seen by satellite pushing off the east coast this morning and as of now it's pretty easy to tell which one is the stronger system. Most eyes shift right towards the organized cyclone off farther to the east off the United States and rightfully so as it's easy to tell that Hurricane Humberto is much stronger right now (Category 4 strength currently). Over the Bahamas a more disorganized complex of thunderstorms has taken shape which is the start of Tropical Storm Imelda. As this storm moves north and east it will begin to strengthen however it is not expected to get as strong as it's bigger brother off to the east. 

Unseasonable warmth continues into October

 Despite the very cool start to September, we finished the month on a very warm note with the entire second half of the month featuring above average temperatures. This included already 8 days with highs above 85° in Rockford, all since the 12th! On average, Rockford only averages 5 days with 85° highs in the month of September.

We may be able to add another day or two to that tally before the month is up, as forecast highs are expected to reach the mid or upper 80s Tuesday and Wednesday, the 29th and 30th of the month. Easterly winds and a few more upper-level clouds temporarily drop afternoon highs a bit Wednesday and Thursday to the low 80s, but we will keep with the well above average trend all the way through the week ahead.

This warm pattern does not come with any rainfall chances for at least a week or so. We may finally begin to see a pattern change with the ridge breaking down next weekend. That will bring an increasing wind aloft and at the surface, which may cause some brush fire concerns over the weekend given how dry everything is.

Weather pattern stuck on repeat through next week

 It has been a warm stretch in the Stateline, with many daytime highs reaching the 80s, including the mid-80s Friday and Saturday. We will see subtle differences in the high through much of next week, but generally we are left with more of the same. Afternoon highs will push the 80s most days while overnights will drop to the 50s. There is a daily chance for at least some patches of fog, but likely not nearly as widespread or dense as Saturday morning.

This warm pattern also comes with zero chances for rain at least through the end of the upcoming week. Long-term outlooks begin to hint at slim chances toward the following weekend. Multiple rounds of heavy rain may be possible as abundant tropical moisture approaches parts of the East coast early next week. Soon-to-be Tropical Storm Imelda will approach the coast before spinning back out into the Atlantic. We will not see any impacts from this storm locally.

Dense fog possible through Saturday morning

 

Dense fog has already begun to set in some spots through the early morning and is expected to continue for the next few hours. Overnight a weak front/boundary stalled out over the state line which has allowed locally higher dewpoints in some spots which has helped develop dense fog in some spots this morning.

As seen by our Sky Track camera in Beloit, Wisconsin the heaviest of the fog is currently in Southern Wisconsin with visibility a bit lower the farther east you go. Conditions may continue to worsen through the morning as with cooler temperatures through the morning we may be able to develop a bit more fog. If you are heading out this early morning, especially in Southern Wisconsin, make sure to give yourself extra time to travel along with extra space for cars on roadways.

For Northern Illinois, trends in fog will be closely monitored however visibility doesn't appear to be as difficult as areas further north. Through the morning though if the previously mentioned front begins to dive south some of the heavier fog may follow.

Dense Fog Advisories are in place for all Green, Rock, and Walworth counties this morning as visibility may drop to a quarter mile or less through the morning. Luckily though, this expires at 8 a.m. when conditions are expected to improve. As we go into the late morning sunny skies will appear over the fog allowing for warmer temperatures at the surface and will clear fog quickly.
 

Dry pattern allows for large daily temperature swings

 Temperatures rose more than 30 degrees from this morning's lows to the afternoon highs. Similar swings will continue into next week as the drier air allows for quicker heating in the morning and cooling at night. Daily highs will reach the low/mid 80s, while lows fall to the 50s.

Dew point temperature is one of many ways to measure moisture at the surface. With low dew points in the 50s, temperatures are able to rise quickly in the morning and fall just as quickly at night. Clear sky also aids in this feature, called radiational heating and cooling.

Areas of fog possible Friday night

 Under another clear sky, we will see patches or area of fog develop overnight. The highest coverage of fog looks to be primarily North and East of Rockford, but patchy fog may be possible across all of the area. Thickest fog may drop visibility down below 1 mile for some.

Under the mostly clear sky and a light Southerly wind, temperatures will drop into the mid 50s. Any fog we see overnight will not last long into Saturday morning, as sunshine will warm us back to the mid-80s by the afternoon.

