More T’Storm Development

After a day that brought ground-covering hail and temperatures near 80 to far northern Illinois, the threat for more thunderstorms is in the forecast. Scattered showers were beginning to develop in Iowa late this afternoon. It is expected that these showers further develop into thunderstorms as the afternoon and evening wears on.


Our chance for thunderstorms increases especially after sunset, as development in Iowa pushes east. A broken line of thunderstorms could produce very gusty wind and large, damaging hail. Frequent lightning and heavy rain will be likely under any thunderstorm.


A Severe Thunderstorm Watch is in effect for far northwest Illinois and south central Wisconsin until 10pm tonight.


Keep it tuned to the weather blog, Facebook, Twitter,, and 13 News Weekend for the latest updates.



Posted under Exactrack|HD, severe weather, Threatrack, weather

This post was written by Joe Astolfi on April 12, 2014

First thunderstorms of the year

threatrackAn area of low pressure will scoot directly overhead around 11pm tonight. A few thunderstorms are expected between 7pm and midnight. A few storms could produce some small hail and brief, gusty wind. No widespread severe weather is expected. For that reason, Threatrack remains at Level-1.

Let us know what you’re seeing in real-time on Twitter! Use @13wxauthority or @ericsorensen to report storms! -Eric


Posted under Threatrack

This post was written by Eric Sorensen on March 27, 2014

Ending October with Thunderstorms

Last week we saw several days with below-freezing temperatures. And if you’re like me, you probably came to grips with the fact that the warmth of autumn is probably behind us. While I don’t believe we’ll have another 60°, sunny day, there’s a good chance we’ll have a rainy 60-degree day this week…possibly two!

First, let’s take a look at how things will change in the next 24-36 hours. This is a look at the dewpoint temperature Monday at 10pm versus Wednesday 7pm.


Check out how the moisture surges northward out of the Gulf of Mexico! While you probably won’t break a sweat, it will feel a bit tropical Wednesday and Thursday with dewpoint temperatures in the middle 50s! 2That means Wednesday Night will be a warm one with thunderstorms and temperatures in the 50s and 60s…at night! Should we see a few sunny breaks either Wednesday or Thursday, we could see a few thunderstorms. The Storm Prediction Center has our area outlooked for possible thunderstorm activity on Wednesday with possible severe weather for parts of Missouri, Kansas, Oklahoma, Arkansas, and Texas.


Posted under Threatrack

This post was written by Eric Sorensen on October 28, 2013

Thunderstorm Update

4:00pm UPDATE:  Showers and thunderstorms have diminished in coverage locally, with severe weather affecting suburban Chicago.  It appears that the threat for any strong thunderstorms has moved out of the Stateline area.

4PM ExacTrack Radar

4PM ExacTrack Radar

(2:24 PM) nwsbot: Local Storm Report by NWS MKX: Como [Walworth Co, WI] trained spotter reports HEAVY RAIN of M1.02 INCH at 02:15 PM CDT — 1.02 inches of rain in 1/2 hour ending at 215 pm.

(1:57 PM) nwsbot: Local Storm Report by NWS LOT: N Capron [Boone Co, IL] public reports HAIL of penny size (M0.75 INCH) at 01:37 PM CDT — relayed via media.

(1:56 PM) nwsbot: Local Storm Report by NWS LOT: Harvard [Mchenry Co, IL] public reports HAIL of penny size (M0.75 INCH) at 01:35 PM CDT — relayed via media.

(1:54 PM) nwsbot: Local Storm Report by NWS LOT: N Capron [Boone Co, IL] cocorahs reports TSTM WND GST of E50 MPH at 01:40 PM CDT — winds estimated around 50 mph and heavy rain.

1:45pm UPDATE: Severe Thunderstorm Warning for Walworth County in Wisconsin until 2:30pm. Moderate-to-large hail (up to half-dollar size) is the main concern, with heavy rain and gusty wind likely as well.

ORIGINAL POST: Saturday morning’s extensive cloud cover, which limited the heating and energy from the sun—one of the components for stronger thunderstorms—has helped to lower our already small severe weather threat.

