Thankfully we're waking up too much quieter conditions across the region today after a very busy weather day yesterday. After starting out with showers early on, we seen the warm front lift through which warmed up our temperatures nicely but did bring in a few rounds of strong to severe storms which not only caused some damage but also produced very heavy rainfall.
In terms of rainfall we got absolutely dumped on yesterday! Multiple locations across the state line seen upwards of 1.50" of rainfall while some areas approached nearly 2" of rainfall! This caused ponding and field flooding in many rural locations however the good news is that flash flooding stayed at a minimum.
When it comes to severe thunderstorm reports most of the region was able to dodge the strongest of the storms yesterday! However, a few stronger storms were still able to develop across the state line yesterday with damaging wind gusts as the most common severe weather report. Most reports came from a storm that tracked through White, Ogle and Lee counties which did produce damage on a few rural properties. A few other stronger storms impacted Carroll County and eventually made their way into Stephenson and Rock Counties where a few tornado warnings were eventually issued. Thankfully, there were no tornado reports across the region yesterday, but the National Weather Service will be out today assessing damage to determine if this damage was done due to a tornado or straight-line winds.
Because of all the rainfall we've seen the over the past few days, especially yesterday, a Flood Watch is in effect through Sunday morning as continued rainfall is expected today. Areas along the Kishwaukee River from Confluence with South Branch Kishwaukee River downstream to the Rock River will need to keep an eye on river levels the next few days as the river is only a few feet from flood stage.
[12:00AM UPDATE] Radar is much more quiet tonight and will remain quiet through Friday morning. There were quite a few storm reports scattered around Carroll, Ogle, and Northwest Lee Counties in Illinois, mainly with high wind gusts and/or wind damage.
[9:30PM UPDATE] Storms continue to wind down, with some small hail and lightning still possible in DeKalb and McHenry County. But the severe weather threat has come to an end. The tornado watch has since been cancelled across the entire area.
[7:40PM UPDATE] Most of the storms continue to push through the Eastern part of the Stateline with a few pockets of severe winds upwards of 60-70 mph possible in parts of Walworth County, McHenry County, and Southern DeKalb County. Further West, the line of storms in Ogle and Lee Counties remain just below severe limits but may still be capable of producing up to 50 mph winds.
[5:50PM UPDATE] A new severe thunderstorm warning has been issued for Rock County in Southern Wisconsin until 6:45PM. This storm is moving Northeast at 40 mph. This storm is capable of producing 60 mph wind gusts and quarter sized hail. A tornado is also possible but not imminent.
[5:30PM UPDATE] A tornado warning has been issued for Western Carroll County, including the town of Savanna until 6:15PM. This storm capable of producing a tornado is in Eastern Iowa but moving West at 50 mph. Radar indicated rotation and half dollar sized hail are the threats with this storm. Take shelter if you are under this warning!
[5:20PM UPDATE] Severe thunderstorm warnings have now been issued for Carroll and Whiteside Counties until 6PM and 6:15PM respectively. Storms are moving Northeast at 45 mph and are capable of producing 60 mph winds and quarter sized hail. A tornado is also possible, but not imminent.
[4:45PM UPDATE] A few isolated showers have attempted to develop locally, but the higher threat is with storms will arrive along the Mississippi River shortly after 5PM. Storms will still reach the I-39 corridor by 6-7PM, then exit after 9PM to the East. Rotation has been shown in these storms, and they are moving into a charged environment favorable for rotation. Tornado watch remains in effect until 8PM for the entire Stateline.
[3:00PM UPDATE] Latest satellite and radar shows the dry slot moving into Eastern Iowa with bright sunshine, heating the surface up rather quickly. This fuel is already producing some severe thunderstorms in South-Central Iowa, which will lift Northeast through over the next few hours. Our primary severe threat now runs from 5PM-9PM from West to East. Tornado watch is currently in effect until 8PM.
[1:45PM UPDATE]: A tornado watch is now out for all of our Stateline counties until 8PM this evening. Severe storms will increase in coverage and intensity through the late afternoon, which could include a few tornadoes.
[1:30PM] It has been a very rainy start to the day with temperatures in the 40s and 50s. But that is set to change quickly this afternoon as a warm front pulls through the Stateline, sending temperatures into the 60s. How quickly this arrives will be the main driver behind how strong our afternoon and evening storms could be.
