Friday, May 4, 2012

Summary of western Wisconsin severe storms, May 2nd-3rd

On the evening of May 2nd, 2012 a stalled out frontal boundary was draped across central MN and  into northwestern WI.  Places south of this boundary saw temps climb well into the 70's and low 80's, with dewpoints into the low 60's.  This boundary, combined with a second boundary lifting from the south served as the focus point for severe storm development across southern and southeastern MN (and with time, far west central MN) 

The first storms fired Wednesday evening in south central Minnesota, and gradually made their way off to the east/northeast.  Eventually the storms crossed into Wisconsin, hitting Buffalo County first.  At 9:33pm, the NWS in La Crosse issued a tornado warning for strong rotation indicated by radar north of the city of Alma, near Highway's 35 and 37.  No confirmed tornado, however, was ever reported.

As the storm continued its trek off to the east it left hail and wind damage in its wake.  There were several reports of trees down and windows broken by hail in scattered areas of the county.  By 10:00pm, the cell was approaching the northern portions of the city of Arcadia.  While the strongest part of the cell avoided the downtown part of the city, its effects were still felt...mostly on the far northern edge of town in a mobile home park.  Many of the homes had broken windows, and the skirting around some of the homes had significant hail damage to them.  Below is a picture of the left over hail, a good hour and a half after it fell.

This is a radar image as the storm passed by to the north of town, with the "X" being where the mobile home park was, and where the picture was taken.  As you can see, downtown Arcadia dodged a bullet with this one.

The storm continued making its way east, with the town of Blair next on its path.  Shortly before 10:30pm, the city of Blair was feeling the effects of this cell.  Strong straight line winds and large hail pounded down on the city, causing significant tree, power line and structure damage to a large part of the town.  Below are radar and storm velocity images.  The cell had slightly weakened as it moved from Arcadia to Blair, but intensified again briefly as it reached the western part of town.

The cell did weaken a bit once again as it passed overhead, and it is possible that this weakening phase created the microbursts that caused the wind damage.  Something else to note is this area had heavy rain the night before these storms, and it is also possible the soft soil made it much easier for the trees to come down.  Luckily there were no significant injuries reported with these storms, which is always a good thing.  Below are several images of the damage through the Blair community, as well as an overview of storm reports.  

This was a common site through town

The siding of a home had extensive hail damage.  A lot of homes had a very similar look to them in town

A part of the roof of the Blair-Taylor High School was torn off, forcing the school to close for a couple days

More roof damage from the school

Part of a barn collapsed in due to the strong winds

More tall trees down, all laying in the same direction...a common site in straight line winds

Sunday, December 4, 2011

Snow storm summary

Saturday evening and night, a swath of snow associated with an area of low pressure lifted northeast out of the south, and passing through south central WI. The band of snow was on the northwest side of the low, dropping anywhere between 3 and 8 inches of snow across parts of Minnesota and Wisconsin. Below is the snow total map, although some areas near the metro didn't receive as much as what is being shown. The map does, however, give you an idea of where the snow did set up, which was a bit further north than previously forecast.

With a fairly sticky snow, and pretty much no wind, the snow was able to stick to tree branches with ease, creating quite the winter wonderland when people woke up Sunday morning. Here are a couple pictures I snapped.

Other than a few shots of cold air coming in, the weather appears to be going back to that boring state yet again. These shots of cold may be able to squeeze some flurries out, but at this point no major systems in the works (other than the GFS bringing in something a week and a half away, but it is too far away to be credible at the moment).

Saturday, December 3, 2011

Winter Storm!

Well after months and months of pure boredom, a weather system of some significance is making its way towards the area, poised to drop the first decent accumulating snow of the season. While this particular system will fall well short of any "Storm of the Century" headline, it will certainly test drivers winter driving skills. At this point, surrounding weather service offices as well as local forecasters are going with a band of 4-7 inches of snow across the area, which certainly seems reasonable given the moisture available for this system to work with, and the fact that the system will move through at a decent clip. Below is a map of snowfall potential, as well as the current watch area, courtesy of the NWS office in La Crosse and Chanhassen. Again, overall this map looks good given what the models have shown at this point.

