April may be early when it comes to severe weather season, but certainly it is not out of the question for wild storms to impact the Badger State. Coincidentally April 11-15th is Severe Weather Awareness Week in Wisconsin. No less, Mother Nature gave us an abrupt start to experiencing storms with large hail, damaging winds and tornadoes.

First here are the stats for April 10, 2011 and how it reflects in the history books in Wisconsin. The 14 tornadoes that touched down set a new record for the most on a single day in April, with additions of and EF1 Tornado in Langlade County and another EF1 near Stockbridge, along with an EF1 Tornado near Necedah and an EF1 in Brown County near Greenleaf. This event topped the 10 twisters that hit on April 27, 1984. The strongest tornado on 4/10 was an EF3 with maximum winds of 140 mph impacted Southern Lincoln County. This tornado tracked for a total of 22 miles, starting near Hamburg and finally winding down in Gleason.

Photo Courtesy NWS Green Bay & Samual L. Hall

Needless to say, I had a strong feeling that severe storms were going to hit our area from Saturday Night to Sunday. The ingredients were coming together, including a warm front driving warm air north (temps in the 70s to low 80s), along with rather high dew points in the 50s to low 60s. Next, we had low pressure with an adjoining cold front tracking across during the afternoon hours Sunday. Last but not least, to stir up the atmosphere, sunshine had broken out in the wake of late night/early morning showers and embedded storms. This only aided in destabilizing things and provided that extra push for storms to get rolling. The “convective cap”, which until about 3pm had kept storm development to a minimum broke, with isolated strong to severe storms blooming back across SE Minnesota, Western Wisconsin and NE Iowa. In addition, mid & upper level winds were strong and working in tandem, steamrolling the storms that developed to the east & northeast at speeds of 55-75 mph. Just that aspect of the fast movement of the storms could have caused downbursts of winds that would have been over 70 mph, let alone having a twister impacting Merrill with winds of 140 mph.

The first tornadoes hit near Augusta in Eau Clare County around 5pm, covering .75 to 1.5 miles and registering as EF1. Then just before 6pm this same cluster of storms rambled into Marathon & Lincoln Counties. Titan Radar had been showing high reflectivities with these storms, in addition to strong rotation as they were working through Clark & Taylor Counties. However 6:13 pm is when the tornado hit Hamburg and began it’s treacherous journey toward Little Chicago, Merrill and Gleason. Around the same time, another very intense storm was ripping across Juneau and Adams Counties, producing a tornado near Arkdale at 6:12pm and traveled 17 miles to Coloma before lifting. After a change in location over a 3 minute time span, a new tornado touched down 6 miles SW of Hancock and plowed across to 2 miles SE of Hancock. The official measurement of distance was a little over 9 miles.

There was then a brief lull in the tornadoes for about 40 minutes, before 2 separate twisters once again made impact in our viewing area. Down in Waupaca and Waushara Counties an EF1 tornado hit near West Bloomfield and traversed to near Readfield. Not that long later the same supercell again brought a tornado to the ground near Poy Sippi and went for about 15 miles to the east into Winnebago County. Farther north, 2 separate tornadoes hit in Forest County, one around Argonne and Newald (an EF2), the other close by to Armstrong Creek (an EF1). Last but not least a final twister hit around Kaukauna in Outagamie County around 8:45pm. When all was said and done, numerous reports of building and structural damage were confirmed, along with injuries from flying debris and folks being caught in collapsed houses. It should also be noted large hail in conjunction with these storms ranged in sized from 1 to 2.5” (quarter to baseball size), along with heavy downpours of rain that exacerbated flood conditions along area rivers that were running high, pushing a fair number above flood stage.

All in all a wild span of 4 hours in North Central Wisconsin and hopefully you stayed safe wherever you might have been. We certainly were staying on our toes in the Weather Lab with live, continuous coverage on 24/7 Weather & wsaw.com, informative updates on Newschannel 7 along with our HD Weather Crawl, frequent updates to the Newschannel 7 facebook page, and up to the moment storm analysis on twitter @wsawweather.

For more details on this severe weather and tornado outbreak along with some dramatic pictures of damage & the twisters, check out the links from: NWS La Crosse, NWS Green Bay, NWS Milwaukee.