2/10/09 FCST: TX/OK/AR/MO/KS

[Michael O'Keeffe]

I thought I'd start a thread for Tuesday which could be a good day according to the 12z GFS. It appears that 1000 j/kg of CAPE will be in place across C TX into E OK with great shear to boot and dews approaching 60F. As of right now I'll bet on this day being the big day out of the week of potentially active weather.

 

[Chad Cowan]

Tuesday is going to be THE day for us Plains folks who don't want to chase in the sticks on Wednesday (which could turn out to be a huge day). I'm hoping the GFS trends towards the slower Euro solution in keeping the storms Tuesday in chaseable territory west of MO and AR. We should have substantial moisture in place by February standards thanks to the shortwave parade bringing multiple days of strong southerly flow.

 

[David Drummond]

Hey Dick! Are you planning on heading out to W. Texas Sunday? I am going to wait and see what the outlooks look like tomorrow before I decide. Looks like a possibility of a few tornadoes before everything merges into a squall line. If I do, I will be heading out around 2-3 am on Sunday and I'll be in Amarillo around noon or 1 p.m. I hope to chase from 4 pm through 7pm and then call it quits and head home from there. Tuesday and Wednesday look like the best days to go. I also agree with your point in your post, i.e. cold core set up. Of course I will be chasing in E. Kansas if I go on that particular day. Good luck to you on your trip!!!

You might want to read the LBB AFDs before making any long treks out here or you are likely to be disappointed.

Early cloudiness and possibly drizzle/rain is expected. This will help keep svr potential down. Not to mention the squall line should be moving at a decent clip. Things could change to improve the situation by then, but I don't think it's likely. Most likely a good rain event for the western part of Texas with some svr wind and maybe a few low end hail reports thrown in for good measure.

 

[Matt Gingery]

You might want to read the LBB AFDs before making any long treks out here or you are likely to be disappointed.

Early cloudiness and possibly drizzle/rain is expected. This will help keep svr potential down. Not to mention the squall line should be moving at a decent clip. Things could change to improve the situation by then, but I don't think it's likely. Most likely a good rain event for the western part of Texas with some svr wind and maybe a few low end hail reports thrown in for good measure.

Yeah, that is sort of what I am waiting on for tomorrow. There are alot of question marks on what will happen. I am not certain on going. At the beginning of the week I was more intent on going, but now it looks as if my best play will be Mon/Tuesday closer to home. Trust me, the last thing I want to do is drive 10 hrs for a marginal event. Word is there will be enough UA forcing and vertical shear to aid in the development of low top supercells. The lates discussions are leaning towards what you spoke of, and it doesn't look like it is worth it. However, I also am hoping this doesn't all just come together at once. I think this first wave is going to open the doors for the next wave on MON/TUE. We will see. Thanks for the input though. . .

 

[Michael O'Keeffe]

Based off of the new 12z GFS Tuesday is really looking like a decent chase day across NW/NC Texas down into WC Texas. CAPE values around 1000 j/kg+ with great back surface winds and temps in the 70s, and dews in the mid-upper 50s along a nice sharp dryline. The upper level winds are very nice with a strong SW flow at 500 mb and a 40 knt. southerly LLJ. With that said there will be GREAT directional and low level shear in place across the region, so I am beginning to contemplate a possible chase this day as it looks to be the best day.

Look at the simulated composite radar courtesy of Twisterdata.com
http://www.twisterdata.com/index.php?prog=forecast&model=NAM&grid=221&model_yyyy=2009&model_mm=02&model_dd=07&model_init_hh=12&fhour=84&parameter=CREF&level=SURFACE&unit=none&maximize=n&mode=singlemap&sounding=n&output=image

 

[Chris Wilburn]

I just glanced at the NAM and agree with what Michael has to say. Mid to upper 50's are forecasted in NW Texas and points south from there. Points from Wichita Falls and south of there may be promising. Anyway nice backed surface winds with a 998mb low in the OK panhandle/SE Colorado region. 850mb (40-50kts) winds due south and 500mb (60-70 kts) winds southwest are fairly nice in regards to both directional and speed shear. I agree this is the best day in regards to chasing and I have been keeping an eye on this day for a couple days now. I haven't looked at this mornings GFS yet but it seems fairly similar to the NAM from what Michael mentions in his forecast above. CAPE near 1,500 and nice helicity values are in place as well. If the models continue to trend towards this it should be a really nice opportunity to chase.

 

[Shane Adams]

IMO Texas is a bust for Tuesday. The dryline is through there and well east by 0z. Even ahead of the DL east of I-35, the surface winds are southwest, which promotes a squall line. The only play for disctrete/tornadic storms (IMO) on Tuesday looks to be E/NE Oklahoma into NW AR/SW MO. Surface backing is excellent in this area, underneath a 60-80kt LLJ streak. On top of that you have 500s from the southwest...these could be a bit more westerly but they'll do.....and nice venelation with fast anvil-level shear as well. Moisture looks to be in place, and although not spectacular, probably adequate for early February. Linear forcing will probably rule this event eventually, but IMO that's the only area that has a shot at tornadic sups on Tues.

