2/11/09 FCST: IL, IN, OH, KY, TN, MS, AL

[Justin Bailey]

just a reminder to everyone...high shear events, such as what may potentially take place tuesday/wednesday, dont have to have a ton of instability to work with. just because the models arent predicting 2,000+J/Kg CAPE doesnt mean this will be a bust. If yall remember, the "Super Tuesday" outbrake on feb. 5th of last year never produced CAPE above 1,000 J/Kg in Tennessee, Kentucky, or Arkansas where 51 of the 59 tornado related deaths occured and where 6 of the 10 tornadoes rated EF3 or higher were produced. im not saying this system will be a 2nd coming of that horrific night by any means. im just saying that ample moisture, great wind shear, and very good helicities can overcome very weak instability.

 

[Benjamin Rock]

just because the models arent predicting 2,000+J/Kg CAPE doesnt mean this will be a bust. If yall remember, the "Super Tuesday" outbrake on feb. 5th of last year never produced CAPE above 1,000 J/Kg in Tennessee, Kentucky, or Arkansas where 51 of the 59 tornado related deaths occured and where 6 of the 10 tornadoes rated EF3 or higher were produced. im not saying this system will be a 2nd coming of that horrific night by any means. im just saying that ample moisture, great wind shear, and very good helicities can overcome very weak instability.

I have to agree. I think it's going to be a brief, but strong squall event.I Hope it doesnt turn out like last year but I wouldnt object either..

 

[Justin Bailey]

just thought i'd go ahead and get this one started. looking like 2/10 and 2/11 could be quite active severe wx events. looking to me like it'll mostly be a linear event on wednesday...but with the kind of shear the 12z GFS is forcasting there could be some imbedded sups in the line and if anything could develop ahead of the line and remain discrete it could get interesting pretty quick. im off wednesday, but im goin to wait til it gets closer to decide if im goin or not. i dont really like chasing rain-wrapped tornadoes from sups imbedded in a squall line in this hilly terrain that most of KY and TN is.

 

[A Newcomb]

Im thinking..at least for the Indiana part...we'll probably have our typical Feburary system. Thundershowers may start off early in western Indiana, before eventually coming together to form a pretty decent looking line....and wouldn't be suprised if there was an isolated embedded tornado....probably taking place late in the afternoon...not really a chase event at all...but still something worth watching. It's kind of far out right now for me to be really pointing much out at my knowledge level of course...

 

[Andrew Pritchard]

The new GFS run has really sped the system up, so aside from some overnight (the night before) or early morning rumbles of thunder with the passing of the big mess of precip I don't see much to get excited over unless the models flop back.

 

[Danny Neal]

http://northernilstormchaser.blogspot.com/2009/02/21109-potential-for-severe-storms-in.html - Threw my thoughts about WED. Not looking for anything significant but a good pre-season equipment check intercept of a fast moving (possibly sub-severe) squall line will end my SDS temporarily.

 

[Andrew Pritchard]

Now depends on which model you want to watch at this point. The GFS has sped things up, but now that this event is within the NAM time range it's showing a considerably favorable setup for this time of the year.

It shows considerable convective activity overnight across the area with a strong dry punch swinging into central Illinois by 18Z with sbcape values AOB 1500 j/kg by 21Z. Not sure if this will remain the case, but with a synoptic system as shown this would be more than enough for supercell structures and potential tornadoes.

Time will tell, as there are huge discrepancies in the models. The new run is out in a couple hours but at of the 12Z runs GFS says early morning rain and the system is in the Great Lakes by late morning. NAM says watch out around the Interstate 70 corridor in Illinois and Indiana.

My SDS goggles are on, but my instincts at this point are leading me to believe the NAM solution for now. Not necessarily meaning that I believe in a tornadic event across the area but given past trends the GFS often will hit timing fairly well at the extended time frame, and then speed things up around 72-96 hours before slowly falling back inline with earlier runs and other model solutions. Time will tell, but I wouldn't be surprised to see the system slow back down a bit on the GFS. Whether or not this brings severe weather to the area we shall see, but at least we'll see warm air in the area for a few more hours on Wednesday than if the low swings out of here quickly.

 

[Danny Neal]

The northern play is catching my attention on the lastest NAM run. Strong heating and good moisture (for February standards) coupled with instability of around 1500 j/kg and decent shear could make for a very interesting weather situation along the IL/IN border by mid afternoon. Again as I said before, I'm (or anyone else for that matter) not forecasting an outbreak of severe weather here, but it looks a little bit more likely to have a low topped minimal tornado/wind damage threat on our hands. Again the GFS is quicker and shows a totally different picture. Like Andrew I am going to stick with the NAM and hopes it evens itself out.

