Summary: First pattern thread of the winter. Just about every medium/long range model (especially the ensembles of the GFS, CMC and Euro, which are used most for trend forecasts beyond about 7-8 days) continues to show (as mentioned in the Christmas Eve snow thread) a major pattern shift to a cold to possibly very cold regime starting by next weekend, with multiple possible storm systems after that, some of which could bring snow (possibly substantial amounts) to the eastern US and our area for much of January. And just about every well-known meteorologist is honking about the upcoming pattern change. Yes, I know it's usually relatively cold and snowy in January, but we're talking likely colder than normal (and possibly much colder than normal - especially in the SE US) and snowier than normal (NB gets about 8-9" of snow, on average in Jan) from about 1/4 through 1/25 and given the paucity of snow for most the past 3 winters this is noteworthy. The cold looks like a lock, at least through mid-Jan, while the snow is always much iffier to predict more than a week in advance, so we'll wait and see. And based on the @e5fdny weather clause, any specific storms that materialize will be covered in separate threads when and if they look real (usually 4-5 days out), with the first possible threat around 1/6. Hope some find this interesting.
Details: The video link, below, from John Homenuk one of the best medium/long-range forecasters out there explains the meteorology behind the pattern change much better than I could, but briefly, instead of the warm pattern we expect to have for the next week, which features strong west to east jet stream flow from the mild Pacific across the US, a strong ridge is forecast to build from Cali to Alaska forcing the jet stream to ride up and over it and then down east of the Rockies, bringing very cold polar air down from Canada into the eastern half of the US, plus high latitude "blocking" is expected with another strong ridge up in NE Canada/Greenland acting to "hold" the cold air in place in the eastern US and to slow down the storm systems that are expected to rotate through the eastern US from about 1/5 onward.
With regard to the teleconnections, which are often used to forecast long range patterns, we're forecast to have the weak La Nina continue and to have the MJO (Madden-Julian Oscillation) move into phases 8 and 1 (associated with cold/snowy here) and to have a sustained combination of a -AO (Arctic Oscillation) and +PNA (Pacific/North America), which is the combo we've had for ~50% of 6"+ snowstorms in NYC, as per the famed DonSutherland on AmericanWx (see his graphic below and his post linked below), plus we'll also likely have a -NAO (North Atlantic Oscillation) and a -EPO (Eastern Pacific Oscillation). Cold air in place, plus moisture from storms could mean significant snow, although it's still too early to predict specific storms (but they are showing up on the long range guidance) and it's always possible the cold/snow just don't work out, as very cold air can suppress storms to our south or if the cold air weakens for a bit, a storm could always cut west of us bringing mix/rain. DT/WxRisk does a great job explaining all of the teleconnections in the video link below.
https://www.americanwx.com/bb/topic/61402-january-2025/?do=findComment&comment=7513129
In addition, NOAA's Climate Prediction Center (CPC) is on board for colder than normal weather for much of the eastern US from 1/4-1/10 (with normal precip amounts) and is also predicting colder and wetter than normal conditions from 1/11 through 1/24 in their Weeks 3/4 forecast; just showing the temp graphics below. FYI, I only did one pattern thread last winter, for a warm/low snow first half of Feb, which verified, followed by a cold and potentially snowy period after that, which did not verify at all for cold, but did verify for above normal snowfall for most from 2/12-2/17. Overall, since 2017 I've done 1-2 pattern threads per winter, featuring 10 of 13 temperature patterns verifying and 9 of 13 snowfall patterns verifying (with below normal, normal and above normal as possible outcomes, random guessing would mean 4 out of 13 verifying). That means the pros kind of know what they're doing.
https://www.cpc.ncep.noaa.gov/products/predictions/WK34/
Details: The video link, below, from John Homenuk one of the best medium/long-range forecasters out there explains the meteorology behind the pattern change much better than I could, but briefly, instead of the warm pattern we expect to have for the next week, which features strong west to east jet stream flow from the mild Pacific across the US, a strong ridge is forecast to build from Cali to Alaska forcing the jet stream to ride up and over it and then down east of the Rockies, bringing very cold polar air down from Canada into the eastern half of the US, plus high latitude "blocking" is expected with another strong ridge up in NE Canada/Greenland acting to "hold" the cold air in place in the eastern US and to slow down the storm systems that are expected to rotate through the eastern US from about 1/5 onward.
With regard to the teleconnections, which are often used to forecast long range patterns, we're forecast to have the weak La Nina continue and to have the MJO (Madden-Julian Oscillation) move into phases 8 and 1 (associated with cold/snowy here) and to have a sustained combination of a -AO (Arctic Oscillation) and +PNA (Pacific/North America), which is the combo we've had for ~50% of 6"+ snowstorms in NYC, as per the famed DonSutherland on AmericanWx (see his graphic below and his post linked below), plus we'll also likely have a -NAO (North Atlantic Oscillation) and a -EPO (Eastern Pacific Oscillation). Cold air in place, plus moisture from storms could mean significant snow, although it's still too early to predict specific storms (but they are showing up on the long range guidance) and it's always possible the cold/snow just don't work out, as very cold air can suppress storms to our south or if the cold air weakens for a bit, a storm could always cut west of us bringing mix/rain. DT/WxRisk does a great job explaining all of the teleconnections in the video link below.
https://www.americanwx.com/bb/topic/61402-january-2025/?do=findComment&comment=7513129
In addition, NOAA's Climate Prediction Center (CPC) is on board for colder than normal weather for much of the eastern US from 1/4-1/10 (with normal precip amounts) and is also predicting colder and wetter than normal conditions from 1/11 through 1/24 in their Weeks 3/4 forecast; just showing the temp graphics below. FYI, I only did one pattern thread last winter, for a warm/low snow first half of Feb, which verified, followed by a cold and potentially snowy period after that, which did not verify at all for cold, but did verify for above normal snowfall for most from 2/12-2/17. Overall, since 2017 I've done 1-2 pattern threads per winter, featuring 10 of 13 temperature patterns verifying and 9 of 13 snowfall patterns verifying (with below normal, normal and above normal as possible outcomes, random guessing would mean 4 out of 13 verifying). That means the pros kind of know what they're doing.
https://www.cpc.ncep.noaa.gov/products/predictions/WK34/
Last edited:
