Indystorm Posted November 11, 2017 Share Posted November 11, 2017 18z GFS today has a 990 system over Chi town at 18z next Friday. Maybe the antecedent system on this coming Wed. might serve as an appetizer and moisten things up a bit for the main entree. Interesting weather ahead as systems normally speed up and deepen as we get into the late fall season. Terrific 130 knot 300 mb jet over St, Louis punching into central IL at that hour. 377 surface CAPE around Champaign/Urbana at this early stage in the game. Low topped squall line most probable at this time frame. Link to comment Share on other sites More sharing options...
Hoosier Posted November 12, 2017 Author Share Posted November 12, 2017 Not saying to not look at CAPE progs, but I'm paying more attention to this at this point Just get decent to good mid level lapse rates into the warm sector and you take your chances. Low level warm/moist advection should be pretty stout in this type of setup, and we may need to heavily rely on that as sun may be hard to come by (obviously that would increase the threat) The twitter hype should be a joy if this thing actually falls on the anniversary of 11/17/13. Link to comment Share on other sites More sharing options...
Chinook Posted November 12, 2017 Share Posted November 12, 2017 In the next few days, you may want to take a look at Euro CAPE maps, which now can be viewed for free. Last night's 00z Euro had some CAPE of about 1000 J/kg near Memphis for this storm. That's why I am thinking this may be a severe event farther south than most of the members of this sub-forum. Link to comment Share on other sites More sharing options...
Hoosier Posted November 12, 2017 Author Share Posted November 12, 2017 imo, but wouldn't be surprised to see SPC outlook a risk area in the next day or two, provided we have relative model/ensemble agreement. Yes, the thermodynamics don't jump off the page (as is often the case at this time of year), but there's something to be said for synoptically evident severe wx setups. And I think we're close enough on the thermodynamics that some relatively small tweaks would make things look quite a bit more threatening in the presence of these dynamics. Link to comment Share on other sites More sharing options...
Hoosier Posted November 12, 2017 Author Share Posted November 12, 2017 12z Euro came in slower, but has some surface CAPE even at 12z Saturday. Point being, there could be a threat even if a diurnally unfavorable solution like this pans out. Link to comment Share on other sites More sharing options...
Indystorm Posted November 12, 2017 Share Posted November 12, 2017 18z GFS for today outlooks the Keokuk IA area on eastward as the place to be for possible svr Friday afternoon with good lapse rates, helicity, and suface CAPE of 577. Of course this will change as we get closer with a slower EURO but at least there is the possibility with a deepening low pressure moving into the Midwest. Link to comment Share on other sites More sharing options...
Stebo Posted November 13, 2017 Share Posted November 13, 2017 Some of the Euro ensembles, about 40% have better instability than the operational. Would be interesting to see how that shakes out. Link to comment Share on other sites More sharing options...
snowlover2 Posted November 13, 2017 Share Posted November 13, 2017 Large day 5 15% area has been added. Quote Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0355 AM CST Mon Nov 13 2017 Valid 161200Z - 211200Z ...DISCUSSION... Latest runs of the GFS and ECMWF appear very internally consistent, with respect to runs from 24 hours ago. However, they remain similarly inconsistent each other with respect to timing as was the case yesterday. As the developing surface cold front crosses the central U.S. late Day 4 (Thursday 11-16) and then Day 5 (Friday 11-17), and finally across the eastern U.S. Day 6 (Saturday 11-18), a 9 to 12 hour timing difference persists between the two models. With that said, the overall pattern continues to suggest a linear band of frontal convection, occurring within a pre-frontal environment featuring modest CAPE but very strong flow from the lower troposphere to upper levels. As such, damaging winds would be the main severe potential, with degree of risk at least partially modulated by the degree of CAPE and associated intensity of the convection. Given this potential, a 15% risk area is being introduced at this time, from the Midwest to the Arklatex vicinity. Partially due to timing differences between the models, a rather large area is being included in the risk, with fine-tuning of the lines left for later outlooks as evolution becomes more certain. At this time, an outlook area will not be included for Day 6 over the eastern U.S., as the GFS shows the front moving offshore during the first few hours of the period, while the ECMWF depicts the front still lying west of the Appalachians through midday. Depending upon the actual evolution, a risk area may be required in later forecasts. ..Goss.. 11/13/2017 Link to comment Share on other sites More sharing options...