The expectation is still that we will see some dry time this afternoon, and maybe even a few peeks of sunshine. That would aid to destabilize the atmosphere -- or provide the necessary fuel for thunderstorm development. That dry slot is currently positioned in Southern Iowa and Northern Missouri.
Once that arrives, temperatures will soar along with thunderstorm fuel. We may see a few storms develop out ahead of this dry slot between 2-3PM on the leading edge of our instability. Some of these could turn strong to severe, but that is not the main window we are watching for.
The line of storms in Western Iowa behind the dry slot will likely be the main show, and it looks to arrive near the I-39 corridor between 7-8PM before exiting the area after 9PM. This may be on a weakening trend as it arrives with the loss of daytime heating and potentially outrunning the best energy. But that will be the window we will need to watch for all hazards, including some tornadoes.
As we have been discussing, there are several things that must fall into place for the severe thunderstorm risk to be fully realized, but the ingredients are in place for a very active evening of severe weather. Another thing I will also note: storms will be traveling at potentially 60 mph, which will leave you less time to seek shelter in the event a severe thunderstorm or tornado warning is issued. So, remain weather aware for the rest of the evening and we will be sure to keep you posted with updates throughout the day!
We're gearing up for not only an active morning but also a very active afternoon as showers and eventual strong to severe thunderstorms will move through the region throughout the day. As of now, rain showers that started around 10 p.m. last night have continued to dump consistent rainfall through the early morning and are expected to continue possibly into the early afternoon.
Showers as well as a few isolated thunderstorms will continue across the region through 11 p.m. today however we do look to at least dry out into the early afternoon as our next warm front lifts through. Temperatures will quickly rise into the 60's by 12-1 p.m. while instability will start to build into the afternoon with any clear skies we may see.
In terms of our severe thunderstorm threat, our probabilities have remained unchanged as an Enhanced 3/5 risk continues for this afternoon and evening. This signifies that the Storm Prediction Center has confidence that multiple severe thunderstorms will occur this evening with damaging wind gusts and a few tornadoes as the primary hazards.
Although the Enhanced risk is rather large, each threat type has both different probabilities as well as covering different regions. Our tornado risk has been trimmed a bit since last night; however, our Enhanced tornado risk does outline most of the state line and areas further west. Storm motions will be in excess of 60 mph today so any tornado that may form will be fast moving and may be strong (up to EF2) as faster storm motions often add strength to a tornado. We also have an Enhanced Wind Risk this evening which would favor storms forming along the cold front this evening especially if storms become more clustered. In any case, any strong thunderstorm that occurs today will be capable of producing wind gusts up to 70 mph.
As we head into the afternoon there will be two main timeframes we'll be watching for strong to severe thunderstorms. The first of which will arrive between 12 pm to 3 pm as instability begins to build. During this round our atmosphere isn't expected to be the strongest yet, however we could still see an isolated strong to severe thunderstorm. Thanks to limited instability we'll see mainly a damaging wind gusts threat through the early afternoon, however an isolated tornado cannot be ruled out either.
Our focus will then shift to the second round of storms expected to move. During this time, instability is expected to grow a bit more which will provide slightly better energy for thunderstorms that do occur. At this time as well, our winds will begin to turn with height which may allow a few storms to rotate. Because of this, our tornado threat will be higher between 3 pm to 9 pm later today along with damaging wind gusts and some large hail.
As the cold front begins to move in closer to 8 pm and possibly later near 10 pm we may still see an isolated thunderstorm if any instability can stick around. However, at this time, instability will be decreasing as we lose our sunshine so storms will be on a weakening trend although a damaging wind gust threat cannot be ruled out this evening.
To sum everything up, we'll be monitoring two separate rounds of thunderstorms this afternoon and evening with the strongest of the two expected to arrive after 3 pm. On the flip side, there is still a chance thunderstorms today are weaker or not as widespread as forecasted. If our morning showers/storms stick around until the afternoon we may see our chances not as significant due to limited instability. We could also see storms develop too far west for them to be severe by the time they reach the region and in a similar case, storms may cluster causing them to fight for available energy. Either way, it'll be crucial to keep an eye on watches and warnings this afternoon/evening!
