bluewave

My only agenda has been getting the pattern correct. I have to chuckle when I see posts such as yours which often use the term agenda. Since agenda is generally a political term that has nothing to do with weather and climate forecasting.

I disagree with your assessment about a cold phase since 1998. The PDO has been shorter cycling than it was prior to the 1990s. So we have been getting alternating +PDO and -PDO cycles since then. This is why the 2010s into the 2020s have experienced such a rapid shift between the record +PDO in 2015 to record -PDO in the early 2020s. Those long 30 year cycles have become a thing of the past. Plus the rapid warming of the Western Pacific has altered the way the PDOs have been relating to our sensible weather. So canonical expectations based solely on PDO phase have not been working out. -PDOs of recent years have been much different from earlier -PDOs due to the 2nd EOF running so warm. So this has lead to much warmer and less snowy -PDOs then were experienced in the past. We also experienced record warmth with the +PDO in December 2015. So not seeing how another +PDO in coming years if it were to evolve would necessarily be any cooler than the recent -PDOs. The colder 13-14 into 14-15 period was more a result of the +TNH and +NPM pattern. But as we saw last winter, the stronger Northern Stream of the Pacific Jet muted that influence. So no cold trough was able to develop in Canada like we saw in 13-14. This is why when I saw the Pacific Jet and storm tracks last December I said early on that we weren’t going to see another 13-14 repeat like some on twitter were calling for.

The very low soil moisture has been pretty persistent as the strong winds quickly dry things out behind the parade of storms through the Great Lakes that have been generally underperforming on moisture.

Yeah, warmer and drier than normal until further notice.

We were in and out of drought quite a bit prior to the precipitation increase since 2003. So those lower totals didn’t really cut it. The good news is that the NYC hasn’t had a drought emergency since then. The dry pattern since last summer has mostly been focused to the S and W of NYC. So the reservoirs to the north are fine. But NJ had had reservoir issues. These strong winds dry things out more as we have seen with the increased brush fires in recent months.

It’s more pronounced to our SW as they are down more than 10 inches since last summer.

I still think it’s too early to be discussing any lasting shift in the Pacific. Since the ridge east of Japan and south of the Aleutians returned right after the winter mismatch ended related to what happened in the tropics last October. Remember, the west Pacific has been having more influence than whether the PDO has been in a positive or negative phase. As the 2nd EOF of the PDO has really been more significant in recent years than the old canonical understanding we used to use.

Here come the wind gusts over 35 mph again to dry things out after the rain. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=140&network=NY_ASOS&station=ISP&syear=1900&sday=0101&eday=0426&varname=avg_wind_gust&w=none&thres=1&year=2025&_r=t&dpi=100&_fmt=png Kennedy Intl PTCLDY 50 33 52 NW26G35

My early guess for next winter is that it’s going to be warmer than this past winter was from Philly to Boston. This is based on past La Niña +PNA mismatches and what happened in the seasons around them. The previous La Niñas with strong +PNA in either December or January were 95-96, 00-01, 10-11, 17-18 and 20-21. The 96-97 and 01-02 winters were milder than the preceding ones. Same went for 11-12 which was warmer than 10-11. 16-17 came before the 17-18 mismatch but I thinks it’s informative of the same general background conditions. We haven’t had a back to back La Niña or a back to back La Niña and a neutral around one of these +PNA mismatches years that were as cold as the first years was. There is always one year in a grouping of La Niñas or La Niña and neutral which is colder than the previous one. 21-22 followed the 20-21 mismatch year with December featuring record warmth in many areas. The MJO 8 in January made January the sole colder and snowier month in a sea of warm that winter. It’s tough to get a two colder La Ninas in a row or a colder neutral following a colder La Niña. But will hold out some hope of at least one decent winter month next winter should we see a 21-22 type mirroring or weak echo. As always, I will wait until we see what the early MJO indicator does in October. This past October we got the strong signal which lead to the +PNA mismatch in December and January which I discussed last October. We haven’t had two in a row before. But you never know if we can get a first time. So I will wait until after October for my 2nd winter guess. Was hoping a few weeks ago that the system could tilt more into El Niño. But this too never happened so soon before going back to at least 1950 following such a strong El Niño. So the EPAC warming still hasn’t become connected to the subsurface further west. And we just saw how the increase in surface winds cooled Nino 1+2. But I still want to see how the summer into fall goes before making a final ENSO call for next winter. Obviously, we saw how the neutral to weak El Niño in 18-19 couldn’t overcome the stronger La Niña background warm pool in the WPAC. So 18-19 had more elements of a La Niña following the 17-18 La Niña mismatch.

I just had some heavier rains here with this first round.

Looks like some much needed rainfall tomorrow. HRRR has 3 rounds of convection. First batch of elevated convection early tomorrow morning with the warm front. Then another round of storms midday with the cold front which becomes more surface based. Which will be followed by more storms in the evening. Also expect windy conditions again lingering into Sunday.

