donsutherland1 Posted January 13, 2014 Share Posted January 13, 2014 January 24-31, 2014 Thoughts... By the time the last week of January rolls around, the thaw that sent temperatures well into the 50s as far as Boston will be a fading memory. Instead, cold anomalies that will have returned ahead of the month's closing week will prevail. There is a growing likelihood that a bout of severe cold could occur at some point during this timeframe, especially as the EPO ridge that predominated through December into the opening days of January returns. The second aspect is that the pattern appears increasingly likely to become snowier from the Great Lakes region eastward to the northern Middle Atlantic and southern New England areas. Both among the teleconnection cases and GFS ensemble's objective analogs in recent days, one finds a number of dates that were fairly close to moderate or sizable snowfalls. Those dates have included late January 1961, late January 2003, and just after mid-January 2005. In short, it increasingly appears that the pattern evolution should result in the above-noted areas seeing above normal snowfall for the January 25 through February 15 period. Below are charts showing the latest ensemble forecast for the EPO, teleconnection cases, combined teleconnection and objective analog cases for which January anomalies were similar to those of the current month to date, and the reforecast ensemble mean 850 mb anomalies: Based on the above charts, I expect the eastern half of the CONUS and Canada to have colder to potentially much colder than normal readings for the last week of January. Even Florida, where winter has been largely absent, will likely wind up with below normal readings for the period as a whole. The western half of the CONUS and Canada should be warmer to possibly much warmer than normal courtesy of the PNA ridge. Should severe cold return to the Great Lakes, Ohio Valley, Mid-Atlantic, and New England areas, that outcome would fit past winters that featured severe cold during the first half of January. Using New York City to illustrate the return of severe cold, during the 1981-2010 climate base period, there were 5 cases when the low temperature in New York City fell 2 or more standard deviations below the January average on at least one day during the first half of January. The January 7, 2014 low temperature was 2.242 standard deviations below the January 1981-2010 average low temperature. The lowest temperatures on or after 1/25 for those cases were as follows: 1981: 8°, 2/5 1982: 9°, 1/27 1988: 9°, 2/7 1996: 5°, 2/5 2004: 7°, 1/25 Link to comment Share on other sites More sharing options...
wildweatherman179 Posted January 13, 2014 Share Posted January 13, 2014 I am definitely very happy for all of the above developments. Here's to hoping for a February to remember! :-) Link to comment Share on other sites More sharing options...
Ottawa Blizzard Posted January 13, 2014 Share Posted January 13, 2014 January 24-31, 2014 Thoughts... By the time the last week of January rolls around, the thaw that sent temperatures well into the 50s as far as Boston will be a fading memory. Instead, cold anomalies that will have returned ahead of the month's closing week will prevail. There is a growing likelihood that a bout of severe cold could occur at some point during this timeframe, especially as the EPO ridge that predominated through December into the opening days of January returns. The second aspect is that the pattern appears increasingly likely to become snowier from the Great Lakes region eastward to the northern Middle Atlantic and southern New England areas. Both among the teleconnection cases and GFS ensemble's objective analogs in recent days, one finds a number of dates that were fairly close to moderate or sizable snowfalls. Those dates have included late January 1961, late January 2003, and just after mid-January 2005. In short, it increasingly appears that the pattern evolution should result in the above-noted areas seeing above normal snowfall for the January 25 through February 15 period. Below are charts showing the latest ensemble forecast for the EPO, teleconnection cases, combined teleconnection and objective analog cases for which January anomalies were similar to those of the current month to date, and the reforecast ensemble mean 850 mb anomalies: Based on the above charts, I expect the eastern half of the CONUS and Canada to have colder to potentially much colder than normal readings for the last week of January. Even Florida, where winter has been largely absent, will likely wind up with below normal readings for the period as a whole. The western half of the CONUS and Canada should be warmer to possibly much warmer than normal courtesy of the PNA ridge. Should severe cold return to the Great Lakes, Ohio Valley, Mid-Atlantic, and New England areas, that outcome would fit past winters that