andyhb Posted March 13, 2012 Share Posted March 13, 2012 12z GFS is caving to the crappy-looking Euro solution... 582 dm March blocking over the Midwest FTL. Wow, talk about a wasted potential if that plays out. That said, the Euro/GGEM both appear better than their respective 00z runs. Link to comment Share on other sites More sharing options...
brettjrob Posted March 13, 2012 Share Posted March 13, 2012 Wow, talk about a wasted potential if that plays out. And just when the window of opportunity looked to be starting its slide shut, the 12z EC comes back to a more progressive solution. So essentially, the GFS and EC completely swapped places between the 00z and 12z runs. The ultra-impressive GFS ensemble solutions from last night are completely out the window for now, though. Unfortunately, as Jim mentioned, past experience suggests this setup may be more likely than not to go downhill from here -- at least in terms of getting back to a progressive, broad-based trough. I think the range of reasonable solutions right now spans the spectrum from (a) multiple days of dryline activity plagued by some meridional flow issues, all the way to (b ) no appreciable convection until Tue/Wed, at which point this should be primarily a widespread heavy rain event with southerlies through the depth of the troposphere. Link to comment Share on other sites More sharing options...
andyhb Posted March 14, 2012 Share Posted March 14, 2012 The ultra-impressive GFS ensemble solutions from last night are completely out the window for now, though. 12z Euro ensembles are pretty damn nasty looking, though... GFS ensembles still show sub-995 mb sfc lows developing in Colorado, which is impressive...and we've seen many times where sfc lows like that have overcome potentially iffy setups and went one to get some dangerous results. Keep in mind these likely will not only be afternoon/early evening ordeals, considering the moisture is very deep and remains strong at the surface after dark. The daylight savings time/diurnal pattern will also encourage a longer potential chase, should one manifest itself. Link to comment Share on other sites More sharing options...
PatrickSumner Posted March 14, 2012 Share Posted March 14, 2012 Looks like GFS is more progressive this run. Severe weather event looks to extend further east as well into the Ohio Valley region if I am seeing things correctly... Link to comment Share on other sites More sharing options...
andyhb Posted March 14, 2012 Share Posted March 14, 2012 Definitely better than 12z and 18z and I like how it keeps the trough in one piece for Sunday/Monday and yes there could be potential eastward should that closed low eject like it does, although the biggest potential is still certainly in the Plains. It may end being more of a heavy rain threat further east. Link to comment Share on other sites More sharing options...
brettjrob Posted March 14, 2012 Share Posted March 14, 2012 This run puts all its eggs on one basket, that basket being Sunday, which looks arguably huge over the southern High Plains. If you multiply SBCAPE by a factor of 1.5-2 to account for the typical GFS bias at this range, it's hard to find much of a weakness with the setup across the TX Panhandle to W KS. Maybe the lack of veering above H5, but I doubt it would hurt too much if you took this run verbatim. Now to wait for the Euro to go back to a 600 dm blocking ridge that impinges all the way into the Plains and keeps the trough from clearing the Sierras until Tuesday... Link to comment Share on other sites More sharing options...
RCNYILWX Posted March 14, 2012 Share Posted March 14, 2012 Definitely better than 12z and 18z and I like how it keeps the trough in one piece for Sunday/Monday and yes there could be potential eastward should that closed low eject like it does, although the biggest potential is still certainly in the Plains. It may end being more of a heavy rain threat further east. Flow is quite meridional/southerly at 300 down to 850, but more backed at 925 down to the surface for those areas farther east. Still huge wind speeds aloft, so the bulk shear values will be off the charts, but the hodos would be pretty unidirectional until just above the surface. Even the earlier runs today looked better for the Plains, where you could infer convection firing for a multi-day period along the dry line. The southern Plains in particular where there may be a southern jet streak aimed into the base of the trough. But as you mention, potential could be there east, especially considering how unstable the warm sector will be. Link to comment Share on other sites More sharing options...
