Wednesday, May 27, 2020

Two Tornadoes Confirmed from Saturday Evening Storms in Northern Illinois

The Chicago National Weather Service released new information regarding damage that occurred in Ogle and DeKalb counties following strong to severe thunderstorms last Saturday afternoon and evening.

An EF-1 tornado, with peak winds estimated between 90-100 mph, occurred about one mile west/southwest of Chana (Ogle County) at approximately 4:30pm Saturday afternoon near the intersection of Rocky Hollow Road and E.
Damage in Chana on Canfield Road
Canfield Road. It was on the ground for 0.3 miles and had a width of 100 yards. This tornado did significant damage to outbuildings at two farmsteads, along with knocking down trees and power poles.

Another tornado occurred at approximately 6:12pm Saturday evening about five miles northeast of Genoa in DeKalb County. This tornado was reported by law enforcement, and estimated as an EF-0. It was reported to have touched down near Melms and Polk Roads, damaging a 40x20 barn, with debris blown into a downstream field. Power poles were also damaged for about a mile from the reported touchdown. This tornado dissipated before reaching I-90.

More information on the severe weather and damage from Saturday's storms can be found here from the Chicago National Weather Service.

More Rain Chances Today & Tomorrow, Drier Towards the Weekend

Yesterday marked the 4th straight day that the Rockford International Airport observed a high over 80°. Rockford's official high was a scorching 87°, which now stands as the warmest day of 2020 so far. Similar to Tuesday, a quiet start to the day will lead to a summer-like afternoon with a chance for scattered activity.

As the Stateline woke up this morning, skies remained partly to mostly cloudy as temperatures once again started out comfortably in the upper 60s to low 70s. This morning's cloud cover should dissipate some as the morning progresses, leaving behind a mix of sunshine and a few cumulus clouds. As these cumulus clouds become more established and grown in size, this will lead to another chance for scattered showers and thunderstorm chances beginning after 3PM.

Unlike the thunderstorms we encountered yesterday, severe weather is not expected later today. Our atmosphere is going to soak up a decent amount of moisture as we head into the afternoon. However, the two components that are lacking is wind shear, or change in wind with height, and available instability.

Any thunderstorm later today will be capable of producing lightning of course, but also heavy downpours and gusty winds. Due to the abundance of atmospheric moisture, any thunderstorm that does develop could drop a quick 1/2" to 1" of rainfall. We've been very fortunate that rain chances over the past week or so have been hit or miss scenarios, allowing river flooding or just flooding in general to slowly improve. Overall, this round of rain will begin to wind down by midnight tonight, leaving the Stateline under a mostly cloudy sky into Thursday morning.

Thursday's forecast comes with another chance for the Stateline to see some rain. However this time, it could come at heavier doses. A cold front that is currently draped across portions of Iowa, Minnesota, and Wisconsin will slide into the region by the afternoon tomorrow. Ahead of of this frontal boundary will be a round of showers and thunderstorms that looks to get start by the mid-day hours. Heavy rain is definitely a possibility throughout the afternoon and evening hours, especially if a thunderstorm slowly roams over your area. Once again, severe weather is not expected. Before the cold front passes through Thursday night, highs for Thursday will end up slightly cooler in the mid to upper 70s.

Thankfully, Thursday will be the last time that we mention a chance for rain until the beginning of next week. Behind this cold front, a cooler and very dry air mass filters into the Midwest and the Great Lakes Region. Clouds will quickly give way to plenty of sunshine for the end of the work week, with highs dropping into the low 70s. What's also going to be noticeable Friday and this weekend will be how muggy the air feels. Dew points after the frontal passage will take a blow, dropping from the upper 60s Thursday, down to the low 50s for Saturday, and into Monday. This will make for a beautiful, sunny, and less humid weekend for the Stateline.

Tropical Storm Bertha Forms Off the Southeast Coast

The 2020 Atlantic hurricane is off to quick start as we witnessed the formation of Tropical Storm Arthur back on the 16th of May.

