Robert Dewey
EF5
Nice BWERs on the BREF 2.5 out of LZK as of 0029Z...
11/27/05 NOW: Central/Eastern Plains
- Thread starter nickgrillo
- Start date
Jeff Snyder
EF5
I do wonder what the policy is at SPC for PDS tornado watches. The latest watch, 879, has been given a 60% prob of an F2+ tornado ( http://www.spc.noaa.gov/products/watch/ww0...w0879_prob.html ), yet it's not PDS. I've seen other watches that are PDS tornado, yet only given like a 40% F2+ tornado probability. IIRc, PDS tornado boxes are issued for the enhanced probability of strong/violent tornadoes, so it's odd that a box with a higher F2+ prob is not PDS, while other watches with lower F2+ probs are PDS (of course, I'm not talking PDS SVR boxes, just PDS tor).
Dave Lewison
EF1
Jason Politte was on the east side of Morrilton AR. He was headed west to take a better look at what looked like power flashes when the inflow picked up rapidly from the south with wrapping rain curtains. He turned it around real quick and blasted east!! West side of Morrilton may have been hit by this thing if those were indeed power flashes that he saw. I'd believe it with those gate-to-gate velocities on the SR data.
He said he's giving up for the day, but the last in the "string of pearls" line is headed right for the where he lives on the west side of Conway. I hope his place is okay when this is all over!
He said he's giving up for the day, but the last in the "string of pearls" line is headed right for the where he lives on the west side of Conway. I hope his place is okay when this is all over!
Gabe Garfield
EF5
I wonder as well. With the MD mentioning the potential for long-track strong/violent tornadoes, I would expect a PDS T watch.
On another note, it appears that the convection is transitioning to a true linear mode. With that, I believe the potential for strong tornadoes is beginning to diminish somewhat (although strong embedded supes exist at the moment). Nevertheless, I think the threat for isolated tornadoes will continue through at least 10 pm.
Gabe
Kevin Bowman
EF4
They might add the wording in a little bit, they didnt add the wording on 1 or 2 of the Nov 15 outbreaks till a half an hour later or so
example (not from current event)
http://www.spc.noaa.gov/products/watch/ww0868.html
Karen Politte
EF5
Dave-
Yep - Jason was headed to his dad's place I believe. Isn't that the most insane thing to be chasing home in the dark and having to contend with these giants in the night??
I believe that he saw the Morrilton circulation's tornado (or rather, the effects of it - power flashes) from the highway. I am very glad and relieved that he is OK - it's not nice to think of a close friend being enveloped in this sort of regime. I've never nowcasted this intensely for anyone before......it somewhat gives me a whole new outlook on things.
FWIW, right now it looks like things are calming down around Conway. For now. Things look much more linear now with what appears to be a gust front having overtaking the main line of discrete storms.
Again - just as long as everybody's alright. I hope that the affected communities from today were well informed and kept everybody safe.
KR
Yep - Jason was headed to his dad's place I believe. Isn't that the most insane thing to be chasing home in the dark and having to contend with these giants in the night??
I believe that he saw the Morrilton circulation's tornado (or rather, the effects of it - power flashes) from the highway. I am very glad and relieved that he is OK - it's not nice to think of a close friend being enveloped in this sort of regime. I've never nowcasted this intensely for anyone before......it somewhat gives me a whole new outlook on things.
FWIW, right now it looks like things are calming down around Conway. For now. Things look much more linear now with what appears to be a gust front having overtaking the main line of discrete storms.
Again - just as long as everybody's alright. I hope that the affected communities from today were well informed and kept everybody safe.
KR
David Draun
EF5
It appears the line is slowing down. It doesn't appear to be any closer to Little Rock than it was almost an hour ago. I don't see the intense shear couplets that were present before, and there are no new TOR's I think the worst might be over with.
Karen Politte
EF5
Jason is home safe and sound in Conway.
I want to take this opportunity to put in a mention for the guys at SPC. Today's call was not an easy one - and they were sh*t hot today from the word go. Rich Thompson's t-boxes were right on the money......I see he was the one working this event up until this evening. He jumped in early with the first t-box in eastern/SE Kansas - and it's just as well because those low-topped storms which were just getting going tornadoes like there was no tomorrow. It was reassuring seeing his decisive, timely work come together to keep everybody informed during this rapidly-changing scenario.
Well done everybody involved in warning and watch coordination and to those who work during every event like this to keep people safe and informed.
