Isolated thunderstorms Tuesday afternoon as strong cold front moves through

 

4:33PM UPDATE: Our overall storm threat continues to decrease late Tuesday afternoon now that the cold front has passed. There has been a noticeable drop in temperatures, with many locations in northern Illinois falling into the 40s. However, clouds are clearing over parts of northwest Illinois, and this is where temperatures have made a small rebound, with Galena back into the low 60s and Monroe back to 50.

We will likely see the temperature in Rockford rebound briefly back into the low 50s before dropping into the 30s overnight. Skies will briefly turn partly cloudy overnight before turning mostly cloudy into Wednesday morning.

ORIGINAL POST: 

Temperatures continue to drop from north to south early Tuesday afternoon as a strong cold front sinks south of the state line. Winds will turn to the north, and then northeast, behind the front ushering in the cooler air mass that'll remain in place through the afternoon Wednesday.

Following a few severe thunderstorms Tuesday morning most of the afternoon has remained quiet. But there are some thunderstorms that have developed just behind the front stretching from north of Freeport, IL up towards Janesville, WI. While the threat for severe weather remains low with the storms this afternoon, a few of the stronger ones are still going to be capable of producing small hail. One such storm is currently moving through southern Rock County in Wisconsin.

The threat for isolated thunderstorms will continue through about 7pm with drier conditions expected tonight. Winds will be breezy from time to time Wednesday keeping afternoon temperatures in the mid-40s.  

Active weather pattern continues through the week

 

After quite the busy evening last night with multiple severe thunderstorm warnings issued, we're waking up to a much calmer situation this morning. As of 4:15 a.m. only a few light showers have hung around the state line with an additional thunderstorm developing over davenport. A few isolated thunderstorms will still be possible through 7 a.m. today however most chances will be higher south of Interstate 88.

Through the rest of the morning and early afternoon the chances for thunderstorms will continue. Towards 8-9 a.m. another round of showers and thunderstorms may develop however those that were to develop would most likely stay south of Interstate 88. This round would conclude by 10-11 a.m.

Another chance for thunderstorms will then evolve into the early afternoon as a cold front begins to move through. Along this front another round of showers and possible thunderstorms may develop closer to 3 p.m. If these were to develop, an isolated severe storm cannot be ruled out with large hail and damaging wind gusts (60 mph+) being the primary hazards.

Transitioning towards the next few days, we'll keep this active pattern around. Thanks to our jet stream shifting to a southwesterly orientation we'll see continued lift and moisture from the Gulf funneled up into the Midwest. This will provide plenty of atmospheric moisture for almost daily shower chances as a few low-pressure systems are also expected to bring enhanced lift to the region.

The highest chances as of now look to come both late Wednesday and into the afternoon on Thursday. These rounds of precipitation will arrive nearly as the same time as our next low-pressure system with the first wave Wednesday night arriving with the warm front with the system.

Temperatures will rise back into the 60's then on Thursday with warmer and more moist air returning to the 60's. This will not only bring the chances of showers once again but also a few thunderstorms cannot be ruled out either as some models have begun to develop some instability. Thursday will need to be watch closely for additional instability developing, as we could see our next possible round of severe thunderstorms begin to take shape.

Thanks to all these precipitation chances we'll be expecting this week to stay on the wet side in terms of our rainfall totals. By the end Friday, we can see multiple areas receive over an inch of rainfall from today and the days to come. Not only will thunderstorms be a threat this week, but the possibility of flooding will also be there with such heavy rainfall forecasted. This will be a changing forecast day by day, so make sure to tune into the First Warn Weather app and updates from the First Warn Weather team!
 

Thunderstorms possible Monday night following record warmth

 

NEW: SEVERE THUNDERSTORM WARNING for Jo Daviess, western Stephenson and northern Carroll counties until 10pm. The storm is located south of Galena, moving east at 50 mph and capable of producing 60 mph wind gusts and half dollar sized hail.

There is another storm moving through DeKalb County, right along I-88. Had a report of quite a bit of hail in Creston (likely some smaller hail but coming down with the heavy rain). This storm is just south of Malta and DeKalb. No warning with this storm, but it is producing quite a bit of lightning, heavy rain, and small hail.

7:45PM UPDATE: Skies are mainly quiet for now, but the showers and thunderstorms developing out west are the ones we are keeping an eye for our risk of thunderstorms later tonight, most likely after 9pm near Rockford. There are some isolated thunderstorms that have developed between Davenport and Clinton, IA and those could impact parts of Carroll and Whiteside counties.

