bluewave

Your Upper Midwest region which includes Michigan has been running colder relative to the means than the Northeast since 15-16. The 21-22 winter finished -2.1 relative to the new 91-20 normals. The 18-19 season was -1.5 relative to 81-10 and 17-18 finished -1.6. But 23-24 was your warmest winter since 1895 at +9.2 relative to 91-20. 16-17 was your 9th warmest winter at +4.6 above 81-10 with 15-16 at +5.4 and 6th warmest. https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/regional/time-series/102/tavg/3/2/1895-2024?base_prd=true&begbaseyear=1991&endbaseyear=2020

Yeah, this is a wider view of the situation.

While UHI is the reason for the urban areas like Phoenix running warmer than the rural locations especially at night, climate change is responsible for the whole region having their warmest summer on record including the low population Death Valley area.

Yeah, using 61-90 climo would be a challenge getting another cold winter in the Northeast if we don’t see some type of shift next 5 winters from last 9. The only parts of the U.S. to experience a cold winter relative 61-90 since 15-16 were the PAC NW and Upper Plains Rockies. As we have frequently seen the smaller geographic area Arctic Outbreaks focus in those areas.

No issue here. Just commenting on what you said. For agricultural and utility customers updating climo like the CPC does every 10 years makes sense. But it does minimize the warming trend when just looking at departures and not rankings.

Using the 61-90 baseline doesn’t fundamentally change the big picture. Whether we use 81-10 or 61-90, 14-15 was the last winter with a cold departure in the Northeast. The rankings are always exactly the same. By 81-10 climo 14-15 was -4.1. It was still a cold winter using the 61-90 baseline at -2.0.

Obviously, El Niños dominate the list. But there were some very warm La Ninas in there also for Canada .Part of the reason that our winters have been so warm in the U.S is a lack of cold in Canada relative to past winters. You will also notice how much the 97-98 super El Niño has been eclipsed by numerous weaker El Niños like 23-24 as the climate has continued to warm. Top 10 warmest winters in Canada and ENSO 2024….+5.2C….El Nino 2010….+4.1…….El Nino 2016….+4.0……El Nino 2006….+3.9……La Nina 2021…..+3.7……La Nina 2012……+3.6…..La Nina 1987……+3.1……El Nino 2007…..+3.1……El Nino 2017……+3.0……La Nina 1998…..+2.9……El Nino

The only colder than average winter in Canada since 14 was the 21-22 La Niña. They use a 61-90 baseline which does a better job at the long term temperature trends. Updating every 10 years like the U.S. does makes the warm departures smaller with each update. Even though the ranking of warmest to coldest winter stays the same. But a new warmest winter in 91-20 climate normals will have a smaller departure than if it occurred in previous decades. https://www.canada.ca/en/environment-climate-change/services/climate-change/science-research-data/climate-trends-variability/trends-variations/winter-2024-bulletin.html# Winter national temperature departures and long-term trend, 1948–2024 Long description The time series graph shows that averaged winter temperatures across the country have fluctuated from year to year over the 1948–2024 period. With the exceptions of 2014 and 2022, average winter temperatures have remained above the baseline average since 1996. The linear trend indicates that winter temperatures averaged across the nation have warmed by 3.6°C over the past 77 years, increased by 0.2°C compared to the last winter.

We are on track for one of the most easterly flow dominant Septembers on record. Nearly half the days this month so far at a station like JFK had their strongest gust of the day from an easterly component. The rest of the month should feature most of the days with easterly flow. Direction of strongest daily wind gust at JFK 9-16….NE…19 9-15….SE…25 9-14….S……15 9-13….S…..16 9-12….SE…17 9-11….SSE..18 9-10….N…..20 9-9…..S……27 9-8…..NW…32 9-7…..W…..34 9-6…..E…..20 9-5….E…..22 9-4….SE….23 9-3….N……29 9-2….NW….37 9-1…..SW….13 Forecast

Yeah, the last 9 winters had the strongest Pacific Jet east of Japan to the Aleutians on record back to 1950. It actually intensified more since 2019. These frequent jet extensions are a part of the reason why the winters have been so warm since 15-16 and less snowy back to 18-19 for places like NYC Metro.

Bradford was the most impressive warm record this summer in PA as it beat the previous warmest summer by nearly a full degree rather than the tenth of a degree at Reading. Time Series Summary for BRADFORD REGIONAL AIRPORT, PA Click column heading to sort ascending, click again to sort descending. 1 2024 68.2 0 2 2021 67.3 0 3 2022 67.0 0 - 2020 67.0 0 4 2016 66.5 0 5 2018 66.3 0 6 2012 66.1 1 7 2023 66.0 0 - 2005 66.0 0 - 1991 66.0 0 - 1975 66.0 0 8 1959 65.9 0 9 2011 65.8 0 - 1993 65.8 0 - 1987 65.8 0

I think this is why we have been getting the big model flips from run to run with the rainfall forecasts. Very strong blocking over SE Canada and New England. Cutoff lows underneath are notoriously difficult for models to forecast. This general pattern looks to continue for at least the next 10 days. Even day 11-15 there is some indication that it may try to continue with lows riding north but perhaps weaker high pressure over New England. Another example of the stuck weather patterns of recent years.

