3/17: FCST: Wednesday in TX, LA and AR

[nickgrillo]

ETA bringing stronger SBCAPE owed to decent low-level temperatures and moisture (yielding more than 2000j/kg in some spots). Anybody chasing?

Discuss:

[Jason Montano]

I dunno, I might, from the look of it there may be a few supercells in NE texas tomorrow. I like the forecast highs and dp's I think the ETA is understating dp's at the moment but GFS is forecasting mid 60's dp. Also with a LLJ and ok shear added to CAPE of >1500 could be nice. That is if the warm front travels north enough b/c favorable winds look to be confined to small area.

I will wait for the 00z update and make up my mind. What do you all think?

[Rich Pena]

Do you think trough will hold out long? It sure seems temps are rather too cool and CAPE values are not looking too good or at least so far maybe find out tomorrow 12z. http://www.spc.noaa.gov/compmap/ Hmm CAPE/CAP , temps and dps though I bet are a problem for tomorrow. Well, I hope at least we get a good lightning show out of it at least in the evening, I want to be able to practice using my new digital camera's over exposure settings. It Sure is cool out now; well I wish best of luck to day time heating and vertical wind shear. :P

[Jim Bishop]

My only major concern is whether initiation will occur. If the shortwave is stronger, or even moves a little faster, I'm probably heading out. Of course, I'm not sure what I'd tell my boss since I'm scheduled....

Happy Chasing everyone,

Jim

[Aaron Kennedy]

Come on Jim... you've got to have about 500 excuses to pick from ;) Just tell him you gotta study for that partial differential equations test next week. :lol:

Aaron

[John Cameron]

73/58 in SPS @ 17Z

:shock:

wish the shortwave was a little stronger

[Bob Schafer]

As of 10:43AM, the theta-e ridge has Td's above 60 just S of the risk area, though with light backing winds on the order of 5 to 10 knots. There is abundant insolation, and the RUC says sfc temps should be ~80.

However, that is a lot of dew depression, and I'm wondering if any storms that can initiate can get rooted.

The biggest problem may be the 700 temps, at 4-6C. That's kinda high for St Patrick's Day, and the synoptic orientation of the upper level system precludes cold air advection in the mid-levels. Plus, 850RH is only about 50-60%, so there's not much help with latent heat there, either. Those two parameters tell me that that's the reason the LI's are only progged at about -4 for 00Z. With such weak instability, UVV's will be low.

I'll guess either cap bust or some (somewhat) high-based and low-topped junk for tonight.

Bob

[Jim Bishop]

You're right Aaron, what was I thinking! I'll tell my boss I'm studying on Saint Patrick's Day! I'm sure that will fly...LOL

I've looked at the data. Basically, there's probably around a 20% chance initiation will occur. The models are showing the vort max a little stronger, and a little further north. This, plus dryline convergence, along with moisture convergence near the low level moisture ridge/tonge could potential provide enough forcing withe surface temps in the lower 80's. I'm betting against it, but there's still a chance. Man I'm gonna be pissed if something goes up, 'cause it will be a freakin sweet looking supercell!

Happy Saint Patrick's Day!

Jim

[Joel Wright]

As of ~1830Z it looks like the beginning of a cumulus field in southern OK.

[Kevin Scharfenberg]

Given a look at satellite trends and a quick modification of soundings, I wouldn't be too surprised to see a good storm go up in the area between Paris, TX and Ada, OK in the next few hours. Still not a very high probability, but that's the area I'm watching.

[Aaron Kennedy]

Man.... just watching the status of the Cu field over Norman was a good reminder of how much I love meteorology. With the sun beating down (over 80 out now!) and the Cu slowly getting bigger, it really gets me pumped for chase season.


Aaron

[David Draun]

So much for high based storms. That convection is surfaced based, people. There is even a thunderstorm watch for the area. Radar looks like severe multicell storms. Cu field go boom! :lol:

[Matthew Hatton]

well there are at two warnings out now but no MD yet?

[David Draun]

I'm betting against it, but there's still a chance. Man I'm gonna be pissed if something goes up, 'cause it will be a freakin sweet looking supercell!

Happy Saint Patrick's Day!

Jim


Well, it must be luck'o'the Irish, because those cells have V-notches on them. They probably are some sweet-lookin supercells. Too bad no tornadoes.

Happy St. Patricks Day!

Dave

[Matthew Hatton]

sorry to ask but what is a V notch? On the ground, would you be viewing a clear slot?

