tombo82685 Posted January 17, 2011 Share Posted January 17, 2011 i think its if your anywhere, you want more digging to get the low to bomb further south. The gfs has been trending this way every single run so far. im not sure. This run has the same exact low placement as the 12z run, but is warmer because its digging the northern stream faster, causing a bigger ridge along the ec. Just going off 18z gfs...phl-bos are all very close to going to sleet. Actually phl is sleet this run Link to comment Share on other sites More sharing options...
ag3 Posted January 17, 2011 Share Posted January 17, 2011 Very solid snowstorm on GFS. It's slowly increasing it's QPF too. Link to comment Share on other sites More sharing options...
Manny Posted January 17, 2011 Share Posted January 17, 2011 Another Interesting Miller B bomb event on the 18z GFS. .5-75" through the City, crushes New England though. Link to comment Share on other sites More sharing options...
Mitchel Volk Posted January 17, 2011 Share Posted January 17, 2011 It looks like the GFS is trending towards the GEM. In addition, the NAM is also looking like the GEM. As stated before if phasing can occur it will occur during this winter. I believe this winter is an analog to 1995/96 winter. A good chance does exists for significant snow for PHL to BOS again. Link to comment Share on other sites More sharing options...
VAsnowlvr82 Posted January 17, 2011 Share Posted January 17, 2011 So anyway we can get this to blow up further south so that everybody gets in on the good fun including DC? Link to comment Share on other sites More sharing options...
baroclinic_instability Posted January 17, 2011 Share Posted January 17, 2011 Can't it be explained by the strong CAA/WAA couplet, with the very cold air behind the surface low causing heights to crash? Usually, when I think of mid-latitude systems bombing out, it's due to the increasing baroclinicity between the warm and cold sectors. I'm just asking questions, because you are looking at things I don't normally look at when forecasting. They both explain the same things of course, but in vastly different manners. I was probably just like you and was taught QG in school--and I used it extensively when I first started forecasting, but then I learned the beauty of IPV. I am still learning it now--by no means any kind of expert--but I think it handles strong/rapid feedback cyclogenesis in a more succinct manner. One development here is the phase and the cyclogenetic trigger that the southern wave plays in inciting the development of that upper level cold front to "develop" towards the surface. This not only enhances the baroclinity at one level it enhances the baroclinity at multiple levels of the atmosphere. The rapid development of the upper level cold front down through the atmosphere results in rapid height field changes and responses to this now very unstable hydro-dynamic flow pattern. Jet circulations are one of the first things to rapidly respond and IPV deals with that as well. The crashing heights are then explained well by QG with decreasing CAA w/ height as the upper level cold front develops towards the surface and the strongest advections are in the low levels. Heights fall on the backside of the trough and the the increased thermal graident in the vertical increases the 500 hpa (and above) flow and increases shear induced and curvature vorticity. At the same time DPVA increases ahead of the wave as all this is occuring, and warm air advection in the low levels commences. With the GOM in play, low level static stability decreases as the moist air converges and releases latent heat of condensation--static stability is in the qg equations as well--and decreased static stability further enhances development--and now feedback develops and every process is feeding off the others. That is just the short of it--but with QG, in reality, a lot of isobaric levels need to be considered to assess potential for deep tropospheric cyclogenesis. IPV is much cleaner and simpler IMO and doesn't require such a long look at things. Link to comment Share on other sites More sharing options...
ag3 Posted January 17, 2011 Share Posted January 17, 2011 Another Interesting Miller B bomb event on the 18z GFS. .5-75" through the City, crushes New England though. It does not crush NE. They get same as us. NNE gets 2"-4" more. http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_p60_114l.gif Link to comment Share on other sites More sharing options...
