Qaanaaq Posted January 23, 2011 Share Posted January 23, 2011 The GFS is warm at 78 hrs with the zero line at the surface north of the Mason Dixon line. However by 84hrs when the evaporation cooling gets going and the low starts really deepening and turn the winds to northerly, the temps collapse. It remains a really tricky forecast. I doubt it is an all snow even but it could be a mostly snow event. Right now I'd still be very circumspect about making any calls about the system but then I tend to like to wait unless we have a feb 5th or Dec 19th type of event. Thanks so much for your rational thoughts. It's clear your ideas are not based on choosing a "model" for an answer. I, for one, really appreciate it. Thanks for sharing, BTW your blog has really broadened the discussions at the Post- it's great. Now, I'll go back to "lurking'. Good luck to all- may all your wildest dreams come true! Link to comment Share on other sites More sharing options...
Dr No Posted January 23, 2011 Share Posted January 23, 2011 Roughly... 78 - CLT 84 - Norfolk 90 - with the SLP sweet!- thank you Link to comment Share on other sites More sharing options...
SeanVA Posted January 23, 2011 Share Posted January 23, 2011 The GFS has been a cold outlier for days now. Not sure what we make of it. Not really much of an outlier, that's the Euro now. Link to comment Share on other sites More sharing options...
PhineasC Posted January 23, 2011 Share Posted January 23, 2011 the euro 500 track is still pretty freakin sweet but i worry we can get that and still rain at least in the city. if i was at ji's house i may feel more comfortable. Yeah, my head says the Euro has been warm for some time and we are just getting rain/slop, but it is really hard to give up on such a nice looking storm track. Link to comment Share on other sites More sharing options...
Ji Posted January 23, 2011 Author Share Posted January 23, 2011 Yeah, my head says the Euro has been warm for some time and we are just getting rain/slop, but it is really hard to give up on such a nice looking storm track. i keep going back to the storm last monday where the euro had me at rain and warm and i ended up with virtually no rain(it was sleet and snow with temps in the mid 20's) Link to comment Share on other sites More sharing options...
yoda Posted January 23, 2011 Share Posted January 23, 2011 Yeah, my head says the Euro has been warm for some time and we are just getting rain/slop, but it is really hard to give up on such a nice looking storm track. Same here. That 5h track looks very nice for us... but it being warm makes me think Link to comment Share on other sites More sharing options...
dtk Posted January 23, 2011 Share Posted January 23, 2011 Each one that looks nice But the FIM does look like the GFS That's because it's initialized from the GFS analysis and uses GFS physics (parameterizations). Link to comment Share on other sites More sharing options...
Ian Posted January 23, 2011 Share Posted January 23, 2011 Yeah, my head says the Euro has been warm for some time and we are just getting rain/slop, but it is really hard to give up on such a nice looking storm track. unfortunately sometimes we get a great track and it is rain Link to comment Share on other sites More sharing options...
dtk Posted January 23, 2011 Share Posted January 23, 2011 But it sounds like it's coordinate system is much different. A hybrid isentropic coordinate system is a bit different than the GFS. I know Louis Uccellini used to be really excited about such a coordinate system but I don't remember the specifics of why. Maybe DTK can comment on it. Exactly right...this was developed by folks out in boulder (using some ideas from the Ruc vertical coordinate, I think...and going from there). It actually uses physical parameterizations (i.e. convection, PBL, etc.) from the GFS, and is initialized from the GFS analysis. At one point I'm sure people were pushing to have the FIM replace the GFS....but that no longer seems like it's even a possibility. Better yet, there are people pushing to try to use a global version of the NMM to replace the GFS (why is nobody ever happy with the GFS ?!? ... but I digress). As an aside, the GFS actually now has an option to run using a hybrid isentropic-pressure-sigma coordinate system (but currently the GFS is hybrid sigma-pressure....i.e. terrain following near the surface and constant pressure as you go toward the model top). Link to comment Share on other sites More sharing options...
richmondsnow Posted January 23, 2011 Share Posted January 23, 2011 onto the 18z NAM Link to comment Share on other sites More sharing options...
Bob Chill Posted January 23, 2011 Share Posted January 23, 2011 unfortunately sometimes we get a great track and it is rain Yes, and most of the time this year we get a bad track and get nothing. Much better this way and I'll enjoy my cold rain if that's what happens. Are you going to snow chase to Ji's? Link to comment Share on other sites More sharing options...
mattie g Posted January 23, 2011 Share Posted January 23, 2011 We've got a good storm track from most models, and we have more cold air from the one model that has been relatively money so far this season. Everything taken together, I'm not feeling too bad about this. I still think this means it'll be a mostly snow event in the DC area (snowier the further west you are), with the details still to be determined. Link to comment Share on other sites More sharing options...
dtk Posted January 23, 2011 Share Posted January 23, 2011 We've got a good storm track from most models, and we have more cold air from the one model that has been relatively money so far this season. Everything taken together, I'm not feeling too bad about this. I still think this means it'll be a mostly snow event in the DC area (snowier the further west you are), with the details still to be determined. Just something to keep in mind, recently the GFS has had a SLIGHT near-surface cold bias while the Euro has definitely run a bit warm. These are hemispheric examples, but demonstrate the point [the black is GFS and red ECMWF....this is the average temperature bias as a function of forecast lead time for the past month or so....each system verified against its own analysis.....this is 1000 mb, so you have to be careful about interpretation): Here is more evidence, but actually implies the GFS has a slight WARM near surface bias at 48 hours. The plot below are the mean fits of temperatures forecasts to RAOBS over NA for 2 day forecasts for the past month (GFS black, ECM red). The dashed line is the bias (solid RMSE)....notice the substantial warm bias between 1000 and 800 on the ECMWF..... I'm not saying this translates to anything specific for this forecast, just something to bear in mind. Link to comment Share on other sites More sharing options...
