Archive for April, 2011

May & Summer Forecast Based on Lezak’s Recurring Cycle
April 30, 2011

Thank you for stopping by the Weather Watch 12 blog!  Late spring and summer, the peak of severe weather season in Wisconsin, and it is almost here.  In this entry we will discuss the long range forecast for May through August based on the LRC.  Included will be temperature and rainfall forecasts, along with date ranges when severe weather may be possible.

The ‘LRC’ which stands for Lezak’s Recurring Cycle is a weather pattern theory based on the following:

  • A unique weather pattern sets up every year between October 1st and November 10th
  • The weather pattern cycles, repeats, and continues through winter, spring and into summer. Identifying the cycle length helps tremendously when making long range weather predictions.
  • Long term long-wave troughs and ridges become established and also repeat at regular times within the cycle. These dominant repeating features are a clue to where storm systems will reach peak strength, and where they will be their weakest.
  • The LRC is a winter-long pattern! There is a pattern! It isn’t just one long-wave trough, storm system, or ridge. It is a sequence of troughs and ridges that are cycling across the Northern Hemisphere.

 

To put this in very simple terms, the weather pattern that occurs in October and November repeats thru the winter, spring, and into summer.

The cycle length will vary each year. I’ve seen cycles of 42-46 days, 60-62 days, etc.  This year’s cycle duration is about 46-52 days.  Overall most of the weather events have repeated about 47-51 days apart.  After analyzing the pattern and surface results from October through April, I was able to get a very good idea of what should occur through summer.

The cycling weather pattern is about to repeat for the 5th time this LRC season!  For this forecast I will highlight the bigger features that should impact our weather over the next few months, and then give the forecast specific forecast for southeast Wisconsin.

Let’s get started by highlighting the two key features of the pattern.  The ‘signature’ storm has produced every time in the cycle for southeast Wisconsin, and it should return soon. 

  • October 26-27  Strong winds and severe weather
  • December 11-12  Heavy rain and snow
  • February 1-2  Massive blizzard
  • March 22-23  Rain in Milwaukee, 17.8″ snow in Green Bay

Here is the 500mb(middle of the atmosphere) map from the last time the ‘signature’ storm hit the area on March 23, 2011. 

500mb March 23, 2011

This part of the pattern should return between May 9-13.  For our area we’ll watch out for rain and the possibility of severe weather.

The weather pattern begins to fade as the summer progresses, but I think a final ‘signature’ storm could arrive around June 29-July 2.  This would fall very close to the start of the 4th of July holiday weekend!

Another feature that has occurred numerous times is the ‘big warm-up’ part of the pattern.  Each time through the cycle much above average temperatures have been experienced for at least 1-3 days.  This part of the pattern occurred around November 10-12, December 30-January 1, February 16-18, and then most recently April 9-11.

Below is the 500mb map from April 10, 2011.  This shows a southwest flow aloft bringing warm, moist air into the region, and also an upper low over the Rockies. 

500mb April 10, 2011

On April 10, Milwakee reached a high of 84 degrees and there were 14 tornadoes reported around the state.

This part of the pattern should return around May 29-31(Memorial Day).  I do expect another big warm-up, and severe weather could accompany the storm system.  If the pattern holds together into later July, this feature may return one final time to Wisconsin around July 19.

The ‘signature’ storm and the ‘big warm-up’ parts of the pattern may return two more times each.  There will also be other highlights mixed in over the next several months.  Here is the entire long range forecast with a discussion included.

————————————————————————————-

Temperatures

  • Below average
  • Less than 11 – 90 degree days in Milwaukee

Discussion:  Average monthly temperatures have been below average for the past 5 months.  Only about 1 degree below average, but this trend will be tough to break.  Last summer we had a number of above average months going into summer, and that result continued.  So for the next several months I expect the average monthly temperature to remain below average. 

If cold air spills in on the backside of the May ‘signature’ storm like it did in March, the potential for a late season frost can’t be ruled out.  IF that was to occur the possible date ranges would be May 13-18.  This time of year the coldest overnight readings generally occur inland on clear, calm nights.

In looking at the overall pattern I think the hottest temperature in Milwaukee will be 93 degrees.  That would likely occur with one of the bigger features in the pattern.  With that said I think the first chance at 90 degrees would come around May 30-31.  Then, if the pattern holds together another run to possibly the warmest temperature of the summer around July 19. 

Rainfall

  • Above average
  • One month of 6″+ possible

Discussion:  April may have been a good preview of how active parts of the summer may play out.  With nearly 6.00″ of rain in April in Milwaukee, I see more wet days in our future.  Extended periods of dry weather should be few and far between through July.  The most active part of the pattern will cycle back from very late May through June, and barring a freak event like last July 22, June may be the wettest month of the summer.

Possible Severe Weather Dates

  • May 9-13  ‘Signature’ storm
  • May 29-31 ‘Big warm-up’ storm
  • June 7-9  Storm from November 22, April 19
  • June 29-July 2  ‘Signature’ storm
  • July 18-20  ‘Big warm-up’ storm

Discussion:  Without question predicting specifics with a severe weather event more than a couple of days out is nearly impossible.  What I’m showing here is when storm systems may return to our area, and ingredients could be in place for severe weather in the Midwest, including southern Wisconsin.  Obviously there will be severe weather that falls outside of these date ranges and I know that.  What I’m showing is when I think chances may be the highest based on the overall pattern. 

If you are curious, the massive tornado outbreak from this past week in the South produced severe weather in other parts of the pattern too in the South…back on November 29-30 and again on March 8-9.  I expect another round of severe weather from parts of the Plains to the Ohio Valley and maybe the South(kind of late in the season for severe weather there) around June 14-16.

—————————————————————————————

Now how does the long range forecast based on the LRC compare to the Climate Prediction Center’s seasonal outlook?  Below is the May-July temperature forecast, which calls for an increased chance of below average temperatures in the upper Midwest and Great Lakes. 

CPC Temperature Outlook 2011

Next is the May-July rainfall forecast, this also has southern Wisconsin in the above average area.

CPC Precipitation Summer Outlook

Typically the forecast based on the LRC differs from the CPC, but this time they actually fell in line with each other. 

I hope you enjoyed reading my thoughts on what’s ahead for the next several months.  Keep in mind the LRC weather pattern begins to fade as the summer progresses.  By August and September the transition period to next season’s pattern will begin, and by October and November a new pattern will reveal itself. 

Please add your thoughts and questions to the discussion in our interactive comments section.  And feel free to email this forecast to any family or friends.

Have a great day!

Jeremy Nelson

Mississippi EF-5 Tornado & Wisconsin’s Weekend Weather
April 29, 2011

***Watch WISN 12 News for the latest weather information and live reports from Alabama!***

Thank you for stopping by the Weather Watch 12 blog.  Before we discuss the weather you can expect this weekend close to home, I want to pass along new information from the tornadoes that hit the south.

The National Weather Service is continuing to conduct storm assessment surveys of the reported 211 tornadoes that hit the U.S. on April 27.  One of those tornadoes has now been classified as an EF-5…the strongest and most violent type of tornado.  That tornado hit Smithville, Mississippi with winds estimated at 205 mph.  It was the first EF-5 or F-5 tornado to hit the state since 1966!

Here is a list of the most recent EF-5 tornadoes in the U.S.

  • Smithville, MS  April 27, 2011
  • Parkersburg, IA  May 25, 2008
  • Greensburg, KS  May 4, 2007

Without question more tornadoes will be rated EF-5 from this most recent outbreak.  The pictures are so hard to believe because the tornadoes hit such a vast area producing widespread damage.  And just the sheer number of tornadoes that day will likely make this the worst tornado outbreak ever!

The picture below is the the path of the Smithville tornado as it spin through the town. 

Smithville Mississippi Tornado

While a slight risk of severe weather exists on Saturday from the mid-Mississippi river valley to the southern Plains, I’m not expecting anything along the lines of what we saw this past week.

On Saturday, a warm front will try to nose into southern Wisconsin.  The surface map below shows the warm front(red color) over the southwest part of the state at 1 p.m.  A trailing cold front is quickly on its heels in Minnesota and Iowa.

The cold front will produce southeast Wisconsin with a chance of showers and t-storms late Saturday.

Surface Saturday April 30

With the warm front holding off its approach until late in the day, gusty southeast winds will rule.  That means winds flowing over the chilly Lake Michigan waters will keep lakeshore areas cooler for much of the day.  Our in-house high resolution computer model…the RPM…is indicating the cooler temperatures near the lake on Saturday at 1pm.

Notice that areas like Milwaukee will be in the 50s, while inland closer to Lake Geneva and Jefferson readings will be in the low to mid 60s!

RPM Temperatures Saturday April 30

As surface winds turn a little more south late in the day, after 4pm, I expect Milwaukee to bounce into the 60s for a time.  But areas like Port Washington and Sheboygan will suffer the ‘cooler by the lake’ syndrome all day!

Scattered showers and t-storms are possible late Saturday, likely holding off until after 5pm in the metro.  Any t-storms that fire should stay below severe levels.  I just don’t think enough heat and moisture will be in place to get the storms to reach severe criteria.

Make sure to watch WISN 12 News for the latest timing on the rain chance for Saturday, and don’t forget to use our interactive radar to track the storms from your home or on the go.  Just click here Interactive Radar

Please leave your thoughts and questions in the comments section of the blog.  Look for the long range May-Summer forecast in this weekend’s blog!

Have a great day!

Jeremy Nelson

April 27 Tornadoes – Alabama & More
April 28, 2011

***Watch WISN 12 News for LIVE coverage of the tornado aftermath in Alabama!***

A devastating once in a generation tornado outbreak hit the deep South on Wednesday.  This tornado outbreak will rival the ‘Super Outbreak’ that hit some of the same areas back on April 3-4, 1974.

Meteorologist Mark Baden will be live in the areas hardest hit bringing the pictures and stories of the event to everyone here in southeast Wisconsin.  Make sure to watch WISN 12 News at 5, 6, & 10pm for the LIVE reports.

So how did this tornado outbreak occur?  In this blog we’ll discuss look at how this tornado outbreak occurred.

Let’s start with this incredible video from the Tuscaloosa News via You Tube showing one of the violent tornadoes from April 27, 2011.

The ‘Super Outbreak’ from April 3-4, 1974 produced 148 tornadoes.  In Wednesday’s tornado outbreak there were 179 reported tornadoes.  We’ll have to see how many are documented, but this will certainly either top or be very close to what many consider the worst tornado outbreak in U.S. history.

Below are the storm reports from the SPC from Wednesday.

Storm Reports April 27

Now why did severe weather form?  In order for severe weather to occur, you need three ingredients – moisture, lift, and instability.  Those ingredients came together to produce strong and violent tornadoes in the south.  The surface map below shows low pressure over Arkansas with a trailing front.  This low helped to pump in warm, moist air over the South on Wednesday.  Dew points(a measure of moisture) were already in the 60s to 70s at 7 a.m. Wednesday.  Also, the surface winds ahead of the low pressure area were south-southeast. 

Surface Map April 27, 2011

While surface winds over the South were out of a south-southeast direction the jet stream was screaming into the region around 100mph out of the west-southwest.  Below is a 300mb map at 1 p.m. Wednesday.  The blue area is called a ‘jet streak’ or where the winds were the strongest.

300mb April 27, 2011

The change in wind speeds and direction with height is called shear.  Shear helps thunderstorms to rotate, and in turn produce tornadoes under ideal conditions.  Shear is probably the #1 ingredient needed for tornado formation once the thunderstorm has developed.  Here is a simulated thunderstorm showing how all of this works.  The model below is from the NSSL. 

