Friday, February 24, 2012

Potential Severe Weather Event on February 28, 2012 (2/24/12)

I am closely watching the potential for some rare severe weather in the Midwest this upcoming Tuesday. Here's hour 114 of the 12z GFS.


Top left image: The top left image is 700mb wind speeds. The 700mb level is generally considered the area where 'jet streaks' (areas of strong winds within a jet stream) are found. Anyway, we see wind speeds of over to 70 knots, which equates to 80 MPH. 80 MPH is fairly strong for the 700mb level and can very well be conductive for severe weather. Seeing as this wind is flowing northeast, storms that form will be influenced and be moving northeast as well.

Top right image: The top right image is 300mb winds, which are the jet stream winds. In order for severe storms to form, there is usually a strong jet stream In this case, we have a jet stream of up to 130 knots present across a big swath of the Midwest, which equates to 150 MPH. 150 MPH is very strong and is nothing to mess with. To give you an idea of how strong it is, the jet stream present for the devastating April 27, 2011 tornado super outbreak was around 150 MPH.

Bottom left image: The bottom left image is 850mb winds. 850mb winds can detect how fast air flows, as the 850mb level is commonly watched for air temperatures at the surface. 850mb winds in this image show that wind speeds will be up to 70 knots+, which as shown above is over 80 MPH. Strong 850mb winds are usually pretty good for tornadic activity, so this will be something to watch.

Bottom right image: This is precipitation. In a couple images before this, the storms appear to form as a squall line turning into a cluster of storm cells. Multicelled storm clusters are typically the most dangerous and can be more conductive for tornadoes than squall lines. This will be something to closely watch.

We did pull up the best possible analogue picked out by the CIPS Analogue system, and here's what it has for severe weather reports from February 24, 2001.
As you can see, it was a pretty active day for severe weather, with 11 tornado reports, 99 wind reports and 59 hail reports. I can see this happening if it was moved north into the Midwest and Lower Great Lakes.

This could be a pretty serious event and will have to be watched.
Any questions can be asked below.
-Andrew

13 comments:

Anonymous said...

what do you mean by "rare"?

Joshua Steiner said...

You forgot to mention the strong veering of winds with height. Surface winds out of the south, 850 mb winds out of the south-southwest, winds out of the southwest at 750 mb, and westerly winds at 300 mb level. This could have significant forecast implifications for the development of tornadic supercells or large squall lines and derechos. The National Weather Service seems more worried about a high wind event with this storm rather than a severe weather event, as moisture and instability will be rather limited, as well as strong lift in the warm sector. I would be more worried about high wind warnings and an event similar to October 26, 2010 than a major severe weather event (even though October 26, 2010 had a major severe weather outbreak)

Aran said...

What states would be affected?

ERN WX said...

Thankfully severe weather events tend to under perform during winter. I am not writing anything off I just doubt that it will be the maximum it can. Joshua, i agree what you say about the lack of moisture and instability. Before I make any big conclusions, I want to monitor the cape levels. Andrew, I understand what you mean. This does need to be watched. People need a heads up. Great work. Btw I saw a 9+ inch snow report in the Chicago CWA. have you learned if it is true? I think it is likely. Hope you got a good amount of snow. Have you thought about doing a weather chat at some time? It would be neat. Thanks ERN WX.

Anonymous said...

The nine inch report was actually very very close to where I live. It is a bit high. I received about seven or eight inches.

Anonymous said...

How are ya doing Andrew!?! I was just looking at different areas around the Northeast with the NWS's "click-on-map" tool to look at the weather and I had to come on here to tell you that costal areas along MA, RI, (Block Island, Nantucket) areas are forecasted tropical storm condition weather (winds 50-60 mph+/rain) for tonight and tomorrow... and this wild winter continues...

- Reid

ERN WX said...

Thanks Anonymous for the confirmation. I know that spotters can over report snow totals. I have seen them measure snowdrifts and use that as their official measurement. They can be goofy fellows. But I am glad to say I am part of that community. Reid, I agree weird winter. I saw that the NWS does have tropical storm cond. possible for the islands. Many of us in the Northeast are experiencing high winds. Across portions of Maine HEAVY SNOW is falling!!!

ERN WX said...

Andrew, just a question. What do you think about doing a live chat at any time you would prefer. I would gladly participate in a wx chat on this blog. This decision is solely up to you. Thank you for everything you do. You run this blog very well and I appreciate it. I am not asking you to change anything. Sorry if I seem intrusive and prying. Thanks again for everything, ERN WX.

ERN WX said...

Andrew, I am very glad to know you are feeling better. Hope you, your family, and pet are doing fine. Keep up the wonderful work. Thanks as always, ERN WX.

Andrew said...

Anonymous: I'm afraid I don't know what you mean. If you can provide the sentence, I could try to explain it.

Joshua: I can only imagine the wind shear that could form from this. Seeing that it will be a strong system there ought to be sufficient moisture, but I haven't gotten a good look at the system in full. I agree that it will be a pretty good wind event if it comes to verify.

Aran: The midwest and Ohio Valley.

Eastern WX: I have heard reports of over 8 inches, but not confirmed 9 inches. Yes- CAPEs are the first step in identifying a severe weather event.

Reid: Wow! Thanks for sharing!

Eastern WX: You are not being intrusive at all. I have actually pondered the idea for a while now and I really do like the idea of having a chat box. I think there will be one soon, if I can get everything to work out.

Aran said...

Could my area be effected?

Aran said...

There were watches for tornadoes and severe thunderstorms on this date last year on this date in the midwest and mostly the Ohio valley according to NWS records.

Aran said...

This also occurred in 09 and 07.