Hoosier Posted November 2, 2017 Author Share Posted November 2, 2017 10 minutes ago, Stebo said: Yeah not much to decipher from the NAM at this point. If anything the inverse NAM principle is in effect. Something I noticed is that even with the weaker surface low, the low level flow in the warm sector looks a hair less veered than the 18z GFS. Link to comment Share on other sites More sharing options...
Stebo Posted November 2, 2017 Share Posted November 2, 2017 2 minutes ago, Hoosier said: Something I noticed is that even with the weaker surface low, the low level flow in the warm sector looks a hair less veered than the 18z GFS. Not surprising since GFS is so notorious for veering the low level flow. The Euro is more backed as well too, which would lead to more credence that the GFS is struggling with low level winds. Link to comment Share on other sites More sharing options...
Indystorm Posted November 2, 2017 Share Posted November 2, 2017 Caveat emptor as always at NAM at 84 but at least it didn't lose the storm. Been rewatching videos of the Washington IL tornado of four years ago and waiting to see what future model runs say. Right now I think any sig tornado activity might be best positioned in north central IL and IN closer to that warm front but things could change. If a stronger southern low does materialize things could get quite interesting. Both Skilling and Sebenste are raising heightened concerns at this time. Link to comment Share on other sites More sharing options...
Stebo Posted November 2, 2017 Share Posted November 2, 2017 The GFS for 3 runs in a row lights up the warm front in Michigan between 18 and 21z, the parameter space is very good there too and the surface winds this run are a bit more backed enhancing the low level shear. Definitely something to monitor and see if it continues as a trend. Link to comment Share on other sites More sharing options...
cyclone77 Posted November 2, 2017 Share Posted November 2, 2017 11 hours ago, Hoosier said: Yeah it does look higher (as currently progged) farther east. Illinois though had widespread 1000-2000+ J/kg that day, which is similar to what's being progged. Bottom line, a high end CAPE day for this time of year with questions on evolution and shear (especially low level). I'd rather have the instability in place and figure out the shear details later compared to the other way around. IIRC the models were somewhat conservative with forecast instability until right before the event when some of the higher res models started to show the higher cape values you mentioned. Link to comment Share on other sites More sharing options...
Hoosier Posted November 2, 2017 Author Share Posted November 2, 2017 9 minutes ago, cyclone77 said: IIRC the models were somewhat conservative with forecast instability until right before the event when some of the higher res models started to show the higher cape values you mentioned. I don't really remember to be honest. The thing I do recall was that we were saying how that outbreak was going to get underway by late morning/noon (and models already had pretty good instability by that time) and that is what happened. Link to comment Share on other sites More sharing options...
cyclone77 Posted November 2, 2017 Share Posted November 2, 2017 20 minutes ago, Hoosier said: I don't really remember to be honest. The thing I do recall was that we were saying how that outbreak was going to get underway by late morning/noon (and models already had pretty good instability by that time) and that is what happened. Blast from the past....thread from the 11/17/13 event.. Link to comment Share on other sites More sharing options...
Stebo Posted November 2, 2017 Share Posted November 2, 2017 Just now, cyclone77 said: Blast from the past....thread from the 11/17/13 event.. Thank you I was going to look for that tonight and read through it. Link to comment Share on other sites More sharing options...
Stebo Posted November 2, 2017 Share Posted November 2, 2017 Already can see on the first page that at this junction of time compared to that event, the models were showing 1000-1500 J/kg, this time it is a bit higher especially if the Euro is correct. Link to comment Share on other sites More sharing options...
Hoosier Posted November 2, 2017 Author Share Posted November 2, 2017 Just in Link to comment Share on other sites More sharing options...
Hoosier Posted November 2, 2017 Author Share Posted November 2, 2017 Those values in northern IL/IN are with temps in the mid 60s... Link to comment Share on other sites More sharing options...
IllinoisWedges Posted November 2, 2017 Share Posted November 2, 2017 4 minutes ago, Hoosier said: Just in Lol, this run has upper 60 dews in C IL. Link to comment Share on other sites More sharing options...
Stebo Posted November 2, 2017 Share Posted November 2, 2017 1 minute ago, Hoosier said: Those values in northern IL/IN are with temps in the mid 60s... Yep 65-68 with dews 63-65, a bit higher along I-70. Definitely a tick upward though. Link to comment Share on other sites More sharing options...
