You’ve probably heard that upgrades to dual polarization has finished in various National Weather Service Doppler Radars in our region including La Crosse and Green Bay.  Marquette’s is currently getting worked on and Duluth’s upgrade will start next week.

The La Crosse Dual Polarization Radar already had a nice workout with some of the storms that moved through this past weekend.  The meteorologists there had a good look at a hail producing storms using their new capabilities.  It allowed them to be more certain of the location of the hail and size of it as well.  Below is an image of some of the things they were looking at with a storm that passed through northeast Iowa.  Please visit the following link from the National Weather Service for a more in depth look at how they utilized it.  http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=arx&storyid=82763&source=0

Posted under Severe Weather, Storms, Technology

After 22 months of testing, NOAA started using a sophisticated new short term weather forecast model.  The Rapid Refresh Model (RAP) for short, will improve predictions of quickly developing severe weather situations such as thunderstorms, winter storms, and aviation hazards like turbulence.  It replaces an older model called Rapid Update Cycle (RUC).

RAP was developed by NOAA’s Earth System Research Lab in Boulder, CO and the National Centers for Environmental Predicton in Camp Springs, MD.  It updates every hour producing a fresh forecasting extending 18 hours over most of North America.  The U.S. is the only country in the world to routinely update a weather forecast model every 1 hour with the latest observations from ground and satellite based sensors, along with radar, ships, and aircraft.

Forecast skill has improved using the RAP model for most variables including wind and precipitation.  For example the RAP did a better job of showing where a large area of extreme rainfall would occur last June over the middle of the country.  Aviation interests in Alaska are seeing improvement to flying safety using this model.  This is especially important to that state because there are numerous sections of Alaska only accessible by airplane.

You can learn more about the RAP model and other forecasting issues from the following link.  http://www.noaanews.noaa.gov/stories2012/20120501_rapmodel.html

Posted under forecast, Science, Severe Weather, Technology, Weather NEws

Photo from the National Weather Service

Five tornadoes tore through parts of southeast Colorado yesterday, leaving several injured and causing considerable damage to farming communities. 

According to the National Weather Service two tornadoes hit Prowers County, two tore through Kiowa County,  and one went through parts of Bent County in the early morning hours of April 27th.

According to the Denver office of the National Weather Service, overnight twisters in Colorado are rare.  The last time an overnight tornado hit the state was April 30th, 1942.  Ironically it hit the same two counties of Bent and Kiowa, the same areas hit this year.

For a look at the damage from the National Weather Service Survey team, follow this link: http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=pub&storyid=82413&source=0.

Posted under Environment, Natural Disasters, Nature, Seasonal Items, Severe Weather, Spring, Tornadoes, Weather History, Weather NEws, Weather Safety

There are numerous shows on TV, like on Discover Channel or the Weather Channel, that glorify storm chasing.  They make it look so fun and cool to be out racing down the highway trying to get right up next to a monster tornado.   Despite being pelted with hail stones, flying branches, torrential rain, and lighting, the vehicles press on with a sense of immortality.  As we all know, TV shows don’t always portray the whole story.  Certainly when it comes to tornado safety, these chasers often push the limits way beyond comprehension.

 Be that as it may, there is an ongoing debate and uncertainty about what is the best course of action if you are in a vehicle with an approaching tornado to deal with.  The conventional wisdom when I was growing up and even during the first decade of my weather forecasting career was that one should always leave the vehicle and go lie flat in a ditch or ravine and cover your head.  Over the past 15 years there have been some high profile cases where people were actually severely injured or killed by leaving their vehicles and going under overpasses or just going out in the open.  Now there is more of a recommendation to use your best judgement based on a number of factors whether to leave your car or not.  Below is a statement from Roger Edwards of the Storm Prediction Center that goes into more depth on this subject.

In a car or truck: Vehicles are extremely risky in a tornado. There is no safe option when caught in a tornado in a car, just slightly less-dangerous ones. If the tornado is visible, far away, and the traffic is light, you may be able to drive out of its path by moving at right angles to the tornado. Seek shelter in a sturdy building, or underground  if possible. If you are caught by extreme winds or flying debris, park the car as quickly and safely as possible — out of the traffic lanes. Stay in the car with the seat belt on. Put your head down below the windows; cover your head with your hands and a blanket, coat, or other cushion if possible. If you can safely get noticeably lower than the level of the roadway,leave your car and lie in that area, covering your head with your hands. Avoid seeking shelter under bridges, which can create deadly traffic hazards while offering little protection against flying debris.

We’ve all seen the horrific images of vehicles twisted around tree trunks 20 feet in the air, or turned upside down and crushed.  Or how about the photos of beams or lumber jabbed straight through a car window or door.  What a horrible thing if someone was in that vehicle in such cases.  I wish I had a hard and fast rule for you when it comes to automobiles and tornadoes.  I hope you never have to make such a tough decision but if you do, try not to panic.  Take care.