am19psu Posted January 17, 2011 Share Posted January 17, 2011 They both explain the same things of course, but in vastly different manners. I was probably just like you and was taught QG in school--and I used it extensively when I first started forecasting, but then I learned the beauty of IPV. I am still learning it now--by no means any kind of expert--but I think it handles strong/rapid feedback cyclogenesis in a more succinct manner. One development here is the phase and the cyclogenetic trigger that the southern wave plays in inciting the development of that upper level cold front to "develop" towards the surface. This not only enhances the baroclinity at one level it enhances the baroclinity at multiple levels of the atmosphere. The rapid development of the upper level cold front down through the atmosphere results in rapid height field changes and responses to this now very unstable hydro-dynamic flow pattern. Jet circulations are one of the first things to rapidly respond and IPV deals with that as well. The crashing heights are then explained well by QG with decreasing CAA w/ height as the upper level cold front develops towards the sirface and the strongest advections are in the low levels. Heights fall on the backside of the trough and the the increased thermal graident increases the 500 hpa flow and increases shear induced and curvature vorticity. At the same time DPVA increases ahead of the wave as all this is occuring, and warm air advection in the low levels commences. With the GOM in play, low level static stability decreases as the moist air converges and releases latent heat of condensation--static stability is in the qg equations as well--and decreased static stability further enhances development--and now feedback develops and every process is feeding off the others. That is just the short of it--but with QG, in reality, a lot of levels need to be considered to assess potential for deep tropospheric cyclogenesis. IPV is much cleaner and simpler IMO. Right, that QG process you described is basically what I am going through in my head as I'm forecasting. I'm obviously not explicitly solving everything that you describe above, but that's the "model" of cyclogenesis I have in my head. Interesting you bring up latent heat release -- it's not something explicitly taught in QG theory (at least not at Penn State), but something I always consider due to my tropical background. I've not really dealt with IPV in a synoptic setting (I've used it more to diagnose subtropical cyclogenesis), but maybe I need to pull out Holton and give it a read again. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted January 17, 2011 Share Posted January 17, 2011 Right, that QG process you described is basically what I am going through in my head as I'm forecasting. I'm obviously not explicitly solving everything that you describe above, but that's the "model" of cyclogenesis I have in my head. Interesting you bring up latent heat release -- it's not something explicitly taught in QG theory (at least not at Penn State), but something I always consider due to my tropical background. I've not really dealt with IPV in a synoptic setting (I've used it more to diagnose subtropical cyclogenesis), but maybe I need to pull out Holton and give it a read again. Exactly my background as well. We did a ton of QG but very little talk on the role of static stability. In a simplistic idea though, they are all there in the denominators of every QG forcing term. Of course solving the equation is a different story. One final note--QG works tremendously well overall, but it poorly explains the rapid upper level wind field changes/ jet stream changes as the vertical thermal gradient rapidly increases as the upper level cold front descends towards the surface--and the jet circulation often times begins to dominate over synoptic forcings--the Christmas bomb was a classic example--and why the overall low was so tiny--and on the inside of the ejecting S/W--not ahead of it like one would think. Howie B in Synoptic/Dynamic Meteo. in Midlatitudes has a nice disco on it and where I learned the beginnings of it. Most came from stuff online after that. I wish I had a tropical background like you--I think it will make it all that much easier to pick up. Link to comment Share on other sites More sharing options...
tombo82685 Posted January 17, 2011 Share Posted January 17, 2011 fwiw the 18z gfs ens mean is further south with the low pressure. Has a sub 1000 low just off southern delmarva. Link to comment Share on other sites More sharing options...
ag3 Posted January 17, 2011 Share Posted January 17, 2011 fwiw the 18z gfs ens mean is further south with the low pressure. Has a sub 1000 low just off southern delmarva. QPF is very similar to operational despite the further south development. Similar also to 12z ensembles. http://raleighwx.americanwx.com/models/gfsensemble/18zgfsensemblep72108.gif Link to comment Share on other sites More sharing options...
Manny Posted January 17, 2011 Share Posted January 17, 2011 It does not crush NE. They get same as us. NNE gets 2"-4" more. http://www.nco.ncep....fs_p60_114l.gif Yeah, just saw that. I meant to say it bombs out near New England. Link to comment Share on other sites More sharing options...
jrodd321 Posted January 17, 2011 Share Posted January 17, 2011 Just an epic signal. Link to comment Share on other sites More sharing options...
bluewave Posted January 17, 2011 Share Posted January 17, 2011 This is another improvement. Phase is better and the Dynamic Trop is still coming down. CIMSS had a really good blog entry after the storm last week. http://cimss.ssec.wisc.edu/goes/blog/archives/7395 Link to comment Share on other sites More sharing options...
earthlight Posted January 17, 2011 Share Posted January 17, 2011 Link to comment Share on other sites More sharing options...
eduggs Posted January 17, 2011 Share Posted January 17, 2011 Just an epic signal. Maybe I'm misunderstanding you. To me this doesn't look like a signal for an epic storm. But if you mean it's a strong - you might even say epic - signal for some kind of storm, then I would agree. I think this looks like a legitimate threat for a somewhat run of the mill moderate snowstorm for a large swatch of the northeast. The synoptic pattern during this period looks relatively progressive and none of the modeling has a longwave trof with sufficient amplitude to thrust this threat into the major category except possibly the GGEM. But even the Canadian, which produces a higher amplitude trof and much more rapidly deepending surface low, moves the SLP along pretty quickly. At second glance the NAM is almost as impressive as the GEM as well. It's true that the GFS has trended away from the dampening flat wave, lagging southern stream scenario, but I feel we're headed towards a moderate snowstorm if the pieces come together. To me this setup does not look epic, ultra dynamic, historical, or however you want to call it. 0.8-1.2 liq. eq. upper limit with something like .4-.8 more likely. Link to comment Share on other sites More sharing options...