featured severe cold during the first half of January. Using New York City to illustrate the return of severe cold, during the 1981-2010 climate base period, there were 5 cases when the low temperature in New York City fell 2 or more standard deviations below the January average on at least one day during the first half of January. The January 7, 2014 low temperature was 2.242 standard deviations below the January 1981-2010 average low temperature. The lowest temperatures on or after 1/25 for those cases were as follows: 1981: 8°, 2/5 1982: 9°, 1/27 1988: 9°, 2/7 1996: 5°, 2/5 2004: 7°, 1/25 Don, I'm not sure if you follow Joe Bastardi on twitter, but he's been making some interesting comparisons between this winter and that of 1917-1918 in terms of the SSTs. What do you think? Here's a link to his latest tweet. https://twitter.com/BigJoeBastardi/status/422838726645932032/photo/1 Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 13, 2014 Share Posted January 13, 2014 Don, I'm not sure if you follow Joe Bastardi on twitter, but he's been making some interesting comparisons between this winter and that of 1917-1918 in terms of the SSTs. What do you think? Here's a link to his latest tweet. https://twitter.com/BigJoeBastardi/status/422838726645932032/photo/1 Thanks for the link. I suspect that his main point concerns the very warm SST anomaly in the Gulf of Alaska then and now and its implied impact on the EPO/WPO. SSTAs: More than likely, the SSTAs led to a persistently negative EPO. The AO probably was negative for the most part for January given the Greenland anomalies and then positive for February. Both January and February 1918 featured widespread cold in North America. In short, the Pacific was probably the leading player in that winter, as has been the case so far this winter. Link to comment Share on other sites More sharing options...
uncle W Posted January 13, 2014 Share Posted January 13, 2014 my problem with JB is he's always quoting an extreme analog...1917-18 is as extreme as you can get for NYC...1993-94 is another extreme analog ...How did he miss 1856-57?...he must be slipping... Link to comment Share on other sites More sharing options...
Ottawa Blizzard Posted January 13, 2014 Share Posted January 13, 2014 Thanks for the link. I suspect that his main point concerns the very warm SST anomaly in the Gulf of Alaska then and now and its implied impact on the EPO/WPO. SSTAs: More than likely, the SSTAs led to a persistently negative EPO. The AO probably was negative for the most part for January given the Greenland anomalies and then positive for February. Both January and February 1918 featured widespread cold in North America. In short, the Pacific was probably the leading player in that winter, as has been the case so far this winter. Thanks for the input Don. my problem with JB is he's always quoting an extreme analog...1917-18 is as extreme as you can get for NYC...1993-94 is another extreme analog ...How did he miss 1856-57?...he must be slipping... I agree for the most part, but he and Dr. Dewpoint (Joe D'Aleo) are doing quite well this year. The maps Don showed do look quite similar to this January...so far. That being said, I doubt NYC gets as cold as 1917-18 this year simply because of the urban heat island effect. NYC is much bigger and more urbanized than it was back then. You guys did get close to 0F last week though. Link to comment Share on other sites More sharing options...
uncle W Posted January 14, 2014 Share Posted January 14, 2014 Thanks for the input Don. I agree for the most part, but he and Dr. Dewpoint (Joe D'Aleo) are doing quite well this year. The maps Don showed do look quite similar to this January...so far. That being said, I doubt NYC gets as cold as 1917-18 this year simply because of the urban heat island effect. NYC is much bigger and more urbanized than it was back then. You guys did get close to 0F last week though. the 1917-18 winter was the coldest on record for NYC...records have been kept since 1869....the minimum that winter was -13 on Dec. 30th, 1917...second only to -15 in February 1934...That winter has the coldest week on record for NYC...This year didn't come close...Here are the coldest weeks in NYC...I really like Joe but he needs to tone it down a bit when it comes to analogs... ave temp...month/day/year... 02.5......12/29/1917-1/4/1918 08.8......2/8-14/1899 10.9......2/3-9/1895 12.2......1/6-12/1968 12.3......1/11-17/1893 12.6......12/28/1880-1/3/1881 12.7......2/12-18/1979 13.5......2/4-10/1934 13.5......1/22-28/1888 13.6......1/9-15/1886 13.6......1/10-16/1912 13.9......1/15-21/1994 14.1......2/1-7/1886 14.6......1/15-21/1935 14.6......1/23-29/1936 ...................... Some recent years... 15.5......1/20-26/1961 15.9......1/12-18/1977 16.1......1/13-19/1957 16.7......2/13-19/1958 17.0......1/18-24/2005 Link to comment Share on other sites More sharing options...
