Alpha5 Posted October 25, 2011 Share Posted October 25, 2011 People looking for a block to look like last December will always be disappointed. Some of the best storms come with Davis strait blocks that look just like this.570 heights over Greenland are the exception. This one will do just fine A lot of KU's came while the blocking was breaking down. You really don't need a block every time Link to comment Share on other sites More sharing options...
earthlight Posted October 25, 2011 Author Share Posted October 25, 2011 The kicker coming into the Pac NW is also a pretty big feature in this synoptic setup. It will de-amplify the ridge over the Rockies and swing east towards the Central US rapidly if it's moving too fast. Link to comment Share on other sites More sharing options...
ORH_wxman Posted October 25, 2011 Share Posted October 25, 2011 A lot of KU's came while the blocking was breaking down. You really don't need a block every time There's a reason that happened. The KUs happened in the first place because the block was resisting the storm cutting further west and as the storm wound up, the block finally dislodges...but if it wasn't there to begin with, you'd be unlikely to have the synoptic pattern in place for a snowstorm. Link to comment Share on other sites More sharing options...
earthlight Posted October 25, 2011 Author Share Posted October 25, 2011 A lot of KU's came while the blocking was breaking down. A myth in understanding. The blocking almost always allows the KU to occur to begin with--the breakdown occurs after it has done it's work and the storm is already stopped from either tracking north or inland. Link to comment Share on other sites More sharing options...
atownwxwatcher Posted October 25, 2011 Share Posted October 25, 2011 sweet. somewhere, atownwxwatcher is smiling. Just for you Link to comment Share on other sites More sharing options...
Alpha5 Posted October 25, 2011 Share Posted October 25, 2011 There's a reason that happened. The KUs happened in the first place because the block was resisting the storm cutting further west and as the storm wound up, the block finally dislodges...but if it wasn't there to begin with, you'd be unlikely to have the synoptic pattern in place for a snowstorm. Well, the block is not the be all end all. I did some analysis recently with KU's and the NAO: You'll see that many KU's took place during a + NAO as opposed to the AO Now, does the NAO always consist of a DS block? No, of course not, but I thought it was interesting how the NAO can really vary. If you look through the KU book, you'll see plenty of storms without a cookie cutter block. Link to comment Share on other sites More sharing options...
ORH_wxman Posted October 25, 2011 Share Posted October 25, 2011 Well, the block is not the be all end all. I did some analysis recently with KU's and the NAO: You'll see that many KU's took place during a + NAO as opposed to the AO Now, does the NAO always consist of a DS block? No, of course not, but I thought it was interesting how the NAO can really vary. If you look through the KU book, you'll see plenty of storms without a cookie cutter block. You can technically have a +NAO many times in a KU, but that does not mean there wasn't some critical blocking. It doesn't have to be in the davis straight every time. It can often be more over Hudson Bay or some other part of E Canada that forces a good PV in place off New Foundland. Even a UK/Iceland block can be effective if you have a good Pacific. But the Greenland/Davis straight blocks tend to give the most margin for error. Link to comment Share on other sites More sharing options...
Edge Weather Posted October 25, 2011 Share Posted October 25, 2011 LOL Just for you Link to comment Share on other sites More sharing options...
Edge Weather Posted October 25, 2011 Share Posted October 25, 2011 Wow, did you guys see the JMA? Over 2 inches of precip and cold. Better than the Euro I think. What a bomb! Link to comment Share on other sites More sharing options...
CooL Posted October 25, 2011 Share Posted October 25, 2011 NO(CHANCE)GAPS lol, cant wait until the clocks go back. Are you kidding me gfs? based on this the euro has a much better handle on things. http://www.meteo.psu.edu/~gadomski/AVN_6z/f96.gif (6z) http://www.meteo.psu.edu/~gadomski/AVN_18z/f84.gif (18z) Link to comment Share on other sites More sharing options...
