11:30PM – Severe storm threat has ended.

(10:27:02 PM) nwsbot: LOT issues Severe Thunderstorm Warning [wind: 60 MPH, hail: 1.00 IN] for De Kalb, Kendall, La Salle, Lee [IL] till 11:30 PM CDT

Update from NWS: …DAMAGE SURVEY TO BE CONDUCTED THURSDAY…

THE NATIONAL WEATHER SERVICE WILL BE DEPLOYING A DAMAGE ASSESSMENT
TEAM ON THURSDAY TO PORTIONS OF EASTERN LEE…FAR SOUTHERN
DEKALB…AND KENDALL COUNTIES. THE TEAM WILL BE INVESTIGATING A
CORRIDOR FROM PAW PAW AND SHABONNA EASTWARD TOWARD PLANO AND
YORKVILLE. THERE WERE SCATTERED REPORTS OF FUNNEL
CLOUDS…TORNADOES…AND SOME DAMAGE OVER THIS AREA.

OTHER AREAS OF DAMAGE OR UNCONFIRMED TORNADO REPORTS MAY BE
INVESTIGATED AS WELL. MORE INFORMATION WILL BE PROVIDED THURSDAY
MORNING.

(7:33:47 PM) nwsbot: Local Storm Report by NWS LOT: Shabbona [Dekalb Co, IL] park/forest srvc reports TSTM WND DMG at 04:35 PM CDT — shabbona lake state park boats tossed onto boats. large trees snapped at trunk or uprooted. power poles down near state park office.

Stormchasers got video of a tornado in Paw Paw, IL in Lee Co.

(6:55:53 PM) nwsbot: Local Storm Report by NWS DVN: 2 S Hanover [Xxx Co, XX] law enforcement reports TORNADO at 06:51 PM CDT — moving southeast.
(6:55:53 PM) nwsbot: Local Storm Report by NWS DVN: Hanover [Jo Daviess Co, IL] trained spotter reports TORNADO at 06:51 PM CDT — moving southeast.

(6:47:16 PM) nwsbot: DVN issues Tornado Warning [tornado: RADAR INDICATED] for Carroll, Jo Daviess [IL] till 7:15 PM CDT …AT 641 PM CDT…A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO WAS LOCATED NEAR HANOVER…AND MOVING SOUTHEAST AT 30 MPH.

(6:02:29 PM) nwsbot: DVN issues Tornado Warning [tornado: RADAR INDICATED, hail: <.75 IN] for Jo Daviess [IL] till 6:30 PM CDT …AT 559 PM CDT…A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO WAS LOCATED NEAR MENOMINEE…AND MOVING SOUTHEAST AT 20 MPH.

(3:43:45 PM) nwsbot: LOT issues Tornado Warning [tornado: RADAR INDICATED, hail: 1.25 IN] for Lee, Ogle [IL] till 4:30 PM CDT …AT 342 PM…A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO WAS LOCATED NEAR WALTON…AND MOVING NORTHEAST AT 35 MPH.

(3:34:19 PM) nwsbot: LOT issues Severe Thunderstorm Warning [wind: 60 MPH, hail: 1.25 IN] for Lee, Ogle [IL] till 4:30 PM CDT

A Tornado Watch is in effect through 9pm. This is a particularly dangerous situation! Storms will affect the Rockford Metro between 4-8pm. -Eric

Posted under severe weather

If you haven’t read through Chief Meteorologist Eric Sorensen’s Tuesday blog post regarding our severe weather threat for Wednesday afternoon, I’d recommend it. You can find his blog post HERE. 

A somewhat stable airmass is in place across the Stateline for Wednesday morning.  Overnight showers and thunderstorms in western Iowa fizzled out before they crossed the Mississippi River into Illinois.  The result is a mostly cloudy morning with a few breaks of sunshine.  Humidity and temperatures will be on the rise throughout the day, with highs expected to reach the middle 80s.

The meteorological ‘ingredients,’ so to speak, are coming together for severe weather later today.  With a surface wind still expected out of the southeast and an upper-atmospheric wind out of the south-southwest, directional wind shear and storm rotation will be a concern this afternoon and evening.  A warm front is still expected to lift into northern Illinois this afternoon, at least as far north as the Interstate 88 corridor.  It is along this front that supercell thunderstorms may develop.  Supercell thunderstorms have the potential to produce strong wind gusts, large damaging hail, and possibly a tornado.  These threats will all be of local concern this afternoon, including torrential rain.

Don’t panic.  However, today is a good day to be ‘weather aware’ and keep an ‘eye on the sky.’  Make sure you have a severe weather safety plan in place.  We haven’t seen a threat like this across the Stateline for a few years.  Let’s plan for the worst and hope for the best.

