BrierCreekWx Posted February 15, 2012 Share Posted February 15, 2012 It often comes to drastically different solutions because the 84 hour NAM is so often in lala land compared to the GFS. The DGEX, even very early in its run, is often so bad because of the garbage just fed into it by the 84 hour NAM as opposed to the then just introduced GFS influence. It is my understanding that the NAM doesn't feed anything into the DGEX. It is the GFS forecast at 78 hours that is fed into the lateral boundary conditions of the DGEX. The DGEX takes the GFS 78 hour forecast and then begins to run with the NAM model configuration. Link to comment Share on other sites More sharing options...
jmundie Posted February 15, 2012 Share Posted February 15, 2012 It often comes to drastically different solutions because the 78 hour NAM is so often in lala land compared to the GFS. The DGEX, even very early in its run, is often so bad because of the garbage just fed into it by the 78 hour NAM as opposed to the then just introduced GFS influence. If you'll read the post again - you'll see that its the NAM algos running on GFS progged conditions. Its not ingesting any data from the NAM. Its only using the NAM's software with GFS output at 84. Its supposed to yield a higher resolution 4-8 day range of the GFS, but it fails miserably. If you'd read the article posted, you would see that. Link to comment Share on other sites More sharing options...
beanskip Posted February 15, 2012 Share Posted February 15, 2012 LOL -- only takes 9 hours for differences between 12z GFS and 12z NAM. At 9 hours, NAM has closed feature on Nev./Calif. border -- it's open on GFS and further south. Link to comment Share on other sites More sharing options...
GaWx Posted February 15, 2012 Share Posted February 15, 2012 It is my understanding that the NAM doesn't feed anything into the DGEX. It is the GFS forecast at 78 hours that is fed into the lateral boundary conditions of the DGEX. The DGEX takes the GFS 78 hour forecast and then begins to run with the NAM model configuration. Someone please clarify. Now I'm confused. Have I been incorrect in assuming that the DGEX is handed off the prior 84 (or 78) hour NAM solution? Link to comment Share on other sites More sharing options...
griteater Posted February 15, 2012 Share Posted February 15, 2012 Morning HPC disco... AMONG LATEST GUIDANCE THE 00Z GFS IS THE CLEAR EXTREME IN BEING FASTER WITH ITS SRN STREAM SHRTWV AND DEEP/SWD/CLOSED WITH ITS NRN STREAM ENERGY TO YIELD A VERY DEEP/NWD SFC SYSTEM. ONCE DISCOUNTING THE 00Z GFS THE REMAINING SFC LOW SPREAD IS STILL QUITE BROAD AS OF EARLY DAY 4 SUN WITH ONE OR MORE CENTERS POSSIBLE IN AN AREA FROM THE SERN CONUS TO OFFSHORE THE CNTRL-SRN MID ATLC COAST. THE 00Z ECMWF WHICH SHOWS ITS BEST DEFINED SFC LOW NEAR THE SERN COAST EARLY SUN IS CLOSER TO HPC CONTINUITY OVER THE PAST DAY. THE 00Z CMC IS SLOWEST WITH ITS SERN CONUS SFC LOW. THE ECMWF MEAN IS MORE BALANCED BETWEEN THE SWRN/NERN SIDE OF THE SPREAD WHILE THE GEFS MEAN/06Z GFS AND TO SOME DEGREE 00Z UKMET EMPHASIZE A LEADING WAVE AS OF EARLY SUN. FOR NOW WILL LEAN CLOSER TO THE 00Z ECMWF TO MAINTAIN SOME CONTINUITY WITH ANY 12Z GUIDANCE TRENDS BEING INCORPORATED FOR THE FINAL FCST. Link to comment Share on other sites More sharing options...
