Isotherm Posted December 15, 2012 Share Posted December 15, 2012 EPO forecasts right now indicate the rapid fall from +2 SD to near -1 SD during the few days prior to Christmas. Shows the EPO back positive after that but these forecasts have been changing every day and aren't reliable at all beyond D 7. However, the north Pacific pattern is progged to improve in the D 5-7 range so what we're looking at in terms of massive height rises over AK is in fact real. This will finally initiate the cross-polar flow, seeding Canada with arctic air, and providing a mechanism for the southward delivery of this air into the nern CONUS. The dying west based -NAO and building of heights in AK will both aid in finally shoving the baroclinic zone southward. Given the pattern depicted, as many of us have already said, late December is probably going to be favorable. I honestly would be surprised if we're snowless through New Years. Not an ideal pattern but much closer to a great pattern than a horrible one for the Dec 20-30 period. Link to comment Share on other sites More sharing options...
Isotherm Posted December 15, 2012 Share Posted December 15, 2012 Anyone notice a difference in the NPAC pattern? Initial: 168hrs (D7) Link to comment Share on other sites More sharing options...
bluewave Posted December 16, 2012 Share Posted December 16, 2012 Anyone notice a difference in the NPAC pattern? Initial: 168hrs (D7) Yeah, I would like to see the Euro ensemble get a little more bullish on the -NAO retrograding further west than it is at day 10. Things would look up for us if the flow can buckle more and we get a ridge to replace that trough out west. It is really tough to try and figure out the details from this far out with the Pacific fire hose jet going. But the temps should step down to closer to seasonable and maybe a bit below for a time around Christmas. Link to comment Share on other sites More sharing options...
earthlight Posted December 16, 2012 Share Posted December 16, 2012 Yeah, I would like to see the Euro ensemble get a little more bullish on the -NAO retrograding further west than it is at day 10. Things would look up for us if the flow can buckle more and we get a ridge to replace that trough out west. It is really tough to try and figure out the details from this far out with the Pacific fire hose jet going. But the temps should step down to closer to seasonable and maybe a bit below for a time around Christmas. These pattern changes can be maddening at times, especially when they feature a step down process. In this situation I think we were duped a little bit with the above normal height anomalies over Greenland and Central Canada. Not only was the origin of the block poor -- but the models were too aggressive with it. So we have to watch for that once again in the medium range with these forecast developments. Nevertheless, the developments are moving up in the time in the medium range...and if we start to get the NAO block retrograding farther west and the ridging out west, I think all bets are off and we will start seeing results very quickly. The GFS is an ideal look with a ULL elongated over Southeast Canada and a huge block to the north of it as well as a huge ridge over Alaska. Link to comment Share on other sites More sharing options...
NorEaster27 Posted December 16, 2012 Share Posted December 16, 2012 These pattern changes can be maddening at times, especially when they feature a step down process. In this situation I think we were duped a little bit with the above normal height anomalies over Greenland and Central Canada. Not only was the origin of the block poor -- but the models were too aggressive with it. So we have to watch for that once again in the medium range with these forecast developments. Nevertheless, the developments are moving up in the time in the medium range...and if we start to get the NAO block retrograding farther west and the ridging out west, I think all bets are off and we will start seeing results very quickly. The GFS is an ideal look with a ULL elongated over Southeast Canada and a huge block to the north of it as well as a huge ridge over Alaska. The ridge over AK is what we really need to develop, I have no trust in it developing at this stage despite the modeling. Link to comment Share on other sites More sharing options...
earthlight Posted December 16, 2012 Share Posted December 16, 2012 The ridge over AK is what we really need to develop, I have no trust in it developing at this stage despite the modeling. I understand your caution to be honest. But it certainly is encouraging to see it develop on every single GEFS member, the OP GFS, and the Euro Ens. http://www.meteo.psu.edu/~fxg1/ENSHGTNH_18z/f156.gif http://raleighwx.americanwx.com/models/ecmwfens/12zECMWFENS500mbHeightAnomalyNH192.gif Link to comment Share on other sites More sharing options...
