Warm, breezy & June‑like with storms chances to follow

Next Severe Potential:

After the active week we dealt with last week, things have been noticeably quieter. That lull won't last completely, though - a few strong storms could roll through northern Illinois late this evening into the early stages of Friday morning. The Storm Prediction Center has maintained the level 1 of 5 Marginal Risk for severe weather for the entire area, with gusty winds being the primary concern.  

Ahead of tonight's thunderstorm chances, a June-like afternoon is shaping up thanks to very dry, but breezy conditions. Winds will be out of the south-southwest, gusting up to 30 mph at times. This will help push temperatures back into the low 80s, marking Rockford's 4th 80-degree day of the year. Normally, average highs towards the final stretch of April are sitting in the low to mid 60s. 
 

Severe Potential Shifts South:

Beyond today, the focus for any severe weather shifts well to our south. Storms capable of producing strong winds and large hail will be possible across Texas, Arkansas, Louisiana, and Mississippi. 

 

  

Heading into the weekend, we'll be watching a classic dryline set up take shape over the southern plains. That isn't a term we typically use this far north when talking about severe weather. A dryline is a boundary where warm, humid air meets dry, hot air. IF a storm were to form along the dryline, supercells capable of producing all severe hazards, including strong tornadoes, will be possible.  

Monday is the day we'll need to keep a closer eye on for strong to severe storms. The Storm Prediction Center has placed the entire Stateline area under a 15% risk, which is equivalent to a level 2 of 5 Slight Risk. A higher 30% risk, or Enhanced Risk (level 3 of 5), is centered further south across eastern Missouri and southwestern Illinois. 
 

 

Warm and breezy Thursday ahead of overnight storm chance

 Thursday will bring yet another day of warmth and sunshine with high temperatures pushing this time into the low 80s. We will only start in the mid-50s with a few patches of fog across far Northeastern Illinois, but sunshine and increasing winds will quickly push the fog out and allow temperatures to begin climbing.

Afternoon wind gusts could push 25-30 mph at times out of the South-Southwest. While the strongest gusts ease after sunset, it will remain breezy into Thursday night.

A chance for storms will develop overnight into Friday morning across the Stateline. Thursday afternoon will be "capped" across the Stateline, limiting thunderstorm activity. But a line of storms will develop Thursday evening in Iowa, then push our direction late into the evening or overnight.

The late evening or overnight timing of the storms will be unfavorable for strong to severe storms, weakening them on approach. While a few isolated instances of gusty winds may be possible, the large majority, if not all, of activity will remain below severe limits.

There is a Level 1/5 Marginal Risk from the Storm Prediction Center, highlighting the very isolated risk for us locally. Stronger storms will likely develop much earlier in the day across Iowa, hence the Level 2/5 Slight Risk that direction. Any storms that produce severe weather locally will be primarily capable of gusty winds, likely under 60 mph for the large majority of them.

A few showers and rumbles of thunder will linger through Friday morning and into early afternoon but drying out for Friday evening. Most of the weekend will be dry with highs in the upper 60s to low 70s.

Warmth surges before the next scattered storm opportunity

Earth Day Forecast:

Northern Illinois is getting a pretty nice forecast for Earth Day this year. Expect a mixture of clouds and sun through the day, making it great for outdoor plans. Like Tuesday, temperatures will feel spring-like, climbing into the upper 70s. All in all, a great day to celebrate our beautiful planet. 

 

Storm Chances Thursday:

Looking ahead to Thursday, conditions will stay dry through most of the day, though it will turn noticeably breezy come the afternoon. 

A warm southerly wind will help temperatures surge into the low 80s, making for a well-above average and more June-like afternoon. That warmth comes ahead of our next storm system and cold front, with scattered storm chances returning Thursday night into the early stages of Friday as the cold front approaches. For that, the Storm Prediction Center has placed the entire area under a level 1 of 5 Marginal Risk for severe storms, mainly for strong winds. With the slow arrival of said cold front, overnight low will only fall into the low 60s with highs Friday climbing into the low 70s.  

Expected Rainfall:

Now, the Rockford Airport is sitting shy of 6" of rain for the month of April. Through April 21st, the 5.81" tallied up if the 5th most on record. Rainfall totals over the next 5 days will end up much higher to the west of the Mississippi River, with most locales ending up in the .50" to 1.25" range. 
 
 

Patchy fog returns Tuesday night as above normal temperatures continue

 

Tuesday may have been a little breezy from time to time but it sure was a nice afternoon. Temperatures jumped a good 20 degrees from Monday, rising into the mid 70s for most. The warmth will continue through Tuesday evening as a cold front slowly sinks south during the night. There were a few very isolated showers/thunderstorms that developed during the late morning and afternoon from southern Wisconsin into northeast Illinois. A few of those showers did slide through southern DeKalb and Lee counties. Now, most of that activity has moved out over northern Indiana.