CooL Posted October 25, 2011 Share Posted October 25, 2011 Just looking over the 12z euro and 18z gfs. --the euro phases the first southern stream s/w with the northern stream feature and boom..so the euro goes all in on the 2nd storm.. --the gfs ejects the southern stream s/w out faster and it joins up with the first storm..The 2nd storm looks all northern stream dominant on the gfs with no "phase" thoughts? Link to comment Share on other sites More sharing options...
Ericjcrash Posted October 25, 2011 Share Posted October 25, 2011 NO(CHANCE)GAPS lol, cant wait until the clocks go back. Are you kidding me gfs? based on this the euro has a much better handle on things. http://www.meteo.psu.../AVN_6z/f96.gif (6z) http://www.meteo.psu...AVN_18z/f84.gif (18z) Lol @ off hour GFS runs. What a joke. Link to comment Share on other sites More sharing options...
Alpha5 Posted October 25, 2011 Share Posted October 25, 2011 You can technically have a +NAO many times in a KU, but that does not mean there wasn't some critical blocking. It doesn't have to be in the davis straight every time. It can often be more over Hudson Bay or some other part of E Canada that forces a good PV in place off New Foundland. Even a UK/Iceland block can be effective if you have a good Pacific. But the Greenland/Davis straight blocks tend to give the most margin for error. I agree, but I encourage you to look through the KU books (if you have them). I was surprised too, not too many storms had a clear cut block. That being said, I was hard pressed to find a storm that did not have a good 50/50 in place. Link to comment Share on other sites More sharing options...
TheTrials Posted October 25, 2011 Share Posted October 25, 2011 Lol @ off hour GFS runs. What a joke. statistically speaking all gfs runs have the same accuracy, so, not sure what the LOL is for. Link to comment Share on other sites More sharing options...
TheTrials Posted October 25, 2011 Share Posted October 25, 2011 You can technically have a +NAO many times in a KU, but that does not mean there wasn't some critical blocking. It doesn't have to be in the davis straight every time. It can often be more over Hudson Bay or some other part of E Canada that forces a good PV in place off New Foundland. Even a UK/Iceland block can be effective if you have a good Pacific. But the Greenland/Davis straight blocks tend to give the most margin for error. made this point earlier today. Link to comment Share on other sites More sharing options...
ORH_wxman Posted October 25, 2011 Share Posted October 25, 2011 I agree, but I encourage you to look through the KU books (if you have them). I was surprised too, not too many storms had a clear cut block. That being said, I was hard pressed to find a storm that did not have a good 50/50 in place. Oh, I've read the KU books...I read them again and again too, lol. I agree a lot of storms don't have a perfect davis straight block...but most do have some form of blocking, whether its Hudson Bay weakness or east based block or something else. But its a good example of why people shouldn't just solely look at Greenland and Davis Straight/Baffin Island. Link to comment Share on other sites More sharing options...
TheTrials Posted October 25, 2011 Share Posted October 25, 2011 18Z GEFS have come a good bit west. Link to comment Share on other sites More sharing options...
TheTrials Posted October 25, 2011 Share Posted October 25, 2011 ensemble height anomaly map continues to be more amplified than the OP, a very good sign. Link to comment Share on other sites More sharing options...
Alpha5 Posted October 25, 2011 Share Posted October 25, 2011 Oh, I've read the KU books...I read them again and again too, lol. I agree a lot of storms don't have a perfect davis straight block...but most do have some form of blocking, whether its Hudson Bay weakness or east based block or something else. But its a good example of why people shouldn't just solely look at Greenland and Davis Straight/Baffin Island. Fair enough. Do you think that having a solid 50/50 is more important than a good block? It seems like without a 50/50 its hard to keep a storm on the coast. Link to comment Share on other sites More sharing options...
Alpha5 Posted October 25, 2011 Share Posted October 25, 2011 GEFS: 4 hits (+1 change from 12z) Link to comment Share on other sites More sharing options...
