bluewave

This looks like the first 5 SD 500 mb block near Greenland during the winter since February 2021. So the million dollar question is whether our best snowfall opportunities will occur prior to and around the peak in mid-February or after. Back in 2021 when the AO went -5 the best snows came in before the block and not after it peaked. This is pretty much unknowable at this point. But at the very least the magnitude of the block now argues for a colder than average February. Before the models started showing the block they were going for +1 to +2 pattern in the means for February. So this could be the first winter since 2002-2003 with all 3 winter months having a cold departure. We are now pretty much assured of having our first colder winter here since 2014-2015. Regardless of the snowfall outcome, this block will be impressive even if doesn’t couple with the stratosphere. So more of a bottom up event. Longer range the models have the AO block weakening in later February and giving way to more of +PNA which is pretty rare for a La Niña February. 5 SD 500 mb anomaly one of the most impressive of 2020s so far

It’s a new 500 mb record for this time of year. Mika Rantanen ‪@mikarantane.bsky.social‬ Follow That is a huge blocking predicted to form over NW Russia. Record-breaking in intensity (for the time of the year), with 500 hPa levels half a kilometre higher than normal. It's like a stone in a river that directs the warm, moist air flow from the North Atlantic towards the Arctic. ALT ALT February 4, 2025 at 8:36 AM Everybody can

New lowest extent record for 2-5 by 500k.

Arctic sea ice thickness and extent at record low levels for this time of year.

This month could be the end of the drought here as the Euro seasonal is wet right through the summer. https://charts.ecmwf.int/products/seasonal_system5_standard_rain?area=GLOB&base_time=202502010000&stats=tsum&valid_time=202506040000

We always get very active patterns around the time of these Arctic warming events.

The 1st half of February has been much more productive since 2010. Individual events and the highest snowfall totals 2022 Jan 28-29….Islip….24.7 2021 Jan 31-Feb 2....Blomingdale, NJ.....26.1 2020 Dec 16-17 East Tremont, NY....12.4 2019 Mar 3-4...Monroe, CT....12.0 2018 Nov 15....Mount Hope, NY.......18.3 Mar 21-22...Patchogue, NY......20.1 Mar 13...Southampton,NY.....18.3 Mar 8....New Farfield, CT..........26.8 Mar 2...Monroe, NY.................14.0 Jan 4...Islip, NY.......................15.8 2017 Mar 14...Montgomery, NY.......23.5 Feb 9...Selden, NY...................16.0 Jan 7...Orient, NY....................12.5 2016 Feb 5...Setauket, NY................12.0 Jan 23..JFK,NY.........................30.5 2015 Feb 2..New Faifield, CT............12.0 Jan 26-27....Orient,NY.............28.5 2014 Feb 13-14...Roselle, NJ............16.7 Jan 21-22....Centerreach,NY....14.0 Jan 2-3......Lindenhurst, NY.....12.5 2013 Mar 8....Harriman,NY..............15.0 Feb 8....Upton, NY..................30.9 2012 Nov 7-8.....Monroe, CT..........13.5 Jan 21......North Haven, CT....12.0 2011 Oct 29.....Harriman, NY.........16.0 Jan 26-27...NYC................... 19.0 Jan 11-12.......Meriden, CT....29.0 2010 Feb 25-26...Mount Hope, NY...27.5 Dec 26........Elizabeth, NJ........31.8 Feb. 10.....Sound Beach, NY....16.2 2009 Dec 19-20....Upton, NY..........26.3

Yeah, the period around the 11-12th may be the best chance for someone in the OKX forecast zones to record a 12”+ total. Statistically February 1 through 15th has featured the highest concentration of 12”+ max events in the OKX forecast zones during the winter since 2010. But the positioning of the gradient and storm track will be key. Roughly 2 week snowfall periods for the 2010's and number of 12"+ snowstorms Oct 29-Nov 15.....3 Nov 16-Nov 30....0 Dec 1- Dec 15.....0 Dec 16-Dec 31....3 Jan1-Jan 15.......4 Jan16-Jan 31.....5 Feb 1-Feb 15.....6 Feb 16-Feb 28...1 Mar 1- Mar 15....6 Mar 16-Mar 31...1 Apr 1-Apr 16.....0

February 2021 was the last time we had a higher number of days in a calendar month with measurable snowfall in NYC. Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Feb Click column heading to sort ascending, click again to sort descending. 1 1964 11 0 - 1920 11 0 2 1926 10 0 3 1962 9 0 - 1924 9 0 - 1923 9 0 - 1916 9 0 4 2021 8 0 - 2014 8 0 - 1936 8 0 - 1914 8 0 5 2015 7 0 - 1994 7 0 - 1972 7 0 - 1950 7 0 - 1883 7 0 - 1879 7 0

We don’t get many successful gradient patterns around here like in 2014 and 1994. So I am not sure yet where the gradient will settle for next week after the next two storms. Those years were much colder than this winter has been. It’s always a challenge when the Southeast Ridge is battling a -AO block over the top. 30 miles can make the difference from the I-78 corridor into NYC between a great pattern and a disappointing one.

