2/24/07 FCST: OH/KY/TN/IA/KS/MO/TX/LA/OK/IL/AR

[Mike Peregrine]

This thing has, and continues to remind me of November 27, 2005.

Yeah - this is what I was thinking too when I talked about Scott C's intercept that day. That day ended up going up further west than I thought it would. Seems like things had trended faster on the system and I really thought the convection would be closer to Topeka, but it ended up in Junction City. Definitely helps to stay flexible with these things until they happen.

Actually, it's reminding me a lot of April 11, 2001 too ... just further west. (Seems like I make this statement every year at some point ... might as well get it over with in February I guess, lol).

 

[Brian Stertz]

This thing has, and continues to remind me of November 27, 2005. Just look at the upper low and sfc low positions on Davie's page for it.

Well in that case...I may as well head to Erie KS and catch the F2 that looked weird but did some damage on it's fast and furious path northeast. Or join Dick and Darin up on I-70 near Junction City KS. Guess you really can't ignore some similarities as Mike pointed out...I guess I had better chase then.

 

[Jeff Snyder]

The analyses from Nov. 27 2005 (CLICK HERE for the Severe Thunderstorm Event page for this day) indeed show some striking similarities to the forecasts for this upcoming Saturday. Just about the only difference that I can find is that the cyclone on 11-27-05 seems to have been more vertically-stacked than this upcoming system, with the current 850mb cyclone looking to be a little east of that of 11-27, which may end up "pushing" the favorable low-topped supercell regime a little farther east. In addition, there's the definite possibility of widespread precip and cloudcover in the warm sector this weekend, moreso than we saw on 11-28.

Otherwise, the general "look" of the 2/24/07 cyclone is certainly quite similar to that of 11/27/05.

 

[beaudodson]

The models continue to indicate two distinct areas of severe weather. One early on in Kansas/Oklahoma/Texas. The second round would be Arkansas/Louisiana/Mississippi. There is almost NO instability further north. IF we believe the GFS. It will be interesting to see how this pans out. A lot of the National Weather Service Offices seem to be giving this a fifty/fifty on whether it is a bust or not. I believe tomorrow we will have the first real model indications of what to expect further north into my area. I will bite on the no-instability if the 0z models show the same tomorrow night.

 

[Brian Stertz]

Tonight's 00z GFS sure looked scary with a vicious looking with a powerful neg. tilted 500 wave moving from SE Kansas and E. Oklahoma into SW Missouri and much of W. Arkansas. This could mean a rough night for residents of E.Oklahoma, SE Kansas, S. Missouri, much of Arkansas, extreme N. Louisiana, NW/WC Mississippi, and W.Tennessee. Unfortunately the toughest part of this event (if the 00z GFS pans out) may occur after sunset. Certainly have to think along the lines of MDT risk if this holds true. The shear and diffluence is pretty extreme, and there should be just enough instability in place to make this a potentially serious tornado setup across E.Oklahoma, SE Kansas, S.Missouri and Arkansas in particular. Even if there is a squall line, there is massive lift and shear present to get some bigtime supercells (some likely imbedded in the line) to cause trouble. Plenty of model runs to go with some changed details for sure, but this looked pretty ominous.

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_500_096m.gif

 

[Bill Tabor]

I agree guys does look similar to Nov 27, 2005. Srfc and mid low on latest 0z GFS run have pulled it slightly further south of last run. That cold core indeed looks to be cold brrrrr. I think the cold core mini-sup chase will work, but I don't think I'm interested. BTW that low will be moving pretty fast too.

On the other hand I'm considering a possible alternative. Seems to me down in the juicer air 60+ dews extend just into southern OK and eventually just into southern MO from 12z to 0z. Center of mid low vorticity at 12z is just west of ABI where it will rocket to ne OK by 0z. During this time it will intercept the southerly extending dryline into north TX. Appears for awhile the jets will all be there. This could mean a very early 12zish and a few hours after supercell and tornado opportunity before all that forcing blasts off for the rest of the country. I'm thinking currently an area bounded by Ardmore, Wichita Falls, and down toward DFW might be prime. Thoughts?

 

[Jim Tang]

FWIW, at 78 hr the NAM progs over 2,000 J/kg CAPE over west central TX (while the GFS says merely 500). Although the NAM is almost 100% likely to be overdone, I think chasers may enjoy the setup on Friday, with a slower system and dynamics that aren't off the charts, I see some nice isolated sups with a couple of tornadoes possible where instability is maximized. I'd say anywhere from KS down to the TX/OK border and south is game. Personally, with capping issues possible further south, I'd play the low and pick Kinsley, KS as my initial, preliminary, virtual chase target for Friday. In addition, there will be this narrow window of opportunity around 12Z where there could enough of a warm sector for a few strong tornadoes further east...continued slowing down says areas along and east of I-35 could be primed for this sunrise activity.

