baroclinic_instability Posted March 1, 2012 Share Posted March 1, 2012 Posted in the OV winter thread, might as well post here too. Also likely why many of the SREF members are all amped up too. Worth watching to see if the globals take more of a rapid intensification approach as it will have a significant influence on the warm sector development/low level flow response. Usually there are strong reasons to be suspect of anything the NAM does, especially when it tends to be a big outlier on the synoptic handling of a system, but the NAM here does (considering it is initializing correctly...always a big "if" these days it seems) have some utility here as this system will be deepening strongly off relatively extreme low level frontogenetic/upper jet scale properties. The cyclone itself is pretty small, and it will also have a strong warm sector moisture feed, so this will also have a tendency to force rapid pressure falls if this comes together correctly. Moist frontogenesis has been known to be drivers for storm intensification...rather rapidly sometimes. The meso models will have a slight "edge" w.r.t. this. 0Z RGEM is not too far off the NAM either. Link to comment Share on other sites More sharing options...
Stebo Posted March 1, 2012 Share Posted March 1, 2012 Posted in the OV winter thread, might as well post here too. Also likely why many of the SREF members are all amped up too. Worth watching to see if the globals take more of a rapid intensification approach as it will have a significant influence on the warm sector development/low level flow response. Usually there are strong reasons to be suspect of anything the NAM does, especially when it tends to be a big outlier on the synoptic handling of a system, but the NAM here does (considering it is initializing correctly...always a big "if" these days it seems) have some utility here as this system will be deepening strongly off relatively extreme low level frontogenetic/upper jet scale properties. The cyclone itself is pretty small, and it will also have a strong warm sector moisture feed, so this will also have a tendency to force rapid pressure falls if this comes together correctly. Moist frontogenesis has been known to be drivers for storm intensification...rather rapidly sometimes. The meso models will have a slight "edge" w.r.t. this. 0Z RGEM is not too far off the NAM either. I copied this into the GLOV thread also, very very good points here. GFS stepping in the direction of a stronger solution with the 00z also.. Link to comment Share on other sites More sharing options...
JoMo Posted March 1, 2012 Share Posted March 1, 2012 Even though the NAM is always suspect, it did handle the "Leap Day" outbreak fairly well. The GFS didn't have enough instability and the dewpoints were too low. Link to comment Share on other sites More sharing options...
andyhb Posted March 1, 2012 Share Posted March 1, 2012 Even though the NAM is always suspect, it did handle the "Leap Day" outbreak fairly well. The GFS didn't have enough instability and the dewpoints were too low. It also didn't keep the surface winds backed. Link to comment Share on other sites More sharing options...
tornadotony Posted March 1, 2012 Share Posted March 1, 2012 The GFS is stronger and slower. Notably so. Link to comment Share on other sites More sharing options...
andyhb Posted March 1, 2012 Share Posted March 1, 2012 The GFS is stronger and slower. Notably so. I also think it underdoes the low level wind response with that deepening SLP. Link to comment Share on other sites More sharing options...
CUmet Posted March 1, 2012 Share Posted March 1, 2012 I too am wary of the secondary low development in the South, which has been hinted at by the various models over at least the past few runs. Even if it were to pan out as currently progged, the local backing of the surface winds and the enhanced LLJ would increase helicities and could result in an elevated evening/overnight tornado threat over portions of northern AL/GA and into SC by dawn, despite the possibly quasi-linear convective mode. As noted by others, the next couple model runs are really important as the main vorticity max comes onshore. As it stands now, I don't see a high risk type of event out of this, but some subtle changes in the trough evolution could change that. Link to comment Share on other sites More sharing options...
JoMo Posted March 1, 2012 Share Posted March 1, 2012 That's a large Day 2 moderate risk with a 45% hatched area. http://www.spc.noaa.gov/products/outlook/day2otlk.html Link to comment Share on other sites More sharing options...
beneficii Posted March 1, 2012 Author Share Posted March 1, 2012 The GFS is stronger and slower. Notably so. I don't see how it's slower. Are you talking about overnight or on Saturday for the Carolinas? Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 1, 2012 Share Posted March 1, 2012 Some of the guidance, namely the stronger bombed solutions like NAM/RGEM, completely wipe out the cap across a broad region of the low level WAA zone feeding into the rapidly bombing cyclone across KY and initiate clusters of discrete supercells. That would pose big problems. It seems SPC is definitely siding with the stronger regional/mesoscale guidance. Link to comment Share on other sites More sharing options...