tornadotony Posted March 14, 2012 Author Share Posted March 14, 2012 This run puts all its eggs on one basket, that basket being Sunday, which looks arguably huge over the southern High Plains. If you multiply SBCAPE by a factor of 1.5-2 to account for the typical GFS bias at this range, it's hard to find much of a weakness with the setup across the TX Panhandle to W KS. Maybe the lack of veering above H5, but I doubt it would hurt too much if you took this run verbatim. Now to wait for the Euro to go back to a 600 dm blocking ridge that impinges all the way into the Plains and keeps the trough from clearing the Sierras until Tuesday... I don't know, the GFS run verbatim would give me some concern as to whether or not you'd have the forcing for an "arguably huge" event. Given a lack of dCVA and being located in the right-exit region of the jet, you're probably going to have at least weak large-scale subsidence. And up from the northern TX panhandle northward into western Kansas, the convergence along the dryline is not impressive. It is more impressive from Amarillo on southward, where there's also likely slightly more support aloft. I could see some nasties that way verbatim from the run, but I have major questions about Sunday's ability to produce. And from there on, the setup is crap. Veer-back-veer to the extreme on Monday. Link to comment Share on other sites More sharing options...
brettjrob Posted March 14, 2012 Share Posted March 14, 2012 I don't know, the GFS run verbatim would give me some concern as to whether or not you'd have the forcing for an "arguably huge" event. Given a lack of dCVA and being located in the right-exit region of the jet, you're probably going to have at least weak large-scale subsidence. And up from the northern TX panhandle northward into western Kansas, the convergence along the dryline is not impressive. It is more impressive from Amarillo on southward, where there's also likely slightly more support aloft. I could see some nasties that way verbatim from the run, but I have major questions about Sunday's ability to produce. And from there on, the setup is crap. Veer-back-veer to the extreme on Monday. Fair points. There's no question that lack of upper forcing is going to be a concern on Sunday, unless we go back to the far more progressive solutions we saw several days ago. Still, that is often the case on days which ultimately produce a handful of completely discrete dryline supercells. Just eyeballing, the dryline looks quite sharp with decent convergence, particularly in the Panhandles. Also, the GFS indicates negligible SBCINH and initiates dryline convection prior to 00z, with widespread activity by 06z. The Caprock factor can't be neglected, either. I don't doubt that future runs may trend less emphatic on the progression of the trough axis Sunday, and it wouldn't take much of a regression to turn the question of upper-level support into a more prohibitive one. Still, as a chaser, I'd probably lock in this run if I could (aside from the unrealistic temps/CAPE). It's not perfect, but looks pretty volatile pending initiation, and I think initiation would be a fair bet. Finally, I agree that Monday is impressing less and less with each new run. Link to comment Share on other sites More sharing options...
andyhb Posted March 14, 2012 Share Posted March 14, 2012 Euro has intitialized, to steal a quote from Twister, "Let's she what she does." Link to comment Share on other sites More sharing options...
andyhb Posted March 14, 2012 Share Posted March 14, 2012 Now to wait for the Euro to go back to a 600 dm blocking ridge that impinges all the way into the Plains and keeps the trough from clearing the Sierras until Tuesday... Well that didn't happen. 00z Euro says possible "game on" at 120 (better than the GFS)...here's an interesting picture: That is some major league surface cyclogenesis, combine that with southwesterly flow at H5 and a 50-60 kt southerly LLJ... Also, from what I can tell, depending upon the flow in the upper levels, it may keep the door open on Monday as well... Wow, maybe Tuesday too depending on the veer-back-veer potential...this is a very nicely progressive run, keeps the trough in one piece, and very strong... Link to comment Share on other sites More sharing options...
brettjrob Posted March 14, 2012 Share Posted March 14, 2012 The most striking thing to me about this run is simply the difference from last night's. I think the 24-hour change in forecast H5 heights during the Sun-Tue timeframe is far larger in magnitude than the most extreme differences you can find on the GFS over the past five days worth of runs. I agree that this looks similar to the new GFS, but slightly more favorable for sig svr. It actually does not explicitly forecast initiation on Sunday, lending credence to Tony's concerns. On the other hand, Monday looks salvageable for some potential roughly along I-35 from OKC to DSM, and even Tuesday could be interesting in the upper Midwest. Link to comment Share on other sites More sharing options...