Tornado Formation

We will continue to update the situation in the South here in the blog and on WISN 12 News.  The tornado outbreak on Wednesday was a topic we discussed along with other severe weather aspects at Farmington Elementary in Kewaskum.  I had a chance to visit the 3rd grade students at the school Thursday morning, they were a great group and had many fantastic questions.  Thank you for inviting me to your school!  Below is a picture of the students.

Farmington Elementary 2

Have a great day and make sure to let us know your thoughts and comments on this very busy month of severe weather across the U.S.!  Just drop a note in the comments section of the blog.

Jeremy Nelson

New Weather Set & Chilly Day Ahead
April 27, 2011

***Watch WISN 12 News for the latest weather information!***

Thank you for stopping by the Weather Watch 12 blog.  Wednesday was a big day WISN 12.  The curtain was pulled back and our new set was revealed!  The entire weather team is ecstatic to have a the new look and a new high tech work area.

Below is one picture of the Weather Watch 12 set.  The two monitors will be seen quite a bit on our newscasts.  When I took the picture the monitors showed the same image, but they will have different cameras and maps in them during our shows.

WISN Weather Watch 12 Set

The second picture is the desk that is part of our work area.  The entire weather set can be seen on WISN 12 News.  Please check it out and let us know what you think in the comments section of the blog.

WISN Weather Watch 12 Set

Good thing we have the set to be excited about, because our weather won’t be much to write home about on Thursday.  Cool weather is back in the forecast.  As a storm departs the area, another chunck of cool air will slide across the area.

Below is the RPM forecast temperature map for Thursday.  The map is valid at 2pm Thursday and shows low to mid 40s in our area!  Keep in mind the average high is around 60!  A little heavier spring jacket may be in order for Thursday.

RPM Temps Thursday

As quickly as the cool weather takes hold, it will fade.  Sunshine is back in the forecast for Friday, and on Saturday if winds turn to the south highs should push well into the 60s.  I think a few spots well inland could touch 70!  Looks like a great day to get yardwork done before the rain arrives.

Not only will it be milder to start the weekend, thunderstorms will be possible later Saturday.  Our in-house high resolution computer model is now picking up on the moisture.

Below is the RPM forecast map at 10am Saturday.  This is as far out as the RPM forecast goes at this point.  This shows t-storms already flaring up in parts of Wisconsin.

RPM Storms Saturday

Also of note is the south to southeast wind.  This would keep lakeshore locations cooler due to the chilly air over Lake Michigan pushing inland.

We are always on Weather Watch, and this weekend I will be here keeping a close eye on the storms.  If any would turn severe we will keep you updated here in the blog and on WISN 12!

In the meantime, check out WISN 12 for not only our new look, but for the latest data on your weekend forecast.  Drop us a comment and let us know what you think about the new set…we would love to hear your feedback.

Have a great day!

Jeremy Nelson

Severe Weather Stays South…For Now
April 26, 2011

***Watch WISN 12 News for the latest weather information!***

Thank you for stopping by the Weather Watch 12 blog!  After two consecusive dry days, something that has happened only TWICE this month.  More rain returned Monday night.  The rain soaked the region, with over an inch in spots.

Here are a few rain totals from around the area.  Please post your totals in the comments section of the blog.

  • Milwaukee Mitchell Airport  1.53″
  • Pleasant Prairie  1.37″
  • Sheboygan  1.22″
  • Kenosha  0.90″
  • Fond du Lac  0.87″

Once the steady rain cleared the area Tuesday morning winds shifted to the southwest and temperatures quickly jumped.  The mild winds pushed highs in Milwaukee into the mid-60s!  Below is a surface map from 3pm Tuesday showing the temporary warm-up from Tuesday.

Milwaukee is labeled ‘MKE’, just click on the map to enlarge.

Surface Map Tuesday April 26

The southwest winds and temperatures in the 60s were a result of a warm front lifting north of the area along with low pressure.

