3/23/09 FCST: NE, KS, OK

[Greg McLaughlin]

The upper air pattern is definitely favorable, but winds will most likely back as the day goes on, so we are going to be fighting time as far as discrete storm motions go.

I'm not seeing anything which would suggest mid-level flow is going to back (across southern KS/OK) during the afternoon and evening hours. Even looking at forecast soundings indicates west-southwest mid-level flow persisting into the overnight hours. That isn't my concern. I actually find it promising how the mid-level flow is forecast to come out across the dryline tomorrow afternoon and evening. I do share everyone's concern with moisture depth/quality tomorrow. Since its close to home I will likely be chasing, however at this point I am not excited about the tornado threat. I think it will be very limited due to lack of deep moisture, however I hope to see a beautiful LP tomorrow. I would be happy with that. Its only March.

 

[mark plate]

The latest NAM, ECMWF, and surface obs continue to confirm what I (and Rich T.) have thought for the past few days...namely that quality moisture will not make it back in time to fully utilize the tremendous dynamics. Dewpoints have mixed away nicely this afternoon all the way down to south Texas, and while they will recover again overnight, daytime mixing will limit the 60+ dewpoints Monday afternoon to far south and east Texas into SW Louisiana...nowhere near where we'd like them to be. Widespread 55-57 degree dewpoints will be likely further north ahead of the dryline, with perhaps a few pockets of 58 Td's...mainly in Kansas. These high shear, low instability setups more often than not do not turn out successfully for most chasers, including myself, and I plan on watching this one from here in Tulsa.

 

[Brian Stertz]

I have seen a few cases of F4's being on the ground with low-mid 50 td's so that in of itself is not a real bummer factor. I will keep an eye on the 00z updates and make my final decision on this model run. It looks a bit more enticing based off the 12z run....particularly down towards the Wichita-Wellington area and points a little east....say after 6pm.

 

[Adam Penney]

Certainly this day is far from perfect, but when you factor in the incredible dynamics that will be in place, it will certainly make for a "decent" early season chase day with hopefully some picturesque LP's. Does it have tornado outbreak written all over it? No. I guess I am in the camp of this is MARCH, and how often does everything really come together this early in the season? If I could, I would be chasing near the ICT area tomorrow. Unfortunately, work obligations have me tied down.

Good luck to all of those that get out tomorrow. This seems like the perfect setup to dust-off the ole equipment and break in the 2009 season if you haven't already. Lastly, if a Day2 MOD risk and 45% hatched probabilities isn't enough for you to get out and chase in March, then what is? I guess I am just different....

Have a great day everyone.

 

[Adam Lucio]

If I sat around waiting for the perfect setup, I would never chase. There probably will be a few tornadoes, will it be Quinter wedgefest part 2...im not expecting it...but you just never know, the weather does what it wants, not what we think it will do.

I share the dislike with the moisture as well, as that seems to be the major fly in the ointment, but some of the hodographs Ive looked at are delicious. with NAM showing CAPE over 1000 j/kg along the I-35 corridor by 0z Tuesday. Everyone knows 1000 can get the job done.

There will be severe weather tomorrow, Im a storm chaser, not a tornado only chaser. Ill take what I can get and will likely be setting off shortly for the ICT area and play points south tomorrow where the better moisture has a chance of advecting north before dark.

Good luck to everyone.

 

[CZandbergen]

Wow, the 00Z NAM run is really pumping up the Td's for tomorrow. Waiting for the rest of the run to render...

 

[Tim Vasquez]

I did a crude hodograph based on the UCAR WRF plots of wind tomorrow evening, and it looks like this in central Oklahoma tomorrow evening.

Even though a glance at constant pressure charts seem to suggest unidirectionality, the high speeds at all levels makes it deceptive and this hodograph shows that there will actually probably be a pretty good amount of helicity. Not much SRH to be realized out of the important 0-1 km layer, but both the normal and right mover eke out a pretty decent amount of SRH through a deeper layer. Interestingly light surface winds are all that's needed to greatly increase 0-1 km SRH... perhaps the after-dark decoupling would provide that.

I haven't gone backward through this thread so someone may have pointed this out already, but I noticed this morning's 12Z WRF brought a rather significant short wave trough across western Oklahoma at 18Z Monday, which moves to eastern Oklahoma by 00Z. So that could delay things until after dark. Well, then again we did get that extra hour of heating a couple of weeks ago.

Based on all this I wonder what the after-dark hours hold for northern Oklahoma.

Tim

 

[Bill Schintler]

Chase Target for Monday, March 23

Chase target - south:
Kingman, KS (38 miles west of Wichita). Storms will develop between 5 and 6 PM CDT, with storm motion towards the northeast at 35 mph.

Chase target - north:
Clearwater, NE (28 miles southeast of O'Neill). Storms will fire by 3 PM CDT, with low-topped supercells along with a tornado or two possible. By late afternoon, storm mode will transition into one or more lines or arcs. Storm motion will be towards the north at 30 mph. Be advised that few bridges cross the Missouri river in this area.