Posted under Education, Natural Disasters, Seasonal Items, Severe Weather, Tornadoes, Travel, Weather Safety

This is Tornado and Severe Weather Awareness Week in Wisconsin.  Luckily we haven’t had much in the way of severe thunderstorms yet, but that will likely change over the next month or so.  It’s always a good thing to review severe weather terms, safety tips, and refresh your severe weather preparedness plans.  Do you and your family members know what to do in a variety of situations whether you are at home, school, work, shopping, driving, or outside?  Please take time to look over this important information.  It could reduce your risk of injury or death from severe weather.

On Thursday, April 19, a tornado drill will be conducted.  At 1 pm, a test Tornado Watch will be issued for all of Wisconsin.  The test watch will be broadcast on NOAA Weather Radio as a Required Weekly Test–RWT.  At 1:45 pm, the NWS Green Bay office will issue a test Tornado Warning.  The test warning will be broadcast as a test on NOAA Weather Radio using the actual Tornado Warning code.  The drill will conclude at 2 pm.

Here’s the schedule for the tornado drill:

1:00 p.m.  -  A test Tornado Watch is issued for all of Wisconsin by the Storm Prediction Center

1:45 p.m.  -  NWS offices in Wisconsin issue test Tornado Warnings using actual Tornado Warning code (broadcast will state this is a test)

2 p.m.  – Drill ends with the issuances of test Severe Weather Statements

Should severe weather be present anywhere in Wisconsin on the day of the drill, the test watch and warnings will be postponed until Friday.  If severe weather is forecast for Friday, the drill will be canceled.  

Wisconsin Severe Weather Facts

Wisconsin averages 23 tornadoes per year, with most tornadoes occurring in the 3 to 9 P.M. time frame.  The peak tornado season in Wisconsin is May through August, with June having the greatest number of tornadoes.  A record-setting 62 tornadoes occurred in 2005.  In 2011, Wisconsin had 38 tornadoes, 15 in northeast Wisconsin alone!

The “average” Wisconsin tornado has a 10 minute duration, a path length of about 6 miles, and a damage width of about 125 yards.

Another hazard of the warm-season is powerful, straight-line thunderstorm winds that can exceed 60 mph.  Every year Wisconsin will get a few storms that generate hurricane-force winds of at least 75 to 100 mph.  Severe Thunderstorm Warnings are issued for these wind events.

Large hail is also a hazard with thunderstorms.  Severe Thunderstorm Warnings are also issued for storms with hail of at least 1″ in diameter.

Other warm-season hazards localized flash floods or widespread river and lowland flooding, lightning, and excessive heat.

To learn much more about all types of severe weather that impacts our region please go to these great link from the National Weather Service. 

http://www.crh.noaa.gov/mkx/?n=taw-part4-tornado_stats

http://www.crh.noaa.gov/grb/?n=safety

http://www.crh.noaa.gov/images/grb/outreach/TAW/TAW5.pdf

http://www.crh.noaa.gov/images/grb/outreach/TAW/TAW2.pdf

http://www.crh.noaa.gov/images/grb/outreach/TAW/TAW3.pdf

http://www.crh.noaa.gov/images/grb/outreach/TAW/TAW1.pdf

Posted under Severe Weather, Storms, Tornadoes, Weather NEws, Weather Safety

Before I get into the severe thunderstorm outlook for upcoming days, I thought you might be interested in seeing how widespread this recent cold snap has been.  Freeze Warnings are in effect Wednesday night all the way down to Tennessee and North Carolina.  A good dozen states or more are covered (the area in blue on the map).

Weather Advisories Wednesday Night

Rain is likely Friday around here with a small chance of a thunderstorm Saturday.  However it looks like the threat of severe storms with large hail, high winds, and tornadoes will stay in the Plains.

The convective outlook from the Storm Prediction Center for Friday shows the risk area mostly in Kansas, Oklahoma, into far northern Texas.  That part of the country will be in a flow of warm and muggy air with dew points climbing into the 60s.  A low pressure system emerging from the Rockies into the Plains along with strong jet stream winds will aid the formation of violent weather.

Severe Thunderstorm Risk Area for Friday

Severe Thunderstorm Outlook for Saturday

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Finally, I want to bring up a sneaky weather feature that occasionally helps to develop or enhance precipitation and storms.  It is called gravity wave.  It is a rapidly moving ripple of energy with alternating up and down air motions.  It normally shows up on satellite imagery as a striped area of clouds with clear breaks between them.  Here is an example in the image below.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This gravity wave train ended up producing a thunderstorm with softball size hail in parts of Texas.  We really have to watch them carefully, especially where they might intersect an existing front or boundary.  That’s usually where the big action is.  You can learn much more about this fascinating case and gravity waves in general by checking out this link from the Storm Prediction Center.  http://www.spc.noaa.gov/coolimg/gwavecb.htm

Posted under forecast, Freeze, Severe Weather, Storms

While we could have a rumble of thunder around here Monday night into early Tuesday, it appears the main threat of strong or severe thunderstorms will remain from far southern Wisconsin down through the Kansas area Tuesday afternoon.  That region is under a slight risk classification from the Storm Prediction Center.  The reason is that warm, and more humid air will be surging north ahead of a cold front.  Temperatures there could reach the 70s making the air rather unstable.  The cold front would be the trigger to lift the air and initiate the storms.  Strong winds in the atmosphere and turning wind direction in height could allow several of the cells to become supercells with rotation.  Thus a few tornadoes are possible, especially from west-central Illinois into Missouri.  Otherwise damaging winds over 50 mph and hail to 1.5″ diameter will be possible as far north as Janesville, WI.