KR
I want to take this opportunity to put in a mention for the guys at SPC. Today's call was not an easy one - and they were sh*t hot today from the word go. Rich Thompson's t-boxes were right on the money......I see he was the one working this event up until this evening. He jumped in early with the first t-box in eastern/SE Kansas - and it's just as well because those low-topped storms which were just getting going tornadoes like there was no tomorrow. It was reassuring seeing his decisive, timely work come together to keep everybody informed during this rapidly-changing scenario.
Well done everybody involved in warning and watch coordination and to those who work during every event like this to keep people safe and informed.
KR
Karen Politte
EF5
Here is an image I saved from GRLevel3 of the Morrilton AR storm just as it's circulation was bearing down upon Morrilton itself. It is at BR Tilt 4 and shows one of the nicest doughnut BWER's (Bounded Weak Echo Regions) I have ever seen:
I have velocity and reflectivity saved from this time too - if anybody is interested in seeing THOSE please PM me and I can stick them up on my domain too.
KR
I have velocity and reflectivity saved from this time too - if anybody is interested in seeing THOSE please PM me and I can stick them up on my domain too.
KR
George Tincher
EF5
Anything new info from the Perryville/Hot Springs area? I was watching that storm move over that area earlier and based on what I saw on radar and the info Beau passed along earlier, feel pretty worried about that town. I certainly hope it's not too bad.
Rich Thompson
EF3
Karen,
Thanks for the kind words. I think we (SPC) had the right idea today with an initially bimodal episode, starting first in KS and later around the Arklatex along a pre-frontal confluence axis. Shear-boundary orientations helped us anticipate the discrete storm modes reasonably well, and a 4km version of the WRF model confirmed our expectations. Looking back, I'm happy with how the KS watch turned out (fortunately haven't heard about any injuries). I think I fiddled around about 30 minutes too long with the AR tornado watch, and I almost went PDS with that watch. You can certainly make an argument now that it could/should have been PDS, but I'll wait and see what comes out of this tomorrow. We would have gone HIGH risk and PDS *if* boundary layer Tds had been in the mid 60s instead of near 60 F.
Jeff asked about the PDS criteria. When we "expect" multiple F2+ tornadoes, we will generally issue PDS. Today we could envision strong tornadoes in the worst case scenario (kind of what played out), though my confidence was a little below what I'd normally like to have to go PDS tornado. SPC policy is to go with PDS tornado watches in HIGH risk areas (the part of the outlook driven by at least 25% SIG tornado probabilities). We also have the option to go PDS in other situations like today, usually with a 15% SIG tornado outlook.
Regarding the watch probabilities, we are supposed to be consistent with watch types. "Normal" tornado watches will have 30-50% probabilities of 2+ tornadoes, and 10% or less for a SIG tornado. More serious tornado watches have likely probabilities (>60%) for 2+ tornadoes, and 20-30% chance of a SIG tornado. PDS tornado watches will normally have the highest probabilities of multiple tornadoes (>60%) and >40% probs of SIG tornadoes. The first AR watch had 70% and 30% probs, while the later AR watch that Jeff mentioned had 60% and 60% probs. I'm guessing that the forecaster thought it was "sig tornado or nothing", and he was leaning toward at least something happening. I'm not sure off hand how we account for that specific combination of probabilities, but it is possible for the watch to "verify" as the correct call (non PDS) if there are 2 tornadoes, one of which is rated F2+. Does that make sense?
Rich T.
Thanks for the kind words. I think we (SPC) had the right idea today with an initially bimodal episode, starting first in KS and later around the Arklatex along a pre-frontal confluence axis. Shear-boundary orientations helped us anticipate the discrete storm modes reasonably well, and a 4km version of the WRF model confirmed our expectations. Looking back, I'm happy with how the KS watch turned out (fortunately haven't heard about any injuries). I think I fiddled around about 30 minutes too long with the AR tornado watch, and I almost went PDS with that watch. You can certainly make an argument now that it could/should have been PDS, but I'll wait and see what comes out of this tomorrow. We would have gone HIGH risk and PDS *if* boundary layer Tds had been in the mid 60s instead of near 60 F.
Jeff asked about the PDS criteria. When we "expect" multiple F2+ tornadoes, we will generally issue PDS. Today we could envision strong tornadoes in the worst case scenario (kind of what played out), though my confidence was a little below what I'd normally like to have to go PDS tornado. SPC policy is to go with PDS tornado watches in HIGH risk areas (the part of the outlook driven by at least 25% SIG tornado probabilities). We also have the option to go PDS in other situations like today, usually with a 15% SIG tornado outlook.