ORIGINAL POST: 

It's a little taste of summer at the end of March as temperatures area-wide warmed into the upper 70s and low 80s. In fact, Rockford made it to 82 degrees which tied our previous record for the 30th of March set back in 1910! And what's even more impressive is the fact we started out in the upper 30s! But the warmth we've experienced this afternoon could lead to a few stronger thunderstorms late tonight.

Rest of the evening/Overnight:

Cloud cover will slowly increase (you're already noticing the higher-level cirrus clouds overhead) through the evening as temperatures remain in the 70s. We should stay dry through at least sunset, if not an hour or two after. Thunderstorms are expected to develop over parts of northern Iowa, extending east towards southwest Wisconsin through 8pm. Between 8pm and 10pm those storms may then move into northwest Illinois, shifting east by Midnight. The storms will be developing along/near a warm front, that currently sits well north of the state line. This front will slowly sink south, likely staying very close to southern Wisconsin and northern Illinois.

The storms will move east along the warm front posing a large hail risk, feeding off the instability we will have aloft - known as elevated instability. However, there should be a gradual weakening trend in that instability the further east you travel of the Mississippi River. The highest potential for large hail tonight could end up in Iowa, far northwest Illinois and southwest Wisconsin. Regardless, our storm window appears to be from around 9pm to 2am. There may be some widely scattered showers and thunderstorms that continue through sunrise Tuesday. Because of the risk for large hail the Storm Prediction Center has highlighted southern Wisconsin and northern Illinois in a 'slight' risk for scattered severe storms late Monday night.

Tuesday:

What happens Tuesday afternoon will depend on what we see Tuesday morning. An area of low pressure will be approaching from the west during the early afternoon, dragging a cold front through with it. We hold on to some instability as the front moves through which could trigger some additional thunderstorms during the early afternoon and evening. Should those storms form, hail and damaging winds would again be our primary concerns.

Temperatures ahead of the front will warm into the low 70s but then are expected to quickly drop behind the front Tuesday evening. By Tuesday night the front will settle to our south and this could temporarily bring an end to our precipitation chances. However, it will be pulled back north ahead of another low that could bring more widespread and heavy rainfall Wednesday night and Thursday. 

Summer like warmth today accompanied by thunderstorm chances

 

Although we may have not reached our forecast high yesterday, it was still a very comfortable day with temperatures in the low 60's! However, today will blow yesterday out of the water in terms of comfortability as certain points of the day may even feel hot outside! We'll reach into the upper 70's across the region this afternoon and combining that with mostly sunny skies, we should see at least a few spots hit 80° today.

With good always comes a little bad though, because of the summer like heat today we'll also have plenty of moisture and instability present in our atmosphere to support a few thunderstorms. However, an atmospheric cap will be in place through the day which will inhibit storms from forming during the daytime hours.

Our storm chances this evening will rely heavily on if we can break this "cap" or lid this evening. Multiple situations may occur later including the possibility of no storms developing! However, if a storm does develop, make sure to pay attention to watches and warnings as the Storm Prediction Center has outlined us in a Slight 2/5 risk this evening highlighting large hail as our primary threat.

The hail risks this evening has not only been increased in chances, but in their latest outlook the Storm Prediction Center added the "hash" or black outline to the outlook highlighting the potential of significant hail this evening. That means, if storms do form later on, the environment will have the potential to support storms capable of producing 2+ inch (egg-sized) which can cause significant damage! These storms may not hit till the overnight hours, so make sure to keep your cellphones on to make sure you can listen to watches or warnings that may be issued later. 

Storms possible Monday night and Tuesday, soaking rain mid-week

 A mild start to the day Monday will result in a very warm afternoon as temperatures push into the upper 70s and near 80 degrees in a few spots. That warmth also comes with substantial instability, or storm energy, to fuel potential thunderstorms beginning Monday night.

But that potential will not be tapped into right away because of a cap in the atmosphere. That cap will prevent storms from developing until at least late evening and could prevent storms from developing altogether. Best chances to break through this cap appear to be after 9-10PM and mainly across Southern Wisconsin.

Any storms that are able to break through the cap will have that instability to tap into. A few isolated storms could turn strong to severe as a result. The primary nighttime window of storms will promote a threat for mainly large hail, but gusty winds may also be possible. The Storm Prediction Center has placed the entire Stateline under a Level 1/5 risk for severe weather, indicating an isolated storm may be able to produce severe weather.

