GaWx Posted November 21, 2010 Share Posted November 21, 2010 If the models are to be believed, the upcoming -NAO blocking is about to become uncommonly strong. Actually, the NAO has a shot at plunging to sub -3 levels on the dailies. Going back to when records started in 1950, I could find only two periods with sub -3 daily NAO's: 7/13-14/1962 and 10/20-22/2002. The lowest on record is the -3.254 of 10/21/02. So, the upcoming -NAO block is looking to reach pretty historic levels! Because unusual SE US snows sometimes accompany or immediately follow very strong NAO/AO blocks, this has me quite interested. The following link is to daily NAO's going back to 1950: ftp://ftp.cpc.ncep.n...1.current.ascii Here is the NAO fcast from the 11/21/10 0Z GFS ensemble. Although it could very well be a little overdone, note how the mean forecast is for it to plunge to near -3 on 11/28 as per the day 7 forecast: Link to comment Share on other sites More sharing options...
Southland Wx Posted November 21, 2010 Share Posted November 21, 2010 PSD ensembles look decent too: Link to comment Share on other sites More sharing options...
CoastalWx Posted November 21, 2010 Share Posted November 21, 2010 Strong -pna/-nao is going to make somebody in the Midwest very happy. Could that extend to the northeast??? Link to comment Share on other sites More sharing options...
Dr No Posted November 21, 2010 Share Posted November 21, 2010 As the models are hinting on, clearly Dec 1-3 is favorable for a storm. Will the block still be strong enough to force the track east as opposed to through the OV/Eastern Lakes? If it bottoms out aub -3, maybe so. Link to comment Share on other sites More sharing options...
earthlight Posted November 21, 2010 Share Posted November 21, 2010 Strong -pna/-nao is going to make somebody in the Midwest very happy. Could that extend to the northeast??? I'm encouraged by guidance and global ensembles attempting to spike the PNA towards neutral or possibly slightly positive near the beginning of December. There's a whole lot of energy coming out of the North Pacific/Canada, so it remains to be seen if the forecast -NAO block and the PNA spike can time themselves well to bring some frozen precipitation to this side of the CONUS. Link to comment Share on other sites More sharing options...
HM Posted November 21, 2010 Share Posted November 21, 2010 Without a retrograding block and 50-50 low, these lows will plow inland with nothing to stop them really. That's what made last night's ECMWF run so interesting and I am looking forward to the 12z run. The GFS completely fails to retrograde the block, like it was doing yesterday on all runs. Link to comment Share on other sites More sharing options...
JBG Posted November 21, 2010 Share Posted November 21, 2010 Without a retrograding block and 50-50 low, these lows will plow inland with nothing to stop them really. That's what made last night's ECMWF run so interesting and I am looking forward to the 12z run. The GFS completely fails to retrograde the block, like it was doing yesterday on all runs. Why wouldn't the block, even un-retrograded, be enough to suppress the lows towards the Coast and away from plowing inland? Link to comment Share on other sites More sharing options...
GaWx Posted November 21, 2010 Author Share Posted November 21, 2010 The 12Z Sun. Euro has a very impressive 575 dm 500 mb NAO block as of hour 192 that has retrograded from Greenland to NE Canada. The rest of this run should be very interesting. Link to comment Share on other sites More sharing options...
HM Posted November 21, 2010 Share Posted November 21, 2010 Why wouldn't the block, even un-retrograded, be enough to suppress the lows towards the Coast and away from plowing inland? You don't have a +PNA and the high frequency wave pattern from the Pacific would plow that thing right down to the ground. Personally, I think the GFS run was a hiccup and not a trend. This is especially true given the ECMWF data! Link to comment Share on other sites More sharing options...
Alpha5 Posted November 21, 2010 Share Posted November 21, 2010 The 12Z Sun. Euro has a very impressive 575 dm 500 mb NAO block as of hour 192 that has retrograded from Greenland to NE Canada. The rest of this run should be very interesting. Euro wants to take the 200 hr storm strait through the lakes Link to comment Share on other sites More sharing options...
Cheeznado Posted November 21, 2010 Share Posted November 21, 2010 12Z Euro has a good storm at 9-10 days.....for the western GL and Midwest. All rain for the East. Link to comment Share on other sites More sharing options...