[mrobinson]

http://img13.photobucket.com/albums/v38/mrobinson68135/31704.gif

I was curious about that myself..

[David Draun]

sorry to ask but what is a V notch? On the ground, would you be viewing a clear slot?

I hope I have my terminology right. Maybe I'm calling it the wrong thing?
the V-notch is what you see on a Nexrad image on the NE or E corner of a supercell. I think it is also known as a "flying eagle" Also, that above radar image looks kind of old. Here's a newer one.


http://www.srh.noaa.gov/radar/latest/DS.p1...0/si.ksrx.shtml (http://www.srh.noaa.gov/radar/latest/DS.p19r0/si.ksrx.shtml)

Note the concave shapes in the echoes ahead of the precip cores.

[Matthew Hatton]

Cheers guys. Have to say that last storm has pretty good radial velocity signatures on it and an apparent TVS, nothing showing to interupt inflow so this could have a chance of a tornado?

[David Schuttler]

spotters seeing wall clouds with lowering, should have went dang it. Muskogee county

[Aaron Kennedy]

V-notch is due to the updraft splitting the upper level flow. Flying or "screaming" eagle typically refers to a full bodied supercell on radar with a hook echo (on base reflectivity).

Aaron

[Gabe Garfield]

Awesome hook echo currently in NE Oklahoma...wouldn't doubt a tornado or two could form as LCLs lower and the low level jet increases. Just amazing!

Gabe

[David Schuttler]

http://bamlock.web.aplus.net/sitebuildercontent/sitebuilderpictures/31704.jpg


This was looking SE from Tulsa about 6:15

[David Draun]

Spc finally had the MD out at about 6:16 CST, and get this, they were not even expecting to issue a weather watch. They just now are showing it.

And let me add, Nice pic! :D

[Joe Guerra]

There are now 5 confirmed mesos. My Swift WX is showing a nice j hook from cell ID A1. Good luck for those chasing and get a twister for me. :lol:

[Matthew Hatton]

even if there are no tornadoes there would surely be a gustnado or two looking at RV - its a bit messy there but certainly possible. Thanks for the info on flying eagles too :D Any further word from those spotters?

[David Schuttler]

MD on this was out by 3pm central time

[Kevin Scharfenberg]

A few notes:

Severe thunderstorm watch #28 was issued by SPC for northeast OK and northwest AR at 5:10pm effective til 11:00pm.

Saying a storm is "high-based" does not imply that the storm is not "surface-based". High-based, to me, means surface-based but with a very high LCL/LFC (whereas "elevated" to me, means the parcels lifted into the storm's updraft are not surface based). So the storms in eastern Oklahoma are high-based but surface-based storms.

The dewpoint depressions are still quite high (20+F) at 7:15pm, and so far the hook echoes and low level shear signatures have been transient and/or weak, so I'm not too pumped about the tornado threat.

Back to watching radar.

[Matthew Hatton]

radar shows those left splitting supercells rather nicely when you run the loop on Weathertap at the moment. Any more news from people in the field?

[David Draun]

A few notes:

Severe thunderstorm watch #28 was issued by SPC for northeast OK and northwest AR at 5:10pm effective til 11:00pm.

Saying a storm is "high-based" does not imply that the storm is not "surface-based". High-based, to me, means surface-based but with a very high LCL/LFC (whereas "elevated" to me, means the parcels lifted into the storm's updraft are not surface based). So the storms in eastern Oklahoma are high-based but surface-based storms.

The dewpoint depressions are still quite high (20+F) at 7:15pm, and so far the hook echoes and low level shear signatures have been transient and/or weak, so I'm not too pumped about the tornado threat.



Back to watching radar.


I'd like to thank the more seasoned weather watchers out there for correcting my earlier errors. I'm not an expert at this subject, but I learn more every day.

Perhaps tornadoes will not occur from these storms, but at least there's some good structure out there according to the spotters. Too bad it's getting dark now.

Dave

[John Gnuechtel]

Since all these people seem to be online talking about this event right now, I'd like to float a question...

Is it safe to assume that at least a few of the tiny storms to the southwest of the main cluster (best visible here http://www.srh.noaa.gov/radar/latest/DS.p1...0/si.ktlx.shtml (http://www.srh.noaa.gov/radar/latest/DS.p19r0/si.ktlx.shtml)) might be LP supercells?