This morning, an area of low pressure off the southeast coast was upgraded to Tropical Storm Bertha. The latest advisory shows Bertha's center is right off the South Carolina coast, and has estimated peak winds of 45 mph. The latest track for this newly formed tropical system has it moving slowly to the northwest, making landfall near Charleston, SC by this afternoon. Folks who live closer to the shoreline are going to be dealing with heavy amounts of rainfall, leading to flash flooding. Another threat that comes with tropical systems is the enhancement of rip currents.

Tuesday, May 26, 2020

Summertime Heat Sticks Around, Showers Possible Late

First off, I hope everyone got to enjoy their Memorial Day holiday yesterday. The "unofficial start to summer" lived up to it's name as Rockford observed 3 straight 80° highs over Memorial Day weekend. It's been a hot minute since the Rockford International Airport saw 3 straight days with highs in the 80s, stretching back to the middle of September last year. With that being said, this summer-like weather pattern is also featured in the forecast for today, with another chance for a few showers late in the day.

It was another comfortable and mild start to our day as the Stateline woke up to temperatures in the low to mid 60s. There were a few showers that streamed into region from the south early on this morning. Once they dissipated, a few clouds were leftover allowing for a a great view of a the  sunrise over the Stateline. With a little more sunshine in the forecast today, temperatures will climb into the mid to upper 80s for highs. However, it will feel muggy out there as a breeze out of the southeast helps dew points rise into the mid to upper 60s once again. Under a mix of clouds & sun, there will be plenty of opportunities to head outdoors today. If you do go outside today, be sure to put on a good amount of sunscreen to avoid the risk of sunburn. The UV index is still pretty high today with an index of 8, which equals a burn time of 20 minutes.

Along with that summertime heat and humidity comes a chance for a few showers, and possibly an isolated thunderstorm later today. An area of low pressure will swing northward into western Iowa by this afternoon, bringing rain chances to the Stateline this evening. The best time frame for these showers and thunderstorms to pop up will be between 6PM to 10PM, but no severe weather is expected at the moment. The higher threat for severe weather is off to the west in central and eastern Iowa, closer to the surface low. Any activity lingering into tonight will fully taper off before midnight, leaving skies partly to mostly cloudy as we head into the middle of the week.

Monday, May 25, 2020

A Very Summer-Like Memorial Day is Ahead, Showers & Storms Possible

Summer wasn't too shy to make an appearance for the "unofficial start of summer. Highs for Saturday and Sunday both climbed into the 80s, marking the first time that the Rockford International Airport observed an 80 degree high since October 1st. If you're keeping count, that is a gap consisting of 234 days making it the 5th longest stretch between 80° highs on record. As we celebrate those that have given the ultimate sacrifice today, this summer-like stretch continues. But it may be essential to keep an eye on the radar throughout the day if you have any outdoor plans.

It was an unseasonably warm start to the holiday as temperatures began in the upper 60s for most locations. To put that into perspective, Rockford's average low for May 25th is 51° a mere 18° to 20° above average. That should just give you a great idea on how the rest of our Monday is going to shape up temperature-wise. The rest of our Memorial Day is going to have similar feel to Sunday, but with a slightly better chance for showers and thunderstorms during the second half of the day. The continuation of these warm southerly to southwesterly winds at the surface will help boost our temperatures into the mid to upper 80s this afternoon. However, we are going to once again feel muggy as dew points will climb into the mid to upper 60s.

Current thinking suggests that we'll see scattered activity increase by the early afternoon hours, and stretch into our evening. Although this activity will remain scattered in nature, I would definitely keep the umbrella on hand just in case. A few of these storms may be on the stronger to severe side as the Storm Prediction Center expanded the Marginal Risk eastward to include a majority of the Stateline this morning. A Marginal Risk is level 1 of 5 in the categories for severe weather, as storms this afternoon and evening could produce gusty winds and heavy downpours. Storm chances hold on into the early hours of our night tonight before drying out to partly to mostly cloudy skies by Tuesday morning.

You will also need to lather up in sunscreen if you are going to be outside today for a long period of time. The late-May sun-angle will contribute to high levels of ultraviolet rays as our UV index is at a 9 today. What does that mean exactly? Signs of sunburn will begin to appear in as little as 15-25 minutes. Whether you're grilling delicious holiday cuisine, going for a run, or going fishing today, its would be wise to put on that sunscreen before heading outdoors.

