Archive for April, 2010

Friday Evening Tornado Reports
April 30, 2010

***Watch WISN 12 News for the latest on the Green Lake County tornadoes***

Severe weather season picked up a head of steam Friday in Wisconsin.  Two tornadoes were reported in Green Lake county.  This was part of a large severe weather outbreak that impacted areas from Wisconsin to northeast Texas.

Here is a little more information on the tornadoes that occurred in Green Lake county.

  • 7:05 p.m. tornado reported 2 miles southeast of Berlin.  Tree uprooted and powerlines down along county road F.
  • 7:28 p.m. brief tornado reported south of Princeton near Lake Puckaway

The National Weather Service will do a damage survey on Saturday…and I will pass along the results in the blog.  Below are the severe weather reports across the nation on Friday thru 10:30 p.m.  The two red dots in Wisconsin are the tornadoes mentioned above.

If you have pictures of the damage from the tornadoes in Green Lake county please post them to the U-Local section and also feel free to email them to   Any picture we receive may end up on WISN 12 News!

For the weekend we are looking at a windy and warm day on Saturday.  Late in the day clouds will return and after 7pm rain showers are possible.  The rain will likely continue into Saturday Night.  Sunday looks like it may start with showers, but clear up by afternoon.  The details of the weekend forecast will be handled on our newscasts.  You can catch them on Saturday from 5-6am and 7-9am, and at 5, 6, and 10pm.  We’ll see you then!

Jeremy Nelson


Tornado Watch Til 10 p.m.
April 30, 2010

***Watch WISN 12 News all day for the latest updates on severe weather!***

***Just updated the blog to reflect extension of tornado watch until 10 p.m.***

We are on Weather Watch!  A Tornado Watch has been issued for Southeast Wisconsin until 10 p.m.  Here is a look at the watch box that covers our area.

The western part of our viewing area will see rain and some thunderstorms between 3-6 p.m., but in Milwaukee our chance for stronger storms will hold off until very likely after 7 or 8 p.m.  The main threat from the storms will be hail and strong winds.  An isolated tornado can not be ruled out, but the threat is really for hail and wind.

You can track the storms right down to where you live with our interactive radar at…

If you have severe weather to report or have pictures of hail or damage to share, please send them to   or post them to the U-Local section of  We would love to share your pictures on our newscasts.  Also, you can post any storm reports or rain totals to the comments section of the blog.  Make sure to join us on Facebook for more updates! 

And for the latest on severe weather, turn to Weather Watch 12 and WISN 12 News!

Jeremy Nelson

Seventies to Storms…Severe?
April 29, 2010

It took awhile, but we finally started warming up this afternoon on very strong southerly winds. There is a slight east component to the wind so lake areas are a bit cooler, but most areas will hit the seventies today. Friday will be another warm and windy day with partly sunny skies. The wind will be more southwesterly tomorrow so everyone should get well into the 70s. Nice way to finish of April.

With the good comes the potential bad. A cold front will be making its way into Wisconsin late in the day on Friday. That cold front will run into the warmer and semi-moist air kicking off thunderstorms. Some of these storms may be severe, especially in western Wisconsin. The timing of the storms still looks to be overnight in our area and that will help keep our chances for severe weather here a little lower than the rest of the state.

Here is the latest from the Storm Prediction Center. They have the whole state in slight risk.

There are a lot of elements to figuring out severe weather chances. I’m going to show you our in-house computer model with some of the important ingredients of severe weather. All of  the following graphics are for the late evening Friday night. First, let’s take a look at the dew point. The more moisture available, the better the instability.

Our RPM model shows the dew points reaching the low 60s. This is not incredibly moist, but would be enough for severe storms if all other elements came together. Next, let’s take a look at the lifted index. This is a measure of  the buoyancy of the atmosphere.

The lifted index is forecast to be around -2. When the lifted index gets lower than -5, we really get interested. Next up is CAPE. CAPE stands for convective available potential energy. Without getting overly technical, it is another measurement of the buoyancy of the atmosphere. The higher the number, the better the chance of severe storms.

I believe the CAPE is a little overdone due to the dew points being slightly higher than I expect. Finally, the surface map.

