Severe Thunderstorm Watch

3:00am Update: A small line of storms will quickly move east out of McHenry County. The severe thunderstorm threat is over.

2:30am Update: Severe Thunderstorm Warning is in effect for Winnebago (east of IL-251), Boone, and northwest McHenry County until 3:15am. Wind gusts to 60mph, quarter-size hail, frequent lightning, heavy rain all likely with this storm. Far east Rockford, Roscoe, Cherry Valley, Belvidere, Poplar Grove, Caledonia, Timberlane, Candlewick Lake, Capron, Chemung, Harvard, Hebron all in line for this warning.

Severe T'Storm Warning until 3:15am

Severe T’Storm Warning until 3:15am

2:00am Update: Gusty wind—up to 50mph—will be possible across Lee, Ogle & Winnebago County ahead of the line of storms. The storms in Stephenson, northern Ogle and Winnebago County will contain some hail and frequent lightning.

Gusty Wind Ahead of the T'Storms

Gusty Wind Ahead of the T’Storms

1:40am Update: Severe Thunderstorm Warning is in effect for western Whiteside County and southwestern Carroll County until 2:15am. Gusts to 60mph, hail, and frequent lightning all possible with this storm. This storm will reach the Morrison and Prophetstown area around 2am.

Severe T'Storm Warning until 2:15am

Severe T’Storm Warning until 2:15am

Origional Post: Severe Thunderstorm Watch is in effect for most of the area until 5am Sunday morning. Clusters of showers and thunderstorms over Iowa have developed into a line of thunderstorms. This line will continue to move east across Iowa and take aim at the Stateline area overnight. An approximate time frame is between midnight and 4am.

Severe T'Storm Watch until 5am

Severe T’Storm Watch until 5am

The main threats overnight will be strong gusty wind, damaging hail, frequent lightning, and heavy downpours. The threat for tornadic activity is extremely low.

11pm Exactrack HD Radar

11pm Exactrack HD Radar

I will update the blog and social media as needed throughout the night.

-Joe

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Posted under Exactrack|HD, severe weather, weather

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

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.

waiting

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.

threatty

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

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

-Joe

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

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

There are 525,948 minutes in a year. How many are spent in a weather warning?

Most of the United States is relatively safe when it comes to severe weather. Of course, we think of Oklahoma and Texas as being prime spots for tornadoes. But a new map shows us the average amount of time spent in a weather warning per county. Daryl Herzmann of Iowa State University released some great maps this week. Take a look!

First, here is the average time spent in a Severe Thunderstorm Warning.
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Of course, the higher likelihood for severe thunderstorms lies in the Tornado Alley state of Oklahoma. But notice the maximum over Eastern Tennessee and even Northern Ohio. It may be a little difficult to see the actual location of states because the dark black lines in this map represent the borders of the National Weather Service offices. Here in Northern Illinois and Southern Wisconsin, we are serviced by three different offices, Milwaukee-Sullivan, Quad Cities-Davenport, and Chicago-Romeoville.

Next up, the map showing the average minutes of the year spent in a Tornado Warning:

tor

A few things on this map stand out. First, the larger counties within a tornado-prone zone have a higher chance of being within a warning polygon. Of note is the number of minutes in McLean Co., IL (Bloomington-Normal) which is the largest county in Illinois in bright red compared to Putnam Co., IL (North of Peoria) which is blue.

Daryl went further and took square kilometers into account with the following map. This one is telling! It shows the highest likelihood of a Tornado Warning (not necessarily a full-fledged, on-the-ground tornado) to be in Mississippi.
tor2

So, while we may think of Tornado Alley being Texas and Oklahoma, the higher threat of tornadoes may reside in the Deep South…at least looking at the data over the past 20 years.

Finally, for your viewing pleasure? The map for Flash Flood Warnings per county. It’s easy to see the highest probabilities for flash flooding in the past 20 years are in Southern Missouri and in the Desert Southwest.

ffw

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Posted under flooding, severe weather, tornado, weather

This post was written by Eric Sorensen on April 10, 2014

Two very different cold fronts

1A quick look at a weather map can usually give us a quick idea whether it will produce severe weather. On the left is the scenario for Thursday. A weak cold front will work in from the north. Because of its east-west orientation, there may be just enough convergence at the surface to produce some showers. However, long-lived thunderstorm activity isn’t expected. With east-west cold fronts, the jet stream is almost always parallel to the front. While rain is possible, big thunderstorms aren’t likely.