As far as timing goes, our array of forecasting products are not on the exact same page. However, the best timeframe for severe thunderstorms to develop is this afternoon and evening.  Storms may begin to form in eastern Iowa around 2pm through 4pm and move east-southeast into our area after that.  Some model solutions begin a bit earlier, some begin later around dinner time.  We do know that this afternoon and evening will be active. 

Don’t forget, you can track the storms on your smart phone with our 13 Weather Authority App or sign up for severe weather text alerts.

-Joe

Posted under rain, safety, severe weather, Threatrack, tornado, weather, Wind

The set up for severe weather Wednesday afternoon is quite ominous. The following forecast is solely based on our Futuretrack model. Other models depict slight shifts north and south. So, while we can pinpoint exact locations of possible severe weather using this model, keep in mind it is just one model solution! We’ll have to forecast as we go through the day on Wednesday to get the exact particulars and locations effected.

Having said that, this is the forecast model I am going with right now. Before I get into the nuts and bolts, please know that a lot depends on the amount of instability available. (In my previous blog post, you can see how distinct the cut-off of instability is. This map shows how we go from a completely charged atmosphere to nothing is. Unfortunately, it’s an all-or-nothing scenario.)

First, let’s look at the surface wind directions. It’s obvious here we’ll have an east-to-west front lying right over Northern Illinois with plenty of convergence along the front (which promotes ascent). Areas north of the front will be slightly more stable, but areas south of the front will yield plenty of instability! Concerning to us is the area where there is a southeastly wind. This usually takes place along and immediately south of the frontal boundary. Clinton, IA, Sterling-Rock Falls, Dixon, DeKalb, Mendota, and the southwest suburbs of Chicago all lie in this sweet spot. (Again, keep in mind, this is one model and this boundary may set up a few miles north or south of there…causing this sweet spot to shift some.)

But we have to think of the atmosphere in three-dimensions. Simply looking at the surface wind gives us no clues as to the potential severity of the storms Wednesday afternoon. In this graphic, I superimposed the wind at 3,000 feet. They are noted as colored lines. The brighter (reds and pinks) indicate stronger wind aloft. Note, that is in Central Illinois. There, we can see quite a bit of “speed shear” which is a form of wind shear where wind increases with height. This set up will bring about the possibility of significant straight-line wind potential for Central Illinois…and Indiana later in the day. Closer to home, the wind over Northern Illinois is much lighter at 3,000 feet, but is moving perpendicular (or at a right angle) to the southeasterly wind. This maximizes the amount of wind shear over North Central Illinois. With that 90° change in wind direction: from southeast at the surface to southwest at 3K feet, I believe this is the area at highest risk for isolated tornadoes on Wednesday afternoon. You can see where the low pressure center is in Central Iowa around 6pm with the warm front extending eastward through Northwest Illinois and then toward the southern end of Lake Michigan. The storm motion tomorrow will be from west to east with a slight movement toward the southeast later in the day. The highest threat for severe weather will exist between 3-8pm.

Be alert for changing weather and have a way to get warning information, whether that’s from the WREX Weather App (Search on the App/Google Play stores) or a NOAA Weather Radio.

Meteorologist Joe Astolfi will be updating the blog first thing Wednesday morning. -Eric

Posted under severe weather

Get ready for more big thunderstorms! A few of you saw hail and heavy rain Tuesday afternoon, especially across Ogle and DeKalb County. This shot taken from near Creston around 3pm.

Our attention will shift to the possibility of thunderstorms during the wee hours of Wednesday and then again in the afternoon. There are indications, an MCS will develop in northwestern Iowa around midnight, tracking east-southeast into the Illinois/Wisconsin stateline area during the pre-dawn hours. This storm will have the potential to produce damaging wind and torrential rain.

We’ll probably get a decent break in the rain for lunchtime with storms refiring for the late-afternoon. Storms will have the potential to produce large hail, damaging wind, and isolated tornadoes. This graphic shows where the atmospheric energy will be at its max (shaded regions). A strong “vort-max” or disturbance will be moving into our region from the northwest. This increases my confidence of thunderstorms to about 90%.

Please be weather-aware on Wednesday! -Eric

Posted under severe weather

Severe thunderstorms are a good bet across parts of South Dakota, southern Minnesota and northwestern Iowa late Tuesday. In fact, the Storm Prediction Center has placed that region in a Moderate Risk (a category that is not issued very often).  Should these storms hold together, there is the potential for a derecho to develop. “Derecho” is a meteorological term derived from the Spanish language word for “straight.”  It refers to a widespread and rapidly-moving wind-storm associated with a bow-echo line of thunderstorms that can last hours and overnight. Straight line winds over 80mph can produce damage across areas hundreds of miles long and more than 100 miles wide.  Typical derecho events see a southeasterly turn in the progression of the line of storms.  However—and I cannot stress this enough—derecho events are extremely difficult to forecast until they have formed.  This will need to be monitored locally as we head into the overnight hours (pre-dawn hours of Wednesday).