 

[Michael O'Keeffe]

IMO Texas is a bust for Tuesday. The dryline is through there and well east by 0z. Even ahead of the DL east of I-35, the surface winds are southwest, which promotes a squall line. The only play for disctrete/tornadic storms (IMO) on Tuesday looks to be E/NE Oklahoma into NW AR/SW MO. Surface backing is excellent in this area, underneath a 60-80kt LLJ streak. On top of that you have 500s from the southwest...these could be a bit more westerly but they'll do.....and nice venelation with fast anvil-level shear as well. Moisture looks to be in place, and although not spectacular, probably adequate for early February. Linear forcing will probably rule this event eventually, but IMO that's the only area that has a shot at tornadic sups on Tues.

Shane, I think you may be talking about last night's GFS model which I agree looked pathetic, but the 12z NAM looks much better.

http://www.rap.ucar.edu/weather/model/index.php?model=eta

 

[Shane Adams]

Shane, I think you may be talking about last night's GFS model which I agree looked pathetic, but the 12z NAM looks much better.

http://www.rap.ucar.edu/weather/model/index.php?model=eta

I use CoD, and for whatever reason, they are always 1-2 hours behind every other source with their updates. Looks like I posted during one of those "layover" windows waiting for an update...because I don't even have Tuesday yet on the NAM

 

[Mike Johnston]

Comparing apples to apples now (12z NAM v. 12z GFS), there remains some difference in the overall pattern. The GFS indicates a just bit of a positive tilt w/ the 500mb trough, while the NAM depicts close to a neutral tilt. Also, NAM has the surface low hanging back over extreme SE CO, and deeper (996mb v. 999 w/the GFS); as a result much more pronounced backing of the surface winds over central OK and north central TX.

If we go w/ the NAM for the moment and check out some of the derivative severe parameters (via Earl Barker's site), north central Texas - and perhaps even up to the OKC area - look quite impressive indeed w/ the STP, Craven Sig Sev, etc.

At this point, I would say Tuesday definitely bears close monitoring for chasers in the area.

 

[Erik Burns]

Based on the NAM Tuesday now looks quite impressive to me given the time of year. This will be the day, If the this model run verifies we will likely see a few tornadoes. Excellent turning with height, 400-500 m2/s2 helicity. Strong surface winds and decent cape to boot. Best area seems to be NW, N and Central TX region.. Also it will be a short drive for me since I live near Dallas.

 

[Chris Lott]

Based on the NAM Tuesday now looks quite impressive to me given the time of year. This will be the day, If the this model run verifies we will likely see a few tornadoes. Excellent turning with height, 400-500 m2/s2 helicity. Strong surface winds and decent cape to boot. Best area seems to be NW, N and Central TX region.. Also it will be a short drive for me since I live near Dallas.

I agree Erik, I might not have to drive far at all for this one. My only concern is the possible cloud cover over the area limiting instability. Shear won't be a problem at all, and hopefully that 1000-1500 j/kg CAPE verifies.

 

[Danny Neal]

Decent CAPE in some spots spiking at 1500, good shear, and do-able helicities (per the NAM) make for an interesting day ahead on Tuesday. I can see discrete supercells developing if cloud cover doesn't hold down the instability. (NAM isn't predicting any precip that morning on the last run) So we will see if it verifies. I kind of like the area of the Red River down to Waco and west to Abilene for a chance of supercells Tuesday afternoon and evening. Of course thats just based on the latest run and everything is subject to change. Even the GFS has been coming around on this event IMO. 3 more days. I likely wont chase this from Chicago, but I lived in OKC or NOLA it would be tempting. It really isn't a bad chase set up for FEB.


http://northernilstormchaser.blogspot.com/2009/02/february-10th-severe-weather.html - same text just threw in a few parameters.

 

[Chris Lott]

Where does everyone intend on chasing? I have classes all day, but if it is feasable, I would maybe head into the E. half of Oklahoma. . .

It tends on which solution verifies, the slower NAM or faster GFS. Hopefully the GFS will slow down as well, and if so I will probably be roaming I-35 from McLennan,Hill,Johnson and Tarrant counties and to the west. Basically from Waco up to Ft. Worth and no further west than probably Stephenville.

 

[Chris C Sanner]

If I had to base a forecast on tonight's NAM run, I'd probably be thinking about my old stomping grounds in SC Oklahoma. The winds are more backed there which leads to a pocket of higher helicities. Cape is 1000ish...but the shear makes for an ok setup. The terrain in SC Oklahoma isn't favorable...but it's far from horrific as well.

However, there is A LOT still not resolved. How much rain and where Sunday/Monday? Any stratus? You know the typical caveats now, and with one system to pass first, I'm not ready to really start locking down on anything for this day just yet.

Put a forecast up on my blog at:

http://www.supercellhunting.com/?p=85