Analysis – 1155 am

| April 26, 2011 @ 11:59 am | 167 Replies


The morning model runs are in now, and it still looks like a significant severe weather outbreak will occur over the SE US today and tomorrow.  I will primarily talk about Alabama here, but this is a large-scale event.

A line of showers is moving through central Alabama now, with no severe weather.  It will move on into east Alabama, and most of us, especially west of I-65, will get sunshine this afternoon.  With dewpoints in the 60s, and temperatures rising into the lower 80s from I-65 west, the air will become unstable.  There will be a small cap, but some storms will likely break the cap and become severe.  The main threat will be damaging winds and large hail, since the dynamics and wind shear are north and west of us this afternoon.

Things will start to change overnight and tomorrow, as the main upper-level system starts to move, bringing the cold front and upper dynamics closer.  By tomorrow morning, a cold front will be from near Indianapolis to Little Rock.  As a large upper-level disturbance and upper-level jet move over the front, a new low pressure area will develop to our west and move along the front.  The models disagree on the timing of this low, one moving it through Memphis early morning then into KY and OH, the other not until afternoon.  That will be one key factor tomorrow, because the highest storm-relative helicity values will be closer to the surface low and low-level jet, making storm rotation more vigorous.

Taking the average of the two, the largest storm-relative helicity, a very high 400 or more m2/s2, will be centered from northern MS into NW Alabama and middle TN by noon tomorrow.  The thing that makes this event more worrisome is that we’re pretty deep into Spring now, with strong sunshine and a warmer Gulf.  Dewpoints tomorrow will rise to near 70 degrees, and assuming we get sunshine, temperatures will rise into the 80s.  With cold upper-level temperatures, this will cause very unstable air.  CAPE will range from 2,000 to 4,000 J/kg over most of Alabama by early afternoon. 

With that combination of wind shear and instability, severe storms will develop, and in the areas of strongest shear, the storms will rotate vigorously and produce tornadoes.  Pinpointing the exact areas that will be the most vulnerable is still tough at this time, since it will depend some on where clouds linger longer in the morning, where today’s storms leave boundaries, etc.  But, the stage will be set most favorably for tornadoes over the northwest half of Alabama this time (it was the south half on April 15).  We are talking about areas northwest of a line from Demopolis to Clanton to Anniston to Gadsden. 

A gauge of the strongest combination of instability (warm, humid air) and wind shear is the STP (significant tornado parameter).  Anything above 1 is supportive of tornadoes, and above 3 indicates a serious threat for large tornadoes.  Here is the model-predicted STP plot for tomorrow at 1 pm:

This is a serious situation.  Just because there have been a lot of severe weather outbreaks this year (similar to 1998), and you have heard a lot of tornado watches and warnings, don’t get complacent.  Tornadoes were all over the place just south of BHM Metro two Fridays ago, and this time it could include TCL, BHM, ANB, Cullman, GAD, HSV, and MSL.  Have a plan for what you will do in a tornado warning at work, at home, wherever you will be.  The schools mainly have tornado plans in place.  Keep an eye on the weather carefully through Wednesday night.

At work, in large buildings, interior hallways on the lowest floors and stairways are often best.  Stay away from windows and outside doors.  In smaller offices, go to the lowest floor, in an interior room, away from windows and doors. 

In the home, the underground part of a basement is best, but get under a work bench, heavy table, etc.  Stay away from garage doors!  They are a weak point on your house in winds.  If you don’t have a basement, go to the lowest floor, interior room or hallway, away from windows, doors, and outside walls.  Hall closets, if on interior walls, are good.  Protect your head.  Put batting helmets, football helmets, bicycle helmets on the kids.  Stay low.  Falling trees can come through the roof, but often stop before coming all the way through.

In mobile homes, leave.  All (or almost all) of the fatalities in April 15 tornadoes in Alabama were in mobile homes.  If an outbreak starts, try to go ahead and go to a sturdy building ahead of time and wait it out.  You are better off in a ditch than in a mobile home.

There is no reason to panic.  Just have a plan ready, follow the weather, and if a warning is issued, execute your plan. 

Another update around 11 pm CDT.


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  1. Will says:

    Is there a way to report abuse of this blog and comments?
    I think yoyo’s comment is offensive and he or it should be banned from the page.

  2. avon says:

    @snowpimp…..Just wanted to let you know that you may not live in or around Tuscaloosa but there are a LOT of people that do. I for one live in between Tuscaloosa and Birmingham. I am very grateful for the coverage on the television and radio. The coverage alerted us to a very dangerous situation and allowed me to get myself and my family to a safe place. I am sorry that you feel your television shows are more important than keeping people safe. I pray that you are never caught off guard by a tornado or severe storm that turns your life upside down. @ABC33/40 weather team….Thanks for everything you do. It is GREATLY appreciated.

  3. paul says:

    its a joke guys. trust me!!! my best friend was killed when a tornado struck his mobile home when i was 9 years old. i have been obsessed with weather since. i’m just baffled at how some people are so ignorant towards weather. it only takes one time for you to be dead and people need to realize that before it’s too late

  4. StevenG says:

    Do these people not “believe” in tornadoes? I guess they only think they pick up little farmhouses and slam them down on mean old witches!