SmokeEater Posted March 1, 2012 Share Posted March 1, 2012 Mods, just a suggestion, since this threat is spread out over 3 different subforums, with separate threads in each, is there any way we could possibly do 1 obs thread for the now casting part of the event at least, in this forum? This way everyone isn't spread out. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 1, 2012 Share Posted March 1, 2012 Mods, just a suggestion, since this threat is spread out over 3 different subforums, with separate threads in each, is there any way we could possibly do 1 obs thread for the now casting part of the event at least, in this forum? This way everyone isn't spread out. Discussing this. Trying to see if we can find a better way to have all disco in one thread for the bigger outbreaks spanning multiple subforums. Doesn't really make sense to have multiple threads discussing the same event, at least IMO. Link to comment Share on other sites More sharing options...
Hoosier Posted March 1, 2012 Share Posted March 1, 2012 This is Ohio on March 2? Really? Link to comment Share on other sites More sharing options...
SmokeEater Posted March 1, 2012 Share Posted March 1, 2012 Discussing this. Trying to see if we can find a better way to have all disco in one thread for the bigger outbreaks spanning multiple subforums. Doesn't really make sense to have multiple threads discussing the same event, at least IMO. Exactly, thanks man. I just worry a lot of good knowledge is getting missed by the different forums. Link to comment Share on other sites More sharing options...
Cheeznado Posted March 1, 2012 Share Posted March 1, 2012 That sounding is unreal for any time of year and any place. That looks like what I was seeing on the models (with less CAPE of course) in AL/MS last April. Link to comment Share on other sites More sharing options...
QVectorman Posted March 1, 2012 Share Posted March 1, 2012 This is Ohio on March 2? Really? Even more impressive than the KIND sounding from earlier in the thread. Same problem though subsidence progged to be over the area With best lift still about 100 miles west. Link to comment Share on other sites More sharing options...
andyhb Posted March 1, 2012 Share Posted March 1, 2012 This is Ohio on March 2? Really? That is incredible. I mean seriously, an EHI of 10.5 on March 2nd? Link to comment Share on other sites More sharing options...
LouWX Posted March 1, 2012 Share Posted March 1, 2012 Amazing soundings and hodos in the OH valley. biggest question is why QPF output is so low in these locales. seems convection may pop by reaching convective temp... nam says that is 74 for sdf at 21z. seems attainable. For the record ECMWF does blow up warm sector QPF more so. thoughts? Link to comment Share on other sites More sharing options...
QVectorman Posted March 1, 2012 Share Posted March 1, 2012 Amazing soundings and hodos in the OH valley. biggest question is why QPF output is so low in these locales. seems convection may pop by reaching convective temp... nam says that is 74 for sdf at 21z. seems attainable. For the record ECMWF does blow up warm sector QPF more so. thoughts? Just said it prior...it's because there is subsidence being forecasted at 850/700/500 mb levels due to mid/upper level forcing synoptically/dynamically. Link to comment Share on other sites More sharing options...
Cheeznado Posted March 1, 2012 Share Posted March 1, 2012 Just said it prior...it's because there is subsidence being forecasted at 850/700/500 mb levels due to mid/upper level forcing synoptically/dynamically. Really not worried about this- I would be shocked to see little precip like the NAM has. This may actually help keep cells more discrete. There will be strong tornadoes tomorrow if the NAM is close to correct. Link to comment Share on other sites More sharing options...
QVectorman Posted March 1, 2012 Share Posted March 1, 2012 If one was to go with the GFS central MS and surrounding region at 18z is about the only place I would bet money on producing tornadoes for this whole event. Decent soundings over that area. Every place else seems borderline wrt to tornado genesis. Svr storms w/ strong wind likely in the other areas as already discussed by the SPC. NAM solution nothing really jumps out at me. It pretty much keeps the best lift to the west of the best thermodynamics and shear every where the entire time period of 18z-0z Link to comment Share on other sites More sharing options...
andyhb Posted March 1, 2012 Share Posted March 1, 2012 If one was to go with the GFS central MS and surrounding region at 18z is about the only place I would bet money on producing tornadoes for this whole event. Decent soundings over that area. Every place else seems borderline wrt to tornado genesis. Svr storms w/ strong wind likely in the other areas as already discussed by the SPC. NAM solution nothing really jumps out at me. It pretty much keeps the best lift to the west of the best thermodynamics and shear every where the entire time period of 18z-0z If you have too much lift, too much convection will go up and you'll get a linear mess. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 1, 2012 Share Posted March 1, 2012 Really not worried about this- I would be shocked to see little precip like the NAM has. This may actually help keep cells more discrete. There will be strong tornadoes tomorrow if the NAM is close to correct. Yeah was discussing this with someone else. Zero QPF means nothing really...has to do more with the 12 km grid and subgrid scale params. Have to be careful with using model QPF as an "initiation confirmation". Not surprising the 4 KM NAM initiates quite a bit of warm sector discrete action across the uncapped region. Shows the difference in how numerical model schemes handle various aspects of the atmosphere. But this is a different discussion. Link to comment Share on other sites More sharing options...