Very dry stretch ahead may raise drought conditions

 

It's been a dry start to fall already with very few thunderstorm chances in the month of September. We would normally expect this month to produce around 3.13" of rain by this point however the state line has only seen a third of its monthly rainfall for the month of September with this year producing only 1.05" up to this point. Because of this drought conditions have become a bit more prevalent in some parts of the region as noted by the Drought Monitor.

Although conditions across Northern Illinois and Southern Wisconsin aren't as severe as areas further south, another upcoming dry spell could raise concerns a bit.

Over the next week we won't see any chance for much precipitation let alone considerable of heavy precipitation. A large upper-level ridge is expected to develop through the entire week which will send any available lift or forcing for thunderstorms well to our north. At this time as well very, little atmospheric moisture will be available for showers or thunderstorms to develop as any moisture available will be near a tropical system in the Carolinas.

Because of the lack of both moisture and forcing very little if any precipitation is expected occur over the next week. This will continue to dry out both crops and grass along with other vegetation at the surface which may lead to worsening drought conditions. Although most crops are past growing season, as fall approaches wind speeds at the surface often increase due to low pressure systems. If this occurs with very dry conditions at the surface, we may have to think about wildfire potential heading into October. 
 

Warm days and cool nights this weekend

 A broad region of higher pressure and drier air will slide overhead into the weekend. This will lead to many warm afternoons and cool nights. Afternoon highs will reach the low 80s while lows tag the 50s through this weekend. There is a chance for patchy fog a few nights, especially Saturday morning.

Relative humidity is forecast to be around 95-100% early Saturday morning, which could enhance some of the fog potential. There is a bit of uncertainty on coverage and thickness of the potential fog, but the threat for areas of fog seems to be highest Friday night into Saturday compared to other surrounding days.

The warm and dry pattern sticks around throughout the entire week ahead. Very little of the Central U.S. will see any measurable rainfall through at least the middle of next week. Zero rainfall is forecast in Rockford through at least Thursday. However, significant rainfall may be possible across the Carolinas with a tropical system. This system will likely strengthen into Tropical Storm "Imelda" within the next few days, according to the National Hurricane Center's latest forecast.

 

Above average temperatures with very little precipitation to come

After yesterday gave us a bit of a break from 80-degree temperatures we will see much of the same stick around into today. Temperatures today will be slightly warmer thanks to more sunshine while conditions at the surface remain comfortable, calm and dry!

Heading into the next few days temperatures will slightly warm as an upper-level ridge will set in over the Midwest allowing slightly warmer temperatures to creep northward. By the beginning of next week temperatures will be summer like, however with the humidity thankfully!

Although temperatures will be slightly warmer, we won't have to worry about precipitation ruining outdoor events over the next week. As mentioned, humidity won't be the biggest concern as we'll see temperatures be summer like, but our atmospheric moisture will stay dry over the next week. Combine that with very weak upper-level winds, there won't be much forcing or lift available to create showers/storms.

This may sound great to some; however, the drought monitor for Illinois has begun to look a bit concerning as we've gone through the month. Luckily for Northern Illinois we've been able to receive some rainfall during the late summer however areas further south may feel bigger impacts with the dry pattern setting in. 

 

Unseasonably warm and dry stretch to close out September

 After a brief stretch of cooler and cloudy weather, we will see a return to summer-like warmth to take us through the last week of September. The upper level pattern will flip on its head over the weekend, bringing another ridge of high pressure over the Central Plains and Midwest.

This will boost our temperatures back to the 80s over the weekend and much of next week. Average high temperature this time of year is near 70 degrees but forecast highs will be about 10+ degrees above that into the weekend.

Only 4 years in Rockford's history have seen the last week average an 80-degree high: 1897, 1905, 1953, and 2021. This year could become the 5th to average an 80-degree high, as our current forecast would result in an average of exactly 80 degrees over the last week of September.

5 days this week are forecast to reach at least 80-degrees. Only 2 other years have seen 5 days reach 80 in the last week of September: 2014 and 2021. Again, 2025 could add to this list as Friday (26th) through Tuesday (30th) are forecast to reach 80 or higher.

This warm pattern also comes with a lack of rainfall. Many computer models are forecasting zero rainfall across Northern Illinois through at least next Wednesday, if not longer. The upper-level ridge may finally start breaking down toward the end of next week, signaling an eventual pattern change after the first few days of October.