HKY_WX Posted February 15, 2012 Share Posted February 15, 2012 Question for mets: What if the s/w holds together and remains closed all the way through to the Atlantic? The 12z NAM shows a gorgeous 850 low over East Texas, presumably getting ready to march east across the south -- obviously big cutoffs come with their own built-in cold air mechanism as is seen over Texas on this run -- could this tranlsate further east??? I think Robert is close on the 04 analog if that happens(in setup only, after that who knows). That would allow a few things to evolve. . 1) this would allow the HP below sitting over Iowa/Wisconsin to slide into the east coast in time for enough cold air damming to make sfc temps marginally good enough for wet snow. That HP is on the back side of the shortwave that keeps showing up on the models over the great lakes. This is the s/w the gfs was phasing with the system last night. Which looked unrealistic to me. 2) It would make this a Monday system b/c the gfs speeds this up once it starts interacting with the polar jet. 3)It would really amp up the dynamical cooling possibilities as you can see over texas. If the nam/ggem combo is correct then this would be a major snowstorm over the whole state. Link to comment Share on other sites More sharing options...
Rankin5150 Posted February 15, 2012 Share Posted February 15, 2012 Robert seemed to love the idea of that last night via facebook...said that idea reminded him of 2004. It would be better for this system to phase closer to Fla. Correct? Link to comment Share on other sites More sharing options...
jmundie Posted February 15, 2012 Share Posted February 15, 2012 Gawx - I think it's a common misconception. But look at hour 90on the dgex and compare to hour 84 on the nam. And again - if you read the dgex site, it says it pretty clearly. I got it backwards in my first post, but that's why it looks like it goes crazy when the nam looks good at 84 and dissimilar from the gfs at the same hour. Link to comment Share on other sites More sharing options...
burgertime Posted February 15, 2012 Share Posted February 15, 2012 It would be better for this system to phase closer to Fla. Correct? In the situation of a cutoff I don't think so...but I'll let a red tagger or another expert answer that since I'm not sure. Link to comment Share on other sites More sharing options...
burgertime Posted February 15, 2012 Share Posted February 15, 2012 Early on 12z GFS looks a lot like 00z GFS with energy placement. Some slight changes but we'll just have to wait and see as to how that effects everything later on...one big change is that 12z is slower with the energy out west. Link to comment Share on other sites More sharing options...
Thrasher Fan Posted February 15, 2012 Share Posted February 15, 2012 The temperature differences at hr48 are quite a bit different with the NAM being a colder scenario vs. GFS Link to comment Share on other sites More sharing options...
beanskip Posted February 15, 2012 Share Posted February 15, 2012 Comparing 6z GFS to 12z run -- no changes of note through 51 hours. Link to comment Share on other sites More sharing options...
SN_Lover Posted February 15, 2012 Share Posted February 15, 2012 I think Robert is close on the 04 analog if that happens(in setup only, after that who knows). That would allow a few things to evolve. . 1) this would allow the HP below sitting over Iowa/Wisconsin to slide into the east coast in time for enough cold air damming to make sfc temps marginally good enough for wet snow. That HP is on the back side of the shortwave that keeps showing up on the models over the great lakes. This is the s/w the gfs was phasing with the system last night. Which looked unrealistic to me. 2) It would make this a Monday system b/c the gfs speeds this up once it starts interacting with the polar jet. 3)It would really amp up the dynamical cooling possibilities as you can see over texas. If the nam/ggem combo is correct then this would be a major snowstorm over the whole state. What storm from 2004 did he mention? Link to comment Share on other sites More sharing options...
Jon Posted February 15, 2012 Share Posted February 15, 2012 What storm from 2004 did he mention? http://www.erh.noaa....27Feb_Snow.html I think... Link to comment Share on other sites More sharing options...
beanskip Posted February 15, 2012 Share Posted February 15, 2012 Through 60 only differences I see between 6z GFS and 12z are: 1) The SW shortwave is a bit SE of the 6z position 2) The 12z run has weakened the little disturbance over Wyoming that I believe grit mentioned earlier. Link to comment Share on other sites More sharing options...
burgertime Posted February 15, 2012 Share Posted February 15, 2012 Well this got interesting...possible CAD @75 with a 1020 HP in NY...meanwhile almost a big phase taking place. LP in south LA with precip blowing up. Link to comment Share on other sites More sharing options...
SN_Lover Posted February 15, 2012 Share Posted February 15, 2012 http://www.erh.noaa....27Feb_Snow.html I think... Wow! That would be one heck of a storm. Link to comment Share on other sites More sharing options...
burgertime Posted February 15, 2012 Share Posted February 15, 2012 @78 HP slides OTS and @84 we have a flood incoming Link to comment Share on other sites More sharing options...
