Here are some important dates to remember:
April 10: Opening of non-operational Wordpress Weather Centre blog.
May 1: Responsibility of posting begins to slowly shift to the Wordpress blog.
June 1: The Wordpress blog becomes operational.
July 10: The Blogspot blog is officially closed. (The site will still be open, but no new posts will be created.)
High level clouds over the Mississippi River are holding a cap in place.
Of more concern is a trough moving rapidly northeastward.
This trough has the potential to break the cap and initiate storms ahead of the cold front.
However, should the trough be unable to break this cap, we would have to wait until the actual cold front arrival.
The Weather Centre believes this could go either way.
The cap appears to be either holding or slightly strengthening.
However, the cap's current values are not too impressive.
For now, The Weather Centre will go with a slight chance of storms in the next couple hours.
SYNOPSIS: Warm front currently lifting north into Central WI is creating a strong capping inversion over the Midwest. Temperatures over the area are surpassing 80 degrees, with dewpoints over 60.
Cold front out west currently accompanied by a secondary low as the main low is moving into Minnesota.
Although the cold front is projected to create storms, the strong cap is in place, limiting storms.
We can expect this cap to rupture going into this afternoon. When it does, strong storms will erupt immediately.
There are even signs of updrafts occurring in the Southern Plains, a sign that convective thunderstorms may be preparing to erupt.
Up in Wisconsin, where there is more concern, initiation of storms is expected to begin in the next hour or two.
Go to the basement. The southwest corner (or any corner) does not offer the best protection. Get under the stairs or under a heavy piece of furniture. If there is no basement go to a small interior room on the lowest floor, such as a closet, bathroom or hallway. Do not open windows! Stay away from windows.
In schools, hospitals, nursing homes, and other public buildings, go to small interior rooms or halls on the lowest floor. Stay away from windows. Avoid large rooms such as gymnasiums or auditoriums.
High Rise Buildings
In high rise buildings, it is not necessary to get to the lowest floor. Go to small interior rooms, halls, or stairwells – but stay away from windows.
Mobile Homes and Vehicles
Make plans to go to a nearby substantial structure when the tornado watch is issued, before the storm hits. If a tornado is approaching and there is not time to get to a place of safety, get out and lie flat on the ground in a low spot or ditch. Nationwide, about 40% of tornado deaths occur in mobile homes. Bridges or overpasses are not good storm shelters. They can act as wind tunnels.
I am in quite a trouble spot here.
The National Weather Service and Storm Prediction seem to be going toe-to-toe with commercial weather agencies.
That is why I am choosing this time to issue an official forecast.
It is possible a couple storms will develop ahead of the cold front. If they should develop, given the instability, they would quickly become strong to severe.
As the cold front moves through, the main tornado threat will shift to the Wisconsin/North IL area.
There will be damaging thunderstorms in those areas.
The threat should end by midnight, CDT.
A main factor will be sunshine, which gives out instability.
Right now, there is considerable weak cloud cover that went unpredicted by the NWS.
Overall, this system is very hard to forecast.
This final post will address the model views of this supposed squall line.
We will use the Significant Tornado Parameter images, because the tornado threat is the risk that diminished.
First, let us see the short range model RUC.
The RUC is very aggressive with this parameter, indicating a potential outbreak may occur in those areas. This wanes away from the SPC's outlooks.
I am not surprised, seeing as how the potential for a significant tornado outbreak collapsed in less than 12 hours.
Next up will be the NAM.
The NAM is much less intense with the risk, but still poses a threat over the Western Great Lakes. That said, it can be predicted a separate outbreak should occur up north.
Finally, we will see the old GFS run.
The GFS actually cuts out the outbreak up north and brings it down to the Lower Great Lakes region. It predicts no outbreak in Wisconsin. However, it does predict this image above.
After reviewing these images, there is still more to say.
-The NAM model is slower than the HPC agency.
-The GFS model is slower than the NAM model.
There are still differences to be worked out, and things will change. We will keep you updated as the day wears on.
Despite the threat being lowered, there is still concern over many areas of the US.
The SPC finally issued today's threat maps, and now we will look at them. First is the overall threat.
We see a moderate risk extending over much of the state of Wisconsin, as well as into Northeast Iowa and Southeast Minnesota. Extreme Northwest IL will also be in that threat.
A slight risk for severe storms exists over the Midwest, West Great Lakes, Michigan, Much of Missouri, Arkansas. Included is Northeast Texas and Southeast Oklahoma.
The first threat box to look at will be the risk for hail. As we can see, despite the lowered risk, an elevated risk of severe weather exists across the Western Great Lakes and Midwest. However, the highest risk is definitely inside Wisconsin and the moderate risk area. It is questionable whether hail risk alone caused the moderate risk issuance. This is due to the tornado threat, which we will look at next.
It would appear that the 15% risk of a tornado 25 miles within any given point warranted a moderate risk, as well as the 45% chance of hail.
Once again, an elevated risk exists in the Western Great Lakes as a whole.
The final image above is the high wind threat. That elevated risk area extends southward, indicating the expected squall line would have a risk of damaging winds everywhere it goes.
The third and final post on this diminishing threat will be posted in a link on this post.
Click here for Part 3.
The severe weather threat has greatly diminished in the way of tornado activity.
This is due to the now expected squall line, as opposed to individual supercells, which raise the tornado risk.
That said, the Storm Prediction Center has not issued weather maps yet, but below is today's real-time risk with radar.
We have obtained short range images from the HPC, and below are the forecasts from 7pm CDT, as well as 1am CDT of Monday's forecast.
This image shows the cold front creating a traditional squall line as a cooler air mass moves in over the area. This was not expected 24 hours ago. 24 hours ago, we were expecting supercells to form out ahead of the cold front, with a weak squall line come with the cold front.
By now, the cold front has hit a warm air mass and has created a defined squall line as seen in the picture. (SQLN means Squall Line)
The main thing needed to enforce this new thinking are the models, which will be issued in a later post.
The link will be posted here on this post as well. Click here for part 2.