High pressure to keep our weather warm and dry into next week

Cloud cover, and a little bit of fog kicks off what is to be a rather seasonable day. Skies will clear up as the morning progresses, leaving us partly cloudy by midday and for this afternoon. 

Temperatures, thanks to a light northeasterly wind, will be end up a little different from the previous few days, landing in the low 70s which is on par for late-September. Conditions then remain quiet overnight as high pressure settles over the Midwest, allowing overnight lows to fall into the low 50s.  

Forecast models then show the upper-level low over the Great Lakes progressing eastward, allowing a ridge to develop out west. This ridge will then shift east, displacing the jet stream north into Canada over the weekend into next week. 

 

  

What does that mean? That means this long-lived summer-like stretch isn't going to back down one bit as we turn the page into October. 

High temperatures to round out the work week will hover around the 80° mark, then climb further into the low 80s Saturday, Sunday, and Monday. Compared to average, this winds up 10° to as much as 13° above late-September standards. 

Rain chances remain very very slim during this stretch. Even with a cold front sliding through late in the day Saturday, it won't have the supply of moisture needed to produce any rainfall. 

Isolated thunderstorms remain likely along advancing cold front

 

A few isolated showers and thunderstorms have developed along a southward advancing cold front Tuesday evening, stretching mainly from Whiteside into Lee County. These storms will continue to move south through the rest of the evening as slightly drier, and cooler, air moves in from the north.

Temperatures are already beginning to fall north of the front with a few locations falling into the upper 60s under a northeast breeze. As the evening settles in there may be some clearing but moisture moving in from Lake Michigan will cause cloud cover to fill back in along with the development of a little fog. Temperatures tonight will fall into the upper 50s, warming into the low 70s Wednesday afternoon.

The precipitation expected for Tuesday night will remain isolated and should quickly weaken as we near sunset. Cloud cover will be slow to clear which will lead to a mostly cloudy, and potentially foggy, start Wednesday.

Summer-like air to stay as we enter the final days of September

While Monday marked the seasonal transition from summer to fall, it has felt anything but fall-like here in the Stateline the past 2 weeks. 

That trend is not only set to continue this weekend, but also into the final days of September. 

Now, we do have a cold front sweeping through this morning, which will leave highs somewhat cooler in the upper 70s. Compared to late-September standards, this ends up 4° above-average.  

 

 

Cloud cover hangs tight and with that cloud cover may come a few showers and thunderstorms. Unlike Monday, any thunderstorm that does manage to form will showcase non-severe characteristics. Overnight low temperatures will end up a smidge cooler in the upper 50s. Some may even wind up in the mid 50s IF a fog layer can become established. If so, you may need to give yourself a few extra minutes for travel for tomorrow morning's commute.

On the backside of today's cold front, low pressure sweeping to our south will keep surface flow out of the northeast, so off Lake Michigan. This will help bring afternoon highs down closer to average for not only Wednesday but also Thursday. Depending on the northern extent of the precipitation shield, we could see a few showers Wednesday. 

The midweek cooldown is brief as summer-like air makes a quick return for the weekend. There is a cold front that forecast models bring in during the first half of our Saturday. However, there isn't much cool air that comes along with it, which will leave afternoon highs near 80° into next week.

Weather to remain somewhat unsettled for the first few days of fall

Astronomical fall begins today at 1:19PM. That is the moment when the sun's light crosses the celestial equator, resulting in nearly equal amounts of daylight and darkness for all parts of the Earth. Sunrise will be at 6:44AM while sunset will be at 6:52PM.

With the first afternoon of fall comes above-average temperatures as well as the chance for additional rainfall. Chances will be isolated and low during the day, though coverage will increase after sunset as our next cold front approaches. Especially for those north of the Illinois/Wisconsin border.

  

For that, the Storm Prediction Center has placed areas north of Freeport, Savanna, Rockton, and Poplar Grove under a Level 1 Marginal Risk. The biggest concern with any storm that becomes severe will be hail up to quarter size in diameter and winds up to 60 mph. By Tuesday afternoon, the focus for further development along this boundary will shift south of I-88. But just to be safe, I did leave an isolated chance for a shower or thunderstorm. 

Temperatures will end up cooler and not as summer-like, landing in the upper 70s today and tomorrow, then in the low 70s by Wednesday. Overnight lows will be rather comfortable, dropping into the low 60s the next few nights before dropping back down into the upper 50s Wednesday night.