Minimal-to-Low Severe Risk

Minimal-to-Low Severe Risk

With the cold front pushing its way across the Mississippi River accompanied by light showers, the best chance for strong-to-severe weather appears to be focused east of Interstate 39.  This is great news, considering this system produced tornadoes in Iowa on Friday.  I’ve lowered our Threatrack to Level 1 west of I-39 and kept it at Level 2 east of I-39, where a few storms from central Illinois could brush our eastern coverage area.

1:30pm ExacTrack Radar

1:30pm ExacTrack Radar

Until the cold front passes, pop-up showers and thunderstorms will contain heavy downpours with potentially small hail.  An isolated stronger storm may also contain gusty wind.  By dinnertime, the front should be east of our area.  Keep it tuned to the weather blog for more updates as necessary.



Posted under Exactrack|HD, severe weather, Threatrack, weather

This post was written by Joe Astolfi on October 5, 2013

Threatrack-3 Saturday

untitledUpdate: New RPM model has come in with similar results to our previous post. Severe thunderstorms will be possible with the frontal passage in the mid-afternoon hours. Be ready for changing weather and have a way to get the warning. Now is a great time to download Exactrack|HD to your iPhone, iPad, or Android device. Just search “WREX Weather” on the App Store or Google Play. Also, you can follow me on Twitter for updates on the forecast. Note: All warnings are displayed on our 13 Weather Authority Twitter page


We are forecasting an Enhanced Risk of severe weather across Northern Illinois and Southern Wisconsin Saturday. For that reason, our Threatrack has been raised to level 3. The blue arrows indicate the direction the storms will be moving.

A strong cold front will be progressing east through the day, reaching the Mississippi River by noon and the Rockford Metro by 3pm. Showers and thunderstorms will be widespread along the front with a few severe. The main threat will be damaging wind and large hail. However, a few tornadoes will be possible!

The severe threat will go down very fast after 5pm as the front passes through completely. This is a look at the simulated radar from our RPM Computer Model (right). untitled2It shows a north-south squall line from Madison through Rockford, down to Bloomington-Normal. However, the strongest storms may not be south of here. Instead, we’ll have to closely watch to see if there are any leftover low-level boundaries that could disrupt the flow of air into these storms. If there are any disrupting boundaries around, storms may begin to spin and produce a tornado before they merge into a line.

SVRnam212F036Finally, in order to accurately forecast what’s going to happen we need to look at similar systems in the past. This graphic shows all of the severe weather reports (green-hail, blue-wind, tornado-red) in the 15 most similar storm systems to this one. It gives us a good idea of the greatest potential. Of note, are a few very long-track tornadoes south of here in the top-15 analogs.

We can’t say whether we will see significant damage from severe, only to urge everyone to be ready for changing weather on Saturday. More people count on us for severe weather coverage than anyone else and the 13 Weather Authority team will be ready! -Eric


Posted under severe weather, Threatrack

This post was written by Eric Sorensen on October 4, 2013

Another Round of Scattered Storms

Much like we witnessed on Friday, scattered showers and thunderstorms will dot the radar again on Sunday.  There are some differences in the forecast, however.  With a fast-moving cold front expected to slide through the area early in the day, there will be a limited amount of time for the sun to warm things up before cloudcover and the threat for rain arrives.  Our high temperatures will likely climb into the middle 80s—perhaps only near 80 in southwestern Wisconsin, where the effects of the front will strike first.


A broken line of showers and thunderstorms will develop along and ahead of the front and push southeast through the region.  FutureTrack depicts this potential line of storms entering the Rockford metro around 1pm.  It appears that some areas well west of Rockford could pick up a shower or two before the afternoon hours.  Moisture is more limited with this system, compared to Friday, so not all areas will see rainfall.  Chance of rain is 50%, so some backyards will remain dry on Sunday.