TheTrials Posted October 25, 2011 Share Posted October 25, 2011 Fair enough. Do you think that having a solid 50/50 is more important than a good block? It seems like without a 50/50 its hard to keep a storm on the coast. the 50/50 keeps the HP from sliding east, and thus helps mitigate any return flow which screws the coastal plain with warm winds off the ocean. Its very important. Doesn't surprise me the biggest storms for NYC have all had one. That being said, the 50/50 has to lift out as the storm approaches or you get 2009 epic fails and supression. Which leads back to the retrograding block or block which breaks down. This allows the 50/50 to move out and the storm to come up. There is a reason KU's, 20 inch storms, etc. are so rare. To get these elements all to come together at once is very very difficutl. Link to comment Share on other sites More sharing options...
Alpha5 Posted October 25, 2011 Share Posted October 25, 2011 the 50/50 keeps the HP from sliding east, and thus helps mitigate any return flow which screws the coastal plain with warm winds off the ocean. Its very important. Doesn't surprise me the biggest storms for NYC have all had one. That being said, the 50/50 has to lift out as the storm approaches or you get 2009 epic fails and supression. Eh, i think thats more of a strong PV in central canada, rather than having a ULL over newfoundland. Link to comment Share on other sites More sharing options...
TheTrials Posted October 25, 2011 Share Posted October 25, 2011 Eh, i think thats more of a strong PV in central canada, rather than having a ULL over newfoundland. no, look at the maps, the PV elongates into the 50/50 position. And it elongates because it gets stretched by the block, moves into position, then moves out as the block breaks down. It all fits. Link to comment Share on other sites More sharing options...
Alpha5 Posted October 25, 2011 Share Posted October 25, 2011 no, look at the maps, the PV elongates into the 50/50 position. And it elongates because it gets stretched by the block, moves into position, then moves out as the block breaks down. It all fits. Yeah I just looked at the charts, that was insane Link to comment Share on other sites More sharing options...
ORH_wxman Posted October 25, 2011 Share Posted October 25, 2011 Fair enough. Do you think that having a solid 50/50 is more important than a good block? It seems like without a 50/50 its hard to keep a storm on the coast. Yes. But usually you need some type of blocking to get it, that was kind of my point. Its a little like saying "do you think a trough in the east is more important than having a block?"...of course it is. Can't have a storm without it...but one generally helps to force the other to happen...blocking helps to keep 50/50 lows in place and helps to promote troughing in the east. There are times where blocking is weak or not there and you get lucky anyway...but you generally do not want to try and get storms that way. Much harder to do. Link to comment Share on other sites More sharing options...
phil882 Posted October 25, 2011 Share Posted October 25, 2011 Hey Guys.... Looks like winter might be giving some folks some flakes a bit earlier than advertised While the first system is looking like a rather significant early event for folks in Upstate NY into the Adirondacks and Catskills, I'm going to spend this post talking about the finer details with the second system, which arguably has a greater amount of attention for folks in the big Cities, especially Philadelphia, New York, and Boston. Seen above is a 500mb height and vorticity animation of the GFS and ECWMF at 48, 72, and 96 hours. You can notice right off the bat that the ECWMF seems to be moving the southern stream shortwave (the key player for this system!) much more slowly and is generally more amplified and further west than the GFS at all time intervals. In addition, the GFS seems to have a much stronger mid-level representation of Rina in comparison to the ECWMF, which may be yet another pivotal factor. There are a few things to note with each model that might give us a clue to how well its handling the synoptic pattern at 500mb. First of all, the ECWMF has been preforming poorly with the intensity of Rina. At this stage, I am much more likely to believe the GFS's handling of Rina than the ECWMF, and I think there will be a significantly stronger system than the ECWMF is forecasting. This is important, because the vertical depth of rita affects the surrounding environment in the Gulf of Mexico and points northeastward. Hurricanes create a strong positive temperature anomaly in the mid-upper level of the atmosphere, causing