That cap will be much less of a problem with daytime heating on Tuesday pushing surface temperatures into the 70s again. A cold front will be the initiating point for storms Tuesday morning and afternoon. Similar to Monday night, we will have substantial instability to work with. The limiting factors Tuesday will be morning showers that could eat into the afternoon energy and the speed of the cold front which could arrive before the end of peak heating. The main threats this time around will be with wind and hail as the SPC has another Level 1/5 Marginal risk for Tuesday.

 

Monday and Tuesday is just the beginning of an active weather pattern through the next week ahead. Behind Tuesday's front there will be brief break in the widespread rain through Wednesday morning. But additional showers return Wednesday night. In total through the end of the week, several spots could see more than an inch of rainfall with pockets of likely higher totals where repeated rounds of storms pass through. There could be a risk for flooding Wednesday night into Thursday as that is when the heaviest rain may come down.

Unseasonable warmth with thunderstorm chances to start the week

 

Starting today, our temperatures will begin to slowly creep back average as high temperatures will be in the 60's and 70's over the next few days! That's in thanks to a consistent southwesterly breeze that will help to steadily improve temperatures along with an arriving low-pressure system by Tuesday morning that will also bring the possibility of a few thunderstorms.

The first of those chances will come late Monday night and into Tuesday morning as a weak disturbance moves overhead. With warm and humid conditions setting up for Monday, instability will gradually develop throughout the day however an atmospheric cap or "lid" will be in place keeping storm potential limited. If we can lift the cap later into the evening, the instability available would support a few isolated thunderstorms which would also carry the potential of producing hail, strong wind gusts, and heavy downpours.

As for Tuesday, if a few thunderstorms fire overnight, another round may still be possible with the disturbance aloft until the morning. However, the higher chances will come later into the afternoon as the arriving cold front may also spark off a few showers and thunderstorms.

Plenty of atmospheric instability is expected to setup both on Monday and Tuesday which will be the main fuel for thunderstorms if they do occur each day. Along with that, some dry air from our west will allow any thunderstorm to develop to carry the potential of large hail and will be capable of producing a damaging wind gust or two. As of now the Storm Prediction Center has the state line outlined in both a Day 2 and 3 Marginal Risk for the possibility of isolated severe thunderstorms. Expect chances to the forecast in the coming days, so make sure to keep an eye on the forecast!

Continued warmth fuels thunderstorm risk Monday night

 It's been a cooler stretch in the Stateline lately, but that's about to change in a big way next week! Starting Sunday, temperatures will rise back above average for the early part of the week. Highs push the mid-60s Sunday, then 70s Monday and Tuesday. Overnight lows will be very mild starting Sunday night, remaining in the 40s and 50s. That is, until our next cold front arrives.

Ahead of this front, we will see substantial instability, or storm energy, develop in the atmosphere Monday. The afternoon will be capped, preventing much if not all storm development. But overnight that cap will erode, allowing storms to form in Northern Illinois and Southern Wisconsin. Timing looks to be primarily after 10PM Monday.

A few of these storms may be capable of producing large hail and gusty winds. Any storms that produce 1" diameter hail or 60 mph wind gusts will reach severe limits. The Storm Prediction Center has placed Northern Illinois into Central Wisconsin under a Level 1/5 Marginal Risk for severe weather, indicating a few severe storms may be possible. Our primary threat will be with the large hail, but an isolated severe wind gust cannot be ruled out either.

Additional showers and storms will be possible along a passing cold front Tuesday as well, with a similar risk for some isolated severe storms. The best coverage will pass South and East of the area by Tuesday evening as cooler and drier air arrives through the course of the day. High temperatures Wednesday and Thursday will likely be back in the 40s.

Warming up this weekend with an elevated fire risk

 After a chilly and breezy Friday, this weekend will bring a steady rise in temperatures back above average. From the low 20s Saturday morning, the afternoon will see highs push back toward 50. The surface high pressure responsible for the chill will slide overhead and past us to the East by then, turning the winds back around to the South and Southwest. Sunday's high temperature will climb even higher, reaching into the low 60s.

That Southwest wind could gust toward 20-30 mph Saturday afternoon, and even higher across Iowa and Minnesota. But moisture will lag well behind the increase in winds. There is still some uncertainty about where dew point temperatures will be in the afternoon, but relative humidity percentages will be close to or below 30% much of the afternoon.

