Wednesday, May 29, 2024

Wednesday morning weather update


Low pressure that brought scattered thunderstorms Tuesday afternoon will continue to depart us to the east, leaving mostly sunny skies for the start of Wednesday. Temperatures under the clearing sky have fallen into the upper 40s and low 50s but should warm quickly through the morning.

Winds will remain light from the north Wednesday afternoon with highs warming into the upper 60s and low 70s. Rockford's forecast high will reach 71 degrees. A little moisture lingering in the atmosphere, combined with a little instability, will cause fair weather cumulus clouds to develop late morning and early afternoon turning skies partly cloudy.

Winds remain light tonight with overnight lows falling into the low to mid 40s. Patchy fog may develop with a light wind. Drier air for Thursday will lead to mostly sunny skies and temperatures warming into the low to mid 70s. Dry weather will continue Friday with the next chance for rain returning Friday night.

Tuesday, May 28, 2024

Rock County tornadoes


The Milwaukee National Weather Service was out in southern Wisconsin Monday conducting damage surveys from the severe storms that moved through Sunday evening.

They concluded that an EF-0 tornado formed 5 miles northwest of Janesville, WI at 5:00pm, traveling northeast towards Milton, WI before lifting at 5:21pm. It was on the ground for just a little over 12 miles and was 50 yards wide. According to the National Weather Service the tornado went through the High School area in Milton, as well as the north-central part of town. Damage was done mostly to trees, but a bleacher section of a baseball field was lofted over a fence at the high school.

The second tornado, also an EF-0 with peak wind gusts of 80 mph, touched down 4 miles east/northeast of Janesville at 5:15pm and traveled northeast before lifting southeast of Fort Atkinson, WI. This tornado was on the ground for 15 miles and was 50 yards wide. Its path took it through mostly rural locations where it caused tree damage.

Storm chances return Tuesday afternoon


Similar to Monday, Tuesday will feature a chance for scattered thunderstorms with the heating of the day late in the afternoon and evening.

Cloud cover continues to clear us to the east this morning with temperatures falling into the low 50s. It's a cool start this morning with a lighter wind, but the northwest breeze will increase during the afternoon, gusting around 25 mph. Another low-pressure system moving in from the northwest will bring with it scattered thunderstorms for the late afternoon and evening. While an isolated shower or two can't be ruled out early in the afternoon, thunderstorm coverage should increase after 5pm.

Instability won't be quite as high as it was Monday afternoon but colder temperatures aloft with the incoming low will cause the air mass to quickly rise from the surface. This will help generate some of the thunderstorms, even without the presence of higher instability. This type of low is known as a 'cold core low'.

The strongest storms will be capable of producing penny to quarter sized hail, along with wind gusts to 60 mph. This is why the Storm Prediction Center has placed southern Wisconsin and northern Illinois under a marginal risk for isolated severe storms Tuesday. Remember, when you see lightning or hear thunder you need to head indoors!

Storm coverage will come to an end after sunset. Skies will remain partly cloudy with overnight lows falling into the low 50s.   

Sunday, May 26, 2024

Sunday morning weather update


9:30pm Update: A line of thunderstorms continues to move through Ogle and Lee counties this morning, producing mostly heavy rainfall. Some of the stronger cores will be capable of small hail, along with frequent lightning and a stronger wind gust or two. These storms are currently moving to the northeast around 25-30 mph.

Non-severe thunderstorms will continue to move across northern Illinois and southern Wisconsin Sunday morning. Biggest threats with the morning activity will be heavier downpours and lightning. A wind gust 30-40 mph will be possible but severe weather is not expected this morning. This scattered activity will last through lunchtime (12pm/1pm).

As the morning thunderstorms move out, skies may try to clear some through mid-afternoon. A warm front displaced well south of the region will make a slow trek back north, but likely fall shy of reaching the Stateline. This will be a key player in thunderstorms redeveloping locally later this afternoon and evening.

There does remain a risk for a few stronger to severe storms this afternoon, but the strength of the storms depends on just how much our atmosphere is able to destabilize later today. With some clearing possible, we could see some isolated thunderstorm activity try to develop around 3pm/4pm. The greatest threat for any significant severe weather will remain further downstate where better instability and wind shear will take place.