2However, with thunderstorms that sweep in from the west, there is usually more convergence which leads to higher rain and thunderstorm chances. Southerly winds in advance of the front can bring in higher levels of moisture from the Gulf of Mexico. In addition, there’s usually a strong jet stream perpendicular to a north-south front. This leads to higher wind shear…and a higher intensity of thunderstorms! So as we head through the spring season, be on the lookout for the north-south orientation on the weather map.

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Posted under severe weather, weather, weather geek

This post was written by Eric Sorensen on April 8, 2014

Blizzard Conditions Overnight

A Blizzard Warning is in effect for Carroll, Jo Daviess, Stephenson & Whiteside County overnight. Winter Storm Warnings are in effect for the rest of our area.  We will all deal with blizzard-like conditions through early Monday morning.  The worst of it will occur now through about 3am.

Winter Weather Alerts: Blizzard conditions area-wide

Winter Weather Alerts: Blizzard conditions area-wide

Winds have become increasingly stronger throughout the evening.  West northwest winds will be sustained between 25 and 35mph with wind gusts approaching 50mph.  Blowing and drifting with whiteout conditions are likely area-wide, with the worst being on rural roads and in open areas.

Avoid Travel Overnight

Avoid Travel Overnight

Avoid travel overnight. Numerous roads are shut down. Many cars are in ditches. Temperatures will fall below zero after midnight and wind chills will plummet to 30 below by sunrise; you do not want to be stranded in these conditions.

-Joe

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Posted under cold blast, safety, severe weather, snow, travel, Wind, winter storm, winter weather

This post was written by Joe Astolfi on January 26, 2014

Frostbite Weather

Dangerous—even life-threatening—cold temperatures and wind chills will keep the Stateline area in the deep freeze through Wednesday morning.  Not only will a gusty north-northwest wind cause blowing and drifting snow in open and rural areas, it will cause our wind chill values to be extremely cold.

Wind Chill Warning

Wind Chill Warning

Our general wind speed will be between 15 and 25mph with gusts up to 35mph now through Monday evening. From Monday night through Tuesday evening, winds will lessen to 10 to 20mph with a few higher gusts.  Air temperatures will bottom out around 20 below zero Monday morning and only rise to near 13 below zero by afternoon.  Temperatures will likely stay below zero for most of us all day Tuesday and not return to the positive side until late Wednesday morning.

Our forecast air temperature and wind speed will allow for wind chill values between 45 and 30 below zero through Tuesday night.  The coldest readings will occur overnight and Monday.

FutureTrack Wind Chill

FutureTrack Wind Chill

What does this mean? Frostbite might occur if you are outdoors with exposed skin in as little as 10 to 30 minutes.  It is best to stay indoors. If you must be outdoors take extra precautions. Wear extra layers of clothing. Have that winter preparedness kit in your vehicle.  And don’t forget about our four-legged friends. Animals can get frostbite too.

Wind Chill Chart

Wind Chill Chart

Stay safe and warm!

-Joe

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Posted under cold blast, FutureTrack, record weather, safety, severe weather, weather, Wind, winter weather

This post was written by Joe Astolfi on January 5, 2014

Severe Storm Outbreak possible

Capture
severethreatParts of the Midwest and Great Lakes States will have the potential for a severe weather outbreak on Sunday. According to the Storm Prediction Center, there is a slight risk of severe thunderstorms for the following cities:
Milwaukee, Madison, Rockford, Cedar Rapids, Davenport, Peoria, Springfield, St. Louis, and Carbondale.
There is an enhanced risk for severe thunderstorms for the following cities: Chicago, Joliet, Champaign, Bloomington-Normal, Indianapolis, Evansville, Louisville, Cincinnati, Ft. Wayne, Detroit, Lansing, and Grand Rapids.

simulatedA strengthening area of low pressure will eject out of the Plains toward Northern Wisconsin during the morning hours. Ahead of a strong cold front, thunderstorms are expected to explode ahead of it. While some models fire the storms over the Mississippi River, tracking eastward, this model (RPM) has storm initiation occurring along the I-39 corridor with damaging wind quickly moving into the Chicago area by 3pm. Mature thunderstorms then affect the enhanced risk area of Northern Indiana, Southern Michigan, and Northwestern Ohio.