The threat for strong thunderstorms exists.  However, given the swift speed of the cold front, the best chance for any severe weather appears to be just south and southeast of our local area.  Central Illinois and parts of Indiana will have more time to warm up on Sunday, creating an atmosphere primed for a few stronger thunderstorms.  The main threats Sunday will once again be hail and gusty wind.  Excessive rainfall, like we saw on Friday, is less of a threat due to the fast-moving nature of the front and associated thunderstorms.  If your travels take you to Bloomington-Normal, Peoria, Champaign, or Indianapolis, keep an eye on the sky.



Posted under FutureTrack, rain, Threatrack, weather

This post was written by Joe Astolfi on August 31, 2013

Threatrack-2 Friday evening

THREATRACKA very hot and humid airmass will be in place across Northern Illinois and Southern Wisconsin ahead of a fairly strong cold front that will move southeast into our area by evening.

Temperatures will surge into the middle 90s with dewpoints in the lower 70s. Instability ahead of the front will promote thunderstorm development, mainly after 4pm. Storms will have the capability of producing damaging straight line wind and possible large hail. Stay with the Weather Authority as we keep you updated, especially if you have outdoor plans Friday evening. -Eric


Posted under Threatrack

This post was written by Eric Sorensen on August 29, 2013

Scattered T’Storms on Sunday

A cool front that moved through the Stateline on Friday night has set up shop as a stationary front in northern Missouri and central Illinois. The hot & humid airmass will remain south of that front.  However, it will begin to push back north as a warm front throughout the day Sunday. As that front moves north, a few scattered showers and thunderstorms will dot the sky across northern Illinois and southern Wisconsin.  Sunday will be mostly cloudy, although a few sunny breaks are likely.  Highs will reach the lower 80s.  While we’ve got the chance to see some wet weather throughout the day, the best chances will come during the afternoon, evening, and nighttime hours on Sunday through very early Monday morning.

Monday should see a midday break with a brief return to the hot and humid air. Expect a partly cloudy sky with highs in the upper 80s. By the evening, more scattered showers and thunderstorms will develop and last into the nighttime hours.

A few heavy downpours are possible at times over the next 48 hours.  However, the rain and thunderstorms will be scattered in nature, so not everyone will receive the same amount of rain across our 13 counties.



Posted under rain, Threatrack, weather

This post was written by Joe Astolfi on July 20, 2013

Severe thunderstorms possible Friday

CaptureA cool front will work into the region on Friday, providing enough lift for thunderstorms in the afternoon. Because the airmass will be fully charged with instability, a few storms could be severe. The main threat will be damaging wind and this will be more of a concern immediately to our east. From Chicago through Lower Michigan, storms could produce extreme wind…possibly on the order of 80-90mph! The further west you go into Eastern Iowa, the threat will be lower due to a lack of wind shear. -Eric


Posted under Threatrack

This post was written by Eric Sorensen on July 18, 2013

Scattered Storms Through Midweek

A warm and humid Sunday night is expected for Rockford and the Stateline, with low temperatures bottoming out near 70 degrees. An stray shower or thunderstorm is possible, with our chances increasing  after 2am as a line of scattered showers and thunderstorms from Duluth, Minnesota to Denver, Colorado pushes east.
A few rumbles of thunder are expected around dawn and during the morning hours of Monday. While we’ll hang onto the chance for a pop-up shower or storm all day, it appears we may catch a break in the action during the midday hours.  Later in the day and into Monday night, that chance will increase yet again.  High temperatures on Monday will be similar to Sunday’s upper 80s. Some backyards will flirt with 90 once again.  Our dewpoints will be in the tropical range and the humidity will be very umcomfortable.  Area heat indices will top out between 95 and 100 degrees!
Tuesday will be another hot and humid day with the best threat of scattered showers and thunderstorms.  Some of the thunderstorms may be stronger during the afternoon and evening hours as a cool front begins to approach the area. Gusty wind and sizeable hail will be a concern, as well as potential heavy and flooding rain.
The threat for scattered storms will linger into the first half of Wednesday as a cool front pushes through the Stateline.  Behind the front, a pleasantly warm and noticeably less humid airmass will arrive with Canadian high pressure.  Thursday through next Sunday will be calm with ample sunshine.

Posted under rain, severe weather, Threatrack, weather

This post was written by Joe Astolfi on July 7, 2013