    Come on people… Weather is real….and it may not happed to most of us tomorrow…but will eventually at some point.

  5. PRW says:

    Jeff, Paul’s comment wasn’t that cruel and it speaks to the only problem that I occasionally have with posts here in situations like this … folks carry the “I’ve got to be my brother’s keeper” attitude too far to the point where it sounds like nagging, to the point where it seems like they think if they say it often enough, strongly enough, people will take this stuff seriously and take precautions and, potentially, their lives will be saved.

    There are people out there who know full well what has happened in the past, and what might happen tomorrow, and they do not care. No amount of strong language from James and his folks, no amount of yelling and hollering from posters here, is going to make them care.

    At some point, you have to let those people make their decisions, understanding fully well that they and their family members may suffer the consequences of their decisions (and this does trouble me, the notion of children suffering for the “sins” of their parents), and move on. God gave us all free will, and the laws of this country reinforce the ability to exercise that free will, and you can’t force people to care.

  6. paul says:

    @PRW that’s exactly my point. the last line of my comment was a joke but what you have hit on is exactly what i want people to realize. i personally LOVE james spann and his dedication to this weather blog and abc3340. i love the wall to wall tv coverage when their is a tornado warning in his viewing area. james spann and his weather team are on this earth to notify the people who want to be notified of the situation at hand. as bad as it may be, some people in this world don’t want to be helped and there is nothing anyone in this world can do about it. again, thank you james and the weather team for EVERYTHING you do.

  7. Elle says:

    Weather is real. It can be beautiful or destructive. I follow James Spann on Twitter and FB. Thank you and the team for all you do.

  8. smiley says:

    i just dont know why people get on here to say crap like its gonna be a bust or whatever.. are they not wanting it to be a bust or something?? The chances of a tornado and especially a violent tornado hitting your home is slim, but it can happen…I used to never think tornadoes were that big of a deal until I was in high school and we had two F3 tornadoes in one night…one took out the elementry school at carbon hill and the other crossed hwy 5 not even a mile from my church and they were having get together in the family life center after church…This tornado was an F3 and was 3/4 mile wide when it crossed hwy5 and missed the church by maybe a half a mile…it couldnt been worse then the situation already was…. I take storms more seriously now and will continue to.. If you dont agree with the abc 33/40 crew then why in the world get on here…thats all i got to say about it, if you want to get on here and mouth off and start stuff then thats your stupidity and showing how immature you are.

  9. Seashell says:

    To everyone that thinks it won’t happen or that the crew is doing it for ratings. I remember the outbreak from 1974 and again when my neighbor was killed in the 80’s. If you don’t want to keep up with the weather or if you don’t think it’s serious then put your tv on a cable channel or pop in a DVD. Maybe the fact that our death toll isn’t as bad as some states can be attributed to the way James and the crew (and other channels) go live when there are tornado warnings.

  10. VonnieDee says:

    Avon, I think I know you. You live between Tuscaloosa & B’ham. Do you have a cousin with a similar name to “Avon”?

  11. Zachary in Blackwater Macedonia says:

    Paul and PRW, YES. EXACTLY. THANK YOU. While it would be great if tornadoes caused no deaths or damage, they do, and if people refuse to take warnings seriously (and ignorance is NOT a valid defense, as they have all the warning they need just one click away, etc) then I refuse to feel empathy for them when they are struck by a tornado. Sorry but that’s just the way it is… people who consciously laugh off tornado warnings, complain about meteorologists just trying to do their job as best they can, and stubbornly ignore the danger are not worth worrying about… they chose their fate. We should spend our time trying to get the warning to people who may not actually realise what’s coming their way (e.g., elderly, newcomers to the state, people in mobile homes, public gatherings and events, etc.) instead of trying to win over the complacent hardheads. Let the fools worry about their own selves.

  12. Zachary in Blackwater Macedonia says:

    @smiley: Oh hey, I might know you; would that church be Edgil Grove?

  13. smiley says:

    yep edgil grove is correct lol….

  14. Paris says:

    Thank you guys for having this blog and being so dedicated to it. I live in North Alabama and I really wish there were something similar for our area. I don’t have cable and so I get more information from this blog than any of our local mets up here.

  15. ifr4 says:

    The thing that gets me is the complete idiocy of statements like “tornadoes don’t hit Jefferson county” (tell that one to someone in Oak Grove). But I had to laugh @Auburnmom’s “I don’t think anything will happen because it never does.” Well, what a highly intelligent scientific deduction! Personally, as an AU alum, I’m offended that someone with a son or daughter at AU would make such an idiotic statement. But I digress.

    For the trolls on board, Dr. Tim, James and crew aren’t the only ones calling for a tornado outbreak. The Storm Prediction Center in Norman, OK is leading the way. They have us under a moderate risk for tomorrow and have hinted that it might be elevated to a high risk. And since I’m sure none of the trolls are familiar with the SPC, I’ll just say that they don’t throw moderate and high risks out everyday; those categories are reserved strictly for potential life threatening events so people will take them seriously.

    But as Ron White says, “you can’t fix stupid.”

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