baroclinic_instability Posted February 19, 2012 Share Posted February 19, 2012 I would agree its probably too far south...for the same reasons I spoke of above. Its non-hydrostatic so it can have a lot of problems when there is a lot of convection far from the center and then convection near the center too at the same time...it will have trouble resolving the larger scale synoptic lift I think...but it obviously could be onto something since its always the first model out with the new 00z data. But I usually just hold it off to the side if it shows a different solution on a new raob primary run and wait for the others to chime in. This was never an obvious system until later in the game where the NAM would be poor...early on it looked a bit more tighter wrapped and it kept trending more strung out with its dynamics and convection, so I think that is where the NAM got in trouble really bad. For those who aren't familiar, "hydrostatic" means an assumed balance in the atmosphere between the pressure gradient and gravity, but when steep convection is evident then this balance can be out of whack a bit...but overall its a good assumption and that is what most global models use...but models like the NAM and most (if not all?) SREFS are non-hydrostatic and actually will go into hydrostatic imbalance if the convection simulates it on their model (which does happen in real life for brief times)....but it can often cause problems in modeling if the convection is off a bit...esp synoptically when the convection is far off from the center. I'm no expert on this, but this is what I have read in the past and seen it play out in actual systems as mentioned above. I could be in slight error in my explanation but I think I managed to cover the basics of it. Anyone who knows more can correct me. If it is too far S it may not be by much. One certainty we know now is convection is well displaced from the main parent cyclone. The frontal zone is grossly elongated with a secondary diabatic low over Florida. Advective processes across the warm sector are being severely inhibited by this, and shortwave ridge building/amplification are weak. The upper shortwave is of much lower amplitude as a result and will thus have a much faster phase speed aloft meaning the defo band will have less time to materialize before the fast upper low begins forcing the development of the secondary coastal. That defo band will not have much time here to dump heavy precip. Link to comment Share on other sites More sharing options...
Clinch Leatherwood Posted February 19, 2012 Share Posted February 19, 2012 Full agreement. IMO the NAM is in a "tough" spot since it is non-hydrostatic at 12 km grid. Subgrid scale paramaterizations in a non-hydrostatic model can wreak havoc in certain situations. It is also those traits that make it so useful with deep PV's over moist and intense baroclinic zones. Slow moving single part systems are its forte. But would that have been negatively impacting it's 12-18h 500mb forecasts for the last 3-4 days? I realize it may come into play now with the QPF and enventual evolution of the system but it seems to have had great difficulty in getting close to pinpointing the position and speed of embeded s/ws even over the continental US. Link to comment Share on other sites More sharing options...
Coach McGuirk Posted February 19, 2012 Share Posted February 19, 2012 atleast you get some QPF and have a chance i guess better than others What are you talking about? You're supposed to get at least 4 inches of snow. Link to comment Share on other sites More sharing options...
ORH_wxman Posted February 19, 2012 Share Posted February 19, 2012 If it is too far S it may not be by much. One certainty we know now is convection is well displaced from the main parent cyclone. The frontal zone is grossly elongated with a secondary diabatic low over Florida. Advective processes across the warm sector are being severely inhibited by this, and shortwave ridge building/amplification are weak. The upper shortwave is of much lower amplitude as a result and will thus have a much faster phase speed aloft meaning the defo band will have less time to materialize before the fast upper low begins forcing the development of the secondary coastal. That defo band will not have much time here to dump heavy precip. Yeah you make a good point...a lot of people say "convective feedback" when a model strings out a low and act likes it wrong...often it is, but it actually does happen and your description is exactly how it happens...it totally shuts down the warm conveyor belt on the front side of the low at times or in the mean really slows it down...so it can be very real which I know Scott (coastalwx) and I often tell people in the NE subforum who are quick to look at convective feedback. Usually when the GFS does it its wrong because its horrible at convection and even if there is convective feedback the GFS usually places it wrong, but when the Euro is doing it, I listen and its been doing it a lot on its runs. Close in, the NAM can finally become useful at it too..its usually cruddy at the far off convection more than 36 hours out, but it can start pinning down MCSs and such within 36 hours which make it better off. But again, I usually still go with the Euro in complex system...when they are tightly wrapped and lots of convection all near the center, I like the NAM...ala Jan 12 last year. Link to comment Share on other sites More sharing options...
