1/7/08 FCST: IA, IL, WI, MN, TX, OK, MO, LA, AR

[Chris Wilburn]

I agree that as things stand now we should have our first tornado watch box of 2008. I have mostly been concentrating on NE OK and SE KS which is the area I am from. I did quickly glance at areas that you mentioned Karen and I agree that things could get interesting in the areas you mentioned (Southern Missouri, Arkansas and NE TX). Being that it gets dark early during the winter and the bad chase terrain in these areas I will stay away for sure, however these areas do look fairly impressive, esp. NE TX into Arkansas in the evening as the LLJ gets cranked up. Instability and moisture will also be greater in this area as 1,500 CAPE is projected in this area by 00z. It will be a wild night for sure for these areas. As far as my area of NE OK and SE KS things don't look quite as good, but should warrant some severe storms for sure with heavy rains and winds reaching severe limits. Supercells do appear possible, esp. early in the period before the cold front crashes through. CAPE up here is only forecasted to be around 500-1,000 which will be enough for severe storms, but not sure about tornado potential as moisture will not be quite as high as other areas. Helicity values are very impressive and storm will be moving fairly quickly which seems to be the usual with these early year systems. It will be interesting to see how things play out for sure and I will just be satisfied with a t-storm watch box and some good old lightning and wind gusts. It sure is nice to have this type of pattern back even though it will only be brief being that it is still early January but I will take it for sure.

 

[Shane Adams]

Monday will be one of those days where there will be a tornado (or a few) worthy of the Storms Of 2008, but will you be in the right spot at the right time as it rockets by at 60mph??? I've been thinking Greenville, TX for two days now.

 

[Joel Wright]

Hmm. My main concern is daylight with this one. The models seem to indicate the vast majority of the storms lighting up after dark. There should still be some action prior to sunset, but just how much is questionable. Northeast TX, much of AR, and far eastern OK look pretty good at this point if convection can get established in the daylight hours.

Further north across IL things look pretty good too, but again the question becomes how much of it will fire before dark. CAPE and helicity look pretty good for this early in the season, that's for sure. Moisture definitely won't be a problem. The WRF shows more of a backed windfield at the surface, particularly further north closer to the surface low track. The NAM and the GEM also indicate a slightly quicker scenario as well, as compared to the GFS.

I have a job interview monday morning so I wouldn't be able to go too far. But if things look decent enough I will probably try to head down to central IL in the afternoon hoping things fire early enough.

 

[Chris Wilburn]

Monday will be one of those days where there will be a tornado (or a few) worthy of the Storms Of 2008, but will you be in the right spot at the right time as it rockets by at 60mph??? I've been thinking Greenville, TX for two days now.

Yeah talk about timing being everything lol. So you don't think chasing 50mph storms at dark in the jungle is very promising huh Those conditions are not ones that I would like to repeat ever again. Just looked at a couple of things and 40kts seems to be about normal for Monday. Like Joel said after dark is when the fun should really start, which isn't going out on a limb since dark is what 5:30 or so. Oh well it is a backyard chase for me so might as well have some fun with it.

 

[Brandon Sullivan]

Well, a relief to see models continuing the trend of getting some strong instability over IL. SPC stretched 5% to include almost all of IL, with the south half in Slight Risk. DVN mentions main threat as hail, which co insides with SPC.. Both NAM/GFS shaky on timing, but with the dynamics and instability present, will likely see some severe wx even if under the cover of night. Agree with previous posters regarding Tor Watch 1 being issued..

Thanks for re assuring me Karen!