ayuud11 Posted January 14, 2014 Share Posted January 14, 2014 Excellent AFD out of MT Holly NWS office. “GENERAL OUTLOOK: THE STAIR STEP DOWN TO NEAR SEASONAL AND THEN BELOWSEASONAL TEMPERATURES WILL OCCUR AS A SERIES OF COLD FRONTS MOVETHROUGH THE REGION. OUR OLD FRIEND, THE POLAR VORTEX CURRENTLY INNORTHWESTERN CANADA IS ABOUT TO TAKE A HIT. AN UPWARD PROPAGATINGROSSBY WAVE IS PREDICTED TO PERTURB AND ELONGATE IT DURING THELONG TERM PERIOD (AND BEYOND). THIS SHOULD ONCE AGAIN SEND PART OFTHE VORTEX INTO NORTHEASTERN CANADA. COUPLED WITH DISTURBANCESCRESTING THE EASTERN PACIFIC RIDGE, THEY WILL ACT IN TANDEM TOBRING COLDER AIR INTO THE FORECAST AREA ONCE AGAIN. THE LATESTECMWF STRATOSPHERIC MODEL SOLUTION POLAR VORTEX HIT IS SO INTENSE,THIS IS THE FIRST TIME THIS WINTER THAT STRATOSPHERIC WARMING(STRONGER AROUND 10MB FOR NOW) IS PREDICTED TO START. WHETHER ITCAN WORK ITS WAY DOWN INTO THE TROPOSPHERE AND WHERE IT DOES,WOULD HAVE AN IMPACT ON THE NORTHERN HEMISPHERE`S WEATHER ANDTELECONNECTION PATTERNS INTO FEBRUARY. BEYOND OUR DETERMINISTIC PERIOD THE WEEK2 TEMPS: THE LINESCONTINUE TO BE DRAWN BETWEEN THE NAEFS (NEAR NORMAL) AND THE ECMWF(DONT ASK). BOTH HAVE BEEN REMAINING IN THEIR RESPECTIVE NORMAL VSCOLD CAMPS. HOWEVER BOTH THE GFS AND ECMWF OP RUNS FROM THISAFTERNOON ARE SHOWING OMINOUS SIGNS THE ARCTIC AIR IS RETURNINGTO THE PATTERN.” http://forecast.weather.gov/product.php?site=NWS&issuedby=PHI&product=AFD&format=CI&version=1&glossary=1&highlight=off Link to comment Share on other sites More sharing options...
Ottawa Blizzard Posted January 14, 2014 Share Posted January 14, 2014 the 1917-18 winter was the coldest on record for NYC...records have been kept since 1869....the minimum that winter was -13 on Dec. 30th, 1917...second only to -15 in February 1934...That winter has the coldest week on record for NYC...This year didn't come close...Here are the coldest weeks in NYC...I really like Joe but he needs to tone it down a bit when it comes to analogs... ave temp...month/day/year... 02.5......12/29/1917-1/4/1918 08.8......2/8-14/1899 10.9......2/3-9/1895 12.2......1/6-12/1968 12.3......1/11-17/1893 12.6......12/28/1880-1/3/1881 12.7......2/12-18/1979 13.5......2/4-10/1934 13.5......1/22-28/1888 13.6......1/9-15/1886 13.6......1/10-16/1912 13.9......1/15-21/1994 14.1......2/1-7/1886 14.6......1/15-21/1935 14.6......1/23-29/1936 ...................... Some recent years... 15.5......1/20-26/1961 15.9......1/12-18/1977 16.1......1/13-19/1957 16.7......2/13-19/1958 17.0......1/18-24/2005 Yes, I sometimes think his incredible passion for the weather gets the better of him, although that passion is contagious. Link to comment Share on other sites More sharing options...
beavis1729 Posted January 14, 2014 Share Posted January 14, 2014 The low of -13 in Bartlesville, OK appears to be their coldest January temperature since 1984 and their second coldest of all time (first is -15 from 1949). Also, the -9 in Kansas City appears to be tied with 1996 as their coldest January temperature since 1985. I think it's their 3rd coldest temp of all-time. It hit -28 on 2/10/2011 (after the Groundhog Day Blizzard). http://www.newson6.com/story/14004100/record-setting-low-temps-across-northern-oklahoma Link to comment Share on other sites More sharing options...
