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03/21/05 FCST: OK/TX/MO/AR/LA

AND bear in mind that there may be a sneak event in extreme northern OK/southern KS with the cod-core low.KR

Cod-core? You guys have fun, I'll be sitting on my Perch here in Nebraska. Hope you don't get road-Scrod and that you don't get bit in the Bass by the topography. Good luck to all who venture Trout. I'm stuck in this Crappie wrap-around cold rain!
 
After morning analysis, I'm seriously considering playing the LOW in northern OK. My main wrench in this particular set of gears was the obvious lack of moisture relative to the Arklatex area, but current surface obs show low/mid 50s throughout most of central/northern OK. Add in the best helicity the day will see, and it looks to me like another sneak-in-the-back door type of set-up, in the tradition of a May 16, 2003 or a November 10, 2004. My one concern is the total lack of anything at 500mb, although the 700/850 barbs are doing Daytona 500 laps around the LOW center. Might that be enough? Maybe the most important fact to consider with this possible target is visibility.

Moving south, I like the US82 corridor between Gainsville and Paris as a starting point, should we decide to play the jungles. UVVs all point to this area, as does the best helicity in the southern target region by 0Z. I don't like areas further south and west towards Waco/Austin because of the veering of surface winds to the SSW. These winds are better-backed the further north you go towards the corner of NE Texas.

Still undecided, but seriously leaning towards playing that LOW...
 
After morning analysis, I'm seriously considering playing the LOW in northern OK. My main wrench in this particular set of gears was the obvious lack of moisture relative to the Arklatex area, but current surface obs show low/mid 50s throughout most of central/northern OK. Add in the best helicity the day will see, and it looks to me like another sneak-in-the-back door type of set-up, in the tradition of a May 16, 2003 or a November 10, 2004. My one concern is the total lack of anything at 500mb, although the 700/850 barbs are doing Daytona 500 laps around the LOW center. Might that be enough? Maybe the most important fact to consider with this possible target is visibility.

Moving south, I like the US82 corridor between Gainsville and Paris as a starting point, should we decide to play the jungles. UVVs all point to this area, as does the best helicity in the southern target region by 0Z. I don't like areas further south and west towards Waco/Austin because of the veering of surface winds to the SSW. These winds are better-backed the further north you go towards the corner of NE Texas.

Still undecided, but seriously leaning towards playing that LOW...

Totally agree with Shane. I'm also caught between the devil and the deep blue sea.

Mmmkay - let's start first - the convection in OK/TX. overnight and into this morning was going to happen and we all knew it. It was NOT the main show :lol: ! I couldn't care less about it and unless it begins to affect moisture return I've already forgot it.

I'm going to stumble off and do my own forecast now FWIW. I am interested by the many on here I see who are not feeling like plunging into the machette-lands and who might be staying back for any n-cntrl OK surprise. Some folks are concerned with moisture, but with it THAT cold aloft you don't NEED globs of caribbean moisture. I think I'll go read some Jon Davies now....

KR
 
Totally agree with Shane. I'm also caught between the devil and the deep blue sea.

Mmmkay - let's start first - the convection in OK/TX. overnight and into this morning was going to happen and we all knew it. It was NOT the main show :lol: ! I couldn't care less about it and unless it begins to affect moisture return I've already forgot it.

KR

:lol: :roll:

Well - I might be eating my hat sometime soon. I've just taken a glance around the radars this morning for the first decent time, and I don't really like what I see. There is a second band of precip. and thunderstorms moving through the D/FW area right now - which will probably be in the NE TX target area shortly this morning. Problem is - will all this stuff have enough time to clear out and allow for the heating/modification of the environment before expected initiation of the dryline this afternoon? It sure looks like it could be a grunge-fest, after all.

KR
 
Sherman TX area (home for me) there is some clearing as of 9:30 AM. Temp right now is 60F and TD is 60F. The LLJ can be seen racing to the north, with surface winds around 18 out of the south. Its still overcast off to the west, but sun is reaching the ground through the breaks in the clouds.

Being that I live near Sherman area, I will just sit put and wait for the DL to come to me. Seems the upper level winds are more favorable here than farther north. Hopefully it will be a decent day.
 