Hoosier Posted November 14, 2017 Author Share Posted November 14, 2017 No matter how the Euro comes in, there's still going to be some significant timing differences among the models. GFS is the quickest and given the historical bias, it's easy to figure that it's too fast. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted November 14, 2017 Share Posted November 14, 2017 Risk area removed for Day 4. Link to comment Share on other sites More sharing options...
Indystorm Posted November 14, 2017 Share Posted November 14, 2017 46 minutes ago, CheeselandSkies said: Risk area removed for Day 4. But SPC will re evaluate the EURO in future runs to see if a risk area needs to possibly be re introduced. Link to comment Share on other sites More sharing options...
Chicago Storm Posted November 14, 2017 Share Posted November 14, 2017 It really wasn't going to be worth a D5 outlined risk anyway. They were way too optimistic too far in advance, just like the last event.Probably will see a low end slight somewhere come Friday. Link to comment Share on other sites More sharing options...
Hoosier Posted November 14, 2017 Author Share Posted November 14, 2017 25 minutes ago, Chicago Storm said: It really wasn't going to be worth a D5 outlined risk anyway. They were way too optimistic too far in advance, just like the last event. Probably will see a low end slight somewhere come Friday. They were too far north last time, but it's not like that event fell apart (2 dozen tornadoes and a decent number of wind/hail reports). Link to comment Share on other sites More sharing options...
Hoosier Posted November 14, 2017 Author Share Posted November 14, 2017 This really comes down to the evolution. If we get an outcome with a rapidly deepening low into the 980s or lower as it's moving through the lakes, then I think we could get a respectable severe event (at least wind; for a recent such example of a lot of wind reports with very little instability, look at 10/31/13). If the flatter/weaker solution pans out, then I'd agree with lower end. Link to comment Share on other sites More sharing options...
Radtechwxman Posted November 14, 2017 Share Posted November 14, 2017 I'm not digging this trend of systems to look so potent in the long range and get weaker as we get closer. It needs to be the other way around. Ha. But based on what I'm seeing I totally agree with you guys. If we see a weaker low and more neutral to positive tilt then I see a marginal to low end slight. If we get the bomb that gfs had before with a potent neg tilt then I say an enhanced is not out of the question. Hopefully sampling in a day or so will help models come to a better consensus Link to comment Share on other sites More sharing options...
CheeselandSkies Posted November 14, 2017 Share Posted November 14, 2017 44 minutes ago, StormChaser4Life said: I'm not digging this trend of systems to look so potent in the long range and get weaker as we get closer. It needs to be the other way around. Ha. I know, right? It seems to have been particularly bad this year, ever since all these model "upgrades." I think I've seen more potentially high-end/high-impact systems fizzle on the GFS in the 84-120 hour range than ever before. One of these years, the atmosphere is going to produce a real big dog over the central CONUS again. The question is, will the weather enterprise see it coming in time to introduce enhanced wording in the medium range, or will they have become gun-shy after all these "false alarms"? Even the mighty EURO has had issues at times with modeling patterns a lot more ominous/hazardous than they turned out to be. Link to comment Share on other sites More sharing options...
Radtechwxman Posted November 14, 2017 Share Posted November 14, 2017 2 hours ago, CheeselandSkies said: I know, right? It seems to have been particularly bad this year, ever since all these model "upgrades." I think I've seen more potentially high-end/high-impact systems fizzle on the GFS in the 84-120 hour range than ever before. One of these years, the atmosphere is going to produce a real big dog over the central CONUS again. The question is, will the weather enterprise see it coming in time to introduce enhanced wording in the medium range, or will they have become gun-shy after all these "false alarms"? Even the mighty EURO has had issues at times with modeling patterns a lot more ominous/hazardous than they turned out to be. Yea it does seems like models are struggling more. Esp the GFS. It is way over amped far out. It did the same thing with the Nov 5th storm system. I would love another Groundhogs Day Blizzard like in 2011. It's been a while since we had a solid 1ft+ snowstorm in my area. But regarding severe I think with the strong wind fields we could see a low topped squall but if this trough ends up more positive tilt we can see more of an anafrontal event with more forcing behind the front. That would kill severe potential Link to comment Share on other sites More sharing options...
