bluewave Posted January 22, 2015 Share Posted January 22, 2015 Both the ECMWF and GFS ensemble means are indicating that heights will rise enough near Greenland to at least temporarily displace the polar vortex south as February begins. The polar vortex dropping south in this -AO pattern will allow Arctic high pressure to remain in place over SE Canada. Most of the time since the beginning of December the polar vortex has remained anchored in place near Greenland in a strong +AO pattern. Any pieces of energy cutting underneath in association the subtropical jet would encounter a fresh source of Arctic air to the north. While it's too early for any individual storm details, there should be a window of opportunity for snow in early February along with Arctic cold. Link to comment Share on other sites More sharing options...
SnoSki14 Posted January 22, 2015 Share Posted January 22, 2015 Looks like the Pacific pattern is also much improved (sustained -EPO) so we may still have opportunities even if the Atlantic pattern is less favorable. Link to comment Share on other sites More sharing options...
jm1220 Posted January 23, 2015 Share Posted January 23, 2015 Good to see you posting again, Bluewave!! El Nino winters are usually back-loaded, and hopefully the Northeast can cash in on a snowy end to the winter. Link to comment Share on other sites More sharing options...
Rjay Posted January 23, 2015 Share Posted January 23, 2015 Good to see you posting again, Bluewave!! El Nino winters are usually back-loaded, and hopefully the Northeast can cash in on a snowy end to the winter. Eh this isn't technically a Nino right? I still hope it's back-loaded. Link to comment Share on other sites More sharing options...
bluewave Posted January 23, 2015 Author Share Posted January 23, 2015 Looks like the Pacific pattern is also much improved (sustained -EPO) so we may still have opportunities even if the Atlantic pattern is less favorable. We'll see if the window of opportunity can produce some snow potential in early February with the forecast rebound in heights near Greenland. Maybe in about 3-5 days or so some individual storm threats may come into better focus as the models handle them best from around 120 hrs and under. Good to see you posting again, Bluewave!! El Nino winters are usually back-loaded, and hopefully the Northeast can cash in on a snowy end to the winter. Good to hear from you again also, JM. All the best of luck with your new job opportunity in Austin. Eh this isn't technically a Nino right? I still hope it's back-loaded. It was weak El Nino conditions with the strongest impact on the STJ in December when California picked up the much needed rainfall. January saw the weakening of the STJ which was a bit more active at times working in a split flow capacity with the northern branch. We'll see if the recent sharp SOI drop will be associated with a more energetic STJ around the beginning of February. Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 23, 2015 Share Posted January 23, 2015 Below is a table showing the AO/PNA tendencies for NYC's 6" or greater snowstorms in February (1950-2014): A PNA+ is relatively less important than it is for January. It is still important for the biggest snowstorms, with 60% of 10" or greater snowstorms commencing with a PNA+ vs. 50% for those in the 6"-9.9" range. The overall sample size for the table is 27. Link to comment Share on other sites More sharing options...
bluewave Posted January 23, 2015 Author Share Posted January 23, 2015 Below is a table showing the AO/PNA tendencies for NYC's 6" or greater snowstorms in February (1950-2014): A PNA+ is relatively less important than it is for January. It is still important for the biggest snowstorms, with 60% of 10" or greater snowstorms commencing with a PNA+ vs. 50% for those in the 6"-9.9" range. The overall sample size for the table is 27. We are just starting to see the GEFS AO index drop around the beginning of February in response to the height rises and higher pressures closer to Greenland. It will be interesting to see how low a level we can reach as we get closer to that time. Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 23, 2015 Share Posted January 23, 2015 We are just starting to see the GEFS AO index drop around the beginning of February in response to the height rises and higher pressures closer to Greenland. It will be interesting to see how low a level we can reach as we get closer to that time. ao.sprd2.jpg I agree. The most recent dip sent the AO down to a little above -1.6 (earlier forecasts were in the -3 to -2 range). If the forecast drop takes place, the 1/29-2/5 period might offer a real window of opportunity for a possible significant storm, especially as the subtropical jet is likely to be fairly active. Perhaps some earlier but not consistent runs showing a large coastal storm during that timeframe are some hints of the potential. If the AO falls to -2 or below, that could be a strong hint that the climatologically-preferred negative state could predominate in February. There's nothing really magical about -2, but the development of strong blocking in late January or early February has typically been a precursor of a predominantly negative AO for February. I remain cautiously optimistic that we can salvage February. A meaningful negative AO winter average appears unlikely, as the AO would need to average -2.302 from tomorrow through the end of February to achieve a winter average of -0.5. Just to reach 0, it would need to average -1.062 during that same timeframe. Both figures will very likely rise given the near-term forecast of a possibly brief period of a strongly positive AO. Link to comment Share on other sites More sharing options...