a significant rise in the tropopause through deep convection. Depending on the orientation of the southern stream shortwave swinging through the southeast by 72 hours, this can create positive interference with the wave pattern (which will promote amplification), or it could produce destructive interference with the wave pattern (which will reduce amplification). At this point, the GFS is quite progressive with the southern stream shortwave, so that by 72 hours, the lowest heights at 500mb are nearly at the same longitude as the mid-level vorticity max of Rina. Taking the GFS solution verbatim, Rina would tend to increase the heights near and around its circulation due to latent heat release within convection. With the shortwave trough directly overhead this would lead to de-amplification of the shortwave. Thus when the northern stream element comes to try to phase, it phases much later and much weaker since the southern stream shortwave had been previously weakened by Rina. Let's look at the ECWMF on the other hand. I already mentioned how much further west it is with the shortwave. Thus, at 72 hours, the southern stream shortwave is much further west of the remains of Rina. The remnants of Rina will still likely be sparking convection that will produce latent heat release, but this time its occurring in front of the shortwave. Thus the corresponding release of warmer air will raise heights out ahead of the shortwave, which is a favorable process for baroclinic growth. This would tend to cause the heights in the shortwave to fall as the heights increase ahead of the feature. The slower progression of the southern stream shortwave would also allow for an earlier phase with the northern stream shortwave. Thus, its not surprising we see a more amplified, more fully phased solution which produces a lot of precipitation for the Northeast and New England. So that is all well and good, but which solution is correct? Well at this point, I'm going to lean more towards the GFS solution. I don't think its likely that Rina will fall apart in the next 48 hours like the ECWMF suggests, so I think its unlikely that we will see a significant release of latent heat into the southern stream shortwave until its too late, when the system is nearly overhead of the tropical cyclone. The ECWMF has also traditionally had a slow bias when it comes to southern stream shortwaves across the Rockies and Middle part of the nation. However, much uncertainty remains with the vent still 4-5 days away, and with a lot of the major shortwaves in play over a pretty data sparse observation area. What will be interesting to see is if the ECWMF finally comes on board with a stronger Rina solution and if it has a major impact its take of the potential weekend noreaster. Link to comment Share on other sites More sharing options...
eduggs Posted October 25, 2011 Share Posted October 25, 2011 The day 4 eastern US trof on the JMA is really impressive. http://grib2.com/jma/CONUS_JMA_500_GPHTMPVORT_96HR.gif The vortmax is in Georgia and the area of sub-540 decameter heights at h5 penetrates deep into the US. No wonder it goes bonkers with qpf. It's classic. Amusingly it develops another deep trof at day 6. Link to comment Share on other sites More sharing options...
TheTrials Posted October 26, 2011 Share Posted October 26, 2011 Hey Guys.... Looks like winter might be giving some folks some flakes a bit earlier than advertised Great post, and I agree with a lot of it, you do a great job of breaking it down. Two things. Rina is already showing signs of weakening as the sheer is increasing. Her western edge is falling aparl. Secondly, while the euro does have a slow bias in the southern stream, it usually manifests itself it when they actually come out of the sw, this one swings down the eastern side of the rockies. Conversely, the gfs loves to rip sw's apart, so the truth may lie somewhere in the middle. It's going to be fun watching this over the next few days. Link to comment Share on other sites More sharing options...
NorEaster27 Posted October 26, 2011 Share Posted October 26, 2011 nice disco by Upton, even if the ECMWF verifed and we had the perfect track for snow, its stil most likely rain for NYC and coastal areas. Link to comment Share on other sites More sharing options...
Analog96 Posted October 26, 2011 Share Posted October 26, 2011 nice disco by Upton, even if the ECMWF verifed and we had the perfect track for snow, its stil most likely rain for NYC and coastal areas. Lol. How did I know you would say that? Link to comment Share on other sites More sharing options...
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