Hoosier Posted November 14, 2017 Author Share Posted November 14, 2017 Can I trot out the ol argument about RAOB sampling? Seemed like we had pretty good agreement on a deeper system when the upper level wave was in the Alaska area, say, on Sunday. Link to comment Share on other sites More sharing options...
Stebo Posted November 14, 2017 Share Posted November 14, 2017 7 minutes ago, Hoosier said: Can I trot out the ol argument about RAOB sampling? Seemed like we had pretty good agreement on a deeper system when the upper level wave was in the Alaska area, say, on Sunday. Hail Mary pass Honestly I think it is safe to say we can sack this one. Link to comment Share on other sites More sharing options...
Hoosier Posted November 14, 2017 Author Share Posted November 14, 2017 9 minutes ago, Stebo said: Hail Mary pass Honestly I think it is safe to say we can sack this one. It's true though that we started seeing those weaker solutions after it moved offshore. I'm not necessarily saying it's because of that, as there could simply be something that changed in this setup to lead to the recent weaker runs. Link to comment Share on other sites More sharing options...
Stebo Posted November 14, 2017 Share Posted November 14, 2017 25 minutes ago, Hoosier said: It's true though that we started seeing those weaker solutions after it moved offshore. I'm not necessarily saying it's because of that, as there could simply be something that changed in this setup to lead to the recent weaker runs. Oh I know, I think the key though is the phasing, the Northern stream sped up since then too. Thus the fractured attempt at phasing instead of previous runs. Link to comment Share on other sites More sharing options...
andyhb Posted November 15, 2017 Share Posted November 15, 2017 Watch this whole schtick carry over to next spring. Link to comment Share on other sites More sharing options...
cmillzz Posted November 15, 2017 Share Posted November 15, 2017 No surprises there. Every and I mean EVERY storm system has trended south and weaker this year. Very foul pattern we're in that will no doubt carry into winter and spring. Can't even remember that last time I've seen an actual bow echo. Link to comment Share on other sites More sharing options...
Hoosier Posted November 15, 2017 Author Share Posted November 15, 2017 There was a decent low before Halloween, but I can't remember the date so it was probably not all that memorable. Link to comment Share on other sites More sharing options...
Hoosier Posted November 15, 2017 Author Share Posted November 15, 2017 Can we take a minute to marvel at the strung out mess that is the NAM? Wow lol Significantly different than the 00z GFS, which actually ticked back in a favorable direction. Link to comment Share on other sites More sharing options...
Hoosier Posted November 16, 2017 Author Share Posted November 16, 2017 NAM looking a bit MUCAPEy overnight Fri/Saturday. Link to comment Share on other sites More sharing options...
Hoosier Posted November 16, 2017 Author Share Posted November 16, 2017 Wondering what SPC will do on the day 2/day 3 outlooks later. Whatever severe threat materializes is likely to get started overnight Friday/Saturday morning... Link to comment Share on other sites More sharing options...
Chicago Storm Posted November 16, 2017 Share Posted November 16, 2017 Looks like marginal risk as best for now, for Fri/Sat. Link to comment Share on other sites More sharing options...
Hoosier Posted November 16, 2017 Author Share Posted November 16, 2017 The NAM(s) are really bullish on having a major low level inversion in a good chunk of the warm sector. The GFS not so much. Both models have been internally consistent but there is a big gap between them as far as that goes. Link to comment Share on other sites More sharing options...
MichelleH Posted November 16, 2017 Share Posted November 16, 2017 Is anyone else having thunderstorm withdrawals?? I would even be happy with a little thunder and a good lightning show! Link to comment Share on other sites More sharing options...
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