andyhb Posted March 14, 2012 Share Posted March 14, 2012 The most striking thing to me about this run is simply the difference from last night's. I think the 24-hour change in forecast H5 heights during the Sun-Tue timeframe is far larger in magnitude than the most extreme differences you can find on the GFS over the past five days worth of runs. I agree that this looks similar to the new GFS, but slightly more favorable for sig svr. It actually does not explicitly forecast initiation on Sunday, lending credence to Tony's concerns. On the other hand, Monday looks salvageable for some potential roughly along I-35 from OKC to DSM, and even Tuesday could be interesting in the upper Midwest. While I do agree with this, I will say that Euro often does not show initiation very well at this range. Central KS and Central NE look good with the sfc low/dryline further east than the GFS. Basically flips the death ridge/omega block the bird too and shunts it into the Atlantic, later in the run. And then at 240, it looks like it is about to drop another trough into the Central CONUS... Link to comment Share on other sites More sharing options...
brettjrob Posted March 14, 2012 Share Posted March 14, 2012 While I do agree with this, I will say that Euro often does not show initiation very well at this range. Central KS and Central NE look good with the sfc low/dryline further east than the GFS. Basically flips the death ridge/omega block the bird too and shunts it into the Atlantic, later in the run. That's true. I actually think its dryline placement is a little unrealistic on Sunday, and would probably pull back at least 50-75 mi. further west. If so, that would put the dryline slightly closer to what upper forcing there is and increase the chance of convection. And then at 240, it looks like it is about to drop another trough into the Central CONUS... To my eyes, the H+240 panel looks like another potentially volatile Plains setup, with a more broad-based trough than we're dealing with this first go-around. It could easily be a ridge tomorrow morning, of course. Regardless, really difficult to wrap one's head around the next 10 days as depicted on the ECMWF being mid-March. Link to comment Share on other sites More sharing options...
andyhb Posted March 14, 2012 Share Posted March 14, 2012 That's true. I actually think its dryline placement is a little unrealistic on Sunday, and would probably pull back at least 50-75 mi. further west. If so, that would put the dryline slightly closer to what upper forcing there is and increase the chance of convection. Also, it looks like the Euro punches more of the core of the incoming jet streak into the area, which would probably lead to a bit better upper support/forcing than depicted on the GFS, and in addition, if you look closely, that shortwave impulse that leads to the surface cyclogenesis (that extension to the 534/540 dm heights on the east side of the trough) may lead to an intensification of the H5 jet over the area. With that said, given the relative consensus of the GFS/Euro tonight and the wording in the Day 4-8 last night from the SPC, I feel that there is definitely a chance we will see a risk area outlined tonight in the new Day 4-8. Link to comment Share on other sites More sharing options...
andyhb Posted March 14, 2012 Share Posted March 14, 2012 And there we go: DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0341 AM CDT WED MAR 14 2012 VALID 171200Z - 221200Z ...DISCUSSION... LATEST MEDIUM RANGE GUIDANCE IS IN REASONABLE AGREEMENT REGARDING THE EVOLUTION OF THE WRN U.S. TROUGH THIS WEEKEND. BOTH THE GFS AND ECMWF ALLOW STRONGER FLOW ALOFT TO SPREAD ACROSS THE ROCKIES INTO THE HIGH PLAINS BY DAY5. GIVEN THE EVOLUTION OF THE LONG WAVE TROUGH IT APPEARS THAT A BROAD WARM SECTOR WILL HAVE SPREAD ACROSS MOST OF THE PLAINS INTO THE SRN PROVINCES OF CANADA BY 120HR...SUNDAY. LATEST THINKING IS CONVECTION WILL LIKELY CONCENTRATE ALONG THE DRY LINE/LEE TROUGH WHERE BOUNDARY LAYER HEATING WILL BE MAXIMIZED AND THIS WILL COINCIDE WITH STRONGER FLOW ALOFT THAT WILL SUPPORT ORGANIZED UPDRAFTS. SEVERE WILL LIKELY ADVANCE DOWNSTREAM DURING THE DAY6 PERIOD BUT THE INCREASINGLY MERIDIONAL NATURE OF THIS UPPER SYSTEM WILL LEAD TO WEAKENING LAPSE RATES WITH TIME. WILL ADDRESS THE SEVERE THREAT BEYOND THE DAY5 PERIOD WHEN CONFIDENCE INCREASES REGARDING THE CONVECTIVE OVERTURNING ACROSS THE HIGH PLAINS AND THE TIMING OF THE UPPER TROUGH. ..DARROW.. 03/14/2012 Could be an interesting birthday for me, and I'll also remind you that this date has some severe weather history... There's probably going to be a lot of chasers on this as well, if it plays out to become a significant event. Link to comment Share on other sites More sharing options...