Early morning forecast open (and likely) to change:

I'm more than a little bit interested in seeing that the "obvious" target of Paris Texas has a dewpoint two degrees less (52) than Alva, Oklahoma (54) right now. YES I know that NE TX. will be under raincooled outflow air for a while yet and YES I know that NE TX. looks impressive - but I'm not sold on it, that's for sure.

Heeding people's concerns about cold outflow with any cold-core low storms that form - I must say that I just can't ignore it. RUC breaks out an area of dashed convective precip. in the Lookout, OK area by 00Z, brings the surface low into the Dewey/Custer Co. OK areas by that time, and has definite trends (obviously) of wrapping moisture & CAPE around the low towards Lookout, OK by this same timeframe.

Given a choice totally of my own making, I would opt for NW OK today. I'm not blown away by what I see happening as far as moisture/return in northeastern TX., and I'd rather be standing on some nice flat Prairie someplace watching an isolated cell that maybe didn't tornado, than blundering around with my machette with a total of 20degrees of view directly above my head in NE TX., while getting battered about the head by some supposedly-tornadic supercell that turned into a piece of pear-shaped outflow on me. (I'd also rather not spend $100+ on gas getting there).

All that said this is probably all moot - as I will go whichever way my husband does.......but it sure is fun wishcasting.

KR
 
I'm still up in the air... split between here (cold core crap) or Sherman TX and points east. Although dp in Paris is only 52, points just west are in the upper 50s... much better than the OK setup. While everything tells me to stick with NE TX (I think it will clear out enough to miss a grungefest), the jungle and gas prices do favor sticking in this neck of the woods.

We'll see where I end up ;)

Aaron
 
cold core

I am working the cold core setup all the way. I don't see anything good happening in NE Texas until after dark in the form of a broken squall line...and it will probably be in Louisiana by then.

We are starting to get some breaks in the clouds here in central Oklahoma...any heating we can get underneath these upper-level temps could lead to a crazy cold-core funnel outbreak.
 
Gabe and I are heading down I35 towards Gainesville, then likely eastward towards Sherman and Paris. The two lines of thunderstorms in TX are partially intercepting moisture return, though all models continue to show ~60 Tds to the red river by early afternoon... Clearing and insolation are occurring to the west of the 2nd line of showers/thunderstorms, so this looks good. Good luck to all those going out today!
 
It looks to me like the storms in progress are the day'show. A look at current surface obs show the dryline is right behind all of this and doesn't look to be slowing down at all. I call these situations "the squeeze," where the DL gets accelrated on one end and sweeps diagonally across the area, pinching off one half of the chase target area (in today's case, NE TX).

My original target of Paris looks good now, but it looks to be behind everything by the time we'd reach it. This seems to be opening the door for OK, where the backed winds and (somewhat meager) moisture seem to combine the best for the longest period of time. Also, RUC breaks out some spotty precip between the 18-21Z time frame, although its gone by 0Z. I just don't think NE TX is an option at this point if you're still in Norman (which we are). I was expecting a second round of storms, but I'm afraid they're already underway.
 
The winds along the I-35 corridor in north central Texas will probably veer by 18z and I doubt initiation will accompany that wind shift along the surface trough. As for chasing near Bonham or Paris, been there & done that. I grew up in Bonham, racing around the Leonard Hills as a teenager, barfing at keg parties in the Fannin County woods. This is not chase country. Out by Texarkana, there are a few gaps in the trees, but it's a not a consideration at the distance I live now.

An analysis of morning obs shows the system is stacked and more neutrally tilted than the last few models showed, so directional shear will deteriorate rapidly as surface to 850 veers south and southeast of the low. I agree with SPC that the morning showers speed out ahead of the dryline to open clear skies for insolation, but so too does the helicity, since the wind shift/sfc trough is *not* the dryline today and the actual boundary lags well behind. Pre-frontal troughs suck--they steal your 0-1k shear while leaving you waiting for the dryline, meanwhile scouring moisture east of the boundary so that there's nothing left when the dryline finally mixes your way. This was the most striking feature of this setup when I first saw it a few days ago, and it's panning out that way.