PhineasC Posted January 23, 2011 Share Posted January 23, 2011 That gives me some hope that maybe the Euro is overdoing the warmth. Link to comment Share on other sites More sharing options...
Kmlwx Posted January 23, 2011 Share Posted January 23, 2011 That gives me some hope that maybe the Euro is overdoing the warmth. A compromise in the middle wouldn't be the end of the world at all. Link to comment Share on other sites More sharing options...
usedtobe Posted January 23, 2011 Share Posted January 23, 2011 Great graphics. I thought the euro was a little warm and the gfs might be the opposite. Link to comment Share on other sites More sharing options...
Midlo Snow Maker Posted January 23, 2011 Share Posted January 23, 2011 someone start a new thread Link to comment Share on other sites More sharing options...
I-83 BLIZZARD Posted January 23, 2011 Share Posted January 23, 2011 continued Link to comment Share on other sites More sharing options...
mattie g Posted January 23, 2011 Share Posted January 23, 2011 Thanks, dtk. Even *I* understood your explanation. (Re: the temp bias of the Euro and GFS so far this season) A compromise in the middle wouldn't be the end of the world at all. That's kind of my take, as well. Like I said, we have relative confidence in a good track, and the temps are fairly close to giving many of us a heavy, wet snowstorm. If they verify on the cooler side, then we're going to be pretty happy. If they tilt the other way, then most of us will have to suck up a cold rain. We're really on a knife's edge, but I'm not terribly pessimistic right now. Link to comment Share on other sites More sharing options...
yoda Posted January 23, 2011 Share Posted January 23, 2011 NOTE: This is dtk's post in the locked thread... thought I would move it over here so all could see and in case it gets lost in the now locked thread Just something to keep in mind, recently the GFS has had a SLIGHT near-surface cold bias while the Euro has definitely run a bit warm. These are hemispheric examples, but demonstrate the point [the black is GFS and red ECMWF....this is the average temperature bias as a function of forecast lead time for the past month or so....each system verified against its own analysis.....this is 1000 mb, so you have to be careful about interpretation): Here is more evidence, but actually implies the GFS has a slight WARM near surface bias at 48 hours. The plot below are the mean fits of temperatures forecasts to RAOBS over NA for 2 day forecasts for the past month (GFS black, ECM red). The dashed line is the bias (solid RMSE)....notice the substantial warm bias between 1000 and 800 on the ECMWF..... I'm not saying this translates to anything specific for this forecast, just something to bear in mind. Link to comment Share on other sites More sharing options...
samdman95 Posted January 23, 2011 Share Posted January 23, 2011 If we get the ideal "needle thread" how much snow could we expect?? Link to comment Share on other sites More sharing options...
Ian Posted January 23, 2011 Share Posted January 23, 2011 new wes post http://voices.washingtonpost.com/capitalweathergang/2011/01/latest_on_the_tuesday-wednesda.html Link to comment Share on other sites More sharing options...
TL97 Posted January 23, 2011 Share Posted January 23, 2011 People in the NYC forum were comparing this storm to the Christmas 2002 storm. How did we do down here in that storm? Link to comment Share on other sites More sharing options...
SomeguyfromTakomaPark Posted January 23, 2011 Share Posted January 23, 2011 If any mets want to explain why models didn't forecast the cold well during the ice storm and if that idea is applicable to this setup, i'm listening. Link to comment Share on other sites More sharing options...
ThreeRedheads Posted January 23, 2011 Share Posted January 23, 2011 People in the NYC forum were comparing this storm to the Christmas 2002 storm. How did we do down here in that storm? Two days ago is was being compared to the PD2 storm. Jeez. I will look the Christmas 2002 storm up in IAN's book. Link to comment Share on other sites More sharing options...
SomeguyfromTakomaPark Posted January 23, 2011 Share Posted January 23, 2011 new wes post http://voices.washin...y-wednesda.html Great read. Thanks for posting! Link to comment Share on other sites More sharing options...
Quasievil Posted January 23, 2011 Share Posted January 23, 2011 People in the NYC forum were comparing this storm to the Christmas 2002 storm. How did we do down here in that storm? My memory tells me that it want very good down here.. we got our payback that February though.. Link to comment Share on other sites More sharing options...
winterymix Posted January 23, 2011 Share Posted January 23, 2011 If any mets want to explain why models didn't forecast the cold well during the ice storm and if that idea is applicable to this setup, i'm listening. I'm going to suggest it was all about cold air damming. The models are somewhat biased and often seem to under-estimate cold air damming. Oddly, for that setup, areas with very borderline boundary layer temperatures changed over to rain, freezing rain or sleet and then expectantly flipped back to sleet and snow. I'm guessing that 850 mb warm air advection underperformed but can't tell you why. Link to comment Share on other sites More sharing options...
SomeguyfromTakomaPark Posted January 23, 2011 Share Posted January 23, 2011 I'm going to suggest it was all about cold air damming. The models are somewhat biased and often seem to under-estimate cold air damming. Oddly, for that setup, areas with very borderline boundary layer temperatures changed over to rain, freezing rain or sleet and then expectantly flipped back tot sleet and snow. I'm guessing that 850 mb warm air advection underperformed but can't tell you why. It was a really interesting event to watch IMBY. I was really surprised how cold it stayed and am hoping cold air can make it happen this time. Link to comment Share on other sites More sharing options...
winterymix Posted January 23, 2011 Share Posted January 23, 2011 new wes post http://voices.washin...y-wednesda.html Thread the needle© Link to comment Share on other sites More sharing options...
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