SEVERE WEATHER COVERAGE

10:55pm – Storms in eastern Iowa drifting southeast right now. Widespread severe weather is not anticipated for tonight. Should these storms stay together, they will affect Carroll, Whiteside, Jo Daviess, Stephenson, and Lee Counties after midnight. As they move into the I-80/I-88 corridor they will be moving away from the boundary they formed on and should weaken further.

9:15pm – A few showers are just beginning to develop across northeast Iowa. However the atmosphere is not nearly as unstable as it was a few hours ago. Should these grow roots in the unstable airmass and sustain themselves for 30 minutes/1 hour, they may last into the night. Right now it’s questionable (without any sunlight) whether they can propagate into a cluster over the Mississippi River and move southeast. Will continue to monitor. Latest coming up on 10@10.

6:30pm – Increasing severe weather threat for the late-evening and overnight. A Severe Thunderstorm Watch may be issued for parts of eastern Iowa and areas west of I-39 in Illinois this evening. There may be just enough turning with height out in Iowa to support an isolated tornado or two. I believe the threat will move toward the Quad Cities and west-central Illinois as the night progresses.
5:15pm – DEVELOPING STORY: At 12:35pm, during a severe thunderstorm, a person was trapped inside a pole barn when it collapsed near Winslow (Stephenson Co). It happened at State Line Road and Swiss Road. As of 4pm the person was rescued and treated for several fractures. Stay with 13News as we continue to fallow this developing story.

  • Machesney Park reports TSTM WND DMG at 01:08 PM shingles blown off roof. small peach tree snapped off one foot above the ground
  • Galena reports TSTM WND DMG at 12:00 PM winds estimated to be 60 mph blew down a 3 to 4 inch diameter branch. time estimated

[live chat has ended]

(11:56:43 AM)
iembot: Storm Prediction Center issues SEVERE TSTM watch till 7pm (Watch Quickview)

(11:55:22 AM)
iembot: DVN issues Severe Thunderstorm Warning for Dubuque, Jackson [IA] and Carroll, Jo Daviess, Stephenson [IL] till 1:00 PM CDT

Update – 11:40 am:
(11:36:08 AM) iembot: DVN extends area+time of Severe Thunderstorm Watch for Jackson [IA] and Carroll, Jo Daviess, Stephenson [IL] till 1:00 PM CDT

Update – 10:35 am: While it doesn’t include our viewing area, another technical discussion was issued. Click here to read it. It mentions the possibility of an additional weather watch being issued.

Original post: A complex of thunderstorms is barreling southeastward through northeastern Iowa and into southwestern Wisconsin. These storms have been producing winds in excess of 50 mph.

Some weakening has been taking place, although the line of storms is expected to reintensify during the first part of the afternoon near our area. The reason for this is that we’ve been experiencing lots of sunshine all morning, and with dewpoints back into the lower 70s, the atmosphere is becoming increasingly unstable.

We’ll be monitoring the progression of this line of thunderstorms through the rest of the morning. I wouldn’t be surprised if the Storm Prediction Center issues a technical discussion that includes our viewing area within the next hour or so.

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This post was written by Eric Sorensen on July 31, 2008

Evapotranspo-what?

In order to make our forecasts understandable and memorable, Meteorologists use ordinary terms to describe our weather. However there’s one thing going on this time of year that only sounds complicated. We’re talking about evapotranspiration. That’s the moisture (or water vapor) that healthy plants give back to the atmosphere. With the help of our friend Bill Steffen over at WOOD-TV in Grand Rapids, our own Justin Gehrts decided to crunch some numbers today.

Each stalk of corn gives 53 gallons of water to the atmosphere via evapotranspiration each year.

There are 20,000 stalks of corn (on average) in each acre of farmland.

That means that an acre of corn will give off 1,060,000 gallons of water each year. During the peak summer months, corn fields can put more water into the air than a lake!