Severe thunderstorms are a possibility again on Wednesday. A round of showers and thunderstorms in the early morning may yield a break during the middle part of the day.  By the afternoon and evening a warm front will lift north toward the Stateline. If we get enough daytime heating, our atmosphere will destabilize and showers and thunderstorms will form.  Some of these storms may take on supercell form, which could produce large hail, heavy rain, strong wind gusts, and an isolated tornado.  Perhaps the highest threat will be just southeast of us from Chicago south to Champaign and east through Indiana and western Ohio. 

This blog post is not meant to scare; it’s meant to inform you of the possibility of severe weather.  Not all of us will be affected; however, the threat exists across our entire region.  It’s a great time to be weather aware!  Join 13 Weather Authority Chief Meteorologist Eric Sorensen at 5, 6, and 10pm tonight for further forecast updates and analysis.

-Joe

Posted under safety, severe weather, Threatrack, weather, Wind

You’ll notice an up-tick in the humidity and heat on Tuesday. That combination will be enough to fuel some thunderstorms ahead of an area of low pressure Wednesday. Here’s the timing of the first round of quick-moving thunderstorms. I don’t expect much here before about 5am Wednesday morning, but depending on the forward movement of the storms, they could produce gusty wind.

As far as rainfall goes, it doesn’t look like we’ll get too much to handle. Model average is around an inch. However, these are large-scale models. We know that individual thunderstorm complexes are not uniform and can put down heavier amounts locally. With that being said, a few 2-3 inch reports can’t be ruled out.

Posted under rain

Missing Copious Showers? No.
Melted Cheese Sandwiches? Nope.
Merry Christmas Songs? Don’t think so.
Mesoscale Convective Systems? Bingo!

In the Midwest, about 10% of our rainfall falls due to Mesoscale Convective Systems. Quite simply, an MCS is a complex of thunderstorms that develops at night instead of during the day. While these types of weather systems don’t usually produce tornadoes or heavy rain (due to their large size and swift speed) but damaging wind can be a real factor. Models are narrowing in on a solution that forms an MCS around Sioux Falls, SD Tuesday night, accelerating it southeastward toward the Rockford Metro by Wednesday morning.

Here’s a look at the simulated radar during the mid-morning hours of Wednesday. Should a bow-echo or a derecho (a stronger, longer-lived version of a bow-echo) form, we could be in the path of some damaging wind potential. Where this sets up and the intensity is really hard to put into forecast at this point. However, the scenario supports some type of nighttime thunderstorm complex Tuesday night into Wednesday morning. -Eric

Posted under weather

Brace yourselves. Clouds and rain are in the forecast….again!  If you thought it’s been cloudy and rainy lately, you are correct.  Looking at the past 30 days, there have been 21 days with at least a trace of rain reported at Chicago Rockford International Airport! 

Sunday will start off mostly cloudy and mainly dry, with just a few isolated showers dotting the radar.  Scattered showers and thunderstorms will become more numerous as we head into the afternoon and evening hours.  A breezy south wind, 10-20mph, will help temperatures rise to near 75 despite the clouds.

This system that is headed our way for Sunday brought severe weather to the Great Plains on Saturday.  While the chance for severe weather is low locally, there is a minimal threat for a few stronger thunderstorms Sunday afternoon. I anticipate the best threat of severe weather to stay just south of our local area, affecting Bloomington, Peoria, Springfield, and St. Louis. 

The showery, thundery weather will continue Sunday night as well.  As the system pushes off to our east, a few lingering scattered showers will remain in the forecast through Monday afternoon. 

-Joe

Posted under FutureTrack, rain, severe weather, Threatrack, weather

It has been a very cool and fairly rainy week, but as we look ahead to the weekend we hope for sunshine and warmth to return. The good news is that the sunshine will indeed begin to return as soon as this afternoon. That sunshine will be ample tomorrow as well, but by Sunday we return to the chance for some on and off showers as a frontal boundary makes its way toward the Stateline. The bad news is that temperatures won’t warm that much within the next three days. Highs today put us in the upper 60s, and both Saturday and Sunday will sit in the low 70s. Warmer does move in by the middle of next week when we could push close to 80 degrees. -Greg

Posted under rain, weather

We have seen an overwhelming response in our Midland Weather Radio campaign this spring! Tomorrow, our next event hits Cherry Valley where your 13 Weather Authority team will be programming them free from 5pm to 7pm. Bring us an older Midland Radio or buy a new one and we’ll make sure it’s programmed to only go off when you want it to! You can buy a radio at any area Schnuck’s store in Rockford, Loves Park, Roscoe, Janesville, Cherry Valley, and DeKalb.

I’ve had many of you ask how easy it is to program on your own. I made a short three minute tutorial that shows you how easy it is! (Although we’d love to meet you at one of our Friday events). Please think about getting something that will alert you when to take shelter. With strong tornadoes happening this spring, we want to make sure everyone is prepared should it happen here. -Eric

Posted under safety