Even with some favorable conditions, the RPM model is not overly impressed about getting severe weather in our area. Make sure you stay tuned tonight and Friday for the latest on WISN-12. We will be keeping a close eye on the potential storms. Thanks for reading.


Tale of Three Models and Severe Chances
April 28, 2010

Happy Wednesday. Nice to have the sunshine. Lake Michigan still refrigerating areas near the shore, but warmer weather is on the way. Temperatures should be near 70 on Thursday except right near the lake, and 75 for everyone on Friday. The next storm system rolls in late on Friday. The three main computer models we use for short-range forecasting are actually in fairly close agreement. The biggest questions that remain in the forecast is when the storms arrive and if they will be severe. The Storm Prediction Center has us in slight risk for Friday.

I think the slight risk is warranted, however, if the storms hold off until after midnight on Friday night, the likelihood of severe weather would be diminished.

I want to show you the three models we use, each from the 7 AM model run of what to expect around midnight Friday night. All three of the models hold the rain until Friday night. I’ll start with the GFS:

The GFS brings us a general rain and maybe a thunderstorm or two, but clearly keeps the severe weather and heaviest rain to our south. Next is the NAM:

The NAM has a line of storms in western Wisconsin, but as the time progresses these storms weaken as they move into southeastern Wisconsin. Finally, our own RPM model:

This also has a few storms in southwestern Wisconsin and also keeps the strongest storms to our south. I like to give you an idea of what we look at here at WISN so you can see some of our thoughts when making a forecast.

At this point, I think our severe chances are pretty low because I think the storm timing will be between midnight and 6AM on Friday night/Saturday morning. All three models clear us out for Saturday so should be a decent start to the weekend. Thanks for reading.


Frost Advisory Tonight
April 27, 2010

Brrr!!! A frost advisory sounds so cold. Frost is likely across the area tonight with clear skies and light winds with low dew point temperatures. That combination of factors created ideal radiational cooling. That means that all the energy from the sun that was absorbed by the earth during the day escapes out into the upper atmosphere. That allows the temperatures to drop quickly and that is likely for tonight. The lake may help keep some locations a little warmer, but everyone will most likely get a frost.

The question that some of you may have is why do we have a frost advisory tonight when we had numerous nights with frost last night. The reason is because we have now entered the growing season. Last week we were not officially in the growing season. So what is the growing season? The growing season is loosely defined as:

Growing Season – the time period, usually measured in days, between the last freeze in the spring and the first frost in the fall. Growing seasons vary depending on local climate and geography. It can also vary by crop, as different plants have different freezing thresholds.

We have passed our average date of the last frost, however, as someone who has been here over a dozen years I don’t recommend planting the sensitive plants like tomatoes until after Mother’s Day.

If you are hoping for warmer weather it starts on Wednesday. Highs will be near 60 on Wednesday, 70 on Thursday, and 75 on Friday. It will be quite windy on Thursday and Friday. Friday will bring a chance of thunderstorms and we will have to watch closely for the possibility of severe weather. Right now, the conditions are not overly favorable.

The above image is from the Storm Prediction Center for Thursday’s chances of severe storms. I would not be surprised if southern Wisconsin is included in the day 3 outlook tomorrow. Stay tuned.

Rainfall should not be impressive as last weekend. The models are still in disagreement over what will happen with Friday’s storm. Some of the models are holding the rain into the weekend, but right now I’m buying the GFS model which clears us on Saturday morning leading to a decent weekend.

Here are the rainfall amounts expected by the Hydrometeorological Prediction center for Friday’s storm. The current forecast keeps us under an inch.

Thanks for reading. Have a great day.


EF vs. F Scale
April 26, 2010






Happy sunny Monday. Nice to have the sun after a crummy weekend. The rain was needed, but I wish it did not happen over the weekend. Thankfully, we missed the severe weather outbreak that ravaged a huge portion of the country. There were damaging storms from Colorado to New York with the worst damage from the tornado outbreak on Saturday in the deep south. Yazoo City, Mississippi was the hardest hit. Tragically, 10 people were killed in the tornadoes. It had been a quiet start to the storm season, but that has now changed. It is a good reminder for all of us of the power and devastation of mother nature.

