Update to Tuesday's Storm Threat

With Tuesday being Primary day in Illinois I know many Stateliners will be out and about on Tuesday. We won't see rain and storms the entire day, but we do look to see rain in the morning and again in the afternoon.

Not much in the set up has changed since the previous post, we are still watching a developing low pressure system that is currently positioned in the northern Rockies. This low will head east and move into the Midwest on Tuesday. Ahead of that low, Tuesday morning, we look to see a line of showers moving through. The time frame for this would be around 8am through the late morning. We will then dry out a bit around lunch with then the threat for thunderstorms ramping up for the afternoon.

As of now, the best time frame looks to be in the late afternoon and early evening for stronger storms to be possible. This would be around 3pm through 7pm Tuesday as a cold front moves east across the region. Storms look favored to develop close to the Mississippi River just ahead of the cold front and then head east.

If you are planning on voting tomorrow, as of now the best timing to do that would  be earlier in the day with the threat for storms centered closer to the evening commute home.

However, there are still questions regarding the system as we are still about 24 hours out. One question is the timing of the cold front, if it arrives later in the day, the storm threat would shift more to the east of us. We will also be watching what happens earlier in the day on Tuesday. If rain were to move through in the morning and we can't get any of the clouds to clear, this would also hinder the storm threat later in the day. Instability is tied to the warmth we are able to get in the afternoon and our temperatures. If we can't get our temperatures up or any sunshine it will be harder to get instability to come by, and again would lower our threat for storms.

I did want to mention that the Storm Prediction Center does have northern Illinois and southern Wisconsin highlighted under the 'slight risk' for severe weather. This is not set in stone, but tomorrow will definitely be a day to keep your eyes to the sky and have a way to receive watches and warnings should we get them.

We will continue to update the forecast as we get closer, so make sure you check back with the First Warn Weather Team for updates.

Storm Threat Tuesday

A fairly active, and slightly cooler, week is shaping up over Northern Illinois and Southern Wisconsin with the area being impacted by several low pressure systems.  The first is what's bringing us rain Sunday afternoon.

Rainfall totals haven't been much with most receiving under 0.40" through Sunday evening, but it's been a pretty steady rain.

The next low will have a little more punch to it and is expected to arrive Tuesday.  This one is currently in the Pacific Northwest and will move into the Central and Northern Plains late Monday.  A warm and moist air mass will be pulled northward into the Plains and Midwest Monday with thunderstorms possible over the Dakotas, Minnesota and Iowa Monday afternoon.  A few of those storms could sneak into Northwest Illinois late Monday night.  However, any threat for severe weather is expected to remain low.

Ongoing showers will be likely by Tuesday morning with skies possibly drying out by the afternoon.  As the low pressure system pulls into the Upper Midwest Tuesday afternoon, a strong cold front will sweep across Wisconsin and Illinois.  Ahead of the front, dew points (moisture) nearing 50 degrees - which is high for this time of year - will be pulled northward into Central, and possibly Northern Illinois.

There remain some differences in key features Tuesday in terms of front and low pressure system placement, which would ultimately have an impact on where the greatest likelihood of strong thunderstorms would develop.  As of Sunday evening, it appears as if the development of thunderstorms would be favorable along and east of I-39 Tuesday afternoon between 3pm and 6pm.  Either way, the Storm Prediction Center has highlighted most of Northern Illinois under a slight risk for severe weather Tuesday afternoon

Tuesday Afternoon
Storm Prediction Center

and evening.  With Tuesday being Illinois Primary day, I really want you to pay close attention to the forecast.  Make sure if you're going to be out, you know where to go in the event severe weather does occur.  And make sure you have a way to receive watches/warnings if you're away from home.

Cooler Temperatures to Return

We have strung together quite an impressive stretch of mild temperatures of late here in the Stateline. In fact, we even saw 70's make a very early appearance. However, all good things must come to an end, right? That phrase will hold true regarding our warm temperatures. Sunday will be chilly near 50°, but upper 50's and 60's return Monday and Tuesday ahead of what will likely turn out to be a strong low pressure system. That low will develop to our west in the Upper Midwest and rapidly strengthen as it moves towards Wisconsin on Tuesday.

As it does so, it will swing a cold front through Illinois and Wisconsin Tuesday evening. Along this frontal boundary exists the chance for showers and thunderstorms. Models do disagree slightly regarding how much rain will develop along the front, and how far south the rain will go. As a result, it is not impossible that the rain stays mainly north of Rockford, but at this time it appears as though at least some rain and thunderstorms will affect the region Tuesday into Tuesday night. This means any voters who venture out during the afternoon and evening could be met with rain.

There are two other aspects to this system. First, winds will pick up significantly Tuesday and Wednesday as the low sits to our north and deepens. Secondly, as is true with most cold fronts, cooler air will filter in beginning on Wednesday as highs are expected to drop into the middle 50's.