 

[Paul Knightley]

Brief summary for Saturday, 18Z:

ECMWF 00Z run - surface low elongated from NE KS - far NW OK, with 500 hPa low close to Pratt

GFS 00Z run - surface low KS/OK border S of Pratt - 500 hPa low E TX P'handle

GFS 06Z run - surface low Cent KS - 500 hPa low near Wichita.

GFS 06Z much closer to ECMWF 00Z run, with E KS looking primed for a cold core situation.

Friday evening - could be some stuff firing on the dry line in the Panhandles area:

For 00Z Saturday:

ECMWF 00Z has 500 hPa feature near 4 Corner, dry line sharpening across P'handles - best instability CDS area, surface low N CO.

GFS 00Z - 500 hPa feature in AZ, dry line P'handles, CDS best instability region.

GFS 06Z - 500 hPa feature in 4 Corners region, similar surface instability as other models, surface low SE CO.

If I was out there, I'd probably head to CDS on Friday for a look around!

Overnight, instability increases over W/cent OK into cent KS - LLJ cranks up - nocturnal tornado probability seems quite high...models break out a fair amount of precip as dryline/cold front is swept eastwards as surface low deepens/lifts NE.

 

[Brandon Sullivan]

I'm kind of time strapped on Saturday night.. So I'm not sure where to head to that I can see some good things.. But make it home in time. I'm still seeing the instability weaker with every run. And extreme shear may end up being too much.. Also, a slower and further south track would make the svr potential almost NIL up here. I did see the SPC extend the 4-8 a little further north though.. Now that the system is coming on shore, models should hopefully clear it up.

I'm trying to remember what happened the last time with a big system.. The GFS originally took the system north.. Then took a southward trend. Then came back to original thoughts! I just want more model runs.

 

[rdale]

The GFS southern trend today is likely due to some convective feedback problems - the GEM & EC both are more to the north and do not suffer from the same issue so given all those factors and the change in the GFS make it a definate outlier...

 

[Bill Tabor]

For 12z runs this morning from what I see compared to last night GFS is more progressive reaching eastern points sooner, and is also displaced further north again for both sfc and 500 hPa low. Last night's run center of mid low vorticity was showing west of ABI at 12z Sat now it is showing ne of CDS!!

NAM is showing a similar track on this run as GFS as far as positioning of sfc low and 500 hPa low.

With that in mind, what I said previously about Sat 12z near the Red seems unlikely. By then on the newer runs the dryline is already in or through DFW as far as I can tell maybe a bit more east. Most of the energy of the vortmax will also pass to the north of that area.

Additionally much of the daylight territory of the cold core is headed from central to eastern KS very early on Sat limiting some of the chase opportunity that was previously available IMO - although people in the area may still be rewarded. MO is much more under the gun on Sat now.

Based on the above and considering my southern location this makes me prefer Friday late afternoon, evening, possibly night for a chase near CDS vicinity.

EDIT: NAM is also showing IMO probably too low of dewpoints in MO by 0z even for cold core torns. There is a tiny blotch of 55's showing in south central KS at 12z but by 0z and into MO most of that is far east and south. So it appears to me the cold core option would only be from 12z to perhaps as late as 20z or so in KS. Of course that is based on this model run, so just stay tuned while we play musical models and we'll see what cards we are dealt this next model run coming soon.

 

[Karen Politte]

FCST: AR

Currently, a weak cold front is working its way through Arkansas. While Tds in southeastern AR are in the mid-upper 50s, Tds in northwestern AR are only in the low-30s and dropping. With northwesterly breezes behind the “cool†front, this will allow for a cleansing of the atmosphere after several days of impressive return-flow since our last Canadian FROPA. This will be just one of the wrenches thrown into the finely working atmospheric mechanisms that must come together for a good chase opportunity this coming Saturday, February 24th, 2007.

That being said, however, the 12Z runs of both the GFS/WRF/ETA are, as a fellow chaser coined it, moving at “warp speed†in comparison to previous runs. All models are far more progressive - which is surprising considering the models have a tendency to slow things down once the system comes ashore. The ETA still seems unrealistically fast - with the stacked sfc. and 500mb lows having blasted well into north-central MO by 0Z Sunday Feb. 25th.

However, the GFS provides some interesting food for thought. Should the increased speed it is forecasting come to fruition, it will consequently offer us a slight chance at a good chase in GOOD chase terrain in AR. Now that it is forecasting the surface boundary/front to be through the LZK area by midday and into TN by 0Z, it is appropriate to speculate on the potential for a good mid-afternoon chase in the flat, low-lying terrain of eastern AR. Our hopes are slowly getting teased.

Moisture still may be a problem……it is, after all, February. Let’s not go head-over-heels here. I am sure that if chasers go out on either Friday OR Saturday - many will be burned. I think most of the scalding will take place on Friday, too.