Edge Weather Posted January 17, 2011 Share Posted January 17, 2011 And how about the DGEX? Maybe I'm misunderstanding you. To me this doesn't look like a signal for an epic storm. But if you mean it's a strong - you might even say epic - signal for some kind of storm, then I would agree. I think this looks like a legitimate threat for a somewhat run of the mill moderate snowstorm for a large swatch of the northeast. The synoptic pattern during this period looks relatively progressive and none of the modeling has a longwave trof with sufficient amplitude to thrust this threat into the major category except possibly the GGEM. But even the Canadian, which produces a higher amplitude trof and much more rapidly deepending surface low, moves the SLP along pretty quickly. At second glance the NAM is almost as impressive as the GEM as well. It's true that the GFS has trended away from the dampening flat wave, lagging southern stream scenario, but I feel we're headed towards a moderate snowstorm if the pieces come together. To me this setup does not look epic, ultra dynamic, historical, or however you want to call it. 0.8-1.2 liq. eq. upper limit with something like .4-.8 more likely. Link to comment Share on other sites More sharing options...
tombo82685 Posted January 17, 2011 Share Posted January 17, 2011 heres the indiv ens mean for the gfs Link to comment Share on other sites More sharing options...
eduggs Posted January 17, 2011 Share Posted January 17, 2011 And how about the DGEX? I like the look of it. Basically a widespread 6-12 inch snowstorm. Very consistent with what I believe is roughly the upper limit of potential. Of course the DGEX is almost always too wrapped up with the SLP, but we can glean something with respect to the threat level from it I think. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted January 17, 2011 Share Posted January 17, 2011 Maybe I'm misunderstanding you. To me this doesn't look like a signal for an epic storm. But if you mean it's a strong - you might even say epic - signal for some kind of storm, then I would agree. I think this looks like a legitimate threat for a somewhat run of the mill moderate snowstorm for a large swatch of the northeast. The synoptic pattern during this period looks relatively progressive and none of the modeling has a longwave trof with sufficient amplitude to thrust this threat into the major category except possibly the GGEM. But even the Canadian, which produces a higher amplitude trof and much more rapidly deepending surface low, moves the SLP along pretty quickly. At second glance the NAM is almost as impressive as the GEM as well. It's true that the GFS has trended away from the dampening flat wave, lagging southern stream scenario, but I feel we're headed towards a moderate snowstorm if the pieces come together. To me this setup does not look epic, ultra dynamic, historical, or however you want to call it. 0.8-1.2 liq. eq. upper limit with something like .4-.8 more likely. I agree and disagree with you. Were this to pan out--saying this isn't "dynamic" is just silly. "Dynamic" is tossed around way too much--but to suggest this isn't impressive is silly. With this dump 20" of snow--of course not. Because it doesn't stall doesn't mean it is impressive though. Link to comment Share on other sites More sharing options...
eduggs Posted January 17, 2011 Share Posted January 17, 2011 And how about the DGEX? Also notice the low amplitude trof, minimally negative tilt, and NW placement of the mid-level circulation. In fact it remains an open wave in the mid-levels until the SLP is well past our location. Link to comment Share on other sites More sharing options...
Jefflaw77 Posted January 17, 2011 Share Posted January 17, 2011 Is that a joke?? What's this exactly depict? My untrained eyes don't want to speculate.. All i see is a pretty decent storm setup! Link to comment Share on other sites More sharing options...
dtk Posted January 17, 2011 Share Posted January 17, 2011 Be careful since the DGEX uses GFS fields to initialize it. It won't be NAM extrapolated verbatim. Actually that isn't true. The DGEX interpolates the NAM at 78 hours to a smaller domain (still 12km resolution)...either CONUS or Alaska depending on the cycle. Then, it runs the 12km WRF-NMM at 12km out to 192 h utilizing the GFS run from the previous cycle for its boundary conditions (because the domain is smaller, it feels a fairly heavy influence of said boundary conditions). Information here: http://www.emc.ncep.noaa.gov/mmb/mmbpll/dgexhome.ops/ Link to comment Share on other sites More sharing options...
