bluewave

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.

The September 1998 Derecho was my only severe storm in Long Beach with .75 inch hail and wind severe gusts. It was also the darkest sky I ever experienced in the afternoon. Drove up to Lynbrook right after the storm was over and the tornado damage was obvious with the concentration of downed trees along a relatively narrow path.

It may not ultimately matter much what the ENSO does as long as we continue to see these record marine heatwaves over the WPAC seemingly run the show. It sets up these tremendous thermal gradients between Siberia and the waters near Japan leading to the acceleration of the Pacific Jet. Which in turn drives the cutter, hugger, and suppressed Southern Stream storm tracks leading to below normal snowfall from Philly to Boston. This is why the 7 year running average snowfall in this region has reached lows never seen before.

It was nothing compared to all the tree damage which effectively began in March 2010. Which was followed up by the September 2010 Derecho in NYC then Irene in August 2011 and then the October 2011 snowstorm when the trees were still leafed out. Sandy was the main event for trees especially in Long Beach when all the Sycamores had to be cut down due to the salt water root damage. Since Sandy we have seen periodic lesser events which have continued to damage the trees like Isaias back in 2021 and numerous other events. Our winds continue to get stronger as we have seen with the record high average wind gusts since December. So tree preemptive tree removal near structures which could potentially fall in storms has become a big business. People just aren’t taking chances anymore. If the tree shows even the slightest damage or potential to fall on a house, people are just getting rid of them.

Yeah, the record run without a 100° day continues at JFK since 2013 due to the new summer onshore flow pattern. Number of Consecutive Days Max Temperature < 100 for JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Period of record: 1948-07-17 to 2025-04-20 1 4294 2013-07-19 through 2025-04-20 2 4016 1999-07-06 through 2010-07-03 3 4009 1972-07-24 through 1983-07-15 4 3610 1983-08-21 through 1993-07-08 5 2210 1966-07-05 through 1972-07-22 6 2185 1993-07-11 through 1999-07-04 7 963 1960-05-02 through 1962-12-20 8 857 1955-03-18 through 1957-07-21 9 817 1951-11-07 through 1954-01-31 10 736 1948-08-28 through 1950-09-02

All the years with 5 or more days reaching 95° or higher at JFK had strong ridging to our west over the Great Lakes and Ohio Valley. But it’s been a challenge getting this pattern in recent years due to the ridges in the West and east of New England. This leaves more of a trough to our west bending the flow SE to SW instead of SW to NW. Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Jan through Dec Click column heading to sort ascending, click again to sort descending annual number of 95° or warmer days 1 2010 10 0 2 1963 8 0 3 2002 7 0 - 1999 7 0 - 1983 7 0 4 2013 6 0 - 1949 6 0 5 2012 5 0 - 1966 5 0 - 1955 5 2

It seems like the record westerly flow since December is a result of the supercharged Northern Stream with storms racing through the Great Lakes. But the jet stream relaxes over the summer. So we would probably need to see where the ridge axis sets up. If it continues to be located more east of New England like recent summers, then the flow will become more onshore as the seasonal jet stream weakening progresses. But if the ridge axis builds more to our west into the Great Lakes, then the westerly flow will continue into the summer.

Right now it looks more like strong upwelling from the record westerly flow than a -AMO producing that cold blob to our east as the rest of the Atlantic is very warm.

It’s easier to get westerly winds during the winter than summer at JFK. So winter 50° days are increasing at a faster rate than summer 90° days. But NJ away from the sea breeze has seen an increase in both.

That graph was just JJA to focus on the summer.

The elongation of the subtropical ridge north to just east of New England has turned the flow more onshore at JFK. But the overall summer average high temperatures have been rising faster than the maximum high temperatures.So the rate of the average increase is faster than the increase in 90 days. This is due to the warmer minimums acting as a higher launch point for the afternoon highs. This results in the rate of 85° days increasing faster than the 90° days. Since the stronger afternoon sea breeze slows the rate of 90° days increasing faster increases. So two things can be true at the same time.

THE NEWARK NJ CLIMATE SUMMARY FOR APRIL 19 2025... CLIMATE NORMAL PERIOD 1991 TO 2020 CLIMATE RECORD PERIOD 1931 TO 2025 WEATHER ITEM OBSERVED TIME RECORD YEAR NORMAL DEPARTURE LAST VALUE (LST) VALUE VALUE FROM YEAR NORMAL ................................................................... TEMPERATURE (F) YESTERDAY MAXIMUM 87 302 PM 92 1976 64 23 55 MINIMUM 58 1242 AM 33 2001 45 13 44 2020 AVERAGE 73 55 18 50 PRECIPITATION (IN) YESTERDAY 0.00 1.97 1978 0.13 -0.13 T MONTH TO DATE 1.85 2.42 -0.57 3.65 SINCE MAR 1 6.43 6.55 -0.12 11.64 SINCE JAN 1 9.71 12.95 -3.24 18.91 SNOWFALL (IN) YESTERDAY 0.0 4.1 1983 0.0 0.0 0.0 MONTH TO DATE 0.0 0.5 -0.5 0.0 SINCE MAR 1 0.0 6.1 -6.1 T SINCE JUL 1 13.6 31.5 -17.9 12.2 SNOW DEPTH 0 DEGREE DAYS HEATING YESTERDAY 0 11 -11 15 MONTH TO DATE 257 267 -10 205 SINCE MAR 1 772 964 -192 711 SINCE JUL 1 3987 4467 -480 3627 COOLING YESTERDAY 8 0 8 0 MONTH TO DATE 9 0 9 4 SINCE MAR 1 9 1 8 4 SINCE JAN 1 9 1 8 4 ................................................................... WIND (MPH) HIGHEST WIND SPEED 30 HIGHEST WIND DIRECTION SW (230) HIGHEST GUST SPEED 46 HIGHEST GUST DIRECTION SW (240) AVERAGE WIND SPEED 14.2

Yeah, moving the ASOS under the trees in the 1990s has kept the 90° day count closer to 20. My guess is that if the ASOS was out in the open like before 1995, NYC would have had well over 40 days reaching 90° back in 2010 instead of only 37. So it’s the only site away from the immediate shore which has had a decrease in 90° days. The sea breeze at Newark has been slowing the rate of increase there relative to sites like Freehold-Marlboro which have avoided the sea breeze. Over 40 days reaching 90°has become the norm away from the sea breeze in NJ during the 2020s. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=74&network=NJCLIMATE&station=NJTEWR&season=all&dir=above&var=high&threshold=90&year=1961&_r=t&dpi=100&_fmt=png

Mid to upper 80s today for the warm spots with very steep lapse rates and gusts approaching 40 mph. But it will be a warm WSW wind instead of the cold NW winds we have recently been getting. So the strongest winds ahead of the front for a change instead of behind it.