4/01/06 FCST: KS/OK/TX

[BrandonWhittington]

Well, everything seems to be coming together rather good. Warm front is starting to make its way back north with tds already into the mid 60s south of the front. Still dry here in Booker with a TD of 36. My only concern with Saturday is the canopy of high cirrus clouds. I do believe that the afternoon sun will start to erode this deck around noon or so. With CAPE around 3000, TDs in the mid 60s, and exellent low level shear, tornadoes are likely, if we can overcome the cap.

My target now is still here at my house/town in Booker, TX(Northeast TX Panhandle) Really hoping that storms can isolate themselves and not become linear. Good luck to all that chases. Look for me in a Blue Chevy S-10 Pickup, with a lot of antennas on top.

 

[Todd Rasmuson]

I think we'll not no thinking about it I feel very strongly later today we will
have a TORNADO OUTBREAK across the oklahoma & texas, looking
over the latest, new spc day 1 outlook feel strongly this is gonna turn into
a high risk day. further more i STRONGLY feel areas along I-44 SPS TO LAWTON
TO OKC need to watch out, spc feels stuff will fire at or about 2100 BUT i
feel storms left over from ongoing storms in nw tx will die out over extreem
nw tx into swrn ok near sps to lawton and will leave discrete outflow boundrys
this area has gotta be closely watched for the threat of LARGE VIOLENT TORNADOES
cant put this wording any stronger but not to send mass panic but in confrence with
several other chasers on here we are in feeling this could be another 5-3-1999 setup
of when that f-5 tornado hit moore,oklahoma. rightnow iam most concerned
with extreem swrn oklahoma, i'm thinking of targeting somewhere near lawton
and have i-44 to go on, becouse i think the cells that form over sw ok have a
real threat of putting out very dangerous, violent, long lived tornadoes
through the afternoon,eve hours...

 

[Marc Austin]

I have to agree with Todd, this setup is looking very similar to 5/3/99. Forecast MLCape values for the Mod risk area have gone up in the last couple of outlooks now estimated to be around 3000j/kg. That seems pretty impressive for this time of year. Lawton would be a fair target, but I don't think OKC is totally out of the woods on this one. I'm foreseeing a very volatile and busy day tomorrow. Is a High risk out of the question? I don't think so. I'm actually somewhat suprised we aren't already seeing a high risk with some of the wording that has been used on the latest outlook. Best of luck to everyone and pray safety for those who live in the bullseye this time around.

 

[Jeff Snyder]

Before we start crying that F5s are going to hit major metro areas, I think we should be a little more cautious. I can't (nor shouldn't) tell anyone what to say, but just think we could be a bit more cautious. Some of us said similar things yesterday (3/29) and that event was largely a nonevent for most of OK. If there's one thing about severe convective forecasting and tornado forecasting, it's that forecasts are extremely difficult, especially for high-end events. There are always failure modes, especially if you take model output exactly as is. Extreme events (such as violent tornadoes) are extremely rare for a reason, and it's not necessarily because models don't forecast environments/setups that appear to favor them. If you look at most chase years, there are usually at least a few setups that look to be favorable for violent tornadoes, and few of those pan out.

I'm still undecided on a specific target for tomorrow. It almost always seems like the area east of the sfc low near the warm front is a good choice, owing to winds that tend to be more backed in that area. However, current model output would lead me to southwestern OK and adjacent areas of TX, where seasonably high Tds will be juxtaposed with strong low-level shear. The NAM is depicting some sort of boundary very near the Red River tomorrow afternoon, as evidenced by a change in the surface winds across the boundary and a rather impressive temperature increase to the south. I'm not entirely sure that I'll believe that solution, but it has been persistent for a couple of model runs. What has also been consistent has been the presence of some weak shortwave (ahead of the main vort max) that the NAM progs to be over western OK by 0z (you can see this in the 500mb height contours as well as the vorticity plots).

I think the main potential failure mode tomorrow involves widespread cirrostratus that would limited insolation and near-surface destabilization. As it stands now, the 0z NAM indicates that mid and upper-level RH >80% will overspread the TX panhandle and begin to affect western OK by late afternoon. In the morning, however, it appears that we should see significant sunshine across the target area. Of course, a visible satellite image tomorrow morning will tell all.