earthlight Posted December 16, 2012 Share Posted December 16, 2012 The GFS analog composite is incredibly exciting...and this is as soon as Days 6-10 (not the extended graphic that is often posted here, days 8 to 14). The next 7 days will be make or break if you ask me...I know I saw Tom post something similar a few days ago. But I truly think we will know where this is headed very soon. If this develops as advertised...we're probably entering a ticking time bomb pattern by Christmas. The trough is centered east of the area initially but retrogrades west as the Alaskan/Canadian blocking connects...you can see 2010 on the analogs and a very similar event transpired during that period as well. The Dec 19 2010 system missed to our east because the pattern was not quite ready yet -- but we were colder due to the true and dominant nature of the block. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted December 16, 2012 Share Posted December 16, 2012 These pattern changes can be maddening at times, especially when they feature a step down process. In this situation I think we were duped a little bit with the above normal height anomalies over Greenland and Central Canada. Not only was the origin of the block poor -- but the models were too aggressive with it. So we have to watch for that once again in the medium range with these forecast developments. Nevertheless, the developments are moving up in the time in the medium range...and if we start to get the NAO block retrograding farther west and the ridging out west, I think all bets are off and we will start seeing results very quickly. The GFS is an ideal look with a ULL elongated over Southeast Canada and a huge block to the north of it as well as a huge ridge over Alaska. The amazing thing is that type of dual block pattern back in 1980 would produce sub zero temps, now it produces lows in the 20s and highs in the 30s...there is definitely some sort of lack of arctic air these days, even when the setup is great. Link to comment Share on other sites More sharing options...
Chris L Posted December 16, 2012 Share Posted December 16, 2012 The amazing thing is that type of dual block pattern back in 1980 would produce sub zero temps, now it produces lows in the 20s and highs in the 30s...there is definitely some sort of lack of arctic air these days, even when the setup is great. I am not too sure about the lack of arctic air per se, it's likely on the other side. Perhaps Christmas 1980 had the cold in Canada or had cross polar flow from Russia? Link to comment Share on other sites More sharing options...
nzucker Posted December 16, 2012 Share Posted December 16, 2012 The amazing thing is that type of dual block pattern back in 1980 would produce sub zero temps, now it produces lows in the 20s and highs in the 30s...there is definitely some sort of lack of arctic air these days, even when the setup is great. That's a fairly zonal pattern depicted on the GFS though, not one that produces record-setting cold. You'd need a deeper trough in the East to get the arctic cold you're looking for. Link to comment Share on other sites More sharing options...
KEITH L.I Posted December 16, 2012 Share Posted December 16, 2012 Christmas 80..12z temp -1F Link to comment Share on other sites More sharing options...
tmagan Posted December 16, 2012 Share Posted December 16, 2012 I was just looking at the Christmas 1980 maps earlier in the week, the Arctic air was short lived to say the least. That was a wild three week period, a couple of weeks later a bitter cold 1981 NFC Championship game in Philly, two weeks later, the warmest inauguration ever. Link to comment Share on other sites More sharing options...
tmagan Posted December 16, 2012 Share Posted December 16, 2012 The amazing thing is that type of dual block pattern back in 1980 would produce sub zero temps, now it produces lows in the 20s and highs in the 30s...there is definitely some sort of lack of arctic air these days, even when the setup is great. Decrease in Arctic sea ice. Link to comment Share on other sites More sharing options...
tmagan Posted December 16, 2012 Share Posted December 16, 2012 Maybe some low-topped convection Friday morning. Link to comment Share on other sites More sharing options...
blinkers88 Posted December 16, 2012 Share Posted December 16, 2012 Decrease in Arctic sea ice. and here we go Link to comment Share on other sites More sharing options...
MJO812 Posted December 16, 2012 Share Posted December 16, 2012 0z GEFS is much colder than the op in the mid to long range. The signal is there for the Christmas storm. Link to comment Share on other sites More sharing options...
NEG NAO Posted December 16, 2012 Share Posted December 16, 2012 0z GEFS is much colder than the op in the mid to long range. The signal is there for the Christmas storm. OZ Euro paints a different picture=once again west and warm= http://raleighwx.americanwx.com/models/euro/00zeuro850mbTSLPUS216.gif http://raleighwx.americanwx.com/models/euro/00zeuro850mbTSLPUS240.gif Link to comment Share on other sites More sharing options...
Guest Pamela Posted December 16, 2012 Share Posted December 16, 2012 OZ Euro paints a different picture=once again west and warm= http://raleighwx.ame...mbTSLPUS216.gif http://raleighwx.ame...mbTSLPUS240.gif Probably a better than even chance of being right...rain, fog and 50 F is more or less standard Christmas weather in the NYC area. Link to comment Share on other sites More sharing options...
tmagan Posted December 16, 2012 Share Posted December 16, 2012 Situation Friday has some similarities (albeit weaker) to January 19, 1996. Link to comment Share on other sites More sharing options...
Weathergun Posted December 16, 2012 Share Posted December 16, 2012 The Euro ensemble mean, doesn't cut-off block over the Alaska region, like the GEFS does. Instead the Euro brings negative 500mb height anomalies back over Alaska, in the 8-10day period (at least). Without that block over the AK region, it will be difficult to sustain a cross-polar flow here, through Christmas week. Even with the west-based -NAO. Right now, I'm not convinced either solution is correct. Link to comment Share on other sites More sharing options...
