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. 

Strong cold front to bring isolated strong storms, brief cool-down

Warmth Continues: 

Spring has wasted no time making itself know in the Rockford area this year. Since March 1st, Rockford has logged four days with afternoon highs reaching the 70° mark, including yesterday. 

 

 

This taste of spring-like weather will try to make another appearance this afternoon as temperatures climb towards the 70° mark. However, we will likely come up just short as a strong cold front is scheduled to push through during peak-heating. 

 

  

Severe Potential:

Staying on the topic of today's cold front, the severe weather threat has also diminished due to the timing of the frontal passage. With the front pushing south earlier in the day, the best values of instability and wind shear will be displaced south. 

This shifts the higher potential for strong to severe storms well to the south and southeast of the area, leaving most of the viewing area under an isolated threat. There is a sliver of Lee and DeKalb County under a level 2 Slight Risk for severe weather. 

A few sprinkles and showers will be possible during the afternoon and into the evening. If a thunderstorm were to briefly form, it would likely pop along or just south of highway 20 and track south and southeast as we enter the evening hours. IF we do end up seeing a strong or severe storm, large hail and damaging winds will likely be the main concerns. Storm chances will diminish as we get into the overnight hours, allowing some clearing to take place into Friday. Remain alert and have ways to receive severe alerts.  

Trending Upward:

Similar to Sunday's cold front, the one schedule to pass on through today will bring a significant but brief drop in temperatures Both Friday and Saturday feature highs in the 40s with Friday's chill featuring a gusty wind out of the northwest. Again, this chill won't last long as warmer flow slides back in by Sunday, landing afternoon highs in the low 60s, then low 70s Monday and Tuesday.

Isolated strong storms on the table Thursday evening

Thursday's Storm Potential:

We've been monitoring this setup for a few days now and the signal hasn't wavered much: the potential for a few strong to severe storms is still on the table as we head into Thursday evening. 

Areas south of Savanna, Freeport, Rockton, and Lake Geneva fall under a Level 1 Marginal Risk, where isolated strong storms may develop ahead of the incoming cold front. Farther south, the southern portions of Lee and DeKalb County are included in a level 2 Slight Risk, indicating storms will be more scattered in nature and will be able to produce strong winds, hail, and heavy downpours. An isolated tornado cannot be ruled out. 

Storm Timing: 

Forecast models suggests thunderstorm chances developing around 3PM and linger through roughly 9PM. Once the cold front is located to the south of the region, the atmosphere will stabilize, pushing the better chances towards the Interstate 80 corridor as we get into the overnight hours. 

Upward Trend:

Thursday's cold front will feel strikingly similar to the one that passed through Sunday, delivering another sharp drop in temperatures. Behind the boundary, high temperatures will be knocked down into the 40s and 50s, bringing a brief period of below-average conditions to wrap up the work week. However, just like before, the cool-down won't last very long as we will see temperatures quickly climb back into the 60s and even 70s as we head into next week. 

Spring warmth builds, thunderstorm threat may tag along

Temperature Swings:

Even with all the sunshine we enjoyed yesterday, high temperatures just couldn't keep up. Highs only made it into the upper 40s, a whopping 33° cooler than Rockford's springlike surge on Saturday. Quite the turnaround, and a reminder than late-March can still pack some chilly surprises. 

 

Temperature Departure:

Temperatures are set to climb over the few days as our next storm system takes shape. Highs today will come in about 2 degrees above average, with a more noticeable jump settling in by midweek. Wednesday features afternoon highs roughly 13 degrees above average with highs Thursday winding up 20 degrees above average. Again, this is all ahead of a system and cold front that will knock us back down some before we get into the weekend. 

Thursday's Severe Potential:

Wednesday's warmth won't come completely trouble-free as a weak disturbance brings a small chance for rain. Most of the Stateline will stay dry, but a quick passing shower can't be ruled out. 

 

 

By the time we get into Thursday, our attention will then turn to the incoming cold front, which may trigger a few stronger storms, especially to the south and east of Rockford where atmospheric ingredients are higher. For that, the Storm Prediction Center has placed a few locales in Whiteside, Lee, Ogle, DeKalb, and McHenry County under a Level 1 Marginal Risk with a level 2 Slight Risk further south across central Illinois, Indiana, and a good portion of Ohio. Storm chances should push away with the front late in the evening into Friday morning.

Midweek warmth could also come with a few thunderstorms

 

Hard to believe that it was just one week ago that the snow was flying following our blizzard warnings that were in place for all of northern Illinois and southern Wisconsin. And what's even more impressive is that we had those conditions last Monday, and at the end of the week the sun was shining bright and temperatures warmed into the 70s, 80s, and even 90s in the Midwest Saturday! But a strong cold front early Sunday put an end to the warmth leaving temperatures in the 40s during the afternoon. The sun was able to return today but there was still a little chill in the air with temperatures staying in the mid 40s.

Clear skies will take us through the rest of the evening with a slow increase in cloud cover tonight. With such a dry air mass in place and a lighter wind from earlier this afternoon, temperatures are likely to drop into the 20s. Tuesday will feature filtered sunshine with highs warming into the low 50s. We'll continue the warmup Wednesday and Thursday with highs reaching the 60s Wednesday afternoon and possibly the low 70s Thursday. But Thursday's forecast comes with a few question marks. So, let's talk about that:

Low pressure moving across Iowa late Wednesday night and Thursday morning will pull a warm front just north of the state line by Thursday afternoon. South of the front temperatures will warm into the 70s and 80s while north of the front temperatures will remain in the 50s and 60s. A surge of moisture (higher dew point temperatures) will also follow the front, reaching northern Illinois during the afternoon. This will gradually lead to an increase in instability across central and some of northern Illinois. But at the same time the warm air aloft will act as a cap, or lid, for much of the day limiting the chance for thunderstorms. As the day goes on the cap may weaken, especially in central Illinois ahead of a cold front. And as of Monday evening, this is the area that has the highest chance for thunderstorms Thursday afternoon and evening.

Should the front slow down some we could see the chance for a few storms locally increase, but should it speed up then chance would be shifted even further to the south. It would also mean that our temperatures likely wouldn't reach the 70s. A brief return of cooler air will arrive Friday before we see temperatures warm once again heading into the weekend and next week.