That combination of stronger winds and low humidity will develop a risk for brush fires. Dry vegetation will burn easily, and the stronger winds could allow for fires to spread rapidly. Avoid burning outdoors Saturday! Sunday could also bring some fire danger, but conditions will be slightly better to prevent widespread risk for brush fires.

The fire risk is only elevated locally but will reach critical levels to the West. Even drier air with stronger winds will result in extreme fire danger across much of the Plains including Minnesota and Iowa. A Red Flag Warning stretches from Minnesota to the Texas Panhandle, signifying the higher risk for brush fires. That's not to say our risk isn't significant, but the more extreme risk will stay just outside of our area.

Bundle up Friday—Milder days return this weekend

Temperature Tumble:

If you think it feels like a completely different season this morning, you're not imagining things. A strong cold front swept through the Stateline yesterday and flipped our weather pattern quickly. After starting the day in the upper 60s and low 70s, temperatures fell into the 50s by the afternoon, and now we are waking up to the 20s and 30s this morning.  

Chilly, Breezy Friday:

Cold air remains locked in place today and into the start of the weekend, though we remain dry. This will give us plenty of sun, however, an organized wind out of the north and northwest will cap afternoon highs in the mid 40s. Bright skies, but a definite bit in the air as we head into the weekend. High pressure will track over the region tonight, leaving us dry but also chilly with overnight lows in the low 20s. 

Weekend Outlook:

Changes are scheduled to spill in over the weekend, allowing this cool-down to be brief. High pressure will shift to our east by Saturday afternoon, allowing winds to turn to the southwest. That will help highs climb back around the 50-degree mark. The trend continues into Sunday, when even warmer air spills in and places highs in the low 60s. Expect this warm up to carry on into next week as forecast models place a warm front to the Stateline's north. 

Warmer, more active pattern begins next week into April

 A few isolated storms developed along a passing cold front Thursday afternoon and evening. Behind that cold front, temperatures drop as a pocket of cooler and drier air works through the area this weekend. But looking ahead to next week, another pattern change is right on its heels.

Stronger Southwesterly flow aloft will develop, which will work to rebound temperatures quickly back above average. This will also work to feed abundant moisture our direction, developing higher chances for rain and potentially some storms.

First with temperatures: The cooler air does not last long as we quickly flip the surface wind back to the Southwest, aiding to bring in the milder air mass into early and mid-next week. A Northerly wind will keep us in the mid-40s Friday, but 60s are back by Sunday with 70s to follow Monday and Tuesday.

While we should be dry through at least Monday afternoon, rain chances will begin to ramp up after Monday evening into Tuesday. Each wave that moves through will determine timing of the next, but we will be entering a more favorable pattern for widespread, soaking rainfalls beginning early next week. First chance for widespread rain begins Monday night into Tuesday.

Thursday afternoon thunderstorm update: Severe risk shifting further south

 8:50PM UPDATE: Our storm threat has pretty much ended across northern Illinois as storms continue to shift to the south. Colder air remains in place with temperatures now in the 30s to our north and northeast. Skies will remain mostly cloudy through the night as temperatures gradually drop back into the upper 20s.

5:35PM UPDATE: Scattered showers with a few embedded thunderstorms continue to move across northern Illinois Thursday evening, with severe storms further downstate. The storm over DeKalb County will be capable of pea sized hail as it quickly moves into Kane County. We may see a small increase in shower coverage through 8pm, but the severe threat is quickly shifting south of the viewing area.

Scattered showers with a few embedded thunderstorms have developed over northern Illinois the last few hours, but the storms have remained below severe limits. In fact, our overall thunderstorms risk has decreased and shifted south as the cold front continues to press south late this afternoon.

The threat for showers and embedded thunderstorms will continue across the Stateline as an upper-level disturbance moves in from the west with a little more coverage developing most likely after 6pm or 7pm. The strongest of the cores may still be able to produce some small hail, along with heavier downpours, but the threat for larger hail remains south of I-88.

The latest severe outlook from the Storm Prediction Center has shifted their outlook for scattered severe storms further south. This lines up better with where the cold front sits, higher instability and incoming upper-level disturbance.

Scattered showers and embedded thunderstorms will continue locally through about 9pm or 10pm, with a gradual clearing in skies through the night. Northerly winds will push temperatures into the 20s Friday morning.