baroclinic_instability Posted January 17, 2011 Share Posted January 17, 2011 Actually that isn't true. The DGEX interpolates the NAM at 78 hours to a smaller domain (still 12km resolution)...either CONUS or Alaska depending on the cycle. Then, it runs the 12km WRF-NMM at 12km out to 192 h utilizing the GFS run from the previous cycle for its boundary conditions (because the domain is smaller, it feels a fairly heavy influence of said boundary conditions). Information here: http://www.emc.ncep....l/dgexhome.ops/ Thanks--I missed the part on it being lateral boundary conditions only. Link to comment Share on other sites More sharing options...
eduggs Posted January 17, 2011 Share Posted January 17, 2011 I agree and disagree with you. Were this to pan out--saying this isn't "dynamic" is just silly. "Dynamic" is tossed around way too much--but to suggest this isn't impressive is silly. With this dump 20" of snow--of course not. Because it doesn't stall doesn't mean it is impressive though. I agree that words like dynamic and phase and many other are overused and poorly understood. As a meteorological colloquialism I consider "dynamic" to refer to processes that induce rapid SLP deepening or the mechanics and physical processes that lead to intense precipitation. Using these basic notions I'm not sold on any extreme dynamics with this upcoming storm. This is the kind of mid-latitude cyclone genesis that happens roughly once every week or two during winter time (at least as currently modeled). Of course each storm is unique and beautiful in its own right, but not all are worthy of hyperbole. I certainly hope this begins to look even more exciting starting at 0z tonight. Link to comment Share on other sites More sharing options...
mulen Posted January 17, 2011 Share Posted January 17, 2011 Were spoiled most years we'd kill for this setup on the coast i guess its an age thing i'll take what i can get we've had some brutal snowdroughts see ya. Link to comment Share on other sites More sharing options...
TheTrials Posted January 18, 2011 Share Posted January 18, 2011 saw the frame before posted, but not this. Link to comment Share on other sites More sharing options...
earthlight Posted January 18, 2011 Share Posted January 18, 2011 I agree that words like dynamic and phase and many other are overused and poorly understood. As a meteorological colloquialism I consider "dynamic" to refer to processes that induce rapid SLP deepening or the mechanics and physical processes that lead to intense precipitation. Using these basic notions I'm not sold on any extreme dynamics with this upcoming storm. This is the kind of mid-latitude cyclone genesis that happens roughly once every week or two during winter time (at least as currently modeled). Of course each storm is unique and beautiful in its own right, but not all are worthy of hyperbole. I certainly hope this begins to look even more exciting starting at 0z tonight. Fair opinion, but I disagree. The dynamics with this system are actually pretty impressive. If it were just a northern stream feature, I guess you might say it's "typical", but even then..the height falls would be impressive and the shortwave dynamic. In this system specifically, as modeled right now, we're seeing a "southern stream" feature getting involved. The reason I quote it is because it's not the definition of a southern stream, but it definitely heads that direction as it breaks off from the Pacific Jet and then dives towards the Southern US. You aren't going to get a 2" liquid QPF bomb with a 970mb low off the coast, but you can't say this system isn't "dynamic". The surface low is already being modeled in the 980's by some models. The UVV's and omega values are already being forecast to be extremely impressive with deep cyclogenesis. This can create a Dec 9, 2005 type snow bomb..where you get very intense snow moving through the area with whiteout conditions for a few hours, owing to the very strong dynamic forcing aloft..and then when the system deepens so rapidly you can often get rapid surface cyclone maturing..and a CCB development. Link to comment Share on other sites More sharing options...
Snowtrain Posted January 18, 2011 Share Posted January 18, 2011 A tiny--but the good thing is the southern wave phases ahead of the trough--that is very important. Yes this is precisely what happend with the boxing day storm, correct? The northern stream latched on the backside of the southern S/W. Is there any significance to this evolution in regards to increasing the dynamics of the phased system. For instance does it cause the trought to tilt negatively quicker or slow down the forward motion of the system? Thanks in advance. Link to comment Share on other sites More sharing options...
Thunder Road Posted January 18, 2011 Share Posted January 18, 2011 18z GFS had 0.57" for KPNE. That sounds like a respectable snow storm to me. I really would love to see the ECM come on board tonight though. Link to comment Share on other sites More sharing options...
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