If we do see thunderstorms redevelop this afternoon our greatest threats would be damaging winds and hail, with an isolated tornado risk. Again, any storm development later today will depend on how fast our atmosphere is able to recover following the storms this morning. There are some indications that at least some destabilization will occur.

If you're planning on being out and about at any point during the day, make sure you are checking

the weather and radar frequently. Be ready to head indoors/seek shelter should any storms move through this afternoon. The storm threat would then decrease after sunset.   

Saturday, May 25, 2024

Pleasant, sun-filled start to Memorial Day weekend

Severe weather once again being the main headline across the Midwest as a strong line of storms pushes across Nebraska, Iowa, and Illinois. 

Wind damage/significant wind reports stretch from N. Kansas to Lake Michigan, which classifies this late-week severe event as a derecho. There was also a lot of heavy rainfall and gusty winds with the second round Friday afternoon/evening.

Fortunately, sunnier times make a brief return as high pressure bubbles up in between Friday's storm system and the one slated for Sunday. This leaves us with A TON of beautiful sunshine, with highs comfortably topping out in in the upper 70s. 

Clouds will slowly increase into Sunday as a round of showers and storms approaches from the west. This makes tomorrow a day where you'll want to ditch the sunglasses and have your umbrella on hand. 

After a quiet Saturday night, rain and evening storm chances increase by mid-morning Sunday. This will mainly feature non-severe storms that will be capable of producing gusty winds and heavy rainfall.

In a similar fashion to Friday, a second round is in the works for Sunday afternoon and evening. This round does feature the low potential for strong to severe storms, hence why most of the Stateline has been placed under level 1 Marginal Risk. 

Those along and south of I-88 are closer to the warm front, thus seeing a slightly higher chance for severe potential. For that, they have been placed under a level 2 slight risk. Hazards locally include damaging winds, large hail, and heavy downpours. The tornado threat is very low and in fact much higher south of I-80. Keep the radar close for Memorial Day as there will be enough moisture for a few passing showers. 

Thankfully, it won't be a washout! In even better news, next week is looking less active. Slim chance Tuesday then dry conditions settle in for Wednesday, Thursday, and Friday!

Friday, May 24, 2024

Severe Thunderstorm Watch issued for northern Illinois

The National Weather Service has expanded the severe thunderstorm watch eastward to include all of N. Illinois and Green County in S. Wisconsin. This will be in place until 1PM.

Storms to the west will be posing a risk for damaging winds, mainly between 8AM-1PM.

Tracking two rounds of storms Friday, both bring severe potential

After a nice two day break from severe weather, the potential returns as we round out the work week. This time, we're not talking just one round, but two. For that, the Storm Prediction Center has all of N. Illinois and S. Wisconsin under a level 2 Slight Risk.

The first is currently progressing eastward across our neighboring corn-loving state to the west, resulting in a severe thunderstorm watch for those areas. 


As this line of storms approaches N. Illinois, it will be in a state of weakening, though may still pose a risk for damaging straight-line winds as it moves through NW. Illinois and S. Wisconsin. Timing for the first round is from 8-9AM to 1PM. 

Forecast models are then hinting at redevelopment in E. Iowa as the associated cold front approaches. If the atmosphere is able to destabilize quickly, a secondary round of strong to severe storms will be possible this afternoon into the early evening. 

Primary concern will once again be damaging winds, followed by a tornado or two. Now, the tornado threat may become a bit higher if the morning activity is able to throw out an outflow boundary. 

This will enhance the low-level shear or spin in the atmosphere, further increasing the potential for a few tornadoes. Similar to Monday and Tuesday, be keep tabs on radar as well as having multiple ways to get watches and warnings.

Once the cold front is through, conditions will quiet down overnight into Saturday. This will pave the way for a less active start to Memorial Day weekend with highs peaking in the upper 70s. 

Storm chances are fast to return by Sunday as a strong low pressure system zips into Minnesota/Wisconsin from the central plains. As of this morning, the severe threat is highest near and south of the warm front in west-central and S. Illinois. With that being said, the Storm Prediction Center has placed much of the region under a level 1 Marginal Risk for severe weather. Something to monitor!