Tuesday seems to begin on a dry note before shower chances increase once again by late afternoon. Surface winds ahead of an slow moving cold frontal boundary are going to remain out of the south-southwest which will lead to another large influx of rich moisture. As of a result, scattered showers and thunderstorms will begin to pop up across the eastern half of Iowa, with a few of these showers spreading eastward into the Stateline by the late afternoon-evening hours. As far as severe weather, tomorrow's threat remains to the northwest in the northeast corner of Iowa and western Wisconsin. Highs by Tuesday afternoon will climb into the 80s for the 4th straight day. It will still feel a bit muggy Tuesday afternoon, but there will be dry hours just like today that will allow for time outside.

Sunday, May 24, 2020

Summer-Like Pattern Continues, Along with Storm Chances

Temperatures for both Saturday and Sunday warmed into the 80s, reaching 80 degrees on Saturday and 85 degrees on Sunday - the first 80 degree weekend this Spring season. The summer-like pattern will continue for the next several days, with highs reaching the low to mid 80s through Wednesday or Thursday. The muggy feeling will also stick around, pushing the heat index likely close to 90 degrees once again Memorial Day.

The next several days will feature many dry hours, but the storm chance increases as we head further into the week. Several upper level disturbances Sunday afternoon and evening allowed thunderstorms to quickly develop over southern Illinois, Missouri and Iowa. While most of this activity will weaken, and likely fade, before reaching northern Illinois and southern Wisconsin an isolated thunderstorm or two will be possible early Monday morning. Severe weather is not expected. Isolated thunderstorms will be possible during the day Monday as temperatures warm back into the mid 80s.

A better chance for thunderstorms will take place Tuesday and Wednesday as the strong ridge of high pressure over the eastern half of the country shifts further to the east and a cold front slides closer to the Stateline. The threat for any severe weather remains low, but thunderstorms will likely have heavy rainfall as moisture in the atmosphere remains rather high. Thursday should be our last chance for rain/thunder for the upcoming week as high pressure is set to follow the passage of a cold front Thursday night. This will lead to cool, easterly flow through at least the start of the weekend with temperatures warming into the mid 70s.

Friday, May 22, 2020

Strong Storms Possible Saturday

The holiday weekend could start off a bit noisy thanks to an approaching storm system. A low pressure system spinning over eastern Nebraska as of late Friday evening will propagate toward the Stateline headed into Saturday. With it, it brings a chance for rain and strong to possibly severe thunderstorms. 

Light showers extending far east from the center of the system will likely arrive in the Stateline overnight. Scattered, light showers are expected to last through Saturday morning. By the afternoon, the rain is expected become a bit more widespread while some of the showers are forecast to intensify into scattered thunderstorms. As the storm’s triple point, the intersection of the storm’s warm, cold, and occluded fronts, moves over the Stateline, a line of strong convective storms is forecast to form and push across the area. As of Friday evening, the greatest chance for strong to severe storms looks to occur between the hours of 3:00 and 7:00 PM.

The likelihood of these thunderstorms becoming severe is rather uncertain at this time. The greatest uncertainties lie with the position of the storm and its fronts and with the amount of instability that will build through the day. Though a good amount of instability is expected to be advected into the area along the storm’s warm front, limited diabatic heating caused by a likely lack of sunshine may restrict the amount of instability that builds in the lower atmosphere through the day. The coverage of these stronger storms is also expected to be very limited. Therefore, the position of the storm’s frontal boundaries in the late afternoon and early evening will be critical in determining where these storms will occur and models are not in good agreement on the storm’s path as of yet. Though ample moisture throughout the atmosphere and a good shear profile will likely promote a well-organized quasi-linear convective system if and where convection should occur.

Any and all severe weather criteria is possible including strong winds, sizeable hail, and tornadoes on top of heavy downpours, though heavy rain and strong winds are by far the biggest concern at the moment. This severe threat should not be long lived as a dry air mass closely following the storm’s center will clear out the rain and begin clearing the cloud cover by the late evening hours.