Because of the massive flooding in Iowa earlier this year, 2 million acres of corn were lost. Adding up all of the lost evapotranspiration yields 2 trillion gallons of water. That’s 2,000,000,000,000 gallons!

As Bill Steffan points out in his blog, that may be a reason why our computer models are overdoing dewpoints, rain chances, and rain amounts. However the fact that there’s less evapotranspiration this summer may mean some pretty mean heat coming in the next few days and weeks.

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This post was written by Eric Sorensen on July 31, 2008

Hurricane Humor


Since Dolly made landfall in southern Texas the tropics over the Atlantic Ocean have really quieted down. The only disturbance even out there is just starting to evolve, but it is thousands of miles away from the U.S. coastline. In the meantime, I think we are due for some hurricane humor. Which track is your favorite path? Mine is the one involving Florida… -ADAM

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This post was written by Eric Sorensen on July 30, 2008

What is the richter scale?

Thanks to Charles Francis Richter, an American Seismologist in the 20th century, we can rate earthquakes! While most of us know the scale goes from 1-10, did you know that going from a magnitude 1 to 5 increases the power of the earthquake by 10000? Each level is 10 times stronger than the previous level. That means the San Francisco earthquake of 1989 was 10 times stronger than today’s! Imagine what would have happened had the 2004 Indian Ocean earthquake happened over land. Still, thousands were lost when the tsunami hit Indonesia.

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This post was written by Eric Sorensen on July 30, 2008

EXCLUSIVE SEVERE WEATHER COVERAGE

PUSH REFRESH FOR THE LATEST WEATHER INFORMATION


9:00pm – From here on out, we’ll be watching southern Wisconsin. For northern Illinois any severe threat (and thunderstorm threat for that matter) is winding down with every minute. A few storms bear watching over South-Central Wisconsin. A few of these may drift southeast toward Janesville and Delavan by 10:30pm.

(8:13:46 PM)
iembot: LOT issues Severe Thunderstorm Warning for De Kalb, Grundy, Kendall, La Salle [IL] till 9:00 PM CDT. Areas in the path of this severe thunderstorm include DeKalb, Sycamore, and Kingston. Brief, gusty winds to 60mph with dime to nickel sized hail can be expected within the next 15-20 minutes.

7:48pm – A small, but potent storm is now over the south side of Oregon. Some pea sized hail is possible as this drifts northeast over Lowden S.P. on its way toward Davis Junction. I sincerely doubt this will turn severe. If anything some small hail and brief torrential rain can be expected.

7:30pm – A cluster of torrential rain has set up from Lena and Pearl City down to Shannon and Mount Morris. Pea sized hail will be possible with these storms as they lift northeast into the Freeport/German Valley areas by 7:45 and eventually Rockford by 8:30pm.

(6:41:42 PM) iembot: DVN issues Severe Thunderstorm Warning for Bureau, Henry, Rock Island, Whiteside [IL] till 7:45 PM CDT

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This post was written by Eric Sorensen on July 29, 2008

Earthquake shakes Southern California

A 5.4 magnitude earthquake struck near Chino Hills, California Tuesday afternoon. Minor damage has been reported. No immediate word on injuries. Luckily Chino Hills is a suburban area with newer buildings and foundations.

For more information, check out the U.S. Geological Survey.

To learn how earthquakes are measured, click here.

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This post was written by Eric Sorensen on July 29, 2008

Recipe for Storms


We do have a good recipe cooked up for thunderstorms to develop this afternoon and evening. The skies are only partly cloudy right now, which is causing the lower levels of the atmosphere to heat up efficiently. Temperatures should have little problem jumping into the upper 80s by 2pm. Dew points are oppressively high right now with most locations sitting in the low 70s. The frontal boundary is sitting out in central Iowa as witnessed by the change in wind direction from the surface data.