Hoosier Posted November 2, 2017 Author Share Posted November 2, 2017 I think Stebo is onto something about the warm front. This would be roughly in a box including northern IL/northern IN/southern MI. That looks like a potentially intriguing target for enhanced tornado chances if the instability is realized, though everybody in the threat area will have some tornado threat with the large low level hodos. Link to comment Share on other sites More sharing options...
Stebo Posted November 2, 2017 Share Posted November 2, 2017 5 minutes ago, Hoosier said: I think Stebo is onto something about the warm front. This would be roughly in a box including northern IL/northern IN/southern MI. That looks like a potentially intriguing target for enhanced tornado chances if the instability is realized, though everybody in the threat area will have some tornado threat with the large low level hodos. Yeah, also I wouldn't sleep on this lasting after sunset which would be an hour earlier too, the LLJ cranks up by 00z and the atmosphere should remain uncapped as well. It may gel into a QLCS by then though too. Still would have a tornado potential though. Link to comment Share on other sites More sharing options...
andyhb Posted November 2, 2017 Share Posted November 2, 2017 2 hours ago, cyclone77 said: IIRC the models were somewhat conservative with forecast instability until right before the event when some of the higher res models started to show the higher cape values you mentioned. 2 hours ago, Hoosier said: I don't really remember to be honest. The thing I do recall was that we were saying how that outbreak was going to get underway by late morning/noon (and models already had pretty good instability by that time) and that is what happened. Yup that is how it happened. The NAM/GFS also had quite a few issues with timing as well, with some of them quite a bit faster/less amplified with the shortwave than what ended up verifying. The forecast instability (at least from the Euro) here is a tick higher than what we saw then tbh (which was a smaller pocket of ~2000 J/kg CAPE centered around PIA, and eventually utilized by the supercell that spawned the Washington tornado), at the expense of somewhat less impressive shear profiles warm sector wide, at least as it sits now. Link to comment Share on other sites More sharing options...
Stebo Posted November 2, 2017 Share Posted November 2, 2017 Day 4 30% Discussion below Quote ALTHOUGH MODEL TIMING DIFFERENCES EXIST, TRENDS CONTINUE TO POINT TO SEVERE THUNDERSTORMS CAPABLE OF LARGE HAIL, DAMAGING WIND AND ISOLATED TORNADOES ON SUN/D4, ROUGHLY FROM ILLINOIS INTO OHIO. A BROAD AREA OF CYCLONIC FLOW ALOFT WITH DUAL/PARALLEL SHORTWAVE TROUGHS WILL AFFECT THE UPPER AND MIDDLE MS VALLEYS, AND POINTS EAST INCLUDING THE GREAT LAKES REGION. SOME EARLY DAY STORMS MAY EXIST ACROSS THE REGION AS SOUTHERLY WINDS CREATE LIFT NEAR A WARM FRONT, BUT THE MAIN SEVERE WEATHER THREAT WILL BE NEAR THE SURFACE LOW AND COLD FRONT AS IT SWEEPS EASTWARD FROM SUNDAY AFTERNOON INTO MONDAY MORNING. COLD TEMPERATURES ALOFT, A CAPPING INVERSION OVER THE WARM SECTOR AND LONG HODOGRAPHS SUGGEST SUPERCELLS MAY BE THE DOMINANT STORM MODE, CREATING DAMAGING HAIL AND WIND. A FEW TORNADOES WILL ALSO BE POSSIBLE GIVEN A 50 KT LOW-LEVEL JET, AND MOST LIKELY WITH ANY SUPERCELLS THAT CAN TRACK EASTWARD ALONG THE INTERSECTION OF THE COLD FRONT AND WARM FRONT/OUTFLOW BOUNDARY. Link to comment Share on other sites More sharing options...
IllinoisWedges Posted November 2, 2017 Share Posted November 2, 2017 Link to comment Share on other sites More sharing options...
andyhb Posted November 2, 2017 Share Posted November 2, 2017 Probably a good time for a separate thread on this? Seems to have the octane for its own discussion away from the more general severe stuff. Link to comment Share on other sites More sharing options...