wildweatherman179 Posted January 14, 2014 Share Posted January 14, 2014 I think it's their 3rd coldest temp of all-time. It hit -28 on 2/10/2011 (after the Groundhog Day Blizzard). http://www.newson6.com/story/14004100/record-setting-low-temps-across-northern-oklahoma That is correct. I worked outside all night that night. Not one I will soon forget. The all time Oklahoma record is actually -31 set the same night at Nowata I believe. Link to comment Share on other sites More sharing options...
iceman56 Posted January 14, 2014 Share Posted January 14, 2014 Don, I'm not sure if you follow Joe Bastardi on twitter, but he's been making some interesting comparisons between this winter and that of 1917-1918 in terms of the SSTs. What do you think? Here's a link to his latest tweet. https://twitter.com/BigJoeBastardi/status/422838726645932032/photo/1 Just an aside, the summer of 1918 featured PHL's all time heat record. Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 14, 2014 Share Posted January 14, 2014 Some morning thoughts... 1. The probability of a return to severe cold during the latter half of the 1/24-31 period is increasing. The GFS ensembles now show widespread 1 standard deviation or greater cold anomalies for the 1/27-30 period. The 1/14 6z run of the operational GFS featured extreme cold for that timeframe across a large part of the eastern CONUS. 2. The GFS ensembles, reforecast ensembles, and ECMWF ensembles all show much below normal height anomalies across southern Ontario and southern Quebec, not far from the U.S. border for that period. 3. Prior to then, the operational ECMWF has a fairly strong, but not really severe, cold shot for the 1/21-23 period. 4. The West will likely remain warmer than normal courtesy of the PNA+, which may only erode slowly through the rest of this month. 5. Despite the recent rather sharp cooling of ENSO Region 3.4 (currently -0.5°C anomalies), the warming in Region 1+2 at this point in time has sometimes been an indicator of the development of an El Niño during the following fall or winter. Examples include 1986, 2006, and 2009 (winters 1986-87, 2006-07, and 2009-10 featured El Niño conditions). From this far out, it's really tough to have any degree of confidence. By later in the spring, the statistical models might provide a better indication. They have done quite well the past several years, so that's where one should be looking for emergent ENSO trends. When it comes to the dynamical models, for the past several years, they have demonstrated much less skill relative to the statistical models. Hence, a large dose of caution is required when looking at the dynamical ENSO models, especially when one goes out more than 6 months into the future. For example, last summer, even when ENSO Region 1+2 remained very cool--historically an almost "slam dunk" indication that there would be no wintertime El Niño--25% of the dynamical models were still forecasting an El Niño. Currently, for the third consecutive winter, they are forecasting the development of an El Niño for the following winter. So far, they are 0-2 in their last two cases, but the historical data suggests that they might fare a little better for winter 2014-15. The statistical models were less keen on an El Niño for the last two winters and are borderline for 2014-15. The performance gap between the dynamical models and statistical ones suggests that understanding of ENSO is still not sufficiently robust for long-term forecasting of ENSO. What is more certain is that there will be no weak El Niño conditions or borderline El Niño conditions through the remainder of meteorological winter and probably spring, as well. Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 14, 2014 Share Posted January 14, 2014 The latest EPO forecast shows the EPO reaching approximately 200 meters below normal toward the end of January. During the 1981-10 climate base period, there were 3 cases in which the EPO fell to 200 or more meters below normal in the January 20-31 period during which January had temperature anomalies similar to what has occurred so far this month: 1994, 2003, and 2010. All featured a lot of cold in February in a large part of eastern North America. Two of those three cases (1994 and 2010) featured above to much above February snowfall from Chicago eastward to the northern Mid-Atlantic and southern New England areas (a larger part of the Mid-Atlantic saw above normal snowfall in 2003 and 2010 then 1994). In short, the latest guidance concerning the EPO adds to my growing confidence that areas (Great Lakes, Ohio Valley, northern Mid-Atlantic, and southern New England) could see above normal snowfall during the January 25-February 15 period. Link to comment Share on other sites More sharing options...
usedtobe Posted January 14, 2014 Share Posted January 14, 2014 Some morning thoughts... 1. The probability of a return to severe cold during the latter half of the 1/24-31 period is increasing. The GFS ensembles now show widespread 1 standard deviation or greater cold anomalies for the 1/27-30 period. The 1/14 6z run of the operational GFS featured extreme cold for that timeframe across a large part of the eastern CONUS. 2. The GFS ensembles, reforecast ensembles, and ECMWF ensembles all show much below normal height anomalies across southern Ontario and southern Quebec, not far from the U.S. border for that period. 3. Prior to then, the operational ECMWF has a fairly strong, but not really severe, cold shot for the 1/21-23 period. 4. The West will likely remain warmer than normal courtesy of the PNA+, which may only erode slowly through the rest of this month. 5. Despite the recent rather sharp cooling of ENSO Region 3.4 (currently -0.5°C anomalies), the warming in Region 1+2 at this point in time has sometimes been an indicator of the development of an El Niño during the following fall or winter. Examples include 1986, 2006, and 2009 (winters 1986-87, 2006-07, and 2009-10 featured El Niño conditions). From this far out, it's really tough to have any degree of confidence. By later in the spring, the statistical models might provide a better indication. They have done quite well the past several years, so that's where one should be looking for emergent ENSO trends. When it comes to the dynamical models, for the past several years, they have demonstrated much less skill relative to the statistical models. Hence, a large dose of caution is required when looking at the dynamical ENSO models, especially when one goes out more than 6 months into the future. For example, last summer, even when ENSO Region 1+2 remained very cool--historically an almost "slam dunk" indication that there would be no wintertime El Niño--25% of the dynamical models were still forecasting an El Niño. Currently, for the third consecutive winter, they are forecasting the development of an El Niño for the following winter. So far, they are 0-2 in their last two cases, but the historical data suggests that they might fare a little better for winter 2014-15. The statistical models were less keen on an El Niño for the last two winters and are borderline for 2014-15. The performance gap between the dynamical models and statistical ones suggests that understanding of ENSO is still not sufficiently robust for long-term forecasting of ENSO. What is more certain is that there will be no weak El Niño conditions or borderline El Niño conditions through the remainder of meteorological winter and probably spring, as well. Don, I looked at the D+11 analogs from yesterday and 7 of the 10 had lows at DCA below sometime in a 3 day window around the 24th. Five had min maxes of 25 or below. Five had 2 inch or greater snows at DCa and two had 7 inch or better at DCA. It's about as good a pattern for DCA as you can get without having a nice 50 50 low and blocking over Greenland. Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 14, 2014 Share Posted January 14, 2014 Don, I looked at the D+11 analogs from yesterday and 7 of the 10 had lows at DCA below sometime in a 3 day window around the 24th. Five had min maxes of 25 or below. Five had 2 inch or greater snows at DCa and two had 7 inch or better at DCA. It's about as good a pattern for DCA as you can get without having a nice 50 50 low and blocking over Greenland. I agree, Wes. The forecast pattern looks better than it has in some time. Hopefully, it will deliver. It would be nice if cities such as Baltimore, Washington, Richmond and eastward to the MD Shore would be able to enjoy one or more nice snowfalls. Link to comment Share on other sites More sharing options...
usedtobe Posted January 14, 2014 Share Posted January 14, 2014 I agree, Wes. The forecast pattern looks better than it has in some time. Hopefully, it will deliver. It would be nice if cities such as Baltimore, Washington, Richmond and eastward to the MD Shore would be able to enjoy one or more nice snowfalls. The best chances are probably from the 24 onward. It certainly looks cold through the month Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 14, 2014 Share Posted January 14, 2014 The best chances are probably from the 24 onward. It certainly looks cold through the month I agree. I'm thinking 1/25-2/15. It will be interesting to see what happens. Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 14, 2014 Share Posted January 14, 2014 For those who are interested, below are the 500 mb height anomaly and surface temperature anomaly maps based on the 11-day objective analogs from the 1/13 18z, 1/14 0z, 1/14 6z, and 1/14 12z runs of the GFS: Link to comment Share on other sites More sharing options...
forkyfork Posted January 14, 2014 Share Posted January 14, 2014 Don, I'm not sure if you follow Joe Bastardi on twitter, but he's been making some interesting comparisons between this winter and that of 1917-1918 in terms of the SSTs. What do you think? Here's a link to his latest tweet. https://twitter.com/BigJoeBastardi/status/422838726645932032/photo/1 the atlantic is a poor match Link to comment Share on other sites More sharing options...