The above picture is of the tornado in Yazoo City. At one point the tornado was a mile 1/2 wide and the path of destruction was almost 50 miles. The tornado was rated EF-3. I will have more on that later in the blog.

The above picture is of the damage in Yazoo City. This picture was from the New York Times. It’s fascinating that the picture shows the massive destruction yet the books are still on the bookshelf.

Tornadoes are rated by the destruction they create using the Fujita Scale. The “F” scale as it is known has now been replaced by the “EF” scale. This is the enhanced Fujita scale. It is an improvement over the “F” scale which overestimated wind speeds in tornadoes. The only problem I have with the change to the “EF” scale is the lack of understanding by the general public. I personally think the National Weather Service should have just changed the scale but left the same “F” scale name.

Here is the old vs. the new scale:

F Number Fastest 1/4-mile (mph) 3 Second Gust (mph) EF Number 3 Second Gust (mph) EF Number 3 Second Gust (mph)
0 40-72 45-78 0 65-85 0 65-85
1 73-112 79-117 1 86-109 1 86-110
2 113-157 118-161 2 110-137 2 111-135
3 158-207 162-209 3 138-167 3 136-165
4 208-260 210-261 4 168-199 4 166-200
5 261-318 262-317 5 200-234 5 Over 200

*** IMPORTANT NOTE ABOUT ENHANCED F-SCALE WINDS: The Enhanced F-scale still is a set of wind estimates (not measurements) based on damage. Its uses three-second gusts estimated at the point of damage based on a judgment of 8 levels of damage to the 28 indicators listed below. These estimates vary with height and exposure. Important: The 3 second gust is not the same wind as in standard surface observations. Standard measurements are taken by weather stations in open exposures, using a directly measured, “one minute mile” speed.

Our weather remains quiet for much of the week. Chilly temperatures at night with patchy frost inland tonight and Tuesday night. Much warmer for Thursday with highs near 70. Thunderstorms are possible on Friday. Stay with weather watch 12 for the latest. Thanks for reading.


Ugly Weekend, Beneficial Rain
April 25, 2010

After being spoiled the first half of April, it is really tough to take a weekend like the one we just had. Cloudy, rainy, windy, and cold. Not a good combination. However, it is not all bad news. We needed the rain. Our rainfall deficit for 2010 was almost five inches coming into Saturday. An inch of rain on Saturday and another .25″ on Sunday put a nice dent in our lack of rain. Most of our deficit was due to a very dry March. We are now above average for April rainfall. Besides the bad timing of the rain for the weekend, the heavy rain never made it up north where they are in the midst of a severe drought.

The above image is the drought monitor across the United States. Thankfully, there are very few areas of the country in the midst of a bad drought.

The above image is zoomed in to show the drought conditions in northern Wisconsin. If you have been up north lately, you probably have seen the lower lake levels. Hopefully, this will improve as we move into the recreation seasons.

As for our rain totals this weekend, take a look:

1033 AM CDT SUN APR 25 2010


LOCATION              AMOUNT
——–              ——
AFTON                  1.05
ALLENTOWN              1.85
ARGYLE                 0.84
BARABOO                1.21
BEAVER DAM             1.56
BELOIT                 0.25
BENTON                 0.91
BERLIN                 1.34
BLACK EARTH            0.95
BRODHEAD               1.40
BROOKFIELD             2.27
BROWN DEER             2.47
BURLINGTON             0.89
CALEDONIA              0.84
CAMPBELLSPORT          1.17
CEDARBURG              3.07
DELAVAN                0.68
EAGLE                  1.33
ELKHART LAKE           2.00
FOND DU LAC            1.50
FT. ATKINSON           1.80
FRANKLIN               1.78
HALES CORNERS          1.50
HARTFORD               1.77
HORICON                1.74
HOLY HILL              3.72
JACKSON                3.07
JEFFERSON              1.93
JUNEAU                 1.44
KENOSHA                0.57
LONE ROCK              1.02
LYONS                  0.85
MADISON                0.87
MEQUON                 2.51
MILTON                 1.45
MT MARY COLLEGE        2.35
MONROE                 1.23
MT. HOREB              1.45
NORTH PRAIRIE          1.69
OCONOMOWOC             2.45
PADDOCK LAKE           0.88
PORTAGE                1.09
POYNETTE               1.07
RACINE                 0.78
RICHFIELD              2.73
REEDSBURG              0.76
SAINT FRANCIS          1.08
SAUK CITY              0.83
SAUKVILLE              3.02
SHEBOYGAN              2.15
SLINGER                2.80
TAYCHEEDAH             1.55
TWIN LAKES             0.83
WATERFORD              1.32
WATERLOO               1.13
WATERTOWN              2.07
WAUKESHA               1.88
WAYNE                  1.62
WEST ALLIS             1.44
WEST BEND              2.50
WHITEWATER             1.11