Amped Posted February 19, 2012 Share Posted February 19, 2012 Rgem is in. Looks like we are finally starting to see a consensus. Link to comment Share on other sites More sharing options...
Logan11 Posted February 19, 2012 Share Posted February 19, 2012 Still looks like it has at least .6" in RIC. RGEM is further south too EZF on north, fuggetaboutit, and probably a bit south of that (per RGEM) Link to comment Share on other sites More sharing options...
MidlothianWX Posted February 19, 2012 Share Posted February 19, 2012 RGEM is further south too EZF on north, fuggetaboutit, and probably a bit south of that (per RGEM) Rgem is in. Looks like we are finally starting to see a consensus. The RGEM may be a nudge south overall with the precip but it is much better than the NAM...the heavier banding still roles through Central VA and areas up to CHO and down toward LYH do well. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 19, 2012 Share Posted February 19, 2012 Yeah you make a good point...a lot of people say "convective feedback" when a model strings out a low and act likes it wrong...often it is, but it actually does happen and your description is exactly how it happens...it totally shuts down the warm conveyor belt on the front side of the low at times or in the mean really slows it down...so it can be very real which I know Scott (coastalwx) and I often tell people in the NE subforum who are quick to look at convective feedback. Usually when the GFS does it its wrong because its horrible at convection and even if there is convective feedback the GFS usually places it wrong, but when the Euro is doing it, I listen and its been doing it a lot on its runs. Close in, the NAM can finally become useful at it too..its usually cruddy at the far off convection more than 36 hours out, but it can start pinning down MCSs and such within 36 hours which make it better off. But again, I usually still go with the Euro in complex system...when they are tightly wrapped and lots of convection all near the center, I like the NAM...ala Jan 12 last year. Completely agree, "convective feedback" is a totally misused and misunderstood term since convection often time plays a massive role in systems of large magnitude. While positive tilt waves can pan out nicely under certain circumstances, this is exactly why I hate positive tilt configs since convection will under nearly all circumstances result in negative synoptic feedback. Negative tilt systems see the opposite effect as DMC can feed through the WCB forcing massive pressure falls and rapid intensification. I will take negative tilt anyday even if it means messing with extreme warm advection killing snow totals and massive dryslots. As for coastalwx, he mentioned to me he is highly interested in latent processes and DMC with synoptic cyclones. I may have to contact him for something I am writing regarding a storm out here. Link to comment Share on other sites More sharing options...
usedtobe Posted February 19, 2012 Share Posted February 19, 2012 The GFS looks to be really sheared so it too will keep dc pretty dry. Time for bed. Link to comment Share on other sites More sharing options...
Ian Posted February 19, 2012 Share Posted February 19, 2012 The GFS looks to be really sheared so it too will keep dc pretty dry. Time for bed. i dunno i think we get some sprinkles Link to comment Share on other sites More sharing options...
dtk Posted February 19, 2012 Share Posted February 19, 2012 This model sucks. This is probably a fluke run too. Even dtk can't defend this model please don't speak for me, thanks. Link to comment Share on other sites More sharing options...
Deck Pic Posted February 19, 2012 Share Posted February 19, 2012 GFS is pretty good for those carolina guys...maybe someone will get hit good Link to comment Share on other sites More sharing options...
stormtracker Posted February 19, 2012 Author Share Posted February 19, 2012 Total and complete debacle. We won't see one flake tomorrow. Remember that dream run of the NAM last week? Link to comment Share on other sites More sharing options...
Ji Posted February 19, 2012 Share Posted February 19, 2012 GFS is pretty good for those carolina guys...maybe someone will get hit good What a disaster for DT who started asking for donations and congratulated himself tonight Link to comment Share on other sites More sharing options...
Ji Posted February 19, 2012 Share Posted February 19, 2012 Total and complete debacle. We won't see one flake tomorrow. Remember that dream run of the NAM last week? EURO had a dream run Thursday at 2:00am....unfortunately, it was one run only...its hiccup....and then DR no came back to take our snow away. The only time Euro is wrong is when it gives us snow Link to comment Share on other sites More sharing options...