OKpowdah Posted January 15, 2014 Share Posted January 15, 2014 the atlantic is a poor match Yeah honestly even if ridging retrogrades over Greenland, that Atlantic ridge isn't going anywhere. It'll just be raging southerlies over the western Atlantic at 500mb. Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 15, 2014 Share Posted January 15, 2014 Morning thoughts... 1. No changes about the coming cold for the last week of January. 2. The GFS ensembles and reforecast ensembles both agree that the EPO ridge (EPO-) will be building as January comes to a close. This could have implications for February. 3. The idea of above normal snowfall from the Great Lakes to northern Mid-Atlantic/southern New England for the January 25-February 15 timeframe still seems reasonable. If one examines the objective analogs from the 1/15 6z GFS and 1/15 0z GFS ensembles, one finds dates close to snowy periods: 1/20/1961, 2/4/2003, 2/12/2006, and 1/22/2009, among others. While the pattern provides no guarantees, it is similar to patterns that have produced in the past. 4. The guidance points to the development of a PNA- toward the close of January. However, some recent forecasts toward that end didn't verify. The pattern evolution might be slower than what the guidance currently shows. 5. Despite some Internet rumors, there still appears to be no high risk of a sudden stratospheric warming through at least the next 10 days. There are some indications of a smaller warming event, but right now the guidance does not show the event reaching the threshold of a sudden or major stratospheric warming event, much less propagating downward. This minor warming might well be a reflection of the recent blocking that has been occurring. Link to comment Share on other sites More sharing options...
wildweatherman179 Posted January 15, 2014 Share Posted January 15, 2014 I'll pass on the January 22, 2009 analog in my neighborhood. To many icy memories of that week. 2 inches worth to be exact. Hoping for snow when the cold gets here but east based cold usually always backfires for us in eastern Oklahoma. Be interesting to watch I guess. Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 16, 2014 Share Posted January 16, 2014 Morning thoughts on the longer-range... If one takes a look at the overnight 1/16 0z and 6z operational GFS runs, one finds both are very cold in the days 7-15 timeframe. Both also feature a strong EPO-. Both also contain a number of analog dates near moderate or larger snowstorms for some parts of the eastern half of North America. But if one looks more closely, there is actually a rather dramatic change between the 0z and 6z runs. The latter shows the development of meaningful Atlantic blocking to coincide with the strong EPO-. Indeed, if one goes to the 11-day objective analogs from each of these runs, one finds the following: 0z Run: Average AO: +0.125 AO > 0: 60% of analogs AO of -1 or below: 30% of analogs AO of +1 or above: 20% of analogs 6z Run: Average AO: -1.128 AO < 0: 80% of analogs AO of -1 or below: 70% of analogs AO of +1 or above 10% of analogs If one checks out the GFS ensemble forecast for the AO, one also finds that the many members are now favoring a negative AO in the extended range: If this forecast verifies and dual Atlantic and Pacific blocking develop, that would increase prospects for a cold February in the eastern third to half of the CONUS, along with southern Ontario and Quebec. The latter cold anomalies would depend on the magnitude of blocking. If the blocking becomes too strong, then the cold anomalies could be driven southward. Such dual blocking would also allow for potentially more opportunities for larger snowfalls. The Great Lakes region, northern Mid-Atlantic (e.g., Philadelphia) and southern New England areas remain on track for above normal seasonal snowfall, as the December outcomes were consistent with such seasons. The pattern ahead looks promising, particularly for the 1/25-2/15 period. If blocking develops, things could also become more favorable further south in the Mid-Atlantic region, including the Baltimore and Washington, DC areas. The takeaway is that the theme of a growing probability of a cold outcome in parts of the eastern CONUS has been sustained in the overnight guidance. In fact, even as it is still outside its skillful range, the CFSv2 has recently shifted from featuring widespread February warmth to an increasingly colder idea for the eastern third to half of North America. This post has been promoted to an article Link to comment Share on other sites More sharing options...
rcannaday Posted January 16, 2014 Share Posted January 16, 2014 Don great work, looks like we are finally getting real winters all over the Eastern Half of the CONUS. Link to comment Share on other sites More sharing options...