On the backside of the low, cooler readings will filter in for Wednesday, so no more 60s in the short term.  A few showers will also be possible.  Below is the forecast surface map from the HPC valid at 7 a.m. Wednesday.

Surface Forecast April 27

While cooler temperatures and a few showers are in the forecast, at least our area is not in a threat for severe weather.  Areas from Texas to the Ohio Valley are in an increased threat for severe weather from the time of this writing on Tuesday into Wednesday.

With the storm system shifting to the east on Wednesday.  The greatest threat for severe storms will also slide east.  Below is the day two convective outlook from the Storm Prediction Center.  This shows a large area from the South to the eastern Great Lakes in a moderate risk for severe weather, including tornadoes on Wednesday.

Day 2 Outlook Wednesday

The tornado count continues on a record pace for April and for any month ever!  As of last check and this number continues to increase quickly, the REPORTED number of tornadoes for April stood at 617.  Remember, reported versus documented are different.

That’s why until we get the documented numbers in at the end of the month, I will hold off talking specific records.  But it does look likely this will be the busiest month all-time! 

While 14 Wisconsin tornadoes have contributed to the 617 so far, when is the next chance of strong storms in our area?  It is still a long way off, but this coming weekend does look like not only will warmer temperatures be in place for a day, but also a storm system will push into the region.

Below is the GFS computer model forecast for 7 p.m. Saturday.  This shows a line of thunderstorms pushing into southwest Wisconsin.  Something we’ll watch closely as the week progresses!

Surface Map April 30, 2011

Make sure to leave your thoughts and questions in the comments section of the blog.  Check out WISN 12 News at 5, 6, & 10pm for the latest data!

Have a great day!

Jeremy Nelson

Rain Returns…Chilly Spring Continues
April 25, 2011

I hope everyone enjoyed the beautiful Monday. It was nice to get plenty of sunshine and a comfortable day.  There is very little sunshine in the forecast for the rest of the week.

April continues to be a brutal month for severe weather and flooding to our south. Take a look at the severe weather reports for the month.

There have been over 5000 reports of severe weather so far this month. April will go down in the record books for number of tornadoes. Over 500 tornadoes have been reported so far and there will be many more tonight and tomorrow.

This has been an incredible month of severe weather especially over the last week and a half. A persistent pattern with a stationary front draped across the South-Central United States combined with a strong jet stream over the same area has led to day after day of severe weather and very heavy rain. Major to catastrophic flooding is possible in Arkansas, Missouri, Tennessee, Kentucky, Illinois, and Indiana. Here is the forecast for rain for the next two days. This is on top of an area that is completely saturated.

We have a fair amount of rain in our forecast as well, but the flooding threat is minimal. Here is our local high-resolution model for rain.

I expect around 1-2″ of rain for most areas. Most of that rain will fall late tonight and Tuesday morning. We are fortunate to be north of the jet stream so the severe weather threat stays to our south.

If you think this has been a cold spring, you are correct. This is the coldest start to spring that we have had for the last ten years. Take a look at the chart and notice the huge difference between last spring and this spring.

Temperatures for first 35 days of spring at Milwaukee in the past 10 years:

Average Overall Temp   Average High Temp
 Rank  T (°F)  Year    Rank  T (°F)  Year
 1  39.2  2011    1 45.9  2011
 2  41.1  2009    2 48.4  2009
 3  42.0  2002    3 49.9  2002
 3  42.0  2003    3 49.9  2008
 5  42.4  2008    5 50.0  2003
 6  44.9  2007    6 53.1  2007
 7  45.3  2005    7 54.3  2005
 8  45.6  2004    8 54.6  2006
 9  46.3  2006    9 55.1  2004
 10  47.2  2010    10 56.3  2010

The average high temperatures have been almost 10 degrees colder this spring vs. last spring. A big thank you to the National Weather Service in Sullivan for the spring comparison.