The composite I posted was both -NAO and -AO at 500 mb as the ridge extended from Baffin Island all the way over to Iceland. So the -AO and -NAO were interchangeable at 500mb on the storm days. The -NAO has linked up with the Southeast Ridge just as much as the -AO. So the recent differences between the indices are more surface pressure related rather than at 500mb where the linkage with the subtropical ridge while the indices were negative has been occurring. March 2023 was the most negative -NAO cold season month in recent years. And the Southeast Ridge had no trouble linking up with the -NAO block that month for the big rainstorm along the coast and interior high elevation snowstorm. https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.index.b500101.current.ascii 2023 3 1 -0.956 2023 3 2 -1.006 2023 3 3 -1.093 2023 3 4 -1.161 2023 3 5 -1.109 2023 3 6 -1.132 2023 3 7 -1.187 2023 3 8 -1.091 2023 3 9 -0.614 2023 3 10 -0.356 2023 3 11 -0.293 2023 3 12 -0.254 2023 3 13 -0.111 2023 3 14 -0.007

The Ambrose Jet kicked in around 5 to 6 pm. But the afternoon initial SE flow delayed it a bit. Even though the Ambrose Jet typically peaks between 4-7pm JFK hourly data Apr 24, 6:25 pm 64 46 52 S 21G26 10.00 CLR 30.22 30.23 Apr 24, 6:20 pm 64 46 52 S 20G26 10.00 CLR 30.22 30.23 Apr 24, 6:15 pm 64 46 52 S 20G25 10.00 CLR 30.22 30.23 Apr 24, 6:10 pm 64 46 52 S 18 10.00 CLR 30.22 30.23 Apr 24, 6:05 pm 64 46 52 S 17G24 10.00 CLR 30.22 30.23 Apr 24, 6:00 pm 63 44 52 S 18 10.00 CLR 30.22 30.23 Apr 24, 5:55 pm 63 44 52 S 18G24 10.00 CLR 30.22 30.23 Apr 24, 5:51 pm 63 45 52 S 18 10.00 BKN250 1023.70 30.22 30.23 Apr 24, 5:50 pm 63 44 52 S 18 10.00 30.22 30.23 Apr 24, 5:45 pm 63 44 52 S 20 10.00 CLR 30.22 30.23 Apr 24, 5:40 pm 64 44 49 S 21 10.00 CLR 30.22 30.23 Apr 24, 5:35 pm 64 44 49 S 18 10.00 CLR 30.22 30.23 Apr 24, 5:30 pm 64 44 49 S 20G26 10.00 CLR 30.22 30.23 Apr 24, 5:25 pm 64 44 49 S 18 10.00 CLR 30.22 30.23 Apr 24, 5:20 pm 66 45 46 S 20G25 10.00 CLR 30.22 30.23 Apr 24, 5:15 pm 66 45 46 S 18 10.00 CLR 30.22 30.23 Apr 24, 5:10 pm 66 45 46 S 18 10.00 CLR 30.23 30.24 Apr 24, 5:05 pm 66 45 46 S 17G25 10.00 CLR 30.23 30.24 Apr 24, 5:00 pm S 18G24 10.00 CLR 30.23 30.24 Apr 24, 4:55 pm 66 45 46 S 18 10.00 CLR 30.23 30.24 Apr 24, 4:51 pm 67 46 47 S 17 10.00 FEW060 BKN250 1024.10 30.23 30.24 Apr 24, 4:50 pm 66 46 49 S 16G22 10.00 FEW060

Yeah, that’s what I was getting at with my post yesterday. This winter was another one with wildly varying competing influences. The overall 500mb pattern had a +PDO flavor with the 500mb low to the SW of the Aleutians and ridging over Western North America. But the storm track was in stark contrast to this type of pattern. The first composite is the DJF 500 mb average pattern. The second one isolates the storm track. I selected the 11 days this winter when .25 and more precipitation fell in NYC. The average temperature on these days was 41.0° which was why the winter snowfall was well below average again at only 12.9”. Also notice the Southeast Ridge linking up with the -AO and -NAO which has become a repeating theme during the 2020s. We can also see the very strong and extended Pacific Jet on the storm days from East Asia right across the U.S. So the dominant storm track had a very distinct La Niña pattern through the Great Lakes. DJF average 500mb pattern 11 storm days for NYC with .25 and more of precipitation

The storm track was actually a moderate to strong La Niña pattern with a very strong Southeast Ridge around the storm days.

