Jim Martin Posted March 12, 2011 Share Posted March 12, 2011 988 mb low on the 22nd at 2 pm edt... I posted this for one reason look at the wind here at 500 mb. 100 knots over southern Missouri and northern Arkansas. Plus 80 knots of shear at 500 mb as well. Link to comment Share on other sites More sharing options...
thewxmann Posted March 12, 2011 Share Posted March 12, 2011 We should just make this the thread for all of next week (er, next weekend and on)... several good opportunities coming up. Link to comment Share on other sites More sharing options...
Jim Martin Posted March 12, 2011 Author Share Posted March 12, 2011 Sounds good to me. Link to comment Share on other sites More sharing options...
Indystorm Posted March 12, 2011 Share Posted March 12, 2011 Not suggesting a repeat of this, of course, since it was so unusual, but look at these comments from the PAH Tri-State tornado webpage and then geographic and meteorological parameters you have referenced for the indicated time period... Models do warrant a good heads up, even if the progged low is over Kansas City. Models will hem and haw all over the place between now and then, however.. That morning, surface low pressure over Northwest Arkansas and Southwest Missouri tracked northeast across Southeast Missouri, Southern Illinois, and Southwest Indiana during the day, reaching Eastern Indiana that evening. Extending east from the low was a warm front, with a cold front trailing to the southwest. As the low tracked northeast during the day, its associated warm front advanced north, allowing warm moist air from the Gulf of Mexico to infiltrate the Tri-State area. In fact, temperatures that started out in the 50s during the morning reached the 60s over most of the tornado track by 1 p.m. and even the 70s in the vicinity of Cairo, Illinois by 4 p.m. So, we know that a lifting mechanism was in place and moisture was abundant with the Gulf opened for business. We can also infer there must have been very good upper-level support. Given the fact that the tornado traveled at speeds of 60 to 70 mph along most of its path, we can safely assume that perhaps a 100-knot upper-level jet max was nosing into the area from the west/southwest. With veering winds (south at the surface becoming west/southwest aloft), wind shear was also present to help initiate the storm’s rotation. There must have been decent instability as well—with warm air advection at the surface and probably cold air advection in the upper levels. Link to comment Share on other sites More sharing options...
jdrenken Posted March 13, 2011 Share Posted March 13, 2011 Give it anywhere from the 22nd-24th. I'm looking at it from a different perspective of 50 days. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 13, 2011 Share Posted March 13, 2011 The 0Z GFS looks a lot more like the 12Z Euro and has a backside shortwave kicking out the Eastern Pacific low by day 6 into the intermountain W. Link to comment Share on other sites More sharing options...
brettjrob Posted March 13, 2011 Share Posted March 13, 2011 The 0Z GFS looks a lot more like the 12Z Euro and has a backside shortwave kicking out the Eastern Pacific low by day 6 into the intermountain W. Looks very impressive for the southern High Plains on Saturday (March 19). Still waiting for third-party sites to update to confirm sufficient moisture/instability, but the several days of ridging ahead of it bodes well in that area. Sunday would likely be active somewhere in the eastern Plains, Midwest, or Ozarks as well. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 13, 2011 Share Posted March 13, 2011 Looks very impressive for the southern High Plains on Saturday (March 19). Still waiting for third-party sites to update to confirm sufficient moisture/instability, but the several days of ridging ahead of it bodes well in that area. Sunday would likely be active somewhere in the eastern Plains, Midwest, or Ozarks as well. all ready set to go to chase sat/sun in the plains, so I'm really hoping everything works out. Haven't had a good weekend chase since june 6th/7th of 2009. Link to comment Share on other sites More sharing options...
TheWeatherPimp Posted March 13, 2011 Share Posted March 13, 2011 Set-up and pattern on both the EURO and now the 00z GFS looks pretty prolific across the Plains and into the Midwest on the 19th and 20th. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 13, 2011 Share Posted March 13, 2011 alot more impressive than the 12z GFS for the 19th..look at that flow Link to comment Share on other sites More sharing options...
Chicago Storm Posted March 13, 2011 Share Posted March 13, 2011 all ready set to go to chase sat/sun in the plains, so I'm really hoping everything works out. Haven't had a good weekend chase since june 6th/7th of 2009. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 13, 2011 Share Posted March 13, 2011 Just the operational--but the 12Z GFS op was a huge outlier amongst its GEFS mean with a positive tilt elongated Pacific trough at 180 hours owing to the large EPO ridge and huge values of planetary vorticity advection on the backside of the low. This retrogrades the back end of the trough which resulted in the elongated upper low. Note the large EPO ridge on the 12Z GFS: Compare to the 0Z at the same time and note the low amplitude jet max undercutting the EPO ridge and merging with the large upper low. This effectively cuts down on the amount of planetary vorticity advection on the backside of the low--and thus it doesn't retrograde and elongate. In other words--it effectively acts as a kicker. I think we can toss the elongated junky looking earlier GFS runs. Compare to the 12Z Euro: Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 13, 2011 Share Posted March 13, 2011 Looks very impressive for the southern High Plains on Saturday (March 19). Still waiting for third-party sites to update to confirm sufficient moisture/instability, but the several days of ridging ahead of it bodes well in that area. Sunday would likely be active somewhere in the eastern Plains, Midwest, or Ozarks as well. It does look interesting- I want to see soundings myself too before I say much--it will be interesting to see how well potential storms do with potential capping as well as what would be somewhat limited CAPE owing to the positive tilt and lack of decent upper level height falls/cooling. Link to comment Share on other sites More sharing options...