Make sure you follow our rain and storms tonight and tomorrow on 12 news at 10pm and again Tuesday morning starting at 4:30 AM. Interactive radar is always available to track the storms on wisn.com/irad.

Thanks for reading and have a great night.

Mark

‘Egg’cellent Easter Forecast
April 24, 2011

***Watch WISN 12 News for the latest weather information!***

Happy Easter to you and your family!  Thank you for spending a few minutes reading the Weather Watch 12 blog.  Dry days have been rare this month, but somehow we lucked out and dry weather landed on Easter weekend.  In this blog entry we’ll take a look at the ‘egg’cellent weather for Easter, and also the ‘rotten’ weather for early this week.

Let’s start with a picture that was posted on the U-Local section of WISN.com  This is Casey the Easter cat, not sure Casey was thrilled with the bunny ears.  The picture was likely photo shopped, but still made me smile.

Casey Easter Cat

Weatherwise for Sunday, clouds to start, then a mix of sun and clouds in the forecast.  More sun the farther north you travel in the state.  Temperatures will also vary.  With a general eastern wind lakeshore locations will be cooler, low 50s for highs.  By afternoon the lakeshore areas may fall back a couple of degrees, where inland areas will warm well into the 50s, and some spots around 60.

Below is the RPM temperature forecast map at 3pm Sunday.  Notice the 60 degree readings near Watertown, Janesville, and Madison.

RPM Temperatures Easter Sunday

Not only mild, but dry!  Sunday will mark the second time in the last two weeks that Milwaukee has recorded consecutive dry days.  Overall it has been a wet and dreary month.

The trend will continue early this week with more rain in the forecast.  Low pressure will push north late Monday and into Tuesday.  The forecast position of the low, along with the associated rain from the RPM computer model is shown below.  This map is valid at 6am Tuesday.  At this time a steady rain could be falling in parts of southeast Wisconsin.  If you are looking to do some yard work, I recommend completing it by Monday afternoon.

RPM Rain Forecast Tuesday

The storm system could produce another 0.50″+ of rain for parts of our area.  Warmer temperatures will push our way by late in the week with highs well into the 60s possible, maybe even around 70!

Have a happy Easter and make sure to leave your thoughts and questions in the comments section of the blog.

Jeremy Nelson

St. Louis Tornadoes, Easter Forecast
April 23, 2011

Happy Easter from Weather Watch 12.

It was a frightening night for people in St. Louis with at least three confirmed tornadoes in the area. Friday evening was a difficult one for me personally because I was worried about friends and family in that area. I grew up in north St. Louis County in Ferguson. This was very near where the strongest tornado hit. I was on the phone with my sister and parents for much of the evening making sure they were safe. Thankfully, the severe weather missed them. My sister lives south of St. Louis and my parents now live in Illinois in a suburb east of the city. My sisters best friend lives in the Maryland Heights area. She had roof damage and her neighbors homes were destroyed. It is very fortunate that no one was killed. Here is a picture she took last night on her street.

The latest damage survey just came out from the National Weather Service in St. Louis.

NWS
St. Louis, Missouri

April 22nd Tornadic Supercell
Greater St. Louis Metropolitan Area 

Overview:

A tornadic supercell crossed the Greater St. Louis Metropolitan Area with many reports of large hail and damage from New Melle in St. Charles County to Granite City in Madison County, Illinois.  Some of the most intense damage occurred in St. Louis County across Maryland Heights, Bridgeton, St. Ann, Edmundson, Lambert St. Louis International Airport, Berkeley, and Ferguson.  Several people were injured by flying debris and glass at the main terminal of the airport.  The National Weather Service will be surveying the tornado damage over the weekend to determine the numberand intensity of tornadoes that occurred.  Below are some pictures of the strom and damage that have been collected from local news outlets.

Preliminary Damage Survey Findings: 

Please note…these findings are preliminary and are subject to change.