Even colder temperatures arrive by St. Patrick's Day and beyond with highs likely remaining in the 40's and lows dropping into the 30's. While models are in pretty good agreement regarding the temperatures next week, they do show significant disagreement regarding precipitation. One of our long-range models suggests rain and even snow remaining in the forecast through Friday night. Meanwhile, the other long-range model takes that precipitation to our east by Wednesday morning. Therefore, a few light showers cannot be ruled out Wednesday, Thursday and Friday, but nothing significant looks likely at this time.

Sun Sets Later, Rain, and More!

We have a lot to talk about in tonight's weather discussion! So let's get started. First of all, we had a beautiful Friday with plenty of sunshine warming our temperatures into the lower 60's. You may have noticed that sun stayed up until roughly 6 PM as well. Our days continue to get longer, and by Sunday evening we will see the sun set after 7 PM as we Spring Forward late Saturday night. So don't forget to set those clocks back and check the batteries in your weather radios and smoke detectors this weekend. More good news is that spring officially starts in less than 10 days!

Sadly, sunshine won't be a very common occurrence over the next several days. We are monitoring two distinct weather systems that will each bring plenty of rainfall to the Stateline. The first wave of low pressure arrives late Saturday night and lasts through late Sunday night. It will bring off and on rain Sunday that could amount to nearly 1" by the time all is said and done. Heavier rainfall totals will be found south of the area.

Monday looks mainly dry, but a second area of low pressure will develop and rapidly strengthen near the region Tuesday. As it does, rain will move in later on Tuesday. There will be a minimal amount of instability available on Tuesday, which could translate into a few thundershowers, but there is no threat for severe weather as it appears now. Tuesday happens to be the Illinois Primary. This means if you are planning on heading out to vote after noon, you will likely run into rain. The chance of seeing rain will increase through the day, so make sure to get out early, if possible! Another inch or so of rainfall will likely fall with this system.

Temperatures will be an even bigger story as we head into next week as our recent spring-like warmth will be a thing of the past come Wednesday. An extended stretch of well-above average temperatures will come to an end as a result of a large dip in the stream forming by Wednesday. This will allow colder air to filter southward from Canada into the Midwest, Plains, Great Lakes, and Ohio Valley. Now it won't be brutally cold, but I do expect temperatures to return to normal levels, if not slightly below normal. Highs will likely stay in the 40's to round out next week and enter next weekend. Soak up the next four days of warmer temperatures if you are not a fan of the cooler weather!

Spring-like Weekend on the Way

After a frosty and foggy morning, and feeling a bit like winter, it will be feeling like spring this weekend.

High pressure settles in this afternoon and keeps the sunshine around. Temperatures will warm into the upper 50's and low 60's with southeast winds at 5-10 mph. We will have sunshine to start the day on Saturday and temperatures will warm into the low 60's. The cloud cover will then increase through the afternoon as a low pressure system gets closer to us.

 If you are heading out to the St. Patrick's Day Parade in Rockford we will have nice weather for that as well. It begins at 3pm on Saturday, the parade route begins near 7th Street and 4th Avenue and end on State Street at Memorial Hall.



Scattered showers will then move in through the late afternoon Saturday and into the evening. We will then see more coverage in the rain on Sunday afternoon but temperatures will still warm to 60°.

This rain is associated with the low that is currently in southern Texas and is bringing historic flooding to the deep south. The low will weaken as it lifts north and brings the rain shield into central portions of the State. Rain will continue to lift northward and arrives in northern Illinois and southern Wisconsin Saturday night and Sunday.

Downward Temperature Trend with Pattern Change Next Week

As the old saying goes, 'All good things must come to an end'.  And that looks to be the case with our warmer weather later next week.  But in the near term, temperatures will remain in the low 60's for the weekend and early next week.  However, a pattern change within the jet stream will pull down cooler air from the north and push the more mild air south and east.

Over the past week, the southern branch of the jet stream has been the dominant jet stream.  The northern branch has been shifted north into Canada.  As we near the official start of spring, next Sunday the 20th, a dip in the jet stream will cause the northern branch to become more dominant pulling down the cooler air.  Now, I wouldn't necessarily say it's going to be an Arctic outbreak but the 50's and 60's we've become used to this past week will drop into the 40's (typical for this time of March), but possibly the 30's.

We'll have to wait and see just how long this cooler pattern sticks around, but it may last through the end of March.

Here is the 8-14 day outlook from the Climate Prediction Center.  You can clearly see where the dip in the jet stream will take place over the middle of the country.  With this cooler pattern, precipitation does look to remain below average.

Time to Spring Ahead! Don't Forget!

Despite it still being Winter, the weather across the Stateline has us feeling Spring Fever! Temperatures this week overall 15-30° warmer than average! We're also noticing a little more daylight as the sun sets later and later everyday - and with that thought in mind - don't forget that we 'spring ahead' this weekend!

Daylight Saving Time begins this weekend, 2:00am Sunday morning to be exact. So don't forget to set your clocks AHEAD one hour before you head to bed Saturday night.