Hoosier Posted November 10, 2017 Author Share Posted November 10, 2017 18z GFS continues with the impressive looking weekend system, though still faster than the Euro. Too early to get deep into details, but it should have at least some severe potential if it evolves anything like the models are suggesting (has a decent EML/steep lapse rates... not quite like the 11/5 system but the rapidly deepening surface low is obviously a big difference this time). Link to comment Share on other sites More sharing options...
andyhb Posted November 10, 2017 Share Posted November 10, 2017 1 hour ago, Hoosier said: 18z GFS continues with the impressive looking weekend system, though still faster than the Euro. Too early to get deep into details, but it should have at least some severe potential if it evolves anything like the models are suggesting (has a decent EML/steep lapse rates... not quite like the 11/5 system but the rapidly deepening surface low is obviously a big difference this time). Naturally the Euro has it coming through on November 17th... Did have enough CAPE in IL to cause some issues (60˚F Tds to PIA) given the degree of shear as well, although I'd like to see some colder temps aloft and sfc temps are also on the cool side, only 60-65˚F. Heh, merge this system with the amount of instability/moisture there was last week and you have yourself a whopper of course. Link to comment Share on other sites More sharing options...
Hoosier Posted November 11, 2017 Author Share Posted November 11, 2017 25 minutes ago, andyhb said: Naturally the Euro has it coming through on November 17th... Did have enough CAPE in IL to cause some issues (60˚F Tds to PIA) given the degree of shear as well, although I'd like to see some colder temps aloft and sfc temps are also on the cool side, only 60-65˚F. Heh, merge this system with the amount of instability/moisture there was last week and you have yourself a whopper of course. Bigly trouble, lol If nothing else, a squall line/wind threat would be in play with even just a bit of CAPE, given the progged dynamics/deepening surface low. Link to comment Share on other sites More sharing options...
Stebo Posted November 11, 2017 Share Posted November 11, 2017 2 minutes ago, Hoosier said: Bigly trouble, lol If nothing else, a squall line/wind threat would be in play with even just a bit of CAPE, given the progged dynamics/deepening surface low. Yeah a squall line threat looks pretty likely with this set up at current capacity. Link to comment Share on other sites More sharing options...
andyhb Posted November 11, 2017 Share Posted November 11, 2017 59 minutes ago, Hoosier said: Bigly trouble, lol If nothing else, a squall line/wind threat would be in play with even just a bit of CAPE, given the progged dynamics/deepening surface low. Euro gets it down to 968 mb at noon Saturday, when in November... Link to comment Share on other sites More sharing options...
Hoosier Posted November 11, 2017 Author Share Posted November 11, 2017 10 minutes ago, andyhb said: Euro gets it down to 968 mb at noon Saturday, when in November... Other than the Octobomb, that would rank well among the all-timers in Fall, pressure wise. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted November 11, 2017 Share Posted November 11, 2017 Would like to see the timing change a little bit on the GFS for severe, it has the cold front coming through between 06-12z. Link to comment Share on other sites More sharing options...
Hoosier Posted November 11, 2017 Author Share Posted November 11, 2017 15 minutes ago, CheeselandSkies said: Would like to see the timing change a little bit on the GFS for severe, it has the cold front coming through between 06-12z. Daylight timing would be nice, though a dynamically driven setup of this magnitude would likely have a severe threat extending after dark. Link to comment Share on other sites More sharing options...
Jim Martin Posted November 11, 2017 Share Posted November 11, 2017 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted November 11, 2017 Share Posted November 11, 2017 Damn this thing flies on the GFS. Western Kansas at 0z FRI to northern Iowa six hours later. Oh to see a cyclone like that in May. Link to comment Share on other sites More sharing options...
IWXwx Posted November 11, 2017 Share Posted November 11, 2017 13 hours ago, Hoosier said: 18z GFS continues with the impressive looking weekend system, though still faster than the Euro. Too early to get deep into details, but it should have at least some severe potential if it evolves anything like the models are suggesting (has a decent EML/steep lapse rates... not quite like the 11/5 system but the rapidly deepening surface low is obviously a big difference this time). Lol at Megan Dodson at IWX in describing the Euro/GFS differences: "A big upper level low is forecast to develop over the Great Lakes, though the placement and strength of the low at this point is up in the air-no pun intended. The consensus blend lost it's mind with 80 percent pops in the Thursday night into Friday evening forecast. This may certainly pan out if we get the upper low, but at this point given significant discrepancies opted to cut them to more reasonable levels-like 30-55%." Link to comment Share on other sites More sharing options...
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