brettjrob Posted March 13, 2011 Share Posted March 13, 2011 It does look interesting- I want to see soundings myself too before I say much--it will be interesting to see how well potential storms do with potential capping as well as what would be somewhat limited CAPE owing to the positive tilt and lack of decent upper level height falls/cooling. The maps just came in on TwisterData. A couple things I noticed that, taking this run verbatim, might hold whatever transpires back from being an apocalyptic, 03/28/07-style scenario for the High Plains: 1) Low-level moisture return, while nothing to sneeze at for mid-March, is not perfect thanks to less-than-ideal trajectories into the Gulf. 2) The trough is becoming positively tilted, as you mentioned, and is also maybe a hair slower than ideal. I think speeding this solution up by even 3-6 hours would alter things noticeably, as heights really begin to crash overnight Saturday night on this run. That being said, I would expect CAPE to be higher than indicated on the GFS even if the pattern evolves similarly to what it shows. Its low bias on instability in the medium range has been particularly noticeable so far this year. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 13, 2011 Share Posted March 13, 2011 The maps just came in on TwisterData. A couple things I noticed that, taking this run verbatim, might hold whatever transpires back from being an apocalyptic, 03/28/07-style scenario for the High Plains: 1) Low-level moisture return, while nothing to sneeze at for mid-March, is not perfect thanks to less-than-ideal trajectories into the Gulf. 2) The trough is becoming positively tilted, as you mentioned, and is also maybe a hair slower than ideal. I think speeding this solution up by even 3-6 hours would alter things noticeably, as heights really begin to crash overnight Saturday night on this run. That being said, I would expect CAPE to be higher than indicated on the GFS even if the pattern evolves similarly to what it shows. Its low bias on instability in the medium range has been particularly noticeable so far this year. Agreed, The Euro on the 12z run had a good deal more of CAPE (2000 j/kg) with dew points about the same as the GFS, upper 50's/low 60's. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 13, 2011 Share Posted March 13, 2011 The maps just came in on TwisterData. A couple things I noticed that, taking this run verbatim, might hold whatever transpires back from being an apocalyptic, 03/28/07-style scenario for the High Plains: 1) Low-level moisture return, while nothing to sneeze at for mid-March, is not perfect thanks to less-than-ideal trajectories into the Gulf. 2) The trough is becoming positively tilted, as you mentioned, and is also maybe a hair slower than ideal. I think speeding this solution up by even 3-6 hours would alter things noticeably, as heights really begin to crash overnight Saturday night on this run. That being said, I would expect CAPE to be higher than indicated on the GFS even if the pattern evolves similarly to what it shows. Its low bias on instability in the medium range has been particularly noticeable so far this year. Yeah I agree regarding the GFS and its low bias on instability. Also still a lot of time to get a slightly better upper level height field config either through a slightly faster system or a stronger leading edge ejecting wave/impulse. Agreed, The Euro on the 12z run had a good deal more of CAPE (2000 j/kg) with dew points about the same as the GFS, upper 50's/low 60's. Euro had 2000 j/kg for the 19/20th? Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 13, 2011 Share Posted March 13, 2011 Euro had 2000 j/kg for the 19/20th? Yep in eastern KS and than near 1500 j/kg in central IA on the 20th. Link to comment Share on other sites More sharing options...
brettjrob Posted March 13, 2011 Share Posted March 13, 2011 Just the operational--but the 12Z GFS op was a huge outlier amongst its GEFS mean with a positive tilt elongated Pacific trough at 180 hours owing to the large EPO ridge and huge values of planetary vorticity advection on the backside of the low. This retrogrades the back end of the trough which resulted in the elongated upper low. Note the large EPO ridge on the 12Z GFS: Compare to the 0Z at the same time and note the low amplitude jet max undercutting the EPO ridge and merging with the large upper low. This effectively cuts down on the amount of planetary vorticity advection on the backside of the low--and thus it doesn't retrograde and elongate. In other words--it effectively acts as a kicker. I think we can toss the elongated junky looking earlier GFS runs. Compare to the 12Z Euro: Unfortunately, it looks like this is far from settled right now. A fair number of the 13/00z GEFS members still want to retrograde the trough next weekend, with the operational run being on the more progressive side of the guidance envelope (though not an outlier, by any means). And now I see the ECMWF is significantly slower through D+7, too, though there's still potential for a Plains event on Sunday depending on how things evolve from there. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 13, 2011 Share Posted March 13, 2011 Euro op verbatim would be too slow to do anything Saturday unless one wants to chase mountain convection. More potential exists with secondary ejecting waves after day 7 after this longwave trough de-amplifies and ejects into the plains. Depending on the exact timing--that could be big as the ejecting low would have a much farther S trajectory and a much more potentially impressive height field config. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 13, 2011 Share Posted March 13, 2011 Unfortunately, it looks like this is far from settled right now. A fair number of the 13/00z GEFS members still want to retrograde the trough next weekend, with the operational run being on the more progressive side of the guidance envelope (though not an outlier, by any means). And now I see the ECMWF is significantly slower through D+7, too, though there's still potential for a Plains event on Sunday depending on how things evolve from there. Ha--you just beat me to it. I will have to take a look at the GEFS. But yeah--Euro op is a tick slower. Should that occur--at least there is still a ton of potential later on as that longwave de-amplfies and ejects into the plains. Link to comment Share on other sites More sharing options...