Synopsis:
An impressive mid-level low will lift slowly EWD as an 80kt H5 streak rounds the trough base while spreading 50-60 kts of deep-layer shear over portions of OK. In the low levels, low pressure will track from the NE panhandle towards SERN SD while undergoing occlusion as a Pacific CF and then an Arctic CF wrap around the low.

Discussion:
LLVL moisture will again be limited, with dewpoints in 50’s common throughout the warm sector. Further N, beneath the ULVL system, MLCAPE’s of 500-1000 J/kg will be possible owing to steeper mid-level lapse rates of 7-8 C/km. This is contingent on a period of SFC heating with partial clearing of the LLVL cloudiness. Further S in OK and KS, somewhat higher moisture will be offset by weaker lapse rates through mid-afternoon. Later in the period, however, a plume of steeper mid-level lapse rates will spread E into WRN OK as the H5 streak rounds the trough base and overspreads the area.

Storms should fire first immediately E of the stacked system and just to the S along a polar front as it occludes the Pacific front/DL. This triple point may be favorable for the development of low-topped supercells before storms evolve into a linear arc with H5 temperatures from -18C to -20C. Extensive ST/SC will blanket areas E of US-183 in NE through 21Z, however convection should fire along an arc from N to S at the leading edge of clearing as the low/mid-level dry push surges towards the NE and a narrow axis of modest instability develops. Forecast hodographs in this area exhibit large clockwise curvature in the lowest 4 km AGL, with the H5 low about 100 miles W of the SFC low at 21Z. LCL levels in the 500m AGL range will also increase tornado potential. One can make comparisons to April 18, 2003 and April 10, 2005.

After 21Z, convection will fire further S in KS and eventually in OK from near Blackwell SW towards Altus. A trailing front of Pacific origin will overtake a DL, from N to S from NE into OK, between 18Z and 06Z, 03/24/09. Here, deep-layer shear vectors will be increasingly parallel to the DL; which, along with weaker overall forcing and straighter hodographs, will result in discrete cells or broken segments. Cloud base heights will also be higher in KS and OK.

- bill

9:49 PM CDT, 03/22/09

 

[Mikey Gribble]

I'm too tired to post any sort of a forecast, but I want to get on any storm firing along the dryline between the Kansas border and Fairview, Oklahoma. I think the most favorable environment for tornadoes is downstream of there and any persistent storm that manages to develop in this area and remains discrete has a good chance of going tornadic IMO.

I'll probably head to Medicine Lodge and drop south from there. Where exactly I set up all depends on surface obs and satellite data. I'll stop to fine tune the target some place down there. I definitely want to stay well north of my preferred area for storm development since I don't want to risk having to chase down a storm that's moving away from me. Remember it's a lot easier to catch a storm that's moving at you than it is to catch one that's moving away from you.

Good luck to everybody that's going out tomorrow. It very well may end up being the first tornado of the year for a lot of us. Just pray to god the moisture advection goes well tonight. I posted several forecasts on my blog if you're interested http://loadedgunchasing.com/blog1/

 

[Brandon McClung]

so with it being the last day of spring break and all, i bit at the forecast 1000 CAPE over the TX panhandle today. i didn't get any action due to thick cirrus clouds over the entire area. fortunately for tomorrow, these cirrus moved over central OK after dark. these will allow for ample moisture to be returned and not be mixed out early in the morning.

also, on the trek home along I-40, there were incredible winds coming out of the south. i had nearly had my steering wheel at a 45 degree angle. i think moisture will be in place tomorrow.

the NAM shear vectors are not perfectly normal to the dryline, so storms may go linear, but there is a strong normal component to the dryline, indicating that storms have a better chance to stay discrete than linear, IMO. this can also be seen at the anvil level winds are nearly normal to the DL keeping the precip from the anvil of one storm from falling into the updraft of the other.

one thing i saw that no one mentioned, was a meso low to the west of the dryline, over the TX panhandle. this can only help the low level dynamics as it helps to back the surface winds, increasing helicity and low level shear. i am pretty excited about tomorrow, not real sure where i will end up yet, but hopefully get north of OKC early and then go from there.

good luck and good night.

 

[Robert Edmonds]

Sitting at the Flying J in Sayre, OK... will catch some zzz's here. I'll very likely need to travel just a little east (about an hour's drive), but I am torn whether I will head north or south of I-40. The morning satellite will, hopefully, clear up where I'm going. The NAM breaks out some precip. just south but I am concerned this may come too late in the day or may not actually occur. However, while it won't make much a difference, further north the storm motion will be faster. Sorry for the short discussion, just a little tired.

 

[Ilya Neyman]

The northeastern Gulf of Mexico has been taking a beating as far as dry northeasterly flow is concerned. The models have had quite a poor handle on the extent to which the GofM has been scoured, with mid 40 degree dewpoints almost as far west as Louisiana. In addition, easterly winds have been consistently stronger than model progs have indicated across the ocean.