The largest totals were in Ozaukee and Washington counties where some places picked up more than 3″. The above totals were from spotters. We would love to have our blog readers send in your rain totals and any severe reports in the future to this blog or our weather watch 12 facebook page.

The above image is from the NEXRAD radar from the National Weather Service in Sullivan. NEXRAD radar has the ability to estimate rainfall totals from the storm. Take a look at the totals and see how it compares to the actual reports.

We dry out nicely this week and we warm up mid-week. We are going to have to start mowing our lawns every other day. Nice shot at rain and possible thunderstorms on Thursday night. Thanks for reading.


More Rain, Lots of Wind…South Slammed
April 24, 2010

***Watch WISN 12 News all weekend for updates on the rain and wet weather!***

Thank you for stopping by the Weather Watch 12 blog!  Right on cue, scattered showers arrived Friday Night and continued on and off for the better part of Saturday.  Rain totals have ranged from a few one hundredths…to around a half inch as of 6 p.m. Saturday.

If you have a rain total to share, please post it to the comments section of the blog.  We are always looking to share your totals on WISN 12 News.

The storm that has given Wisconsin cool and wet weather, has provided parts of the Mississippi Valley and South with dangerous storms.  This storm system has produced over 60 tornadoes in the past 2 days.  The storm reports have been numerous.  Here are the storm reports just for Saturday, thru 6 p.m.


One thing this map is lacking, are reports in the upper Midwest and Great Lakes.  That is due to a warm front staying well to our south.  In order for severe weather to occur, 3 ingredients are needed; moisture, lift, and instability.  With a cool and cloudy airmass in place, southeast Wisconsin is lacking the instability ingredient.

As the main area of low pressure surges north Saturday Night into early Sunday…periods of rain and thunderstorms are expected.  Some of the rain may be heavy at times.  When the rain ends sometime Sunday, a few spots could see 1.50″ to 2.00″ of rain.  Here is the latest rainfall forecast from our in-house RPM model.


Remember…you can track the rain day or night by using our interactive radar.  Check it out…you can zoom in to any location.

Along with a few showers on Sunday, winds will be very gusty.  A few wind gust will likely approach 40 mph!  Talk about a raw day!

If you follow the blog…you know that I have been expecting this wet period that we are now in.  Below is from a blog entry that I did April 13.  The reference to the late March blog…was an entry posted March 30.  Enjoy!


Back in late March I issued the long range forecast for April and May.  In discussing April I said the pattern would be active, and that Milwaukee would very likely see over 4.00″ of precipitation.  We are now 13 days into the month, and precipitation has been recorded on 8 of the days, totaling 2.05″ at Milwaukee-Mitchell. 

In the April forecast that I said the final 8-9 days of April would be wet, with some areas picking up 2″ of rain in this timeframe.  What did I base this on?

Let’s look back at the previous 3 cycles that correspond to roughly April 20-29 here in Milwaukee.

October 20-28

  • Rain recorded on all days but 1
  • Rain total in this period: 2.85″

December 20-28

  • Rain or snow recorded on all days
  • Precipitation in this period: 1.70″
  • Snow total: 6.8″

February 20-28

  • Rain or snow recorded on all days but 1
  • Precipitation total during period: 0.34″
  • Snow total: 5.4″

Have a great weekend and watch WISN 12 News for the updates!