Sundog Posted December 16, 2012 Share Posted December 16, 2012 and here we go You're right a massive disruption in the amount of sea ice and volume can't possibly have an affect on the subsequent Arctic air masses that form. In fact arctic sea ice might as well be a closed system because nothing external affects it and Arctic sea ice levels have zero effects on the rest of the Arctic. Link to comment Share on other sites More sharing options...
bluewave Posted December 16, 2012 Share Posted December 16, 2012 Record blocking just 2 years ago which set the table for the Boxing Day Blizzard only 10 days later. Link to comment Share on other sites More sharing options...
MJO812 Posted December 16, 2012 Share Posted December 16, 2012 0z NAEFS. Looks better than the GFS and Euro. Link to comment Share on other sites More sharing options...
bluewave Posted December 16, 2012 Share Posted December 16, 2012 Unfortunately, both the Euro and GFS ensemble means are still showing the Pacific overpowering the pattern with a big trough out west and a fire hose Pacific jet to close out the last week of December. Euro GFS Link to comment Share on other sites More sharing options...
Weathergun Posted December 16, 2012 Share Posted December 16, 2012 Unfortunately, both the Euro and GFS ensemble means are still showing the Pacific overpowering the pattern with a big trough out west and a fire hose Pacific jet to close out the last week of December. Euro GFS Yes. But the GEFS still has higher heights across the AK region. And maintains a cross-polar longer than Euro ensemble mean. A system will break away from the NE Pacific trough, sometime between 25-27th. If we still have the cross-polar flow and the west-based -NAO in place, we can see snow. Link to comment Share on other sites More sharing options...
NorEaster27 Posted December 16, 2012 Share Posted December 16, 2012 I understand your caution to be honest. But it certainly is encouraging to see it develop on every single GEFS member, the OP GFS, and the Euro Ens. http://www.meteo.psu.edu/~fxg1/ENSHGTNH_18z/f156.gif http://raleighwx.americanwx.com/models/ecmwfens/12zECMWFENS500mbHeightAnomalyNH192.gif Euro is already backing away from the idea Link to comment Share on other sites More sharing options...
SnowGoose69 Posted December 16, 2012 Share Posted December 16, 2012 Can anyone see last year pooping up in there mind when seeing that now the euri is backing off the change listen I hope too god I'm wrong and I look like a total ass for saying this but im sorry your lying if you say you haven't thought about last Winter when seeing everything always being ten days out again so far this winter Its quite a bit closer than 10 days...the last few GFS runs show that after the big Upper Lakes blizzard and strong cold frontal passage for the entire East Coast at around 120 hours there is noticeable difference across the TN Valley and Plains...unlike the past 2-3 weeks where a ridge immediately starts building there and progressing east and the entire East immediately warms following the FROPA, this time that pattern goes flat and everyone from about 35-37N stays cold. The Euro however by 170-180 hours and just 2 days of cold weather starts showing another big storm developing over the SW. I'm not so sure I buy this because the Euro is notorious for over energizing things down there. My guess is the storm shown on the Euro at Day 9-10 will be much weaker and further south and east than currently shown. The one thing I do believe right now is it will be seasonal to below seasonal for a good part of the NE U.S. from the 22nd-27th. I'm just not sure what happens after that. Link to comment Share on other sites More sharing options...
Guest Pamela Posted December 16, 2012 Share Posted December 16, 2012 The one thing I do believe right now is it will be seasonal to below seasonal for a good part of the NE U.S. from the 22nd-27th. I'm just not sure what happens after that. 5 whole days of seasonal temps? We must have been *very* good all year to have earned that. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted December 16, 2012 Share Posted December 16, 2012 5 whole days of seasonal temps? We must have been *very* good all year to have earned that. LOL, well it may prevent a few places from having their warmest December on record. Nobody in the Northeast will really come close, however, there are quite a few big cities in the Midwest/TN Valley and south that have remarkably good chances right now, as a matter of fact some places like MEM/ATL/BHM are on pace to absolutely annihilate 1984 right now, even with a near normal rest of the month they'd have it beat by a reasonable margin. Link to comment Share on other sites More sharing options...
earthlight Posted December 16, 2012 Share Posted December 16, 2012 Weathergun is on point with his discussion about the Alaskan ridge breaking off from the main ridge west of the Aleutians. That can be a game changer if it the GFS is correct and it occurs. Unfortunately the Euro ensembles are not as enthused. But you can see the development here if you loop through the height anomalies around 120-160 hours. http://www.meteo.psu.edu/~fxg1/ENSHGTAVGNH_6z/ensloopmref.html Link to comment Share on other sites More sharing options...
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