At the same time, however, the pool of 70+ dewpoints sitting over a large portion of the western GofM has, too, not been sampled well by the models. It will be interesting to note how both the dewpoint minimization, and the surplus will be factoring into the moisture flow ready to commence northward. Already buoys off the SE Texas coast are indicating dewpoints in the 64-65 degree range just off Houston. As low level flow continues to veer tonight this moisture should be making its way onshore across S Texas, then northward toward the southern Plains late tonight and throughout tomorrow. The depth of this moisture is somewhat in question, and given ferocious mixing that took place earlier in the day across Texas this is a factor that will be a sticky point. Nevertheless, the presence of solid 60s dewpoints moving in overnight bodes well for decent moisture increase heading across Monday. 00z NAM and GFS also hint at a few pockets of 60 dewpoints scattered about the moist sector, encroaching on the dryline. Solid 58-59 dewpoints on the western edge of the moist sector may be sufficient, given the dynamics, and this may not be a far cry from reality by 00z.

Tomorrow certainly looks like a potent late March setup. Many parameters are very impressive, and if the dewpoints came in 5 degrees higher an outbreak would be anticipated.

FWIW, forecast soundings do show weakening capping and surface-based parcel freedom between 21z-00z across OK, with good low-level lapse rates, substantial moisture depth, increased CAPE and really really high severe indices.

But, no one really knows what's it all going to come down to. That's the big question.

 

[Alex Lamers]

The latest NAM, ECMWF, and surface obs continue to confirm what I (and Rich T.) have thought for the past few days...namely that quality moisture will not make it back in time to fully utilize the tremendous dynamics. Dewpoints have mixed away nicely this afternoon all the way down to south Texas, and while they will recover again overnight, daytime mixing will limit the 60+ dewpoints Monday afternoon to far south and east Texas into SW Louisiana...nowhere near where we'd like them to be. Widespread 55-57 degree dewpoints will be likely further north ahead of the dryline, with perhaps a few pockets of 58 Td's...mainly in Kansas. These high shear, low instability setups more often than not do not turn out successfully for most chasers, including myself, and I plan on watching this one from here in Tulsa.

I'm not encouraged by the best moisture being locked up in the SAT-LFK corridor and southeast to the Gulf right now. I think if the dewpoints were about 5 degrees higher everywhere, this would be a lot more chaseable.

In any event, it will be a marginal moisture/instability setup with strong dynamics and shear. As Tim V noted, the 0-1km SRH is not that high especially in OK or southern KS. I'm not going to make a big drive tomorrow.

It will all come down to whether or not things are looking good close to OKC around 3 or 4 pm. It might be one of those days where it takes awhile for storms to fire, and the real show is from sunset to about 1am as the better deep forcing arrives. In any event, I'll sit around in Norman until things fire and then head northwest if I go out. In all likelihood I'll save gas money and catch up on some homework.

AJL

 

[Chris Wilburn]

I will be heading to Enid tomorrow for an early target that may change of course. The NAM is showing NW OK with a tad bit more moisture and instability than points south of there into SW OK. Also, the models show between 12c-13c td's at the 850mb layer which is pretty good for deep moisture. If we can actually realize 58-60 dews with fairly good moisture depth we should be ok given the shear is very good. Once in this general area it will be the usual watching of visible satellite and keeping an eye on the dryline. I also think the further north you go the better chanceyou have at getting something during daylight. I guess anywhere from Medicine Lodge down to Fairview (like Mikey mentioned) and Watonga should be a safe bet. I also think further into SW KS may not be a bad play due to strom speeds as you can catch more cells coming up from the south/southwest in this position. Thinks look to get very interesting in N OK along the KS border after dark with CAPE and dewpoints increasing or at least maintaining what they were during daylight hours. SRH values from say Stillwater to the east towards Tulsa are very very high, esp. the later on in the evening it gets. I will say that the WRF forecasted base reflectivity model shows pretty much linear convection and actually greatly decreasing in intensity as it gets further east to say the Tulsa area. I was hoping it would spit out one of those 3-4 discrete cell looks to it lol. Oh well hope for the best I guess.

 

[nickgrillo]

In any event, it will be a marginal moisture/instability setup with strong dynamics and shear. As Tim V noted, the 0-1km SRH is not that high especially in OK or southern KS. I'm not going to make a big drive tomorrow.

It isn't? Heck, the 024hr NAM forecast hodographs for ICT and HUT shows substantial low-level curvature, leading to very impressive (widespread) 0-1km SRH of 250-400j/kg across the warm sector. Yes, there is a rather deep-layer of unidirectional flow, but boundary layer directional shear is quite substantial (hence the pronounced low-level cyclonic curvature) and supportive of low-level mesocyclones. Thermodynamically speaking, the 1000-1500j/kg of surface-based CAPE isn't exactly "marginal" for a March setup, neither.

Needless to say, I'll stick to my original (albeit I'm not chasing this setup, nor any others for at least a few more weeks) target of ICT. I think there is a fair shot at a productive tornadic supercell in southcentral KS tomorrow afternoon.