Current headline map (posted 12:46am Saturday)

The current storm track takes the low from northern Missouri to a near Madison, WI and off to the northeast. This low also looks like it will have a decent tap into the Gulf of Mexico, as shown in the 850mb moisture transport. Below is the GFS forecast map from the Penn State e-wall site.

Taking a look at Bufkit, both the NAM and GFS show an area of dry air that will have to be overcome before snowfall can begin. If this particular dry air can be overcome sooner than models show, amounts could potentially be higher. If it takes longer for it to saturate, then amounts will be trimmed. At this point, Bufkit data from the GFS and NAM both show full saturation for EAU sometime between 4 and 5pm Saturday evening, so I would expect the snow to begin in that time frame. Below are images from the 00z run of the NAM and GFS. You'll notice omega values around -10 overlapping the snow growth zone, so fairly good dynamics showing up with this. I would expect snow rates to be approaching at least an inch/hour for a few hours time, and this could be the bulk of our accumulation.



While a watch is up now for the area, I fully expect this to be upgraded to a warning, maybe not so much for snow totals, but the fact that it is the first system of the season, and the NWS hopes it will force more caution on people. I also expect perhaps a tier or two of counties surrounding the warning area to be given an advisory, again just to keep people aware of what's going on. This system should keep us in all snow here in Eau Claire, with areas further south near La Crosse will probably see more mixing potential. So again to summarize, it looks like a decent band of 4-7 inches of snow is possible for the area, but keep in mind if some convective bands can form, as was the case a few weeks ago near St. Cloud, there could be amounts higher than 7 inches. However, given the very isolated nature of these bands, they are near impossible to forecast right down to the city. Stay safe out there everyone!

Tuesday, September 27, 2011

Stubborn "Cut-Off" Low

What a gloomy past 5 days it's been around the Northern Plains/Great Lakes region. The culprit...something those in the weather world call a "cut-off low". A cut-off low is an area of low pressure that is removed from the main jet stream. Usually systems move along the jet stream, and are here and gone within a day or so. On occasion, areas of low pressure become removed from the main jet, therefore stalling out until a front comes through and pushes it along. This has been the case with this low, which really started affecting our weather since last Thursday. Below is an image of where the low is, and where the main jet currently is (way up in Canada).

It does look like, however, that some relief is finally on the way as a trough/cold front looks to sweep across the area, and will therefore push the low off to the east. It is still a good 48 hours away, so we are probably going to have to deal with the clouds and gloom through the day Tuesday, and likely even most of the day Wednesday before the clouds break. Below is an image of where the low is forecast to be, with the blue lines showing the trough that will push the low off to the east.

That trough will also deliver a shot of cooler air, with the European model being more aggressive than the American models, but it will certainly look and feel like fall. We will warm back up though, with the CPC predicting above average temps in their 6-10 day outlook.

Tuesday, September 13, 2011

Can wildfires enhance instability for thunderstorms?

Recently in my boredom, I thought I would take a peak at the visible satellite loop in northern Minnesota to see if the smoke could still be seen. Looking at the loop a couple times, I did spot the smoke, but there was something else that I noticed as well. It looked like thunderstorms were developing right over where the smoke was. At first, I thought it was a weird coincidence, but after watching the loop a few more times, it looked like the clouds kept billowing and storms kept developing over that same spot. At that point I thought to myself, can the heat from wildfires actually provide extra instability to the atmosphere to help with thunderstorm development? I know I've seen mini tornadoes in the fire of wildfires, but wasn't sure if it went beyond that or not. So, I'm interested in any input from people on their thoughts. Did the fires assist in thunderstorm development, or was this just a mere coincidence. Below are some stills I got of the visible satellite images.

Monday, August 29, 2011

Hurricane Irene...too much hype?

As Hurricane Irene, or at least what's left of her, continues to wind down, it would seem as though more than just death and destruction were left in her path. There seems to be some debate going on in the weather world, with people wondering if there was too much hype and build up as Irene developed from a tropical wave, to a tropical storm, and eventually a hurricane, and as her track became more defined. I personally am not a fan of hype, and looking back at things now I would agree that there was too much an extent.