LithiaWx Posted February 15, 2012 Share Posted February 15, 2012 This 12Z run isn't going to get it done for the southeast. Way too many pieces of the puzzle missing. Link to comment Share on other sites More sharing options...
beanskip Posted February 15, 2012 Share Posted February 15, 2012 Faster than 6z -- going west? Well this got interesting...possible CAD @75 with a 1020 HP in NY...meanwhile almost a big phase taking place. LP in south LA with precip blowing up. Link to comment Share on other sites More sharing options...
tnweathernut Posted February 15, 2012 Share Posted February 15, 2012 I want to shoot that low pressure in the lakes. It's definitely not helping an already marginal situation on this run of the gfs Link to comment Share on other sites More sharing options...
RaleighWx Posted February 15, 2012 Share Posted February 15, 2012 The GFS remains much quicker with the evolution of things when compared to the NAM. At 78 hours the GFS has the low over SW Alabama, while the NAM is near Houston. The NAM keeps the streams more seperate through this process while the GFS opens up the SW low and begins to phase, this results in a faster, more intense system, but also slows down the northern stream s/w and accompanying cold front. Therefore it is likely this run will show a strong storm but snow will likely not be the predominant type in the SE. Link to comment Share on other sites More sharing options...
burgertime Posted February 15, 2012 Share Posted February 15, 2012 Per 12z GFS congrats PA and NY. Link to comment Share on other sites More sharing options...
LithiaWx Posted February 15, 2012 Share Posted February 15, 2012 Biggest missing piece is a really good cold high pressure system. I really can't see this trending towards what we need. Missing a 50/50 low, also the energy over the lakes is not going to help us but it could mean kaboom for the northeast if the track is right. Link to comment Share on other sites More sharing options...
burgertime Posted February 15, 2012 Share Posted February 15, 2012 Faster than 6z -- going west? It ended up staying east but way too warm. Ack what we wouldn't give for that precip with cold. Link to comment Share on other sites More sharing options...
WeatherNC Posted February 15, 2012 Share Posted February 15, 2012 My issue with the GFS starts around 51-54 hrs, not buying that the southern stream just opens up like that... Vort is strong and my best guess is the GFS is having some difficulty resolving that, at 54 you can see all that energy near the base, and to envision that somehow it just opens up between 51 and 54 hrs is a stretch. Especially when looking at the difference between this run and the 9z SREF open wave in S TX... compared to potent ULL still in MX Link to comment Share on other sites More sharing options...
beanskip Posted February 15, 2012 Share Posted February 15, 2012 It's almost comical to compare the 500mb map for the 12z and 6z GFS: The 12z has our main s/w over northern Alabama -- on the 6z it was over southern Miss. The 6z had a nice s/w over southern. Ill. On the 12z it's pretty much gone. But a new surprise s/w has shown up over eastern NC on the 12z that wasn't there at all on the 6z. The Pacific NW and the Great Lakes are similarly incongruous. This model is terrible. Link to comment Share on other sites More sharing options...
burgertime Posted February 15, 2012 Share Posted February 15, 2012 If the CMC stays in line with it's previous runs and the NAM...the GooFuS is probably out to lunch. Gotta see what the good Doc has to say about this as well. What a disaster this must be for anyone paid to make a forecast. At this point I would probably go with sunny and 50 as well I mean why not? Link to comment Share on other sites More sharing options...
SN_Lover Posted February 15, 2012 Share Posted February 15, 2012 Situation is looking very bleak for the entire NC. Really hope this changes, but it does not look good. The AO is + now and the NAO has gone -. So this would concur with the models running the storm up the east coast. Link to comment Share on other sites More sharing options...
WeatherNC Posted February 15, 2012 Share Posted February 15, 2012 If the CMC stays in line with it's previous runs and the NAM...the GooFuS is probably out to lunch. Gotta see what the good Doc has to say about this as well. What a disaster this must be for anyone paid to make a forecast. At this point I would probably go with sunny and 50 as well I mean why not? Of course after I post that, take a look at the UKMET and it looks like the GFS, at-least at 96hrs, ~995 off the VA Capes, maybe a little too far east for a NE hit based on 120hrs, but not by much \ Link to comment Share on other sites More sharing options...
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