On a different note, I did a talk at the Simek Library in Medford Saturday regarding weather technology and other topics.  One question from the audience came up regarding the Fujita scale.  That scale has been around for numerous decades as it was developed by Dr. Theodore Fujita in the 1960s and 70s.  It ranks tornado strength on a scale from F0 to F5, with F5 being the strongest.   Research in the past 10 years regarding how winds damage buildings has allowed an upgrade to the scale.   It is now called the Enhanced Fujita scale or EF scale.  You can read all about the scale and how it’s applied by reading this article from the Storm Prediction Center.  http://www.spc.noaa.gov/efscale/

Posted under forecast, Severe Weather, Spring, Storms, Tornadoes

Did you know that March 12th – 16th is Flood Safety Awareness Week in the U.S.?  Flooding is one of the top weather killers every year in the country.  Of course it also produces huge amount of property damage.  I’ve seen some streams and small rivers out of their banks the past few days with the rapid snow melt and light to  moderate amounts of rain we’ve had.  Most of the flooding has been lowland and agricultural in nature so far.

 We are really lucky we didn’t have a 2 to 3″ rain storm or we could have been in a lot of trouble when it comes to flooding.  Even though the snow melt flood risk is diminishing now because we never really built up that huge snow base like other winters we still need to be on guard.  This is especially true because the developing pattern is one that could feature shower and storm chances for about a week in a row starting this weekend and going through next week.  Seeing that it will be unseasonably warm and humid, some of the showers certainly could produce heavy rain.  Therefore we can’t rule some flooding problems as the month goes on.

This is certainly a great time to refresh your memory on what flood terminology means, see what new technologies are helping us forecast floods better than ever, and consider buying flood insurance.  These topics and many more are covered in a great brochure put together by the National Weather Service.  It has many fascinating photos of flooding and its power within it as well.  Be sure to check it out at this link.   http://www.nws.noaa.gov/om/brochures/Floodsbrochure_9_04_low.pdf

Posted under Education, Flooding, Natural Disasters, Seasonal Items, Severe Weather, Spring, Weather NEws, Weather Safety

I would like to delve a little more into the science and weather news of the day but the impending Winter storm has taken up most of my time and I suspect it is on everyone’s mind anyway, so today’s blog will once again be about the potential snowfall, and rainfall, and sleet-fall (if that is a word).

So what has changed since yesterday’s analysis? I have dropped the snow totals slightly and shifted the heaviest potential snow a little north of the Wausau metro area. As you can see from the graphic, I am now forecasting 3 to 6 inches of heavy wet snow (mixed with rain and sleet at times) for Marathon county and the highway 29 corridor. The line for the heavier snow (and not as much rain or sleet, is likely to be just north of the Wausau metro area and on up into the Northwoods. For areas south of Marathon county, there is a good chance there will be more rain and sleet than snow. Right now I am looking at 1 to 3 inches of snow in the southern areas late tonight, followed by some heavier rain around daybreak.

Snow Potential

With the rain and milder temps developing in the morning, the roads might not be too bad south of Marathon county.

A couple key things to remember with this storm is that there could be some rather extreme differences in snow totals in the transition zone between rain/sleet and snow – that means Marathon county. As I was mentioning yesterday, in the transition zone there can be a 9 inch snow report just a few miles away from a 1 inch report. There could also be some thundersnow at times that can really enhance the snowfall. Thundersnow can produce snowfall rates of 4 or 5 inches per hour. This is also possible in the transition zone.

The second thing to remember is that the heaviest rain, sleet, and snow will occur quite early in the morning, through about 7 or 8 am for central Wisconsin. For the rest of the day on Wednesday, the weather will likely be mild (a few degrees above freezing) with only a little drizzle and patchy light snow. The only locations that could pick up an additional 2 to 4 inches of snow later in the morning through early afternoon are in the northwoods.

NAM snow forecast

For a comparison to our StormTrack9 snow potential graphic, I have also included one computer model projection of snowfall. This particular computer model (the NAM) calculates a maximum of 19.7 inches of snow in the northwestern corner of the state and generally 10 to 15 inches of snow for the northwoods. It also shows a sharp cut-off of where there will be a lot of snow and where there will be none. It does have a known bias of over-estimating precipitation, but it seems fairly close this time around.

There will be another storm system moving into the upper Midwest on Friday, but at this time it looks like the highest potential for accumulating snow will be confined to the far southeastern part of the area, in cities such as Shawano, Waupaca, and Wautoma.

Have a nice Tuesday! Meteorologist Justin Loew.

Posted under forecast, Severe Weather, Winter Weather

Posted under Education, Environment, Natural Disasters, new media, Records, Seasonal Items, Severe Weather, Storms, Weather NEws, Weather Safety