Despite all of these wonderful ingredients in place, nothing has started developing and some of the models aren’t completely sold on brewing up storms. The GFS model has our probability of precipitation at less than 20%, while the NAM merely has us at a 30% chance. As of 11:30am, the Storm Prediction Center had taken the Stateline OUT of the slight risk for severe weather. This could very well be an all or nothing event. From my viewpoint, the highest likelihood for the timeframe of these storms to get going would be between 3pm – 8pm. Now it is just time to play the waiting game. If anything starts to spark, I am sure Eric will get the live chat up and running. -ADAM

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This post was written by Eric Sorensen on July 29, 2008

It’s a bird, it’s a plane, it’s…


The National Weather Service doppler radar is picking up car/truck traffic on I-39. They show up as yellow blips between Rockford and Rochelle. Pretty neat, huh?

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This post was written by Eric Sorensen on July 29, 2008

Slight risk of severe storms on Tuesday


Techincal forecast discussion from the Storm Prediction Center. Looks like I will be tracking storms (when not cleaning around here). :-) -ERIC

  ...UPPER MS VALLEY INTO THE WRN GREAT LAKES...
NOCTURNAL STRONG/SEVERE STORMS MOVING EWD/SEWD OVER THE NRN PLAINS
MAY PERSIST INTO PARTS OF WRN IA/SRN MN AREA AT THE START OF THE
PERIOD. THESE STORMS MAY WEAKEN DURING THE MORNING AS THE NOCTURNAL
LOW LEVEL JET VEERS AND WEAKENS. HOWEVER...THE AIR MASS AHEAD OF
THIS ACTIVITY IS EXPECTED TO UNDERGO SUBSTANTIAL DESTABILIZATION
DURING THE DAY AS DEW POINTS INCREASE IN THE WARM SECTOR AND
ELEVATED MIXED LAYER AND ATTENDANT STEEP MID LEVEL LAPSE RATES
SPREADS EWD FROM SRN MN AND IA INTO NRN IL/WI/LOWER MI. THIS WILL
RESULT IN MLCAPE VALUES OF 2000-3000 J/KG DURING THE AFTERNOON AND
EVENING ACROSS PARTS OF SERN MN/ERN IA INTO WI AND NRN IL.

THUNDERSTORMS ARE EXPECTED TO INCREASE DURING THE AFTERNOON
ALONG/AHEAD OF THE COLD FRONT MOVING ACROSS THE UPPER MS VALLEY IN
RESPONSE TO DYNAMIC FORCING IN ADVANCE OF THE SHORT WAVE TROUGH. IN
ADDITION...IF MORNING STORMS CAN PERSIST INTO THE EARLY AFTERNOON
THE LIKELIHOOD OF INTENSIFICATION IS LIKELY AS THEY MOVE INTO AN
INCREASINGLY UNSTABLE ENVIRONMENT. WINDS ALOFT AND RESULTANT
VERTICAL SHEAR /35-45 KT IN THE LOWEST 6 KM/ WILL BE MOST FAVORABLE
ACROSS THE NRN PARTS OF THE OUTLOOK AREA...HOWEVER SHEAR IS EXPECTED
TO BE SUFFICIENTLY STRONG TO ENHANCE STORM ORGANIZATION AS FAR SOUTH
AS SERN IA AND NRN IL. STRONGER STORMS WILL HAVE POTENTIAL TO
PRODUCE LARGE HAIL AND DAMAGING WINDS AS THEY MOVE EWD/ESEWD THROUGH
THE EVENING HOURS.
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This post was written by Eric Sorensen on July 28, 2008

Official Results


First off, thanks to Justin for making these graphics last night. Unfortunately, he was on Eric’s side of the bet. I hope you enjoyed the fantastic weather from this past weekend. The official climate data at RFD will go down as not receiving one drop of liquid between 7am Saturday morning and 7pm Sunday evening. Thanks to the 38% of you in the blog poll that had faith in me! I would make sure you watch the news tonight at 5, 6, or 10 because I am quite confident there might be some footage of your favorite chief meteorologist cleaning the weather center! -ADAM

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This post was written by Eric Sorensen on July 28, 2008