tornadotony Posted March 14, 2012 Author Share Posted March 14, 2012 That's true. I actually think its dryline placement is a little unrealistic on Sunday, and would probably pull back at least 50-75 mi. further west. If so, that would put the dryline slightly closer to what upper forcing there is and increase the chance of convection. To my eyes, the H+240 panel looks like another potentially volatile Plains setup, with a more broad-based trough than we're dealing with this first go-around. It could easily be a ridge tomorrow morning, of course. Regardless, really difficult to wrap one's head around the next 10 days as depicted on the ECMWF being mid-March. Whatever the time may be, though, it lends credence to my current thinking, which is that the trough behind this one (because this one will likely lift and keep a good bit of the eastern warm sector intact) will likely pose a bigger threat. Link to comment Share on other sites More sharing options...
blackjack123 Posted March 14, 2012 Share Posted March 14, 2012 Whatever the time may be, though, it lends credence to my current thinking, which is that the trough behind this one (because this one will likely lift and keep a good bit of the eastern warm sector intact) will likely pose a bigger threat. I am starting to feel a little eerie myself. In my area(Central Kansas) we could have a number of days with temps in the upper 70s to as high as 85 in some areas and dewpoints well into the 60s which is high for this time of the year. There is a 5 day area highlited for Western Kansas. Like you all said earlier May 4, 2007. Is this going to shift east overtime. Will this be like a dry line setup? Will it be a multiple day outbreak? I know its to hard to say at this point but I get this feeling something very bad is going to happen. Link to comment Share on other sites More sharing options...
andyhb Posted March 14, 2012 Share Posted March 14, 2012 Is this going to shift east overtime. Will this be like a dry line setup? Will it be a multiple day outbreak? I know its to hard to say at this point but I get this feeling something very bad is going to happen. Yes this will likely be a dryline setup for someone. 18z GFS looks better than 12z for Sunday, and possibly even Monday too, still some veer-back-veer profiles, but it isn't nearly as apparent as some of the runs yesterday. And then in the longer ranges, it shunts the ridge east and another trough drops into the west coast. Note this wind profile/hodograph from DDC from 18z on May 23rd, 2008 (it is similar to a lot of the wind profiles I'm seeing for Sunday/Monday): And then look at this instability at 51 hours on the 18z NAM, yes that is 4000 J/kg popping there, and we may be able to expect values like this come Sunday/Monday. There are also lift indices of -10 and below: Link to comment Share on other sites More sharing options...
PatrickSumner Posted March 15, 2012 Share Posted March 15, 2012 Too many questions, but yes this will likely be a dryline setup for someone. 18z GFS looks better than 12z for Sunday, and possibly even Monday too, still some veer-back-veer profiles, but it isn't nearly as apparent as some of the runs yesterday. And then in the longer ranges, it shunts the ridge east and another trough drops into the west coast. Note this wind profile/hodograph from DDC from 18z on May 23rd, 2008 (it is similar to a lot of the wind profiles I'm seeing for Sunday/Monday: And then look at this instability at 51 hours on the 18z NAM, yes that is 4000 J/kg popping there, and we may be able to expect values like this come Sunday/Monday. There are also lift indices of -10 and above: Looks like a threat further east too??? Link to comment Share on other sites More sharing options...
andyhb Posted March 15, 2012 Share Posted March 15, 2012 Looks like a threat further east too??? Probably mostly heavy rain further east. Allow me to remind you that this is mainly a Plains threat, with the meridional nature of the trough...I know you are eager to see something in your neighbourhood, but this system will probably not be the one to give it to you... Link to comment Share on other sites More sharing options...
hm8 Posted March 15, 2012 Share Posted March 15, 2012 Looks like a threat further east too??? Every one of your posts in this thread have been something like this. Take some time and read what others are saying and you'd get your answer. Link to comment Share on other sites More sharing options...
andyhb Posted March 15, 2012 Share Posted March 15, 2012 00z GFS looks impressive for Sunday from an SLP/H5 perspective (reminds me very much of the 00z Euro last night) although the veer-back-veer profiles may be showing up again, it would be nice if the upper level flow wasn't quite so meridional... Monday: Link to comment Share on other sites More sharing options...