So what will serve to focus convergence and convection in the high-dollar targets of southeast OK and northeast Texas? I'm not sure. Boundaries left over from the morning's convection? I don't know. I'm certain storms will fire there, but less sure about how you would arrange to meet them. All I see in my mind are trees when I try to imagine the setup for that area. LOL. It's like the forest even interferes with forecasting. Another possibility is that the weak CIN erodes completely and the WAA regime simply explodes all sorts of showers and storms, with supercells embedded in that activity. That's a typical March grungefest and another argument for staying in northern Oklahoma.

A very telling indice today for those staying home is the 0-1k EHI value, which measures SRH and CAPE (SB, I believe) and has proven effective at discriminating between tornadic and non-tornadic supercells. Despite the boffo moisture in east Texas, I expect EHI values will be approximately similar for east Texas as for the cold-core target in northern Oklahoma since helicities up north will hold longer. The values will be much more impressive in east Texas the longer the surface flow remains backed, however.

Purely for visibility purposes, I'd play the OKC cold-core target. Might be some beautiful structure with those and a tornado or two can't be ruled out.
 
Not surprisingly, DDC's 12Z sounding realized the 500mb temp of -22oC or so.

Interesting to correlate what we are seeing today with the paper by Jon Davies and Jared Guyer that has been previously posted here.

KR
 
A glance of the SPC composite 500mb obs show winds from 30-45kts as far north as central OK, which is very significant IMO, as the models seemed to have underforecast this feature. With "the squeeze" eroding away the southern target, I'm feeling good about still being on my couch in Norman. I think the show of the day now looks to be very close to home, or at least in OK.
 
Models are notorious for missing out on factors with cold-core low supercells and tornadoes - so if youre going to be forecasting for the NW OK area I'd be concentrating on soundings, surface obs, radars and gut-feelings.

I've no idea where we'll be going - I'm at work currently and finish at 12noon - which should leave me ample time to jump on anything in OK that is of interest. I don't know what Gene's decided as I haven't heard from him......this makes me suspect that he hasn't decided on anything, either!! :lol:

KR
 
Chase Target for Today, March 21, 2005

Target
Sulphur, OK

Timing:
3 PM CST

Discussion:
A strong and dynamic system is lifting into the southern planes. The left-exit region of a 110 kt (250 mb) jet max is resulting in very strong diffluence, while very strong vorticity advection is lifting towards the target area. As advertised, a large area of precipitation and ST is ongoing ATTM. Expect a widespread severe even today, with a full spectrum of severe weather including some weak tornadoes. Most of the severe weather today will take place in supercells embedded in larger precipitation and storm areas, making for very poor chasing conditions. For this reason, I am choosing to target an area closer to the upper-level system, where very cold temperatures at the mid- and upper-levels – with 500 mb temps cooling to -22C and 700 mb temps around -4C; coupled with surface dewpoints in the upper 50’s and temperatures near 70. Expect some low-topped supercells in an area where storm visibility will be good, as excellent low-level directional shear will be in place NE of the dryline. ATTM, the ST has lifted E of the area, and BL recovery has commenced. A dryline/confluence line will be the focus for renewed convection in this area. Storms will move to the ENE at 20 mph.

- bill
 
Re: Chase Target for Today, March 21, 2005

Target
Sulphur, OK

Timing:
3 PM CST

Discussion:
A strong and dynamic system is lifting into the southern planes. The left-exit region of a 110 kt (250 mb) jet max is resulting in very strong diffluence, while very strong vorticity advection is lifting towards the target area. As advertised, a large area of precipitation and ST is ongoing ATTM. Expect a widespread severe even today, with a full spectrum of severe weather including some weak tornadoes. Most of the severe weather today will take place in supercells embedded in larger precipitation and storm areas, making for very poor chasing conditions. For this reason, I am choosing to target an area closer to the upper-level system, where very cold temperatures at the mid- and upper-levels – with 500 mb temps cooling to -22C and 700 mb temps around -4C; coupled with surface dewpoints in the upper 50’s and temperatures near 70. Expect some low-topped supercells in an area where storm visibility will be good, as excellent low-level directional shear will be in place NE of the dryline. ATTM, the ST has lifted E of the area, and BL recovery has commenced. A dryline/confluence line will be the focus for renewed convection in this area. Storms will move to the ENE at 20 mph.