[Kevin Scharfenberg]

Perhaps tornadoes will not occur from these storms, but at least there's some good structure out there according to the spotters. Too bad it's getting dark now.

No doubt these are very interesting storms to watch...I hope someone got out there to take some pictures! :)

[David Schuttler]

The storm just sout of Tulsa just got a storm warning for it. Okmulgee County

[David Draun]

The storm just sout of Tulsa just got a storm warning for it. Okmulgee County



There are about a half dozen warnings for these cells, hail to golfball size seems to be the main threat.

[S.P. McCool]

Allright boys (& girls), this thread has convinced me. No more waffling on where I want to live when I can buy some property (about a year I hope - but y\'all know about the best-laid plans of mice and men)...I gotta live in Oklahoma! :D

[Tim Vasquez]

Storms near Sallisaw have pretty good notches. As of 0147Z SRM velocity is showing 45 kt of cyclonic gate-to-gate shear 12 NW of Sallisaw and a TVS. The other storm has 32 kt of gate/gate 11 ENE of Sallisaw but it's a bit further away. No tornado warning though.

[Karen Rhoden]

There are now 5 confirmed mesos. My Swift WX is showing a nice j hook from cell ID A1. Good luck for those chasing and get a twister for me. :lol:

Don't fall into the trap of relying solely on what a computer software package is constantly feeding you.

Think about it - have there been/are there any current tornado warnings out for this cluster of cells? That tells me something.......
With 45 degree dewpoints in northeastern Oklahoma, it's looking pretty dry up there.....and tornadoes don't like "dry".

"5 Confirmed Mesos" (AKA spinny hoops) means absolutely nothing.

I would be surprised if there were ANY tornadoes from today's events.....but anything's possible and I'm no expert.

______________________________

Karen E. Rhoden

[Gabe Garfield]

Don't fall into the trap of relying solely on what a computer software package is constantly feeding you.


I would be very surprised if there were ANY tornadoes from today's events.

Karen, you are right in saying they mean very little. Mesocylclone and tornado detection algorithms are far from accurate...in fact, they tend to be more off the mark than they are on.

Gabe

[Joe Guerra]

I spoke too soon. :oops: I would think from what i learned i would not jump to conclusions like that. There are mesos though but i have been informed it is mid-level rotation and i will now be surprised if we get one. I think i jumped to conclusions because i am now suffering from SDS (Supercell Deprivation Syndrome) But 2 inch hail is possible in this storm.

[Karen Rhoden]

Karen, you are right in saying they mean very little. Mesocylclone and tornado detection algorithms are far from accurate...in fact, they tend to be more off the mark than they are on.

Gabe

I just worry that somebody will actually eventually get themselves into serious trouble sooner rather than later, using/relying on those type of packages with their here-we-come-to-save-the-day type algorithms in the field in a serious, real-life storm situation.

Give me a highway and a pair of binoculars anyday.

______________________________

Karen.

[David Draun]

I spoke too soon. :oops: I would think from what i learned i would not jump to conclusions like that. There are mesos though but i have been informed it is mid-level rotation and i will now be surprised if we get one. I think i jumped to conclusions because i am now suffering from SDS (Supercell Deprivation Syndrome) But 2 inch hail is possible in this storm.

MD 197 is now out for AR/OK. It talks about an increasing threat of downbursts from the supercells approaching Ft. Smith, as the boundary layer is cooling and lapse rates are steep. About SDS, perhaps AMA should identify this chaser-afflicting disease. They could easily identify symptoms, and perscribe some treatment? :lol: What could doctors perscribe for SDS?

[David Draun]

Weather channel's Jim Cantore just put out that storm spotters in Ft. Smith have reported 70 mph wind gusts and power outages. Must be the downburst event starting.

[mikegeukes]

Severe Weather Event is over, removed information.

Mike

[David Draun]

what is a V notch?

A radar reflectivity signature seen as a V-shaped notch in the downwind part of a thunderstorm echo. The V-notch often is seen on supercells, and is thought to be a sign of diverging flow around the main storm updraft (and hence a very strong updraft)


Mike

That's exactly what I thought a V-notch was. The storms in AR are expected to weaken as they move toward Little Rock and into cooler air.

[David Draun]

The storms have merged into a MCS with a nasty lookin bow echo into central Arkansas. A new watch was issued earlier to cover this new threat.
Perhaps anyone there could get some CG lightning shots? What an active evening!

Happy St Patty's Day!


Dave