The risk for widespread severe thunderstorms has increased across northern Illinois and southern Wisconsin Thursday afternoon and evening, but it's not a guarantee as there are a few things that could limit the severe risk locally. So, let's look at how things will develop through the night Wednesday, into Thursday morning:
REST OF EVENING/OVERNIGHT:
Skies will remain mostly cloudy through the night as a chilly east/northeast breeze keeps temperatures in the 30s. A warm front/stationary boundary currently sits in central and southern Illinois where showers have been ongoing for much of the afternoon. As the front begins to pull back north a surge of moisture will arrive with it. This will lead to an increase in rain showers beginning around 8pm, becoming more widespread through Midnight. Severe weather is not expected but periods of heavy rain will be likely with a few embedded thunderstorms. The steady and heavy rain will continue through the night and into Thursday morning. Rainfall totals by the morning are likely to range between half an inch, up to an inch. Temperatures will remain in the 30s before climbing near 40 degrees by daybreak.
THURSDAY MORNING:
Ongoing showers and thunderstorms can be expected during the morning Thursday, likely lasting through at least mid-morning. The warm front will still be to our south, which will serve as the focus for the showers during the morning. It is possible that some of the precipitation could last a little longer through the morning and early afternoon. If that occurs it could help keep the warm front to the south a little longer, delaying the return of higher instability until late in the day. Temperatures through the morning will remain in the mid and upper 40s, to low 50s around I-88 by late morning.
THURSDAY AFTERNOON:
Low pressure near Kansas City will move into Iowa during the afternoon, pulling the warm front north as it does. If the rain from the morning ends around mid-morning, we could see a second wave of showers and thunderstorms develop around Noon, lasting through 3pm or 4pm. The severe threat with this round would be low with the strongest producing heavy rainfall and strong winds.
It looks like our main window for severe weather would occur between 3pm/4pm to 8pm as the main cold front comes through from west to east. This would be when all hazards of severe weather would be possible, including the threat for tornadoes. Instability is expected to increase behind the warm front, spreading north and northeast into Illinois by mid to late afternoon. At the same time, winds within the mid and upper levels of the atmosphere will also be increasing.
As the cold front moves east from Iowa thunderstorms are expected to develop ahead of it before shifting into northwest Illinois. By the afternoon the warm front should be in southern Wisconsin with temperatures locally warming into the mid-60s. Dew points are likely to surge as well, nearing 60 degrees as far north as the state line. This would be enough to help fuel the storms as they shift east into Illinois.
Storms will be more discrete with supercells at the onset which would pose a risk for tornadoes initially, especially over eastern Iowa and areas west of I-39 in Illinois. This risk appears highest for areas that are near the warm front and low-pressure system. As the storms move east, they will form into linear clusters with more of a wind threat through the evening east of I-39.
But as I mentioned above the severe risk (including tornadoes) is not a guarantee. If any of the morning or early afternoon rain and thunder activity last longer into the afternoon, it would decrease the amount of time our atmosphere would have to recover, keeping the highest instability focused further southwest and west of the Stateline. It's also possible that the storms that form out west in Iowa fall apart, losing their strength by the time they reach the Stateline.
Unfortunately, some of these failure points may not be realized until tomorrow, and perhaps even until early in the afternoon. However, if everything were to come together for these storms to develop then there is the risk for tornadoes to occur in northern Illinois. And that is something we will need to keep a close eye on as we go throughout Thursday morning and afternoon.
Over the next 24-48 hours we're anticipating quite the wet and active stretch as our next low-pressure system tracks in from our west. A few isolated showers will be possible this morning, however chances will greatly increase past 8 p.m. today lasting through the overnight hours which may lead to heavy rainfall accumulations and possible flooding concerns.
As we head towards the evening, both upper level forcing and atmospheric moisture will continue to increase which will eventually lead to widespread showers across the region. At times heavy downpours will be likely this evening however our chances for thunderstorms will stay on the lower side. However, with such a large amount of atmospheric moisture present heavy rainfall will remain possible with a half an inch or more of precipitation possible in spots by tomorrow morning. The main concern tonight will be flash flooding due to rainfall over the last few days including any additional rainfall we see later.