As it stands, this more classic dryline southern plains setup look to offer the potential for a couple of strong tornadoes. While flow aloft is not particularly strong, deep-layer shear should be in the 40-45kt range (certainly favorable for supercells given the CAPE).

 

[Tony Lyza]

I have to agree with Todd, this setup is looking very similar to 5/3/99. Forecast MLCape values for the Mod risk area have gone up in the last couple of outlooks now estimated to be around 3000j/kg. That seems pretty impressive for this time of year. Lawton would be a fair target, but I don't think OKC is totally out of the woods on this one. I'm foreseeing a very volatile and busy day tomorrow. Is a High risk out of the question? I don't think so. I'm actually somewhat suprised we aren't already seeing a high risk with some of the wording that has been used on the latest outlook. Best of luck to everyone and pray safety for those who live in the bullseye this time around.
[/b]

I hope that Todd isn't mad that I reveal that I'm one of those that he has been conferencing with, but I completely, 100% agree with him. I am shocked by the ETA placing 0-1km SRHs of up to 400 m**2 s**-2 in the outlook area with SBCAPE of 2000-2500 J/kg juxtaposed on top. This screams disaster, IMO, along a Woodward to Altus line. I think the Altus area is really where the highest risk for very violent tornadoes exists. A high risk tomorrow would in no way surprise; in fact, I half expect it.

Also, for those of you who struggle with hail cores (I may be joining you Sunday, but that's another thread), the hail outlook from the SPC should probably have you shaking in your boots.

 

[Jeff Snyder]

I hope that Todd isn't mad that I reveal that I'm one of those that he has been conferencing with, but I completely, 100% agree with him. I am shocked by the ETA placing 0-1km SRHs of up to 400 m**2 s**-2 in the outlook area with SBCAPE of 2000-2500 J/kg juxtaposed on top. This screams disaster, IMO, along a Woodward to Altus line. I think the Altus area is really where the highest risk for very violent tornadoes exists. A high risk tomorrow would in no way surprise; in fact, I half expect it.

Also, for those of you who struggle with hail cores (I may be joining you Sunday, but that's another thread), the hail outlook from the SPC should probably have you shaking in your boots. [/b]

Where do you see 0-1km SRH of 400 in the target area? Looking at http://weather.cod.edu/forecast/ETA/SP/etaSP_1km_hel_24.gif , I see an area of ?175m2/s2 of 0-1km SRH near and east of I35 near the Red River, which is considerably removed from the dryline target. Other than that, however, 0-1km SRH doesn't look very impressive near the dryline, at least according to the NAM output I am looking at.

On a FCST note, I should say that I love that we have a few 68-70F TD obs in central TX! I see a td=69F northwest of Austin, and a 71F Td in Uvalde (east of DRT). I do wish that the surface flow was stronger, however. It'll take some time to get that true Gulf moisture (>65F td) up into the target area if winds are only 5mph!

 

[Chad Ringley]

I think the main potential failure mode tomorrow involves widespread cirrostratus that would limited insolation and near-surface destabilization. As it stands now, the 0z NAM indicates that mid and upper-level RH >80% will overspread the TX panhandle and begin to affect western OK by late afternoon. In the morning, however, it appears that we should see significant sunshine across the target area. Of course, a visible satellite image tomorrow morning will tell all.[/b]

Also some model-to-model consistency between the old NAM (ETA) and new NAM (WRF) in terms of the UL RH fields and the possibility of a cirrus canopy. I think it underlines a very important point...theres quite a few unresolved questions and uncertainies, particuarly with respect to cloud cover in the warm sector from ascent and convection. Just because a setup looks good on paper, or the SPC goes gangbusters with it in an outlook, doesn't imply its a money-in-the-bag tornado outbreak.

I am shocked by the ETA placing 0-1km SRHs of up to 400 m**2 s**-2 in the outlook area with SBCAPE of 2000-2500 J/kg juxtaposed on top. [/b]

I think you might be referring to 0-3 km SREH. As Jeff showed, the 00 UTC NAM 0-1km SREH is fairly low near the dl, and it's very rare to get 0-1 km SREH that high from a "Midwestern" setup. High SREH in the 0-1 km layer is more reserved for tropical supercell setups with fast flow above the boundary layer and significant veering.