SnowGoose69 Posted February 19, 2012 Share Posted February 19, 2012 EURO had a dream run Thursday at 2:00am....unfortunately, it was one run only...its hiccup....and then DR no came back to take our snow away. The only time Euro is wrong is when it gives us snow Thats pretty much the case with any model when you live in a region that only averages 10-15 inches of snow per season, the medium range snowier solutions in the long run are going to bust more than the non-snowy ones. Link to comment Share on other sites More sharing options...
ravensrule Posted February 19, 2012 Share Posted February 19, 2012 Thats pretty much the case with any model when you live in a region that only averages 10-15 inches of snow per season, the medium range snowier solutions in the long run are going to bust more than the non-snowy ones. He averages 23" per season. Link to comment Share on other sites More sharing options...
Coach McGuirk Posted February 19, 2012 Share Posted February 19, 2012 Wow, I got the jackpot on the NAM and GFS this run. I'm sure it'll be mostly rain though. Link to comment Share on other sites More sharing options...
Ji Posted February 19, 2012 Share Posted February 19, 2012 Thats pretty much the case with any model when you live in a region that only averages 10-15 inches of snow per season, the medium range snowier solutions in the long run are going to bust more than the non-snowy ones. it wasnt medium range. It was Thursday for a storm that was suppose to start Saturday night Link to comment Share on other sites More sharing options...
Ji Posted February 19, 2012 Share Posted February 19, 2012 He averages 23" per season. but i never get 23 its either 60 or 80 or 4 or 9 Link to comment Share on other sites More sharing options...
SnowGoose69 Posted February 19, 2012 Share Posted February 19, 2012 He averages 23" per season. I wasn't sure where he was but I was taking into consideration the majority of people in this particular subforum probably are in areas that average under 20 inches minus those north of IAD and in western WA....make that western VA. Link to comment Share on other sites More sharing options...
Sparky Posted February 19, 2012 Share Posted February 19, 2012 Wow, I got the jackpot on the NAM and GFS this run. I'm sure it'll be mostly rain though. check with DT. Link to comment Share on other sites More sharing options...
ravensrule Posted February 19, 2012 Share Posted February 19, 2012 I wasn't sure where he was but I was taking into consideration the majority of people in this particular subforum probably are in areas that average under 20 inches minus those north of IAD and in western WA....make that western VA. DC proper get's less than 20" but the majority of regular posters here average above 18", but like JI said recently we either get 80" or less than 10" Link to comment Share on other sites More sharing options...
Deck Pic Posted February 19, 2012 Share Posted February 19, 2012 Thats pretty much the case with any model when you live in a region that only averages 10-15 inches of snow per season, the medium range snowier solutions in the long run are going to bust more than the non-snowy ones. you should probably learn climatology but thanks for your insight! Link to comment Share on other sites More sharing options...
SnowGoose69 Posted February 19, 2012 Share Posted February 19, 2012 DC proper get's less than 20" but the majority of regular posters here average above 18", but like JI said recently we either get 80" or less than 10" We discussed the same thing in the NYC subforum yesterday. We've regularly been getting top 15 least and top 15 snowiest winters the last 15-20 years. I'm convinced its a product of the insanely warm climate and I'm not much of a global warming hound either. Link to comment Share on other sites More sharing options...
Coach McGuirk Posted February 19, 2012 Share Posted February 19, 2012 I average 8 inches of snow a season. It's either 20 or under 3. Link to comment Share on other sites More sharing options...
Ji Posted February 19, 2012 Share Posted February 19, 2012 I average 8 inches of snow a season. It's either 20 or under 3. really....who cares about you? Link to comment Share on other sites More sharing options...
Deck Pic Posted February 19, 2012 Share Posted February 19, 2012 I wasn't sure where he was but I was taking into consideration the majority of people in this particular subforum probably are in areas that average under 20 inches minus those north of IAD and in western WA....make that western VA. wrong Link to comment Share on other sites More sharing options...
clskinsfan Posted February 19, 2012 Share Posted February 19, 2012 wrong Yeah I agree. Closer to 30 for me. But whatever. We all have been stung this year. It's really pathetic and 2 winters in a row for me. Link to comment Share on other sites More sharing options...
Coach McGuirk Posted February 19, 2012 Share Posted February 19, 2012 really....who cares about you? Obviously, not you. Link to comment Share on other sites More sharing options...
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