QVectorman Posted March 1, 2012 Share Posted March 1, 2012 Really not worried about this- I would be shocked to see little precip like the NAM has. This may actually help keep cells more discrete. There will be strong tornadoes tomorrow if the NAM is close to correct. Hope you're right for radar viewing pleasure. Too many times I've fallen victim when I was younger to this thinking that all the CAPE in the world would over come progged subsidence and generate monsters. 9/10 doesn't happen...especially east of the Mississippi. Discrete cells will probably develop, go severe with mainly wind...switch over to QLCS with strong winds/bow echos and wawa...no tornadoes. Looking at the 3z, still strong subsidence, I would say there could be 1 or 2 tornadoes. Definitely don't see an outbreak like I would expect if we replaced the subsidence with some lift. But again this is all semantics since it's still 40+ hours away. Things will change between now and then Link to comment Share on other sites More sharing options...
thewxmann Posted March 1, 2012 Share Posted March 1, 2012 Hope you're right for radar viewing pleasure. Too many times I've fallen victim when I was younger to this thinking that all the CAPE in the world would over come progged subsidence and generate monsters. 9/10 doesn't happen...especially east of the Mississippi. Discrete cells will probably develop, go severe with mainly wind...switch over to QLCS with strong winds/bow echos and wawa...no tornadoes. Looking at the 3z, still strong subsidence, I would say there could be 1 or 2 tornadoes. Definitely don't see an outbreak like I would expect if we replaced the subsidence with some lift. But again this is all semantics since it's still 40+ hours away. Things will change between now and then I'm by no means sold on a major tornado outbreak either, but with the parameters shown, you'd think that even if convective mode is primarily linear, there'd be several spinups along the line. Link to comment Share on other sites More sharing options...
Stebo Posted March 1, 2012 Share Posted March 1, 2012 I'm by no means sold on a major tornado outbreak either, but with the parameters shown, you'd think that even if convective mode is primarily linear, there'd be several spinups along the line. yeah I agree however most model do show cellular convection except the gfs where the grid scale is too large to pick it up. In a situation like this especially considering how different the solution is wrt to the other models I would almost toss the gfs out right. As noted by others the gfs hass a tendancy to struggle with setups like these to begin with Link to comment Share on other sites More sharing options...
RCNYILWX Posted March 1, 2012 Share Posted March 1, 2012 http://www.eas.slu.edu/CIPS/ANALOG/COLD/wwproducts.php?reg=EC&model=GFS212&fhr=F048&flg=&HH=-99&map=SVR Total SPC storm reports based off top 15 CIPS Analogs for this set-up are pretty ominous, including several long-tracked tornadoes. Link to comment Share on other sites More sharing options...
Stebo Posted March 1, 2012 Share Posted March 1, 2012 http://www.eas.slu.e...&HH=-99&map=SVR Total SPC storm reports based off top 15 CIPS Analogs for this set-up are pretty ominous, including several long-tracked tornadoes. Yeah the difference between the GFS/NAM is pretty much only location of the significant part of the outbreak. GFS would argue South mostly, NAM says North then possibly in the South too. Link to comment Share on other sites More sharing options...
icebreaker5221 Posted March 1, 2012 Share Posted March 1, 2012 Just said it prior...it's because there is subsidence being forecasted at 850/700/500 mb levels due to mid/upper level forcing synoptically/dynamically. Where are you seeing any widespread subsidence over Ohio? Sure the strongest ascent is still west, but that's still ascent. Or was that just in earlier runs? Link to comment Share on other sites More sharing options...
Stebo Posted March 1, 2012 Share Posted March 1, 2012 Where are you seeing any widespread subsidence over Ohio? Sure the strongest ascent is still west, but that's still ascent. Or was that just in earlier runs? Yeah I didn't understand that one either.. Link to comment Share on other sites More sharing options...
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