N. OF PIKE Posted January 16, 2014 Share Posted January 16, 2014 Im highly skeptical on modeled blocking transpiring to anything that resembles a real block at least till mid feb if not later in March. Perhaps a 50/50 low or transient block can be well timed soon...but i think blocking calls will go down the drains until mid feb earliest. Don what blocking would be consistent w the OPI forecast ...march blocking? Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 16, 2014 Share Posted January 16, 2014 Im highly skeptical on modeled blocking transpiring to anything that resembles a real block at least till mid feb if not later in March. Perhaps a 50/50 low or transient block can be well timed soon...but i think blocking calls will go down the drains until mid feb earliest. Don what blocking would be consistent w the OPI forecast ...march blocking? IMO, it's still too soon to be confident in the modeled outcome, but it is something to monitor in coming days. It is somewhat encouraging that earlier runs that saw a renewed spike in the AO have yielded to more promising ones. As we get closer to the possible blocking, we'll see what happens. Also, it should be noted that at present the AO is running somewhat below the OPI forecast (approximately a +0.8 average through today), especially as 14 of the last 19 days had weakly negative to negative AO figures, though the pattern hasn't really been consistent with stronger blocking episodes. Moreover, during the January-February period, climatology has favored an AO < 0 since 1950. One argument against the modeled outcome would be the lack of a sudden stratospheric warming or major warming event. None are currently modeled, though such events sometimes are a reflection of strong blocking not a precursor to it. Link to comment Share on other sites More sharing options...
StudentOfClimatology Posted January 16, 2014 Share Posted January 16, 2014 One argument against the modeled outcome would be the lack of a sudden stratospheric warming or major warming event. None are currently modeled, though such events sometimes are a reflection of strong blocking not a precursor to it. The GFS is progging a significant warming event out in LaLa land from 1-10hpa. However, there is no bifurcation of the PV: Link to comment Share on other sites More sharing options...
Ottawa Blizzard Posted January 16, 2014 Share Posted January 16, 2014 Morning thoughts on the longer-range... If one takes a look at the overnight 1/16 0z and 6z operational GFS runs, one finds both are very cold in the days 7-15 timeframe. Both also feature a strong EPO-. Both also contain a number of analog dates near moderate or larger snowstorms for some parts of the eastern half of North America. But if one looks more closely, there is actually a rather dramatic change between the 0z and 6z runs. The latter shows the development of meaningful Atlantic blocking to coincide with the strong EPO-. Indeed, if one goes to the 11-day objective analogs from each of these runs, one finds the following: 0z Run: Average AO: +0.125 AO > 0: 60% of analogs AO of -1 or below: 30% of analogs AO of +1 or above: 20% of analogs 6z Run: Average AO: -1.128 AO < 0: 80% of analogs AO of -1 or below: 70% of analogs AO of +1 or above 10% of analogs If one checks out the GFS ensemble forecast for the AO, one also finds that the many members are now favoring a negative AO in the extended range: If this forecast verifies and dual Atlantic and Pacific blocking develop, that would increase prospects for a cold February in the eastern third to half of the CONUS, along with southern Ontario and Quebec. The latter cold anomalies would depend on the magnitude of blocking. If the blocking becomes too strong, then the cold anomalies could be driven southward. Such dual blocking would also allow for potentially more opportunities for larger snowfalls. The Great Lakes region, northern Mid-Atlantic (e.g., Philadelphia) and southern New England areas remain on track for above normal seasonal snowfall, as the December outcomes were consistent with such seasons. The pattern ahead looks promising, particularly for the 1/25-2/15 period. If blocking develops, things could also become more favorable further south in the Mid-Atlantic region, including the Baltimore and Washington, DC areas. The takeaway is that the theme of a growing probability of a cold outcome in parts of the eastern CONUS has been sustained in the overnight guidance. In fact, even as it is still outside its skillful range, the CFSv2 has recently shifted from featuring widespread February warmth to an increasingly colder idea for the eastern third to half of North America. Great write-up Don. This has the potential to be Toronto's coldest winter since 1995-1996, perhaps even 1993-1994 when you take into effect that December 1993 was actually very mild until the end of the month, unlike December 2013. Link to comment Share on other sites More sharing options...
WxMidwest Posted January 17, 2014 Share Posted January 17, 2014 Don, I was talking to Ryan Maue on Twitter from WxBell, He literally said some of the model runs as of late had a -7 sigma EPO value, which is just quite crazy. Link to comment Share on other sites More sharing options...
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