Jeremy Nelson

Wet Weekend Ahead…Forecast Rain Totals
April 23, 2010

***Watch WISN 12 News at 5, 6, & 10pm as we track rain on the Doppler 12 Radar Network!***

After 10 consecutive dry days, some much needed rain is on the way!  Thank you for stopping by the Weather Watch 12 blog.  In today’s entry we will discuss the timing and amount of rain that is expected this weekend. 

If you want to track the rain, check out our interactive radar.  Give the radar a try, I love it!

So far in April, Milwaukee has picked up 2.05″ of rain, that is 0.87″ below average as of Friday afternoon.  That isn’t a huge deficit, but considering the deficit for 2010 stands at 4.84″, the weekend washout isn’t all bad news.

A very large storm system is currently in the nation’s mid-section.  This storm has a couple areas of low pressure and surface boundaries.  The first piece of the storm arrives Friday evening/night and lingers into Saturday.  The second much stronger part of the storm will move our way Saturday Night.  This is when heavy rain could drench southern Wisconsin.  Right now it just looks like heavy rain, and no severe weather.  The severe weather should stay out of Southeast Wisconsin, but thunderstorms are still possible.  If any locations in southern Wisconsin see severe weather, it would likely be in south central or southwest areas.  The main threat would be marginally severe hail.

Below is the Severe Weather Outlook for Saturday.  This forecast is issued by the Storm Prediction Center.  Notice the moderate risk area, this is where the greatest threat for tornadoes will be.

The main energy with this storm system will surge north late Saturday and Saturday Night.  Below is a surface map showing the main surface low and its position by Sunday morning.

A period of heavy rain will likely occur very early Sunday between Midnight and 6 a.m.  This is when 1″ or more of rain is expected.  The rain total for the entire storm could top 2″ in spots.

Below is a rainfall forecast from our in-house computer model.  This is just ONE of many computer models we use to make our forecasts.  Use this as guidance…as I will show our ‘official’ rainfall forecast on WISN 12 News.  Not out of the question that rain totals may near 3″ in spots.


With the wet weather expected this weekend, please share your rain totals with us in the comments section of the blog, or on Facebook at WeatherWatch 12  I will be using viewer rain totals on WISN 12 News all weekend long!

Look for more blog updates all weekend long!

Jeremy Nelson

Happy Severe Weather Awareness Day/Earth Day
April 22, 2010

Happy Earth Day. Earth Day and I turn 40 this year. No matter how you feel politically, I hope we all agree we should be doing all we can to conserve our resources and do our part to make sure the next generation gets a planet as clean as the one we inherited. Earth Day makes us stop and realize the Earth is not as big as we think. I want my kids to be able to enjoy the bounty of Wisconsin just as I have. Ok, I’m off my soapbox.

We have a nice slide show of Earth Day images from this year.

Not only is it Earth Day, but it is also severe weather awareness day in Wisconsin. Many of you likely heard the sirens sounding today at 1:20 PM with a mock tornado warning. Even better would be if you have a weather radio and you heard that alarm today. For those of you who do not have a weather radio, WISN 12 is teaming up with Walgreens to offer weather radios for $29.99.

A weather radio can be a lifesaving device much like a smoke detector. A weather radio sounds an alarm when a watch or warning is issued for your area. This is important because much of our severe weather in Wisconsin comes in the middle of the night when many of us are sleeping. Many communities do not have tornado sirens. Even if your area has tornado sirens, you may have a hard time hearing them if you are sleeping with the air conditioner on. I promise I am not getting a kick-back from the weather radio sales. I just think it is vital for everyone to have one.

Now, on to our weather. Another sunny April day, but near Lake Michigan was a bit chilly today. Highs were only in the upper 40s.  It has been a dry start to 2010, but we have some needed rain on the way Friday night-Sunday. Our rainfall deficit for the year is almost up to 4.75″. We will put a dent in that this weekend with most areas receiving around an inch. The northern part of Wisconsin needs the rain the most as they are in a severe drought, but most of the rain will be in southern Wisconsin.

It will not rain continuously all weekend, but if you have any outside plans have an umbrella handy. Have a great day and thanks for reading the blog.