 

[Brian Emfinger]

I agree we will see tornado watch #1. Its looks like the models have been fairly consistent in having CAPE values of 1000 in Eastern Oklahoma and I do think 1000 is enough to deal with the strong winds. I would be and will be worried if we end up having only 500 CAPE. As it stands currently there will likely be scattered showers and storms before sunset but most of the strong/severe storms will probably hold off to around and just after sunset. I would go and sit on the northern side of the red river if the storms fired at least a couple hours before sunset but with the likelihood they won't and as Shane mentioned "will you be in the right spot at the right time as it rockets by at 60mph?" so I don't want to be right on these things when they develop. Hopefully they will be moving more like 40-45mph. I think I will probably target Mena, AR at least initially. I probably should just stay there but I will probably end up being too impatient and head further S-SE only to lose the storms and have Mena be 15 minutes away and get hit.

edit: Looking at things much closer now and I am happy to see that Mena has 135 0-3KM cape at 3Z (75 at 0z). Given the strong wind fields thats a good sign to have that much LL Cape. The hodograph looks ok from 0z - 3z although I could do without the anticyclonic twist that shows at 3z. Further north (Fort Smith) they are more straight lined.

 

[Angie Norris]

I'm looking at the Arkalatex area for tomorrow...best CAPE, good moisture, great shear and best of all, slightly backing winds. Unfortunately, it's looking like it's all going to be after dark and moving about 50mph. Right now I think I'd pick DeQueen, AR as my target, since the road options look pretty good there.
IL is definitely worth keeping an eye on as well...models seem to be pretty insistant on that little spot of instabilty in the middle of the state. AND being closer to the warm front, all is possible.

 

[Tony Lyza]

Well, let's try this a third time (whatever I do, I cannot press alt-1).

I am seriously contemplating a chase across northern Illinois tomorrow afternoon. For several runs in succession, both the GFS and NAM have painted a rather interesting warm-frontal scenario across the region. For example, here is the NAM forecast sounding for Peoria, IL, at 21z Monday.

(Mods, if that is too big, please make it a link.)

Things of note on this forecast sounding:
1) No near-sfc inversion.
2) 0-1km SRH of 265.5m^2s^-2.
3) CAPE at 3km of 188.7J/kg.
4) MLCAPE of 966.4J/kg.
5) LI of -3.8.
6) STP of 3.4.
7) LCL of 690.9m.

Other things to keep in mind:
1) The models, which are normally terrible with WAA, have been pathetic so far with this system. In TX and LA yesterday, the models undercut the temps by a good 10-15 degrees. Even up here, the 12z runs are off a good 5-7 degrees on the dewpoint in just 6h time.

2) For northern Illinois, the warm frontal positioning is key to who gets it and who doesn't. With that said, there is a very nice snowpack across WI and MI that is ready to fight advancement of the warm front. With such a strong WAA regime underway, I could forsee the slowing of the front in northern Illinois, which could lead to moisture pooling between the I-80 and I-72 corridors and increased instability across the region.

All in all, the only thing keeping me from a definite chase is school until 2 PM. After that, I've got about 3h to see what I can see. I will not chase this system at night because I'm not fond of rockets I can't see.

 

[Joel Wright]

Look at all the moisture already in place (relatively speaking of course). Dewpoints are already over 50 from northern IL all the way down to the gulf, with 24+hrs still to go from the event. I agree with Tony about potential moisture pooling south of the warm front. There is a lot of snow that has melted and is still melting near where this boundary will setup, which will only add to the pooling. Sort of like how the corn in the summer evapotranspirates copius amounts of moisture into the air.

It's looking like the low will move up through eastern IA by later afternoon. This should keep the surface winds slightly backed over the northern half of IL. With temperatures at or over 60, and dewpoints nearing 60 I would think there could be some decent storms.

 

[Joel Wright]

Latest Day 2 just came out, and keeps the severe threat pretty far south. I disagree with the slight not being extended further north. With MLCAPE between 500-750 by later afternoon, I find it hard to believe there won't be some organized severe weather further north. Winds will increase with height fairly nicely further north as well.

Unless the models change any I would expect that slight to be extended further north on future outlooks...

 

[Dick McGowan]

I agree with Tony and Joel with the Illinois target. That's where I would be if I were chasing this system tomorrow. It doesn't look all of that promising, but I think there could be a brief window for a few tornadoes close to the surface low where 0-3 km CAPE will be sufficient for low-topped supercells. 500 temps should be cool enough at -16 - -18 with steep low level lapse rates beneath them. My only concern would be the clearing that may not take place and the surface winds don't back more with the already unidirectional 500/850's. Further south into the MO/AR/TX region, I think things will evolve into a fast moving squall line/ broken line segments, which wouldn't be enjoyable in that terrain and with such fast storm motions, but I'm sure there will be a lot of tornado warnings issued tomorrow. These speed shear storms seem to be always low contrast, high precipitation, and difficult to chase.