Hoep that helps!

 

[nickgrillo]

I'm liking tomorrow -- albeit the relatively small SRH forecasted by the NAM for tomorrow along the dryline (e.g. 50-75m2/s2 0-1km SRH). The forecast soundings around northwest OK around 21z are quite favorable for slow moving, chaseable classic supercells -- with relatively decent tornadic potential with them (especially with any deviant moving storm which would, of course, increase the SRH). Nonetheless, the combination of very large SBCAPE and deep-layer directional shear for supercells will of course make me wanna chase [I'm still in KS til SUN]. The NAM forecast sounding for Enid, OK at 21z SUN shows a very favorable kinematic profile for supercells -- with beautiful thermodynamics progged across the moist sector (e.g. 60-65 Tds helping to support the 2500-3000j/kg SBCAPE).

--> http://wwwt.emc.ncep.noaa.gov/mmb/mmbpll/c..._hybl35_f24.gif

I wanna be with one of those twin sups in nw OK/sc KS :lol:

 

[Todd Rasmuson]

Morning Guys, it is 6:08, looking over all the latest data, not to pleased with the
morning cloud deck here at my location just n of ardmore BUT RUC is showing
some precip forming near sps by 18z and spreading ne into sw,sc ok by 21z
iam fairly concerned with this in the fact we could get a couple large supercells
with the threat to produce a couple strong tornadoes in this region, for the fact
of overnight convect in this area, which will leave outflow boundrys, so my target
area attm is still gonna be on as lawton area & i-44.... post more in a bit



Todd Rasmuson

EDIT: TAKE A LOOK AT THE EHI INDEX FOR SC, SW AND CENTRAL OK FOR 0Z
SHOWING IT MAXING AT A 7! ACROSS SC OK CLOSE TO ADM OVER TO AROUND LAWTON
VERY IMPRESSIVE!!

EDIT 2: ALSO TAKE NOT HERE AT MY LOCATION AT THE HOUSE JUST N OF ADM
CLEARING SKYS!! SUN IS COMING OUT... IAM EXPECTING A HIGH RISK TODAY..
SPC SHOULD ALSO HIGHLIGHT THE S END OF THE RISK AREA OF SC OK INTO NW
TX, IF ANYTHING BLOWS THIS AFTERNOON IT WILL BEYOND MAJOR, VIOLENT TORNADOES
IN THAT AREA POSS LATER...

 

[Aaron Kennedy]

I disagree with Todd's assement of the apocalptyic - May 3rd - Andover - super-de-duper wedge fest outbreak...

While hodos are certainly quite nice for supercells, I'm just not seeing the low level shear required for a significant wedge fest. Add in uncertainties in the cap strength/storm mode and I'm just hoping to get on some isolated supercells. I highly doubt SPC will go high...

Aaron

 

[Tony Lyza]

Where do you see 0-1km SRH of 400 in the target area? Looking at http://weather.cod.edu/forecast/ETA/SP/etaSP_1km_hel_24.gif , I see an area of ?175m2/s2 of 0-1km SRH near and east of I35 near the Red River, which is considerably removed from the dryline target. Other than that, however, 0-1km SRH doesn't look very impressive near the dryline, at least according to the NAM output I am looking at.

On a FCST note, I should say that I love that we have a few 68-70F TD obs in central TX! I see a td=69F northwest of Austin, and a 71F Td in Uvalde (east of DRT). I do wish that the surface flow was stronger, however. It'll take some time to get that true Gulf moisture (>65F td) up into the target area if winds are only 5mph!
[/b]

Um, not to make this an argument (I really don't want that), you're much more advanced with your knowledge than I am, but I'm not insane, and I know 400+ m**2 s**-2 0-1km helicities when I see them. First off, I'm talking about 0600z (midnight), which was the 30 hour map last night. Secondly, and, perhaps, most importantly, it's still there. To prove I'm not crazy (feel free to scale down if needed):

.

I'm still concerned about the chance for a couple violent or potentially violent tornadoes. I'm not screaming that an F5 is going to strike a metro area, but I think that metro area should keep a careful eye on the situation.