Currently we are left with a disorganized wind pattern across the southern Plains and MS river valley. However, by tomorrow evening our winds should recover to turn easterly and, in turn, southerly again.

What then? It’ll be time to sit back and let mother nature do what she will. It’ll be time to finish work on Friday evening and let the balmy southerly wind regale us as it plays with our wind chimes on the front porch……hopefully, that’s not the only piece of atmospheric music we will be hearing this weekend.

 

[Mike Peregrine]

I don't think I'm as concerned with moisture/instability at this point. Once the low level jet kicks in, I'm pretty confident that enough moisture will move into place. The Gulf is unseasonably warm right now. It's cooking up a big pot of moisture stew for us down there. Like Karen, though, I couldn't help but notice quick progression of this system. Good gracious. Chasers in northeast Missouri should be able to catch the same storms that chasers in Kansas saw like an hour earlier. Here's the ETA storm motion forecast. It can actually still be do-able if a person is in the right spot. I don't know about Arkansas, though. It's looking pretty wild and wacky down there.

This looks to be a lot like 11/05 in that there will likely be a very strong batch of nocturnal storms over Missouri/Arkansas with a southerly component to the system, which has the potential to be pretty damaging. I actually have a funeral to possibly attend Saturday at noon. Still trying to decide what to do. Would really like to get out there if at possible. Still feeling pretty confident in my initial target. We'll see.

 

[Kevin Askew]

I agree this system holds alot of similarities of 11/05 Did a bit of homework & found Instibility here in So. illinois was very low AOB 500. Dews around 55-60. That event was very exciting producing an F4 (Now would be classified EF5). Looks like this system will be dragging a bit more moisture here with much better Jet dynamics. 100-110 jet in 05. Now the jet is forecast at 130 or so. So with this said, an EF 5 is VERY possible in the KPAH warning area. Sat or sat night. Yeah that sounds like a soothsayer but if history repeats itself we will have a nearly definate outbreak of tornadoes in this neck of the woods. Convective tail in Arklams area seems ragged but bootheel through So Il. actually looks VERY similar to 11/05, but with a bit better instability. Hold on to your hats it might get a little rough in KPAH area saturday/sat night.
Kevin

 

[beaudodson]

I agree this system holds alot of similarities of 11/05 Did a bit of homework & found Instibility here in So. illinois was very low AOB 500. Dews around 55-60. That event was very exciting producing an F4 (Now would be classified EF5). Looks like this system will be dragging a bit more moisture here with much better Jet dynamics. 100-110 jet in 05. Now the jet is forecast at 130 or so. So with this said, an EF 5 is VERY possible in the KPAH warning area. Sat or sat night. Yeah that sounds like a soothsayer but if history repeats itself we will have a nearly definate outbreak of tornadoes in this neck of the woods. Convective tail in Arklams area seems ragged but bootheel through So Il. actually looks VERY similar to 11/05, but with a bit better instability. Hold on to your hats it might get a little rough in KPAH area saturday/sat night.
Kevin

Posted my thoughts here as well
http://www.easternuswx.com/bb/index.php?showtopic=126195&st=880&gopid=1792462&#entry1792462

I live in the KPAH area...few miles from the PAD Office. Hopefully you are wrong. We are all concerned though and I will be glad when the weekend is over. Images from the below comments can be viewed there.

I am anxious to see tonights models.

This is what I believe from past experience and the reason I have been holding tight to my outlook. The biggest bust potential on my outlook is going to be north but I included them because of the high wind potential. Severe is severe whether we are talking hail, winds, or tornadoes.

1. The models normally don't handle instability well on day 5-6-7-8 and so on. They normally start to show it around day 4 or so and then increase it through the event.
2. Moisture return is always an issue on the long range models - how to and how not to handle it. A low of this intensity, even the upper end of what the models are showing, will have a tremendous moisture fetch - and there are hints at the Pacific feed as well on the NAM.
3. Models already indicate a plume - finger - if moisture streaming north across this region on Saturday. This is at most levels - deeper moisture than earlier on back in OK and KS. Some issues there with moisture.
4. Helicity values are extremely high.
5. MODEST instability will be more than enough to cause problems.
6. As I posted earlier and will post again below - wind fields are tremendous with this thing. Divergence is also extreme hitting over 40 on some of the models. 40+ from Haby is considered to be incredible divergence.
7. The extreme negative tilt across this region and south a bit.
8. The event is now starting to look like a DAY event around here. Late Saturday Afternoon into the night hours.

I expect wind fields to be extremely impressive. Models will likely continue to catch up on some of this.

Believe we see a moderate to high risk over us and southward. I think we see a mod to high risk both days...as it first hits the Plains and this east. Unsure on the Southeast as Jk talked about. Seems to be a weaker solution for that area. Unsure what SPC has said as I have not read that...he commented on it so I assume they are thinking strong for the Southeast as well.