I am a firm believer in advanced warning when it comes to hurricanes, as I would hope everyone else is. The sooner a person knows what is potentially coming towards them, the sooner they can plan to get out of town and to safety...unless of course you work in the TV or storm chasing world, in which case you drive to town, and away from safety. I think regardless of the amount of hype that went into some of the national headlines, the cities along the east coast did things right. They got out of town, away from danger, and hoped for the best. That is the whole point of having an advanced warning system. Now today, people are saying that Irene was a weak storm, and didn't live up to "expectations". At least 21 people have lost their lives because of the storm, and a large part of the northeast will be experiencing flooding for days, perhaps even weeks if more systems go through there and drop more rain. The feeling I am getting from people is that they expected more death and destruction. Usually people should be rejoicing that Irene didn't come through as forecast, yet it sounds like some are disappointed. In my eyes, it is better to over prepare than it is to under prepare. When there are that many people potentially at risk, you just don't take chances. You get out, and hope for the best. The fact that many people did evacuate very easily may have saved lives. I realize there is the "cry wolf" factor, in that people will hear a warning later and ignore it because "forecasts with the last one were bad and it ended up weakening a lot, so we are staying." My thoughts on that are, that regardless if it was expected to be a Category 4 storm or a Category 1 storm, people are set on what they want to do. Hurricane Katrina is a prime example of that. People were warned days in advance that this was going to be a massive life threatening storm, but some just insist on staying either because they are stubborn and won't leave, or think that it won't be as bad as predicted. Days later, those people are on their rooftops, angry that no one is there to help them. Don't get me wrong, I feel horrible for those people and what they went through, but they were warned to get out. Yet every time there is a hurricane headed for the US, we see interviews on television of people who just won't go.

Forecasters may be taking a lot of heat by some, because Irene didn't live up to their "expectations"...but let me ask you this. What if forecasters said this wasn't going to be a big storm, but then a Cat 3 crashes into New York, and hundred of people die because they didn't think it was going to be bad. Again, the heat would be on the NWS, and local weather outlets. Sometimes it is just a lose/lose situation.

In closing, the next time a storm is heading for the east, people still need to take things seriously. Plan for the worst, hope for the best...that is something I was taught, and still think about today. Just because one storm happens to not pan out as exactly precisely projected, doesn't mean the next one would do the same. I would just caution national outlets on their headlines that they use. I realize it's all about ratings and getting web clicks, but I think that can easily be done without adding too much sensationalism. HURRICANE IRENE EXPECTED TO TRACK UP THE EAST COAST, PACKING STRONG WINDS AND FLOODING RAINS. Boom...that gets the point across. It's honest and straight to the point. "DAY AFTER TOMORROW" STORM TO MOVE IN TONIGHT...ummm really? Ok, so that headline wasn't used, but I believe the movie reference was made at some point. I guess we'll see what lessons were learned from this storm once the next tropical system takes aim at the east/northeast US. We may not have to wait too long either, as some models are spinning up what may end up being Katia, and the second hurricane in this Atlantic season. Stay tuned!

Tuesday, May 24, 2011

Dangerous situation unfolding across Kansas, Oklahoma, and northern Texas


15z surface analysis shows a low pressure system in the panhandle of Oklahoma, with a stationary front extending northeast across central Kansas, through Iowa and into northern Illinois. A cold front is extending down from the low, and bending around through the panhandle of Texas. A dryline extends south of the low, out in front of the cold front, and will be the focus of today's storms.

The combination of surface heating, high dewpoints, and strong wind shear will lead to an outbreak of supercells capable of producing very large hail, damaging winds, and several large tracked tornadoes, with the area within the high risk the most likely to see these tornadoes. Below are the list of risks, issued by the SPC at 1630z.





Here's a peak at the first tornado watch of the day, covering the higher risk area for today, with the probability of seeing several strong tornadoes being quite high.

Taking a look at current meso analysis shows significant tornado probabilities climbing quite high, and are expected to continue to increase as the day wears on. 0-6km bulk shear is also climbing rapidly across western Oklahoma, and will continue to move east, and increase as the low level jet strengthens later this afternoon. SPC is forecasting explosive development of cells, with very large hail being the initial threat. As that LLJ continues to strengthen, the tornadic threat will also increase.

Enhanced Tornado Index

0-6 Shear

850mb GFS forecast

People across these risk areas need to pay attention to the changing weather conditions, as several more watches will likely be issued as the day wears on. Any cell that forms will become supercellular rapidly, and has the potential to become tornadic.