GaWx Posted November 21, 2010 Author Share Posted November 21, 2010 12Z Euro has a good storm at 9-10 days.....for the western GL and Midwest. All rain for the East. I wasn't even thinking about the details about this storm. I'm noticing a beautiful 500 mb block that has moved all of the way to N/C Canada with an accompaying 1042ish high at hour 240. This tells me that early Dec. could very well be quite exciting for the E US, including the SE. Link to comment Share on other sites More sharing options...
Amped Posted November 21, 2010 Share Posted November 21, 2010 The 12Z Sun. Euro has a very impressive 575 dm 500 mb NAO block as of hour 192 that has retrograded from Greenland to NE Canada. The rest of this run should be very interesting. Yeah it also takes most of the cold air out of Canada Link to comment Share on other sites More sharing options...
OKpowdah Posted November 21, 2010 Share Posted November 21, 2010 12Z Euro has a good storm at 9-10 days.....for the western GL and Midwest. All rain for the East. whoa, give New England some love, That's a huge snow storm for central and northern New England! Link to comment Share on other sites More sharing options...
Lee Posted November 21, 2010 Share Posted November 21, 2010 Yeah it also takes most of the cold air out of Canada -8 850's down to Tennessee. Looks like the cold in Canada is being shoved south. Link to comment Share on other sites More sharing options...
wxmeddler Posted November 21, 2010 Share Posted November 21, 2010 Link to comment Share on other sites More sharing options...
GaWx Posted November 21, 2010 Author Share Posted November 21, 2010 Yeah it also takes most of the cold air out of Canada That's good if you want it cold down in the E US. Note that the 12z Euro ensemble mean is quite cold in the E US during the 11-15 as the cold is forced down from Canada by the block as Canada warms. Link to comment Share on other sites More sharing options...
WeatherNC Posted November 21, 2010 Share Posted November 21, 2010 That's good if you want it cold down in the E US. Note that the 12z Euro ensemble mean is quite cold in the E US during the 11-15 as the cold is forced down from Canada by the block as Canada warms. Larry, not sure how much stock we can put into the 12z EC given the discrepancies with its previous run. However, a big storm up the TN Valley would pull a sig cold front down in the extended. It also may set the stage for a storm along the east coast if the first low gets locked into the 50-50 position given the blocking scheme, and below normal temps already in place. Link to comment Share on other sites More sharing options...
CAD_Wedge_NC Posted November 21, 2010 Share Posted November 21, 2010 Larry, not sure how much stock we can put into the 12z EC given the discrepancies with its previous run. However, a big storm up the TN Valley would pull a sig cold front down in the extended. It also may set the stage for a storm along the east coast if the first low gets locked into the 50-50 position given the blocking scheme, and below normal temps already in place. Agree....... As I read in an earlier post, It will come down to whether or not the block can lock in a 50/50 low. If so, then the east may be in a good position for a coastal storm. Link to comment Share on other sites More sharing options...
tacoman25 Posted November 22, 2010 Share Posted November 22, 2010 I'm honestly beginning to wonder if I went too warm for the East in my winter outlook...there continues to be a strong tendency towards -NAO, just like we saw last year around this time. If even a moderately -NAO dominates this winter, the Eastern half of the CONUS will probably be colder than a lot of people were thinking. Link to comment Share on other sites More sharing options...
JBG Posted November 22, 2010 Share Posted November 22, 2010 I'm honestly beginning to wonder if I went too warm for the East in my winter outlook...there continues to be a strong tendency towards -NAO, just like we saw last year around this time. If even a moderately -NAO dominates this winter, the Eastern half of the CONUS will probably be colder than a lot of people were thinking. I would still think a lot of back and forthing on temps, without too much snow. Think 1970-1 for a decent analog. That was one of the few La Niña winters that were on balance below normal temperature-wise as a result of a fairly cold December and positively gellid period from early January (though to late to save snowpack from January 1, 1971 8" storm) almost to end of January. February had its share of torches. Link to comment Share on other sites More sharing options...
New England Storm Posted November 22, 2010 Share Posted November 22, 2010 I'm honestly beginning to wonder if I went too warm for the East in my winter outlook...there continues to be a strong tendency towards -NAO, just like we saw last year around this time. If even a moderately -NAO dominates this winter, the Eastern half of the CONUS will probably be colder than a lot of people were thinking. That might be, however I would split at the moment, to cold or to warm . I went with a warmer outlook around october but, I just dont know anymore. Link to comment Share on other sites More sharing options...
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