If I could chase, I'd be in NE MO/ WC IL/ SE IA by noon and would adjust from there and hope the clouds break, as storms could fire by 2 p.m or earlier.

http://wxcaster4.com/nam/CONUS_ETA_0-3KM_CAPE_30HR.gif

 

[Michael O'Keeffe]

I'm not sure if anyone has looked at the latest Tulsa HWO, but it said storms will initiate by late afternoon east of the dryline. I didn't know a dryline was going to be in place. That makes this more interesting I think.

Anyway between 00z-06z NE OK is looking pretty good for some severe weather. Widespread CAPE values of 1000-1500 j/kg looks to be in store, helicity is decent, and the wind fields look great. I think we will initially see supercells congealing into a broken squall line of some sort that races east into Arkansas overnight Monday. As for the tornado threat it looks like we could see a few, but no outbreak or anything.

 

[David Wolfson]

Alas, I wish there were more encouragement in the DEV2 RUC. The (decaying) shortwave impulse indeed has kicked off a surface low (995Mb or so around 21Z near MSP) but it's too separated from the thermodynamic energy to crank the sort of advective focus you want to see in January. The synoptic features and timing aren't that different from when this thread was started, but are a pale shadow of their progged intensity, with two days of brisk gulf flow into the target region, a closed mid-level trough with negative tilt, and a surface low in the 980s.

The gloom is just now lifting a bit here in RST. Dead calm, mid-upper 30s, dirty snow remnants melting away. Blecch. IMO those around the southern/western tips of IL/KY might catch some severe mid-day on the 8th, but that's another thread....

 

[Chad Cowan]

Waking up this morning to a 50 dewpoint and looking at the SPC made me check my calendar... yep, still January. Watching this system evolve on the models has helped ease my SDS quite a bit.

Does anyone know why the SPC is calling the dryline a "pre-frontal confluence band" in the Day 2 outlook? Is this not a dryline? 0z Temp 0z Dewpoint

My new toy from x-mas is a white board with a US overlay for hand analysis and forecasts. Here's my first forecrap:

The green area is where I think the general tornado threat will be, the red area is where I think the highest tornado probabilities are, and the black dot is where my chase target would be, around Durant, OK. There will be a risk of strong tornadoes with the low LCL's and high shear. I would expect the SPC to have 5% TOR probs in the Day 1, and maybe upgrade to 10% in an afternoon outlook depending on how much insolation is realized. The severe threat will shift ENE through the night into MO and AR and evolve into broken line segments with embedded supercells possible, but the main threat will be straight line winds.

Good luck to anyone who tries to chase these speed demons!

 

[Chris Wilburn]

I'm not sure if anyone has looked at the latest Tulsa HWO, but it said storms will initiate by late afternoon east of the dryline. I didn't know a dryline was going to be in place. That makes this more interesting I think.

Anyway between 00z-06z NE OK is looking pretty good for some severe weather. Widespread CAPE values of 1000-1500 j/kg looks to be in store, helicity is decent, and the wind fields look great. I think we will initially see supercells congealing into a broken squall line of some sort that races east into Arkansas overnight Monday. As for the tornado threat it looks like we could see a few, but no outbreak or anything.

I noticed the dryline, but it is very diffuse and not very sharp at all. It is still good to have it in place though. Shear is really good down here and td's should be in the upper 50's to near 60. Forecasted CAPE is in the 500-1,000 range. Initial supercells would be my guess as well before turning into a line and speading towards wester Arkansas and SW MO. If we can actually get 1,000 CAPE instead of say 500 things should get interesting. This is the only area I am considering being it is my backyard and terrain here is really good. Once things get into SW MO south of Joplin and into NW Arkansas it is pretty much game over. I will chase extreme NE OK and extreme SE KS into SW MO near Joplin and points north, but that is about it with this setup.