As the front comes through tonight winds will turn to the east and northeast. This may allow some patchy fog to be pulled inland from Lake Michigan, impacting some of northeast Illinois. But any fog that does develop shouldn't last too long and temperatures are expected to warm back into the mid-70s Wednesday afternoon.

High pressure building in Wednesday afternoon will conditions dry through Thursday evening but the chance for a few showers and thunderstorms return late Thursday as a cold front moves through northern Illinois and southern Wisconsin. As it stands Tuesday evening, our severe threat remains low - with a higher threat for severe weather west of the Mississippi River during the afternoon and evening. Should the cold front speed up then there could be a couple thunderstorms we'd have to watch to the west. And if the front slows down at all, then we may see the storm threat carry over into Friday afternoon.   

Another tornado confirmed as less active weather settles in

Tornado Update: 

We're continuing to get more information from last Friday's severe weather, as another tornado has now been confirmed. The National Weather Service says an EF-1 tornado touched down in Jo-Daviess County near the Galena Territory, remaining on the ground for about seven minutes. As additional survey results and details become available, we'll be sure to share the latest information with you! 

Tuesday's Forecast:

Looking ahead, severe weather potential remains low in the days to come, especially today. The Storm Prediction Center has most of the area highlighted in the non-severe risk category for this evening into early tonight. A few showers, isolated thunderstorms will be possible during that time period. Otherwise, expect dry conditions with partly cloudy skies and afternoon highs in the low 70s.  

Storm Chances Thursday: 

Dry conditions are expected to hold on through the day Wednesday and much of Thursday, with highs climbing into the 70s. We could even see a spot or two touch the 80° mark Thursday. From there, storms across Iowa may move in late Thursday evening into Thursday night, but these storms are expected to weaken on approach, limiting the severe threat locally. As of right now, half of Jo-Daviess County is under a level 1 of 5 Marginal Risk.

A late April freeze to start, calm weather to follow

Frigid Start:

It's a downright cold start to the morning across the Stateline with temperatures in the upper 20s. Because of that, all of northern Illinois is under a Freeze Warning through 9AM, a reminder that winter isn't quite ready to let go just yet. 

After a frigid morning, conditions improve nicely as the day progresses. High pressure building into the Great Lakes region will bring dry, sun-filled skies across northern Illinois. As that system settles in, winds will turn to the south and southwest, helping temperatures to climb into the mid 50s. Compared to late-April standards, this comes a few degrees below average for the city of Rockford. Overnight low will fall into the upper 40s under a partly to mostly cloudy sky. 

Storm Chances Tuesday:

Moving forward into Tuesday, much of the day will be dry under a partly cloudy sky. However, late in the day and into the evening, a weak disturbance moving in aloft could spark up a few thunderstorms. Coverage looks limited, hence the "non-severe" risk given by the Storm Prediction Center. Afternoon highs will be much warmer, landing in the low 70s. Highs will also peak in the 70s on Wednesday. 

Understanding supercells: LP, Classic, HP explained

Low Precipitation (LP):

Supercells are the most intense and well-organized types of storms, known for producing large hail, damaging straight-line winds, and tornadoes. But not all supercells look the same or post the same set of hazards. Differences in moisture, wind shear, and storm structure can result in very different behaviors from one supercell to the next. 

First, we have LP or low-precipitation supercell. This type of supercell is often the most striking visually as you more of a structure show given the low amount of precipitation being developed. These storms form in environments with strong wind shear but limited moisture, which keeps the rainfall production limited. Despite the lighter rainfall, LP supercells are known for their large hail production and can produce tornadoes. 

Classic (CL) Supercell:

The most common type of supercell is the "classic" supercell. These storms typically form in environments with sufficient moisture, strong wind shear, and lots of storm fuel, allowing them to maintain a well-defined rotating updraft - known as a mesocyclone - while still producing a decent amount of rainfall. Visually, classic supercells often feature a rain-free base, a visible wall cloud, and a precipitation core that is separated from the updraft. Because of this, they are capable of producing all severe hazards including large hail, wind, and tornadoes. 

High Precipitation (HP):

Now, the storms we dealt with last Friday are known as high precipitation or HP supercells. These storms form in moisture-rich environments where heavy rain wraps closely around the updraft. This is why this type of supercell is considered the most dangerous of the three because any focused area of rotation or tornado will quickly become "rain-wrapped". Again this is strikingly similar to what Lena went through as the tornado started out visible, but then became rain-wrapped as it approached town. On radar, they appear messy, but can still produce tornadoes, large hail, and damaging straight-line winds.