The main threats for the Rockford Metro will be all or nothing. A few things are very interesting to me. The folks at St. Louis University have developed a computer program called CIPS. It takes the computer model output and compares it with similar outcomes in the past. Ominously, the CIPS analog shows the closest comparison to be the November 22, 2010 outbreak that produced tornadoes here in Northern Illinois and Southern Wisconsin. (See Caledonia tornado information here) (See Caledonia tornado photos here).

frontsAnother thing that is concerning is if a “triple point” is present here in Northern Illinois. This maximizes the amount of turning wind with height. In this surface map by the NWS, a cold front (blue), a warm front (red), and an occluded front (pink) intersect in Northern Illinois. A triple point was close by for both the Caledonia and Poplar Grove tornadoes.

For the Rockford Metro, there will be a severe weather threat (mainly straight line wind) between 3am and 9am. A few isolated tornadoes will be possible, especially east of I-39 between  9am and 1pm. After 1pm, the front and chance of severe weather will sweep east by 50 miles each hour.

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Posted under severe weather

This post was written by Eric Sorensen on November 16, 2013

Fewer Tornadoes in 2013: Nationally, Not Locally

Even though we are heading into the colder months, it is important to remember that severe weather and tornadoes can happen anytime during the year. 

With the main tornado season behind us, both Illinois and Wisconsin have had less tornado activity than expected. This follows the national trend.  Only 770 tornadoes (as of this blog post) have been reported across the United States, fewer than any year since 2005.

Illinois & Wisconsin Tornadoes since 2004

Illinois & Wisconsin Tornadoes since 2004

 

Just 20 tornadoes have been reported in the Land of Lincoln from January 1st through today (October 16th).  The number is even less for Wisconsin, with 15 confirmed tornadoes.  Illinois sees 54 tornadoes on average every year; Wisconsin averages 24 tornadoes.

One of the main reasons why this year’s tornado count is so low was the weather pattern during Spring.  Spring was filled with extended periods of rain and slow-moving weather systems, which helped keep temperatures down.  Tornadic thunderstorms often thrive when there is a clash of airmass and temperature, something which did not happen much in 2013.

As we transitioned to Summer, the jet stream–which drives our weather–moved well to the north along the Canadian border, keeping much of the nation in a 3 month period of drought.

Believe it or not, 40% of Illinois’ tornadoes this year occurred in the Stateline area!  With 8 tornadoes between May 19th and June 24th, we had an above average year.  Since 1950, the Stateline sees 3 or 4 tornadoes on average per year. 

In 2013, most local tornadoes were brief and rated EF-0.  But on June 12th, an EF-2 tornado touched down in western Carroll County near Savanna and Mount Carroll.  On the same day, an EF-1 tornado pushed through southern DeKalb County near Shabbona.

2013 Local Tornadoes

2013 Local Tornadoes

The year is not over, but hopefully we will not have to endure anymore tornadoes.  They can and do occur at anytime of year (Caledonia Tornado in November 2010, Poplar Grove Tornado in January 2008).

-Joe

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Posted under 13 Climate Authority, news, Project: Tornado, science, severe weather, statistics, tornado, weather

This post was written by Joe Astolfi on October 16, 2013

Stateline Tornadoes Since 1950

A recent report shows that the United States has had fewer than normal tornadoes during 2013.  Illinois and Wisconsin, as a whole, have witnessed the same trend.  That is not the case locally, however.

Number of Local Tornadoes by County Since 1950

Number of Local Tornadoes by County Since 1950

The Stateline had 8 confirmed tornadoes so far this year, all occurring between the end of May and the end of June.  Since 1950, our local area averages 3 to 4 tornadoes every year.  Within our 13 county area, Lee & Whiteside County in Illinois and Rock & Walworth County in Wisconsin have picked up the most tornadoes since 1950.  We all have the same exact risk, however, as nothing in our geography prevents tornadoes from forming or the paths they take.

Let’s hope the national trend continues locally for the rest of the year!

-Joe

 

 

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Posted under 13 Climate Authority, news, Project: Tornado, severe weather, statistics, tornado, weather

This post was written by Joe Astolfi on October 16, 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.

 

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

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