Another day with stronger winds gusting over 30 mph. So areas near the shore stayed cooler. It’s interesting that the strongest winds wound up near Newark again. Peak wind gusts 4-24 EWR….36 mph LGA…..27 mph JFK…..28 mph ISP……26 mph

The Western Pacific has been having a larger influence over our sensible weather since 18-19 than ENSO which is a Central and Eastern Pacific phenomenon. We saw in 18-19 how the WP La Niña background state overpowered the weak El Niño influence. Then in 19-20 the record IOD reversal near the Maritime Continent combined with the strong SPV to essentially erase a weak El Niño Modoki SST signature pattern. 20-21 featured a strong La Niña +PNA mismatch which went against typical La Nina climatology. Then in 21-22 we had the record MJO over the WPAC warm pool drive the record December warmth and +13 at DFW. We lucked out in January 22 as we got a clean MJO 8 which was the last really snowy month experienced from ACY to ISP and BOS. But south of New England the snowfall shut off again in February 22 22-23 featured the strong marine heatwave east of Japan which combined with the La Niña and warm Maritime Continent MJO phases for record warmth and lack of snow. This overpowered the near record December -AO for a La Ninas which featured very snowy outcomes during past instances. The repeating -AO and -NAO March was also overpowered along the coastal plain. As the Southeast Ridge link up with the -AO has become a reoccurring theme during the 2020s. 23-24 had the borderline super El Niño with record WP MJO 4-6 activity which muted the typical El Niño trough normally experienced over the Mid-Atlantic region. So this allowed the typical Canadian El Nino Ridge to expand into the Eastern US. 24-25 saw the La Nina mismatch +PNA which I pointed out with the early MJO indicator last October. So this feature going against the typical La Nina response was a big player. But the continuing marine heatwave near Japan and very strong Northern Stream of the Pacific Jet muted the +PNA and -EPO influence. So we had an opposite response in terms of temperature and snowfall to 13-14 especially with the record ridging in Eastern Canada which had the deep cold vortex in 13-14. So the ENSO has been getting tempered more and more by the record marine heatwaves and forcing west of the Dateline. But it still has been having an input in the climate system. It’s the new ENSO interaction with the WPAC which has been driving our sensible weather.

Very strong 30-35 mph Ambrose Jet will keep the South Shore beaches in the 50s with 80s away from the shore today.

Yeah, Labor Day 1998 was probably the top ranking derecho when you include NYC and Long Island. The speed at which it turned from day to night with darkness of the clouds really stood out. Many boaters were caught off guard as the storm swept in so fast. Spoke to friends who saw how dark the sky had become and immediately ran down into the basement. The September 2010 event was very impressive but more narrowly focused in NYC. My top ranked event for continuous lighting was 5-31 to 6-1-85. That began as one of the most severe tornado outbreaks in PA before evolving into a squall line with record lightning flash rates.

My focus has mostly been along the coastal corridor from around Philly to Boston. As gaining some elevation in the regions you mentioned has been a big plus in recent years. As we were reminded with the March 2023 snowstorm.

I don’t take it that way. I really enjoy the back and forth here. This format is really great as it allows for the expansion of ideas and extended conversations.

Repeating pattern going forward. Warmer weather next several days before the next cold front. Then stronger winds over 30 mph or 40 mph yet again.

It’s possible that with a bump up over a year or two that the bolded mean may rise off these levels in another 7 years. But my guess is that the reversion will ultimately settle below what we had as a mean when the climate was colder. It’s challenging to get a mean at the level when things were colder since we were able to nickel and dime our way to average between the early 60s to 90s when it was colder. This winter was a nickel and dime special that finished well below average. That was a benefit of a colder climate. More options to get to average or higher.

We don’t need 7 years in order to know the range of options since the all or nothing snowfall pattern began in the 1990s which is a full 30 years of data. As winters began to warm in places like NYC, the winters mostly became well above or well below average snowfall. The middle range snowfall scenario season became few and far between. So as the winters have continued warming this decade, the below average outcome has become more likely. Hopefully, we can see a snowfall bounce in one or more seasons over the next 7 years. So I agree with one aspect of your comment as to which range of outlined options we experience. But the reversion to the mean you speak of will be a lower mean than was experienced in a colder climate. For the past 7 seasons, Boston has reverted to what used to be the snowfall mean closer to NYC. NYC has reverted to what was average around Philly in a colder era. And Philly snowfall has become more likely the old climate in DC. So in effect the northward shift in storm tracks also shifted the snowfall climate zones more to the north.

The significance of past snow droughts ,which were weaker than what we have been experiencing over the past 7 years, is that they were due to cyclical drier patterns in a significantly colder climate. So once the dry patterns abated, the snows returned with record seasons in the early 1930s, early 1960s, late 1970s, and early to mid 1990s. This has been the first snow drought from Philly to Boston that has largely been the result of both warm winters and warm storm tracks. Which is the function of a steadily warming climate. It will be a significant challenge for this climate to produce another winter snowfall outcome like 1933-1934, 1957-1958, 1960-1961, 1977-1978, 1993-1994, and 1995-1996. Those were the winters which followed past very low 7 year snowfall stretches. It’s has become too warm to get cold and snowy winters of that magnitude. So this leaves a few options going forward. Option one is a continuation of this very low snowfall regime right into the 2030s. The next scenario is a bounce back to snowier than the last 7 years, but well below what was experienced in the 2010s. Such a bounce would probably be transient before the lower snowfall totals resume in the 2030s. The lowest probability outcome next 7 years is a return to the 2009-2010 to 2017-2018 snowfall bonanza since many of background climate signals from that era have shifted warmer including storm tracks and overall warmth.