 …INITIAL DAMAGE SURVEY INDICATES EF4 DAMAGE IN NORTH ST LOUIS COUNTY…

THE NATIONAL WEATHER SERVICE DAMAGE SURVEY TEAM IN NORTH ST LOUIS COUNTY HAS FOUND EF4 DAMAGE IN THE BRIDGETON AREA…NEAR OLD ST CHARLES ROCK ROAD AND HARMON ESTATES.

EF4 DAMAGE INDICATES WINDS OF 166 TO 200 MPH.

SURVEY TEAMS HAVE NOT YET REACHED LAMBERT FIELD…SO NO DAMAGE RATING IS AVAILABLE AT THIS TIME (305 PM 2/23/11)

…INITIAL DAMAGE SURVEY INDICATES EF2 TORNADO DAMAGE NEAR PONTOON BEACH ILLINOIS…

A NATIONAL WEATHER SERVICE DAMAGE SURVEY TEAM HAS DETERMINED THAT THE DAMAGE IN THE PONTOON BEACH AREA WAS PRODUCED BY A TORNADO…WITH A DAMAGE RATING OF EF2. THE DAMAGE TEAM FOUND AN APPROXIMATELY 100 YARD WIDE DAMAGE TRACK FROM THE LEVEE RD ABOUT 2 MILES SOUTH OF I-270 TO THE INTERSECTION OF ALTON ST. AND PONTOON ROAD NEAR THE RAIL ROAD TRACKS. THE MAXIMUM DAMAGE FOUND WAS IN A NEIGHBORHOOD BETWEEN HWY 203 AND MARYVILLE ROAD. THE DAMAGE WAS RATED EF2 IN THAT LOCATION. THE DAMAGE SURVEY TEAM IS CONTINUING TO BACKTRACK THE TORNADO TO THE WEST. ADDITIONAL TREE DAMAGE OF EF1 INTENSITY WAS NOTED ON THE MISSOURI SIDE OF THE MISSISSIPPI RIVER NEAR THE INTERSECTION OF RIVERVIEW DR AND CHAMBERS RD.

EF1 DAMAGE INDICATES WINDS OF 86 TO 110 MPH.

EF2 DAMAGE INDICATES WINDS OF 111 TO 135 MPH

…INITIAL DAMAGE SURVEY INDICATES EF1 TORNADO DAMAGE NEAR NEW MELLE…

A NATIONAL WEATHER SERVICE DAMAGE SURVEY TEAM HAS DETERMINED THAT THE DAMAGE IN THE NEW MELLE AREA WAS PRODUCED BY A TORNADO…WITH A DAMAGE RATING OF EF1. THE TORNADO TRACKED JUST NORTHWEST AND NORTH OF THE TOWN OF NEW MELLE. THE INITIAL TOUCHDOWN OCCURRED JUST SOUTH OF FORISTELL ROAD…AND THE TORNADO LIFTED JUST EAST OF HIGHWAY Z. THE TRACK LENGTH WAS APPROXIMATELY 4 MILES…WITH A DAMAGE WIDTH OF AT LEAST 150 YARDS.

EF1 DAMAGE INDICATES WINDS OF 86 TO 110 MPH.

An EF4 tornado hitting a major metropolitan area without major injuries or deaths is close to a miracle. I want to share some of the pictures of the damage, but want to start with a radar velocity image of the tornado as it moved over St. Louis International Airport. The airport took a direct hit and is still closed.

I want to thank Scott Metsker for sharing the image with me. The area of greatest concern is the bright green area just southeast of St. Charles. This is not a couplet that you would see in a tornado, but actually something that is known as a debris ball. After the tornado hit Maryland Heights it picked up a lot of debris (parts of houses, trees, etc.). This is then seen on the radar as bright radar return. When this becomes visible it is not a good sign. It means the tornado is strong enough to pick up debris and that it is likely a destructive tornado. Here are some of the damage pictures.

This was in Bridgeton. Just west of the airport.

This picture is from Lambert Field. A shuttle truck was actually pushed nearly off of the parking garage.

Before the supercell started forming tornadoes, huge hail was falling in Central Missouri. This picture of baseball size hail is from Hermann.