Weathergun Posted January 23, 2015 Share Posted January 23, 2015 Me, Isotherm, Doug, and others have been talking about these changes for awhile. The MJO it will strengthen in phase 8 during the first of week February. 500mb composite for the MJO ifor February a supports -AO/-NAO: Link to comment Share on other sites More sharing options...
uncle W Posted January 23, 2015 Share Posted January 23, 2015 today's ao forecast is encouraging...after a big rise it falls again...one member is in outer space but most are negative... Link to comment Share on other sites More sharing options...
Isotherm Posted January 23, 2015 Share Posted January 23, 2015 Me, Isotherm, Doug, and others have been talking about these changes for awhile. The MJO it will strengthen in phase 8 during the first of week February. 500mb composite for the MJO ifor February a supports -AO/-NAO: Agree weathergun. I've found the roundy plots to be fairly accurate this season in terms of ascertaining the progression of tropical forcing in the Pacific, generally more representative than the MJO plots. We should maintain conducive forcing over the next couple weeks to continue to tilt the AO negative, after a transient positive surge, and possibly initiate a -NAO episode the first week of February. I'm not confident on a longer-term / persistent -NAO just yet, but I do think the AO will be predominately negative going forward. Stratospheric trends support that as well. We have seen a fairly sharp decrease in solar parameters which could help increase heights near Greenland in the medium term. Link to comment Share on other sites More sharing options...
SnoSki14 Posted January 23, 2015 Share Posted January 23, 2015 Always believed February would deliver and the signs are very encouraging. Such a nice cold look with the displaced PV and things don't look very dry as subtropical jet remains active. Link to comment Share on other sites More sharing options...
JBG Posted January 24, 2015 Share Posted January 24, 2015 Always believed February would deliver and the signs are very encouraging. Such a nice cold look with the displaced PV and things don't look very dry as subtropical jet remains active.Your lips to G-d's ears. Though nothing, including today's "storm" seems to be working out this winter. Link to comment Share on other sites More sharing options...
PB GFI Posted January 24, 2015 Share Posted January 24, 2015 Always believed February would deliver and the signs are very encouraging. Such a nice cold look with the displaced PV and things don't look very dry as subtropical jet remains active. You what ? You have canceled winter 100 x . Dude you posted predicting the long range is a joke and how everyone is going to bust. So many of us wrote that El Niño winters were back loaded winters. You were not in our camp. If you thought we would see some meager snowfalls that's about it. There are a lot of cxl winter posts missing I believe NEG NAO saw that too. So please do not say you saw what's coming or that Feb would produce. What's coming may rival some of the best periods you've seen if it holds. Your coldest 5 day period is in front of you. KNYC should beat its 4 from early Jan and if things break right we do very well in the snow dept. Feb cold could have some real staying power. Now I've written about cold all winter , that has not erased. Link to comment Share on other sites More sharing options...
uncle W Posted January 24, 2015 Share Posted January 24, 2015 so far January 2015 is averaging 30.5 including yesterday...It could drop a degree or two with a very cold last week of the month...Last years coldest 30 days averaged 28.5...We have a good chance for a colder 30 day period than last year...snowfall has a long way to go to catch up with last year...I still think NYC will end up with 30-35"...TWT... Link to comment Share on other sites More sharing options...
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