As always more in depth here every time a new model run comes out and I have free time....... http://northernilstormchaser.blogspot.com/2009/02/update-21109-svr-wx-potential.html

 

[Danny Neal]

Blah, the NAM has sped up like GFS has and now looks like the front will push through by noon. Basically cancels out any legit (if there ever was one) tornado threat. Like in my first post, I believe it may be a marginal severe wind morning-mid afternoon event. Of course this is just model to model analysis so things can change.

 

[A Newcomb]

Well...the models show less favorable things for the West Indy Metro area now. Of course, Things will shift back and forth plenty between now and when I get out of school Wednesday. Last winter...The 1/29/08 event didn't really seem like much until it was on top of me.

Instability looks like the biggest problem, of course, because it is early Feb, and it will probably overcast all night and day, with the mornings rain showers lingering and holding things down. The LLJ will be rather strong at 70kts. Looks like NW parts of the IND CWA could see 2.5"+ rain locally, rest of us I'm guessing around an inch. Tomorrow will be a breezy day, and Wednesday will be rather windy as the system approaches.

 

[david diehl]

looking at the latest nam, I am going to make a target between Fort Wayne, IN, and Van Wert Ohio.
Looking at Bufkit soundings showing Helicity at 400, however the Cape is only 550, not very high, however it is Feburary, and Feburary has fooled us before.
This target area might change for me a bit, but I am not looking to go very far out this eairly.

 

[beaudodson]

Increasing concern in this region about gradient winds on Wednesday (see NAM with 850 wind speeds of 70-80 knots over the area Wednesday). GFS would indicate gradient winds of greater than 50 mph over a very large area - MO/IL/IN/KY/OH. This comes after one of the worst ice storms in recent history for this area. Lot of tree limbs, power poles, and trees are broken and or leaning. These gradient winds would certainly cause problems for emergency management and power companies.

Looks like a fast moving squall line should form Tuesday night over portions of Arkansas and race northeast and east at speeds of 60+ mph. NAM shows storm motions of 70+ mph. Defin not chase friendly.

The biggest question remains - can some supercells form ahead of the squall line on Tuesday night and spread into Northeast AR and West TN (an area prone to early morning tornadoes).

At the very least I believe the KPAH region will see a squall line with widespread wind gusts over 50 mph - most likely moving through West KY between 4 AM and 10 AM. Then the gradient winds could cause problems during the late morning hours and into the afternoon over most of our counties. Models show the low deepening fairly rapidly over South Missouri into Illinois (see GFS at 984 mb as it moves into Indiana - Wednesday morning).

Not a big fan of predicting tornado activity in this region during the 2 AM to 10 AM time period. We rarely see them. Areas a tad south of here (KPAH), though, seem to be a magnet for early AM tornadoes. Would be concerned over portions of East AR into Tennessee.

If the NAM and GFS are to be believed then a ribbon of higher instability should remain or form after the line moves through West KY. Enhancing the tornado threat over portions of Indiana/Ohio/Kentucky. Finer mesoscale details of this event are most likely not going to be figured out until late Tuesday night and Wednesday morning. I would throw my dart towards a square marked by Evansville, Indiana to Indianapolis, Indiana back to Louisville, Kentucky then down to Hopkinsville, Kentucky. Tough call though on squall line vs a few discreet cells that might form. Embedded spin ups with the squall line would be a typical February event for this region.

 

[Bob Hartig]

It's February and I'm desperate. I'll be delighted to see a squall line, and hopefully to get some lightning photos. Looking at the 18Z run, I don't see that the NAM has sped up. But maybe I missed a previous run, and this run has slowed it down again? Regardless, I have no high expectations of this system, and besides, as has already been mentioned, it's moving like a meteor. Still, if that crazy LLJ can transport 55+ Tds a bit farther north than the models indicate, I'll have some hopes for the warm front. As for any kind of CAPE, NAM-WRF forecast sounding shows 806 j/kg SB and 142 3km ML around Kokomo by 21Z, the best read I've found for Indiana.

 

[Chip Redmond]

Looking for a good target tomorrow and have decided if we go, we will shoot for the Oxford, OH area. There will be more things limiting severe weather tomorrow than things promoting the development of storms. I see it having a hard time getting rid of the clouds and rain by mid-afternoon. It does appear that the storms will go linear, its just a matter of when and if enough instability will be available ahead of the line to help storms ahead of it. We will be heading out to late to go south very far so thats what we have to hope for. Capes barely reaching 500j/kg mu and sf, along with LI's of only -1 to -2. The dewpoints look ok, as they will be 52-54 F which could really help things along. I'm biting my lip bigtime. Guess we will have to just sit back and see what the next few runs do. Sure want to get out there bad..

Chip

 

[Andrew Pritchard]

My forecast for tomorrow:

http://wxcaster4.com/nam/CONUS_ETA_0-3KM_CAPE_18HR.gif