9:22am 4/1/06 EDIT: You can juxtapose a MLCAPE of up to 2020 J/kg (or a little less, I know the ETA can be robust with instability) right on top of the 0-1km SRH of 450 m**2 s**-2 and you get a rough 0-1km EHI of 5.68.

 

[BrandonWhittington]

First off, I just want to say that the cloud cover, in my opinion, will not be an issue at all this afternoon. Temperatures have already reached 70 in the southern Texas Panhandle, and upper 70s in northwest Oklahoma. Also, i'm concerned with the dryline. Dryline appears to be setting up farther west that models state. Storms should fire in the central Texas and Oklahoma Panhandle and quickly oraganize into supercells. My target still stands, here at my house/town in Booker, TX. Next, I strongly believe that the greatest tornado threat is the Oklahoma and Texas Panhandle Border (not just southwest OK)

 

[Jeff Snyder]

Tony,

The F5 hitting a metro area reference wasn't direct towards you.

As it happens, SRH will almost always increase after dark with the nocturnal strengthening of the low-level jet. However, the low-levels also begin to stabilize after peak heating (generally), so the chances of surface-based convection usually drops to near 0 by 6-8z. We'd be in a world of hurt if we could keep surface-based convection through the night on many of these chase days

I'm still undecided about heading sw or NW out of OKC. The 12z NAM doesn't show any precip south of I40 today, which is a bit concerning. Deep moisture will return as the warm front lifts northward, with a good chance of ~3000+ CAPE in sw OK (which is impressive for Apr 1!). The dryline is progged to be pretty diffuse, though I expect it a bit tighter than models are indicating now since they tend to decrease strong gradients that are often present near such boundaries as dryline. I'm a tad concerned about convection firingalong the dryline in TX, but taking its sweet time to work into the better shear environment in western OK.

The 12z NAM came in with weaker vort max in far western TX by afternoon, which you can also see in the UVV charts (weaker vort max = weaker DPVA = less upward motion on the larger scale). I think this partially explains why the NAM doesn't show much in the way of initiation before 0z. In addition, while the shape of the shear profile and hodogrpah look good, the overall intensity of the shear is a bit weak. Yes, it'll increase after dark, but that's after dark. With the prog of a little stronger 500mb flow north of I40, and best CAPE south of I40, I think the best now is to head west and keep the N and S options open until things become more clear later today.

 

[Andrea Griffa]

First off, I just want to say that the cloud cover, in my opinion, will not be an issue at all this afternoon. Temperatures have already reached 70 in the southern Texas Panhandle, and upper 70s in northwest Oklahoma. Also, i'm concerned with the dryline. Dryline appears to be setting up farther west that models state. Storms should fire in the central Texas and Oklahoma Panhandle and quickly oraganize into supercells. My target still stands, here at my house/town in Booker, TX. Next, I strongly believe that the greatest tornado threat is the Oklahoma and Texas Panhandle Border (not just southwest OK)
[/b]

12Z Eta run shows that the 65 Tdew's area is increased and we have nearly 70 in southern Ok. It's true that we have not a very strong low level shear but it's sufficient to have some strong tornado IMO. And I think south central KS and Woodward OK will have a moved evening.

Only a thing: I don't like so much that moistening at 700 mb in South central KS at 00Z.

 

[Brian McKibben]

First off, I seriously doubt the SPC will upgrade to a HIGH risk. There are a number of factors inhibiting a widespread tornadic outbreak. First the 850 flow is far to weak to warrant an upgrade. Via the NAM, the max we will see during daylight hours is about 30kts, which increases overnight as the LLJ sets up to eventually push moisture into MS Valley. Also note that for most of the period the directional shear in the 0-1 isn't that great. 150-250 m2/s2.

The reasons why we could possibly see some significant tornadoes, is due more in part to the large instability. Td's in the mid-up 60s and Temps getting to the 80 F range, all combined with increasing flow across which will eventually cool 500temps and will help yield sbCape near or above 3000j/kg. Perhaps more where surface heating and moisture are maximized. This large instability is more than enough to help force a tornado in the S. Plains. I have actually done research on this. Combine the large instability with the marginal shear that increases throughout the period and that is why we could see some large tornadoes today. However, it will not be to the extent of a Tornado Outbreak.

With that said, I like SW, KS at this point or extreme NW Okla.

God Speed