Regarding the watch probabilities, we are supposed to be consistent with watch types. "Normal" tornado watches will have 30-50% probabilities of 2+ tornadoes, and 10% or less for a SIG tornado. More serious tornado watches have likely probabilities (>60%) for 2+ tornadoes, and 20-30% chance of a SIG tornado. PDS tornado watches will normally have the highest probabilities of multiple tornadoes (>60%) and >40% probs of SIG tornadoes. The first AR watch had 70% and 30% probs, while the later AR watch that Jeff mentioned had 60% and 60% probs. I'm guessing that the forecaster thought it was "sig tornado or nothing", and he was leaning toward at least something happening. I'm not sure off hand how we account for that specific combination of probabilities, but it is possible for the watch to "verify" as the correct call (non PDS) if there are 2 tornadoes, one of which is rated F2+. Does that make sense?
Rich T.
Mike Peregrine
EF5
Damage reports are starting to show up from northwest Missouri/northeast Kansas. Downtown Weston was hit by something - possibly just a high wind event - that has caused a building collapse, downed power lines and a damaged tobacco barn. I'm assuming this is the same storm that passed very close to my mother's house in between St. Joseph and Faucett - she had hail and high winds and went to the basement for a bit. My brother intercepted the inflow on this storm and said it had unbelievable winds. Excelsior Springs also had some damage with a car dealership that had windows blown out. The Riley County, KS storm damaged 32 homes as it moved toward the Marshall Co. line (this is the storm that Darin and Dick intercepted).
Rich - thanks for the interesting explanations ... and also to all your team - and all the local NWS offices as well - for their great work today.
Rich - thanks for the interesting explanations ... and also to all your team - and all the local NWS offices as well - for their great work today.
Sheila_Ward
EF4
Damage reports are coming in. Most have been focused on the Morrilton and Bee Branch areas. I haven't heard a report from Perryville yet. Last I heard emergency personnel were trying to get to the worst damaged areas.
Unfortunately, there has been one fatality reported so far. This occured along I40 near Plumerville. State police are reporting the wind blew the car over. There is also a lumber yard right on I40 that got hit, so you can imagine the amount of debris that produced.
And yes, I spent a few moments in the fraidy hole myself.
nickgrillo
EF5
Very strong low-level mesocyclone pushing RIGHT THROUGH the St. Louis area... I do wonder about the storm, however... I would think the storm is slightly elevated due to a nocturnally strengthening capping inversion, and is likely not feeding off surface-based parcels. Low-level shear is pretty impressive invof the storm (>400m2/s2 0-1km SRH) and it is certainly helping storms to spin...
I would guess the strong low-level flow / approaching deepening surface low will help keep the boundary layer at least semi-well mixed through tonight.
I would guess the strong low-level flow / approaching deepening surface low will help keep the boundary layer at least semi-well mixed through tonight.
Ronnie Bradley
EF1
Finally, my internet connection came back up. The line weakened somewhat as it reached White County (where I live) but a storm just to the south of Pangburn had some decent rotation which prompted a tornado warning for extreme NW White county, extreme SE Cleburne county and SW to central Independence county. The line is now becomming a LEWP.
Unfortunately for me, I had to work today. I have LII and LIII data of KLZK saved before my internet connection went down (radar was showing the line just east of Searcy when I walked in @ 10:45pm) and the cable modem connection light was blinking off/on...
Yeah, it was amazing when the line of storms upon entering SW and W. central AR evolved into a line of discreet to semi-discreet supercells. It somewhat reminded me of the 1/21/1999 incident, though not as severe. You want a string of pearls?! View that Jan 21, 1999 KLZK data and you'll see 'em!!
It now appears that the strongest upper level winds (250~300 mb level) are now swinging their way up toward W Illinois, E Missouri. Winds that were previously responsible for all the tornado outbreaks in AR.
I'll post radar pics, particularily the velocity couplets tomorrow. I'm tired and I'm about to hit the hay. It's been a long day for me.
Unfortunately for me, I had to work today. I have LII and LIII data of KLZK saved before my internet connection went down (radar was showing the line just east of Searcy when I walked in @ 10:45pm) and the cable modem connection light was blinking off/on...
Yeah, it was amazing when the line of storms upon entering SW and W. central AR evolved into a line of discreet to semi-discreet supercells. It somewhat reminded me of the 1/21/1999 incident, though not as severe. You want a string of pearls?! View that Jan 21, 1999 KLZK data and you'll see 'em!!
It now appears that the strongest upper level winds (250~300 mb level) are now swinging their way up toward W Illinois, E Missouri. Winds that were previously responsible for all the tornado outbreaks in AR.
I'll post radar pics, particularily the velocity couplets tomorrow. I'm tired and I'm about to hit the hay. It's been a long day for me.