February 11-12 will be the make of break moment for the entire winter so far around NYC Metro. That 0z OP Euro was similar to the multi day KU event at the same time around 2-11-94 with that gradient. So getting the gradient to settle just in the right spot will key here to getting a more memorable storm around NYC. It’s why we need these big KU events for normal to above normal seasonal snowfall. But we really have to take the next few storms first to see what the actual track will be. Since the exact wave spacing and gradient location left in the wake of the previous storms will determine whether we can get something really special or not. Just 30 miles can mean everything for a spot like NYC.

Classic case of hydroclimate volatility which makes accurate long range precipitation forecasting very challenging in the new climate. https://weatherwest.com/archives/43181 Hydroclimate volatility broadly refers to unusually rapid and/or high magnitude swings between unusually wet and dry conditions (or vice versa) relative to what is typical for a given location and season. Such rapid transitions can often generate hazards that are distinct from their constituent wet and dry extremes (e.g., floods and droughts), meaning that hydroclimate volatility can yield overall societal and ecological risks that are “greater than the sum of their parts.”

Yeah, they just exceeded that old record set back in 2022.

Today is a great example of how much of a change can occur with an ensemble mean from 360 hrs to 240hrs. The biggest change at day 10 is the much deeper trough digging into the West around Valentine’s Day. So any speculation based on the present 360 hr run is going to look different when it gets to 240 then 120 and 0 hrs. This is why you want to maximize opportunities closer in since you don’t know what the pattern is going to look like from day 10 and beyond. New run Old run

This is the first time we had a gradient pattern in the 2020s with the SE Ridge battling blocking over the top.

I agree. The risk with gradients is that we get mixed precipitation events when the systems really amped like the next few. Then if a system is too weak the confluence to the north can be too strong leading to suppression. What we want next week is a goldilocks scenario right in the middle.

Warmest January SSTs on record east of Japan provided the fuel for the new all-time heaviest snowstorm there.

One of the least favorable winter patterns we have seen for Arctic sea ice thickness.

We have no idea how long this will continue past the 20th since this is more of a reflective event which is subject to reversal longer range.

We can trace it back to the wave break last week with the record low just east of Hudson Bay due to the enhanced temperature gradient after the +11°C January.

With gradient patterns we generally have to take it one storm at a time. Since each storm coming through the fast flow determines exactly where the gradient will be for the storm behind it. So I agree with the sentiment that any snowfall forecasts beyond around 5 days are very uncertain. Typically the snow to mix to rain occurs between I-78 to I-84. But it’s possible that after the 10th we can get a storm or two that comes in a little further south than over the next week or so. As for the longevity of this pattern it’s even more uncertain beyond the 20th. So just enjoy the active pattern for now.

Thanks. Moved in near the end of the summer back in 2023. Enjoying the much better radiational cooling than I had back on the LI South Shore. Not too far from the Sound so still get great sea breezes in the warm season.

I am definitely doing better here along on the CT Shoreline than I was back on the LI South Shore with these type of gradients. Picked up 3” earlier and still have 2” left on the colder surfaces. High of 43° here today.

We can trace the -AO development back to that big wave break with the record low east of Hudson Bay last week. It lead to a near record Scandinavian Ridge which will retrograde back toward Greenland. Hopefully, something happening near Hudson Bay can finally be of some benefit this winter. By Central Jersey I am referring to anything from the I-78 and south for posters in that area.

While this is still very much a La Niña base state, a -AO signal emerged over the last 3-4 days of runs for the mid-February 10th through 20th period. The AO has been very volatile in recent years with big swings to positive and negative over short periods. Hopefully, the gradient can sink far enough south over that period for Central NJ to cash in. But it’s still very uncertain where the gradient will settle. Short range features like how amplified the trough out West gets along with AO strength will probably have to wait a while. That being said, it’s uncertain how much beyond the 20th the -AO can last with the fast changes we have been seeing in recent years.