kab2791 Posted March 13, 2011 Share Posted March 13, 2011 Nonetheless, look at that warmth. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 13, 2011 Share Posted March 13, 2011 Ha--you just beat me to it. I will have to take a look at the GEFS. But yeah--Euro op is a tick slower. Should that occur--at least there is still a ton of potential later on as that longwave de-amplfies and ejects into the plains. The more I think about it--the less I like Saturday afternoon/evening. The Euro being a tick slower is not a surprise--and these developing long waves almost always trend a tick slower. The lack of any significant leading edge shortwave apparent in either the Euro or GFS leads me to believe the GFS is too fast--and this will only continue to trend slower with time unless some unforeseen developments occur. Link to comment Share on other sites More sharing options...
Stebo Posted March 13, 2011 Share Posted March 13, 2011 Nonetheless, look at that warmth. Indeed sir indeed and no snow pack left to modify it too. Link to comment Share on other sites More sharing options...
brettjrob Posted March 13, 2011 Share Posted March 13, 2011 The more I think about it--the less I like Saturday afternoon/evening. The Euro being a tick slower is not a surprise--and these developing long waves almost always trend a tick slower. The lack of any significant leading edge shortwave apparent in either the Euro or GFS leads me to believe the GFS is too fast--and this will only continue to trend slower with time unless some unforeseen developments occur. I tend to agree with you, at this point. The Euro is out all the way now and looks to be about 24 hr. slower than the GFS; right on the verge of being too late for a Sunday show. I wouldn't mind a compromise verifying, which would likely set up a substantial event somewhere in the Plains on Sunday, but it may well be even slower in reality. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 13, 2011 Share Posted March 13, 2011 upper 50's dews points isn't going to cut it. Link to comment Share on other sites More sharing options...
brettjrob Posted March 13, 2011 Share Posted March 13, 2011 upper 50's dews points isn't going to cut it. Depends on location. The 12z GFS for next Saturday actually shares a lot of quantitative similarities with the 2007-04-21 Tulia outbreak along the I-27 corridor, which was highlighted by low-mid 50s dew points along the instability axis. I'm sure you remember the seemingly-unimpressive moisture on the Dumas day last year, too. If we can get a setup on the western High Plains (over 3000 ft.) on the first day this trough begins to eject, I think it holds some significant potential. Climo says it's quite a rarity to see sig svr out there this early, of course, so I'm not holding my breath until we get a few days closer. I do agree that the modified moisture return may not cut it for a big event farther E, though. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 13, 2011 Share Posted March 13, 2011 Depends on location. The 12z GFS for next Saturday actually shares a lot of quantitative similarities with the 2007-04-21 Tulia outbreak along the I-27 corridor, which was highlighted by low-mid 50s dew points along the instability axis. I'm sure you remember the seemingly-unimpressive moisture on the Dumas day last year, too. If we can get a setup on the western High Plains (over 3000 ft.) on the first day this trough begins to eject, I think it holds some significant potential. Climo says it's quite a rarity to see sig svr out there this early, of course, so I'm not holding my breath until we get a few days closer. I do agree that the modified moisture return may not cut it for a big event farther E, though. Yep I remember that day ..think we were pulling low 60 dews into the northern TX PH, I have my sfc map around here somewhere, I will put it up if I find it. further north in CO had tors I believe as well that day. found it, did this after we ate lunch in Dalhart. a bit hard to see but had upper 50's near 60 dew points at 18z acoss the northern TX PH with low 60's near CDS Link to comment Share on other sites More sharing options...
tornadotony Posted March 13, 2011 Share Posted March 13, 2011 This system is just the bellwether for what's to come after. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 13, 2011 Share Posted March 13, 2011 Geez Sunday in western OK looks quite nice with that tight dryline with backed sfc winds ahead of it with low 60 dews pooling on it with decent instability and good shear. can't get too giddy yet given were a week away Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 13, 2011 Share Posted March 13, 2011 Not posted last nite--the Euro ensemble mean is a bit more positive tilt than the neutral op. Not terribly impressive looking--although it is a tick faster. Link to comment Share on other sites More sharing options...
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