The potential for severe weather increases Tuesday, Tuesday night

ROCKFORD, Ill. (WIFR) – For the fourth day in a row, temperatures were in the 80s at Stateline on Monday. However, Monday’s warmth came with a price.

Since the humidity was significantly higher than in the past few days and some fairly severe disturbances moved through our airspace, showers and thunderstorms formed several times. Widespread showers and thunderstorms moved through the area in the mid to late morning hours Monday, followed by a second wave in the afternoon, ultimately leading to a severe weather warning being issued for much of the area and even a few border counties a severe weather warning.

Storms are a thing of the past and we should generally expect calm conditions during most evening and night hours. However, it is possible that a few showers or storms will at least flirt with or possibly even penetrate the state line as we approach dawn. More likely, the region will be hit by a series of storms around or shortly after sunrise as a warm front moves north.

There will be a lack of abundant energy in the atmosphere at this time of day, so these initial storms are unlikely to be severe. However, heavy rain and small hail are possible.

After the first storms pass through, there will be partial, if not complete, sunshine for a while. This can quickly destabilize or recharge the atmosphere, allowing more storms to develop.

This is exactly what high-resolution computer models predict for the mid to late afternoon hours. Since new storms can generate much more energy, a threat of severe weather certainly comes into consideration. Gusty winds, large hail and even a few tornadoes would be possible with storms that develop during this time.

This group of storms is expected to be followed by another break before the main event, which is expected to take place on Tuesday. The next round of storms may not have quite as much energy available, but there will be significantly more wind shear in our atmosphere. Early Tuesday evening, winds will be south/southeast near ground level, but will shift to the south/southwest at about 4,600 feet above the surface and to the southwest at about 10,000 feet. When wind direction changes with altitude in the atmosphere, it stimulates the rotation of storms.

Therefore, we will pay close attention not only to the main line of thunderstorms moving through the area in the evening hours, but also to individual cells that form in front of the main line, as shown in the graphic series below.

With all of these ingredients in place, we have a very favorable recipe for the development of widespread, severe storms. The Storm Prediction Center has upgraded the entire stateline to Level 3, enhanced risk of severe storms, except for portions of Lee, Carroll and Whiteside counties, which have been upgraded to Level 4, moderate risk.

Widespread damaging winds pose the greatest threat of severe weather Thursday evening, with some models even suggesting a derecho-like system is developing, with wind gusts in the 80-90 mph range not out of the question. Given the expected wind shear profile, tornadoes are also in play. In fact, the Storm Prediction Center believes some strong ones (EF-2 or higher) are possible, particularly in the areas with the black dashed lines in the graphic below, which includes the Rockford Metro. Large hailstones, perhaps up to the size of a golf ball, also pose a threat, but this is expected to fade quickly as the sun sets.

Suffice it to say that this is potentially a very serious situation that may develop during the second half of Tuesday and into Tuesday evening. It’s not a slam dunk yet, but it’s safe to say this is one of the most worrying atmospheric situations I’ve seen here in a while.

It would be wise to review your severe weather plan this evening or early Tuesday and ensure that you have multiple options for receiving warnings in the event that one or more warnings are issued where you are.

Rest assured that the WIFR First Alert Weather team will continue to monitor the situation very closely and updates will be provided on-air, here on wifr.com, on our social media platforms and around the clock on First Alert Weather App .

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