As showers begin to weaken towards the morning, cloud cover will stick around early tomorrow morning. We'll be keeping a close on this cloud cover because it will heavily determine how much atmospheric instability, we can develop into the afternoon. Any atmospheric instability that develops will be the fuel for thunderstorms into the afternoon tomorrow with the possibility of a few severe thunderstorms. As of now the Storm Prediction Center has the state line outlined in a slight 2/5 with damaging wind gusts, large hail, and a few tornadoes possible.
With the afternoon round both the intensity and likelihood of showers and storms will depend on instability as previously mentioned. Even if we don't see storms around 3-6 p.m. chances for precipitation will continue to increase towards the late evening tomorrow night as the cold front comes in which may force even more thunderstorms. Depending on how our atmosphere evolves over the next day, we could see very high rainfall totals in local areas with nearly 1-2" possible in some areas.
4:33PM UPDATE: Our overall storm threat continues to decrease late Tuesday afternoon now that the cold front has passed. There has been a noticeable drop in temperatures, with many locations in northern Illinois falling into the 40s. However, clouds are clearing over parts of northwest Illinois, and this is where temperatures have made a small rebound, with Galena back into the low 60s and Monroe back to 50.
We will likely see the temperature in Rockford rebound briefly back into the low 50s before dropping into the 30s overnight. Skies will briefly turn partly cloudy overnight before turning mostly cloudy into Wednesday morning.
ORIGINAL POST:
Temperatures continue to drop from north to south early Tuesday afternoon as a strong cold front sinks south of the state line. Winds will turn to the north, and then northeast, behind the front ushering in the cooler air mass that'll remain in place through the afternoon Wednesday.
Following a few severe thunderstorms Tuesday morning most of the afternoon has remained quiet. But there are some thunderstorms that have developed just behind the front stretching from north of Freeport, IL up towards Janesville, WI. While the threat for severe weather remains low with the storms this afternoon, a few of the stronger ones are still going to be capable of producing small hail. One such storm is currently moving through southern Rock County in Wisconsin.
The threat for isolated thunderstorms will continue through about 7pm with drier conditions expected tonight. Winds will be breezy from time to time Wednesday keeping afternoon temperatures in the mid-40s.
After quite the busy evening last night with multiple severe thunderstorm warnings issued, we're waking up to a much calmer situation this morning. As of 4:15 a.m. only a few light showers have hung around the state line with an additional thunderstorm developing over davenport. A few isolated thunderstorms will still be possible through 7 a.m. today however most chances will be higher south of Interstate 88.
Through the rest of the morning and early afternoon the chances for thunderstorms will continue. Towards 8-9 a.m. another round of showers and thunderstorms may develop however those that were to develop would most likely stay south of Interstate 88. This round would conclude by 10-11 a.m.
Another chance for thunderstorms will then evolve into the early afternoon as a cold front begins to move through. Along this front another round of showers and possible thunderstorms may develop closer to 3 p.m. If these were to develop, an isolated severe storm cannot be ruled out with large hail and damaging wind gusts (60 mph+) being the primary hazards.
Transitioning towards the next few days, we'll keep this active pattern around. Thanks to our jet stream shifting to a southwesterly orientation we'll see continued lift and moisture from the Gulf funneled up into the Midwest. This will provide plenty of atmospheric moisture for almost daily shower chances as a few low-pressure systems are also expected to bring enhanced lift to the region.
The highest chances as of now look to come both late Wednesday and into the afternoon on Thursday. These rounds of precipitation will arrive nearly as the same time as our next low-pressure system with the first wave Wednesday night arriving with the warm front with the system.
Temperatures will rise back into the 60's then on Thursday with warmer and more moist air returning to the 60's. This will not only bring the chances of showers once again but also a few thunderstorms cannot be ruled out either as some models have begun to develop some instability. Thursday will need to be watch closely for additional instability developing, as we could see our next possible round of severe thunderstorms begin to take shape.
Thanks to all these precipitation chances we'll be expecting this week to stay on the wet side in terms of our rainfall totals. By the end Friday, we can see multiple areas receive over an inch of rainfall from today and the days to come. Not only will thunderstorms be a threat this week, but the possibility of flooding will also be there with such heavy rainfall forecasted. This will be a changing forecast day by day, so make sure to tune into the First Warn Weather app and updates from the First Warn Weather team!