tornadotony Posted March 15, 2012 Author Share Posted March 15, 2012 There's no veer-back-veer from cntrl KS through OK and nrn TX...gotta say...I'm growing more impressed...slowly. I would like to see stronger upper-level flow (250 hPa). Link to comment Share on other sites More sharing options...
andyhb Posted March 15, 2012 Share Posted March 15, 2012 There's no veer-back-veer from cntrl KS through OK and nrn TX...gotta say...I'm growing more impressed...slowly. I would like to see stronger upper-level flow (250 hPa). And now that I look closer, Central/Eastern KS/OK into MO/AR looks pretty nasty on Monday, very little veer-back-veer and on wundermaps, the GFS actually visually pops a bunch of convection between 12z and 06z Tuesday in this area... Near SGF at 00z: Link to comment Share on other sites More sharing options...
andyhb Posted March 15, 2012 Share Posted March 15, 2012 If the Euro holds serve and we see another day 4-8 outlook, I'm leaning towards starting a specific thread for this in C/W, considering it is likely the region that will be most affected by this and then leaving this thread for further threats later in the month. Edit: Euro a bit less favorable than the GFS, but at least the trend of keeping the trough in one piece through Monday continues. GFS ensembles on board with the OP, generally speaking: Link to comment Share on other sites More sharing options...
andyhb Posted March 15, 2012 Share Posted March 15, 2012 Lol...if the last major outbreak of tornadoes in the Plains was in 2010...what was May 24th last year? Henry Margusity http://www.accuweath...by-sunday/62750 Link to comment Share on other sites More sharing options...
andyhb Posted March 15, 2012 Share Posted March 15, 2012 Given relative model concensus, the fact that the C/W forum area is likely to be the main/only area impacted by this system and that we are now entering the closer range, I think it's about time to start a specific thread for this board. Both Sunday and Monday have been outlined from the SPC. DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0334 AM CDT THU MAR 15 2012 VALID 181200Z - 231200Z ...DISCUSSION... ECMWF/GFS CONTINUE TO SUGGEST A PROGRESSIVE...ALBEIT SLOW-MOVING...UPPER TROUGH WILL TRANSLATE ACROSS THE WRN U.S. INTO THE PLAINS DURING THE MEDIUM RANGE PERIOD. LEADING EDGE OF STRONGER FLOW ALOFT SHOULD SPREAD ACROSS THE LEE TROUGH/DRY LINE FROM WRN NEB INTO WEST TX BY SUNDAY EVENING. ANY STORMS THAT DEVELOP ALONG THIS BOUNDARY COULD POTENTIALLY ORGANIZE AS 500MB FLOW INCREASES IN EXCESS OF 50-70KT. BY DAY5 STRONGER FORCING WILL SPREAD DOWNSTREAM AND THE GREATEST SEVERE THREAT IS EXPECTED TO EXTEND FROM THE KS/OK BORDER...SWWD INTO THE HILL COUNTRY OF TX. BEYOND DAY5 THERE IS CONSIDERABLE UNCERTAINTY REGARDING THE SPEED/MOVEMENT OF THE UPPER TROUGH...AS WELL AS CONVECTIVE MODE. ..DARROW.. 03/15/2012 Either way, the chasers are going to be out en masse on this one, in all likelihood. There are still a few variables that need to be worked out (like veer-back-veer shear profiles given the rather meridional nature of the trough), but given the strength of this incoming trough and its resultant kinematics and the highly favorable nature of the warm sector (plentiful low level moisture, instability and a non-thermonuclear cap) I think there is definitely significant potential here, whether that comes from tornadoes, is still somewhat up in the air. Link to comment Share on other sites More sharing options...
andyhb Posted March 15, 2012 Share Posted March 15, 2012 06z GFS really broadens the base of the trough Sunday through Monday (Sunday still has similar potential)... And then Central/Eastern Texas looks nasty on Tuesday...that is a damn impressive run. Link to comment Share on other sites More sharing options...
Derek30 Posted March 15, 2012 Share Posted March 15, 2012 Definitely looks like an impressive multi-day event on the way for the Plains. It's been awhile. Not as long as Henry Margusity says but the point does stand. Last year was awful March through May in southern/central Plains. Things did pick up further north come summer, though. Both the ECMWF and GFS would bring some elevated convection into southern Manitoba on Monday or Monday night. ECMWF would be the more favorable solution for me as it keeps me just east of the low centre and frontal boundary longer. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.