am19psu Posted December 7, 2011 Author Share Posted December 7, 2011 Link to comment Share on other sites More sharing options...
Srain Posted December 7, 2011 Share Posted December 7, 2011 ... Link to comment Share on other sites More sharing options...
am19psu Posted December 8, 2011 Author Share Posted December 8, 2011 +EPO and this strong Nina forcing (http://www.atmos.albany.edu/student/carl/weather/timeLon/u.anom.30.5S-5N.png) should allow the Eastern US to average out warm to very warm overall through Dec 20, at least. There doesn't look to be much help from the tropics until New Year's (using the Roundy forecast, not the Euro weeklies - the weeklies are even worse). Link to comment Share on other sites More sharing options...
ayuud Posted December 8, 2011 Share Posted December 8, 2011 +EPO and this strong Nina forcing (http://www.atmos.alb...om.30.5S-5N.png) should allow the Eastern US to average out warm to very warm overall through Dec 20, at least. There doesn't look to be much help from the tropics until New Year's (using the Roundy forecast, not the Euro weeklies - the weeklies are even worse). R.I.P Winter Link to comment Share on other sites More sharing options...
wxmx Posted December 8, 2011 Share Posted December 8, 2011 We are fully dependant on the EPO, right now, to provide us from some artic air. As a matter of fact, the "4 big ones", areal coverage wise, since 1950 that brought the coldest temps to the CONUS had very +NAO and a very -EPO... yes, it's a very supressive pattern, but at least areas from the mid Atlantic could benefit from it in the absence of a -NAO. I didn't include the Jan 1985 artic express, since it had slightly less CONUS converage because it was east biased (thanks to a west based -NAO). 500mb mean heights 500mb anomalies Surface temps This pattern is known as the McFarland signature, and though I'm not predicting one this winter, it's possibly our best chance for Artic cold pouring down for late this month and most of January. The good news is that we are in a long term -EPO period, and though we hadn't had any significant -EPO episode so far, ridging is closer to the west coast than what we would expect from the Pacific pattern, and it is refusing to retrograde much. Link to comment Share on other sites More sharing options...
Srain Posted December 8, 2011 Share Posted December 8, 2011 Oh how I miss the old days of those awesome discussions from BRO and McFarland... Link to comment Share on other sites More sharing options...
wxmx Posted December 8, 2011 Share Posted December 8, 2011 Look at the similarities of the 1951 & 1962 patterns with the current one...we "only" need the cross polar flow Link to comment Share on other sites More sharing options...
am19psu Posted December 8, 2011 Author Share Posted December 8, 2011 In 'Merika, we spell it "Arctic," Jorge. Link to comment Share on other sites More sharing options...
am19psu Posted December 8, 2011 Author Share Posted December 8, 2011 great post Two questions: 1. Where is the potential -EPO coming from? Himalayan MT next time the MJO gets into the IO? 2. Isn't the EP/NP pattern the opposite of the EPO? Link to comment Share on other sites More sharing options...
wxmx Posted December 8, 2011 Share Posted December 8, 2011 Two questions: 1. Where is the potential -EPO coming from? Himalayan MT next time the MJO gets into the IO? 2. Isn't the EP/NP pattern the opposite of the EPO? 1. Dunno, I just think it's a more feasible to get a -EPO than a -AO/-NAO for the next 45 days. 2. You're right, I assumed they were directly correlated, but it's the other way around. Which would make sense in a -PDO phase. Strike that. Link to comment Share on other sites More sharing options...
okie333 Posted December 8, 2011 Share Posted December 8, 2011 We are fully dependant on the EPO, right now, to provide us from some artic air. As a matter of fact, the "4 big ones", areal coverage wise, since 1950 that brought the coldest temps to the CONUS had very +NAO and a very -EPO... yes, it's a very supressive pattern, but at least areas from the mid Atlantic could benefit from it in the absence of a -NAO. I didn't include the Jan 1985 artic express, since it had slightly less CONUS converage because it was east biased (thanks to a west based -NAO). 500mb mean heights 500mb anomalies Surface temps This pattern is known as the McFarland signature, and though I'm not predicting one this winter, it's possibly our best chance for Artic cold pouring down for late this month and most of January. The good news is that we are in a long term -EPO period, and though we hadn't had any significant -EPO episode so far, ridging is closer to the west coast than what we would expect from the Pacific pattern, and it is refusing to retrograde much. Was that what happened in February 1899 also? Link to comment Share on other sites More sharing options...
wxmx Posted December 8, 2011 Share Posted December 8, 2011 In 'Merika, we spell it "Arctic," Jorge. Yeah, spanish spelling slipped. Link to comment Share on other sites More sharing options...
wxmx Posted December 8, 2011 Share Posted December 8, 2011 Was that what happened in February 1899 also? No upper air data from back then, but reanalysis suggests a well coordinated mod. -EPO and -NAO evolving into a -WPO, +PNA and very - west NAO...almost like shepherd dogs directing the massive cold to the CONUS sheep shed. Link to comment Share on other sites More sharing options...
okie333 Posted December 8, 2011 Share Posted December 8, 2011 Where did you get the daily composites? Link to comment Share on other sites More sharing options...
wxmx Posted December 8, 2011 Share Posted December 8, 2011 Where did you get the daily composites? http://www.esrl.noaa.gov/psd/cgi-bin/data/composites/plot20thc.day.v2.pl Link to comment Share on other sites More sharing options...
okie333 Posted December 8, 2011 Share Posted December 8, 2011 Link to comment Share on other sites More sharing options...