- bill

Hmmm........I think your target of Sulphur OK will land you right between the two possible action-areas. I think it looks like either NErn TX., OR NWrn Oklahoma. You know that your target is just east of I-35 in southern Oklahoma, right??

KR
 
I'm glad I stuck with my "gut feeling" to sit this one out and stay here in Norman. Actually... didn't have a choice. Work keeps me here until noon at least, then we'll see what happens. This is typical for early storms, so don't get discouraged. Hey, at least we're having some chase weather (finally !!) :wink:

I have noticed that the winds are REALLY backing in and around Ponca City / Stillwater and those areas southwest of Tulsa, north-northeast of Oklahoma City. I'm not sure if I'd chase in northwest Oklahoma, but north-central perhaps. Looks like, if we can just get these low clouds to erode and get some surface heating, that perhaps the Ponca City, I-35, Guthrie, Stillwater, Perry, Enid, to Oklahoma City will be a fun place to "play" today. I don't envy those who chose to spend the $$ and drive hundreds of miles down into Texas. I don't have much confidence in the setup down there... I think a squall line will form and RACE off at speeds way to fast to navigate with poor roads and visibilities.

I'm with playing the upper low as it comes in. I'd say the winds are plenty backed with a 30mph surface wind in Enid and east winds in Ponca City.

Happy chasing everyone!
 
The last few loops the low is digging SE instead of east. If i could get off work (not a chance today) I would play just north of I-40 in central Ok. Ok city may get it yet. Nice clearing just SE of low and instability is climbing. I think NE Texas is going to squall quickly and will be unchasable anyway due to visibilty and speed of storms.

Anybody heading to NW Oklahoma wont have to go that far before they run into instability and clear air. NW Ok itslef is already clouding up so finding that small area of clear AND moist air will be difficult but worth it.

Target: Enid, Ok.
 
I'm hoping for some good action in south/southeast Texas between I-35 and I-45. Working in west Houston 'till 5pm, all I can do is take off and hope I can catch a cell before the sun goes down....

Appears storms are trying to initiate across north central Texas and central Oklahoma now (1830utc). Looks like the action's about to begin and it's going to happen for that area!
 
tornado watch

Looks like a tornado watch will be issued very soon for central Oklahoma from the Kansas border to the Texas border.

The upper system is pushing east...cold core tornadoes at the very least.
 
Visible satellite loop in TX, OK

Does anyone want to attach any significance to the developing CI shield S of an Ardmore, OK to Abilene, TX line. Clearly associated with the stronger jet stream winds. It may be enough to reduce the already marginal instability in TX - and recent satellite trends of the CU line support this - bill
 
Just got off work early and sitting in Round Rock waiting for some tail end charlies to fire up. OK is too far to drive so hopefully the timing the the next upper level pulse into central TX will be before sunset. We're warming up rapidly and after this mornings convection blew out of here and left all this moisture, things could get good here in central TX later this afternoon.
 
This is starting to remind me of 4/11/01. Remember that these types of storms do not appear impressive on radar usually, and their structure is compact. I would pursue just about any of these blips showing up right now on satellite intersecting the tor-watch box, particularly in SE Oklahoma from I-35 east. There is a distinct bulge in the southern half of the box showing up now and signs of building CU. Just remember that they will be short today and probably NOT anvil out or contain impressive lightning, etc. But the tornadoes will be there nonetheless.
 
RE: 4/11/01

This is starting to remind me of 4/11/01. Remember that these types of storms do not appear impressive on radar usually, and their structure is compact. I would pursue just about any of these blips showing up right now on satellite intersecting the tor-watch box, particularly in SE Oklahoma from I-35 east. There is a distinct bulge in the southern half of the box showing up now and signs of building CU. Just remember that they will be short today and probably NOT anvil out or contain impressive lightning, etc. But the tornadoes will be there nonetheless.

Exactly! I was thinking the same thing. I witnessed a tornado in Eastern Iowa that afternoon. No lightning at all. And the storm updrafts were bent over at something like 60 degrees, with very little in the way of anvil structure. I *do* think 700mb was quite a bit colder that day then today, however. bill
 
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