Our weather pales in comparison in a very good way. After a nice Saturday, Easter Sunday looks pretty good. The only problem is that a lake breeze will form by midday Sunday. This means it will not be as warm as Saturday. I think we will still have some sunshine Sunday morning, but clouds will quickly fill in. Highs will be in the middle to upper 50s inland, but only in the lower 50s near the lake. Happy Easter.

Mark

Easter Weekend Forecast
April 22, 2011

Not a very nice start to the Easter Weekend. Showers and storms rumble through this evening. Can’t rule out some small hail in the elevated storms. Elevated storms are thunderstorms that get their lift from above the surface. This happens in Southeast Wisconsin a lot. The easterly wind makes it very stable at the surface, but warmer air aloft helps initiate the storms as the low-level jet brings the moisture over the colder air.

The good news is that the storms will push out of here rapidly leaving a nice weekend ahead. Check out the visible satellite image from 7pm. Note the nice clearing in Nebraska and Iowa. That heads our way for the weekend.

Saturday will be the warmer of the two weekend days, but it will be breezy. Westerly winds will keep any lake breeze away so all areas will warm into the upper 50s with plenty of sun. Here is the Saturday forecast across the state.

I would not be surprised if some areas touch 60 on Saturday. This will be the warmer of the two weekend days. Sunday will start out sunny. Easter egg hunts could actually be done outside. More clouds will move in as Sunday goes on. The big difference between Saturday and Sunday is the wind direction. The wind on Sunday will be east or northeast. That means it will be cooler everywhere, but especially near the lake. Here is the statewide forecast.

Monday and Tuesday will bring another chance of rain, but just try to enjoy the nice weekend ahead. Happy Easter.

Mark

Pattern Update & More Rain Ahead
April 21, 2011

***Watch WISN 12 News for the latest weather information!***

Thank you for stopping by the Weather Watch 12 blog!  Dry and sunny days have been hard to come by this month.  Only 8 of the 21 days so far in April have been dry.  One of those dry days occurred today(Thursday).

The dry weather will be short-lived, as another storm system is pushing in our direction.  The map below is from the GFS(Global Forecast System) computer model.  It is a 500mb map, which is the middle of the atmosphere.  The map was valid at 7am Thursday.

Notice the little ‘X’ marks over the Rockies and West Coast.  These are vorticity maximums.  These are disturbances in the middle of the atmosphere, think areas of low pressure, and they are headed toward Wisconsin.

GFS 500 April 21, 2011

The vorticity maximums are often associated with storm systems, and will result in a good chance of rain in our area on Friday.  The overall weather pattern continues to repeat.  Remember we are on roughly a 50 day cycle, so this part of the pattern has occurred before.

Below is the 500mb map from November 23, or 149 days ago.  The timeframe of November 23-25 matches well with the storm system that will impact our area over the next 48 hours.

500 November 23, 2010

Showers and a few thunderstorms are possible in southern Wisconsin on Friday and Friday night.  The rain will add to our above average total so far this month.

Below is the RPM forecast rainfall for the next 48 hours.  The rain should exit by early Saturday.  Just click on the map to enlarge.

RPM Rainfall Total

Once the storm pulls away Saturday, there is promise for a decent weekend.  We’ll have to watch a system to the south closely, more for Sunday.  But as of this writing Easter Sunday does look dry.

Temperatures will also be a touch warmer over the weekend.  Highs should top out in the 50s.  Below is the NAM(North American Model) temperature forecast map for Sunday at 7 p.m.  Notice the 50s inland, with 40s closer to the lake.  But during the afternoon I think most areas should top out in the 50s.

NAM Temperatures April 24, 2011

Enjoy any dry weather over the weekend, more rain arrives early next week!

Make sure to post your weather questions and thoughts to the comments section of the blog.  Check out WISN 12 News at 5, 6, & 10pm for the hour by hour forecast. 

Have a great day!

Jeremy Nelson