Hailstorm Posted December 9, 2011 Share Posted December 9, 2011 <p> No upper air data from back then, but reanalysis suggests a well coordinated mod. -EPO and -NAO evolving into a -WPO, +PNA and very - west NAO...almost like shepherd dogs directing the massive cold to the CONUS sheep shed. What does the "WPO" stand for and at what phase of it favors East Coast cold? Unless it was a typo for "EPO?" Thanks. Link to comment Share on other sites More sharing options...
am19psu Posted December 9, 2011 Author Share Posted December 9, 2011 What does the "WPO" stand for and at what phase of it favors East Coast cold? Thanks. Here is the positive phase of the WPO. The negative phase marginally helps bring cold air to the East, but it's not a strong correlation. Link to comment Share on other sites More sharing options...
Hailstorm Posted December 9, 2011 Share Posted December 9, 2011 Here is the positive phase of the WPO. The negative phase marginally helps bring cold air to the East, but it's not a strong correlation. So with a -WPO, there are warm anomalies over Eastern Siberia which thus breaks down Alaskan troughs and an Aleutian ridge so that colder air is dislodged more to the East Coast? Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 9, 2011 Share Posted December 9, 2011 The 12/8/2011 18z run of the GFS suggests that the 11-15-day period (12/19-23) could be colder than normal in the East. However, the operational GFS is not supported by the 18z GFS ensembles. Which is more likely to be correct? At this point, given everything that has been noted in this and the AO thread, I believe the ensembles have a better idea. Below is a chart that compares the Operational GFS with the results of: 1. The 18z GFS ensembles (850 mb temperature anomalies) 2. Composite 500 mb height anomalies based on an AO in the +1 to +2.5 range; PNA in the -0.5 to +0.5 range, ENSO R3.4 anomalies in the -1.50 to -0.75 range, for the 12/15-25 timeframe (1950-2010) 3. Composite 850 mb temperature anomalies based on an AO in the +1 to +2.5 range; PNA in the -0.5 to +0.5 range, ENSO R3.4 anomalies in the -1.50 to -0.75 range, for the 12/15-25 timeframe (1950-2010) 4. The NAEFS (12/16-22 range -- closest period in question) Unfortunately, it appears that the operational GFS is alone in its extended range forecast. While things could still change, my guess at this point in time is to favor an idea based on the GFS ensembles. There is a continuing risk that the area of warmth could be more expansive than shown on the GFS ensembles, especially if the EPO goes positive. Link to comment Share on other sites More sharing options...
BethesdaWX Posted December 9, 2011 Share Posted December 9, 2011 Hahaha, well, if I'm doing this right, it seems December 1898 featured a powerful +AO as well as did most of January. Interesting to note 1898 was part of a multi-year La Nina event, while likely weak, also featured the +AMO, -PDO, and a less active Sun. December: January: February: Link to comment Share on other sites More sharing options...
BethesdaWX Posted December 9, 2011 Share Posted December 9, 2011 Those say 1998-1999 I don't think they do. Edit: Yep it's 1898/99, this is February 1999 Link to comment Share on other sites More sharing options...
JoMo Posted December 9, 2011 Share Posted December 9, 2011 Strange, says "9" on the images though, prolly a bug. Link to comment Share on other sites More sharing options...
okie333 Posted December 9, 2011 Share Posted December 9, 2011 Strange, says "9" on the images though, prolly a bug. 1899 not 1999... only says "99". Despite the name, the 20th Century Reanalysis goes back to 1871. Link to comment Share on other sites More sharing options...
wxmx Posted December 9, 2011 Share Posted December 9, 2011 Time to revive the old meme: All your cold r belong to us Link to comment Share on other sites More sharing options...
Srain Posted December 10, 2011 Share Posted December 10, 2011 Yet another very interesting pattern shaping up for the Rockies into the Great Plains. Link to comment Share on other sites More sharing options...
pcbjr Posted December 10, 2011 Share Posted December 10, 2011 Amazing the differences between the 2 models in the same time frame ... Link to comment Share on other sites More sharing options...
WxUSAF Posted December 10, 2011 Share Posted December 10, 2011 Yet another very interesting pattern shaping up for the Rockies into the Great Plains. Forget them, there's blocking over the pole! Link to comment Share on other sites More sharing options...
wxmx Posted December 10, 2011 Share Posted December 10, 2011 Blocking is a strong word...some ridging in a probably neutralish AO...good signals anyway, though the PV near the HB it's not a good location for the East Coast, but with a good Pacific it's perfect for the W 2/3. Link to comment Share on other sites More sharing options...
Srain Posted December 10, 2011 Share Posted December 10, 2011 Blocking is a strong word...some ridging in a probably neutralish AO...good signals anyway, though the PV near the HB it's not a good location for the East Coast, but with a good Pacific it's perfect for the W 2/3. Which is exactly why I posted as I did... Link to comment Share on other sites More sharing options...
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