I thinks it's due to the higher heights near the Pacific Northwest and Vancouver in recent years compared to the older -PDO era. So we are getting a split -PNA vortex. One piece this week stays up in Alaska and another digs into California. The height rises in the middle register as a +PNA. In the older -PDO era we didn’t see this pattern much since the -PNA vortex was more consolidated. Could also be related to competing marine heatwaves changing the character of how we used to understand the teleconnections in the old days. As we have also seen changes in the North Atlantic with the AO and NAO not as in sync as they used to be. This was evident with the very strong winter -AOs during the 2020s and the NAO more neutral to even positive during those -AO intervals. As recently as 09-10 and 10-11 the -AO and -NAO were more evenly matched during stronger blocking intervals. Split -PNA vortex this week Weaker -PNA vortex in recent years with higher heights near PAC NW and Vancouver during La Ninas and -PDO Stronger and more consolidated -PNA vortex in older era during La Ninas and -PDO

At least 10 days of easterly flow with a big high to the north and low pressure to the south.

Newark actually tied for the most 89° days in a year. This recent era has seen much more onshore flow than from 2010 to 2013. It’s what happens with the strongest ridges setting up near or east of New England. Just enough high pressure to the east allows more SSE flow at Newark.

The cool pattern during the last week of May that I pointed signaled Newark not getting to 40 days reaching 90° this year. Most of the past Nino to Nina transitions like 2016 and 2010 made it to 40 days and were much warmer the last week of May. This is a result of the much stronger sea breezes than usual this summer. Notice how Harrison just inland from Newark further from the bay made to 41 days. It was also much warmer the last week of May than the airport. This is a rare event for Harrison going over 40 and Newark staying under. Data for May 25, 2024 through May 31, 2024 HARRISON COOP 88 NJ CANOE BROOK COOP 87 NY BAITING HOLLOW COOP 87 NJ CALDWELL ESSEX COUNTY AP WBAN 86 NJ TETERBORO AIRPORT COOP 86 CT DANBURY COOP 85 NY PORT JERVIS COOP 84 NJ NEWARK LIBERTY INTL AP WBAN 84 Number of 90° days Data for January 1, 2024 through September 14, 2024 Click column heading to sort ascending, click again to sort descending. NJ HARRISON COOP 41 NJ CANOE BROOK COOP 37 NJ NEWARK LIBERTY INTL AP WBAN 33 NJ CALDWELL ESSEX COUNTY AP WBAN 33 NJ TETERBORO AIRPORT WBAN 31 NJ TETERBORO AIRPORT COOP 30

That’s just how the CPC calculates the PNA. Most use the CPC since thats how people compare their seasonal PNA forecasts to what the CPC verified. The CPC method allows for a deep trough in the west and when heights are positive in Canada and calls that a +PNA. Usually if there is a ridge somewhere in SW Canada it’s considered a +PNA.

It’s interesting how the Euro seasonal can have a great summer temperature forecast for the U.S. but miss on the hurricane forecast. My guess is that the seasonal forecasts can’t handle competing marine heatwave interactions with the base ENSO climate state. Same way the winter forecasts were way too cold and missed the record warmth last two winters. The model had the stock La Nina and El Nino composites but missed the much warmer MJO interactions.

By one degree but a few days early. THE NEWARK NJ CLIMATE SUMMARY FOR SEPTEMBER 14 2024... VALID TODAY AS OF 0400 PM LOCAL TIME. CLIMATE NORMAL PERIOD 1991 TO 2020 CLIMATE RECORD PERIOD 1931 TO 2024 WEATHER ITEM OBSERVED TIME RECORD YEAR NORMAL DEPARTURE LAST VALUE (LST) VALUE VALUE FROM YEAR NORMAL ................................................................... TEMPERATURE (F) TODAY MAXIMUM 87 212 PM 94 2016 79 8 81 MINIMUM 63 547 AM 45 1975 62 1 63 AVERAGE 75 70 5 72

What we saw in 20-21 matches the theme of the blocks becoming more AO and KB dominant since the 15-16 super El Niño. Just check out the winter spread between the AO and NAO indices during recent years. Some months had strong -AO readings but hardly registered negative on the NAO scale. Our older stronger -AO winter months usually had a stronger -NAO response also. So a combination of more south based blocks linking up with the Southeast Ridge and lower heights near Iceland. This is why we see that cold pool frequently showing up near Iceland as the winds have increased there over time.

The PNA was weakly positive on the CPC site in January 2023. https://origin.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table 2023 0.21

This record increasing atmospheric moisture has become the become the real deal.

These brief dry vegetation patterns never last.

It was another case of 60°warmth around the snowstorm in ACY during January 2022 that we have also frequently seen around NYC with our snow events since 2015-2016. The overpowering +PNA and +AO was just a little too progressive west of a line from ACY to FRG and ISP. The interior areas like BGM did much better in 2020-2021 due to the south based -AO linking up with the WAR to the east of New England. So the storm track went over ACY instead of ACK especially in that December record snow of 40” for BGM. But the raging Pacific Jet was able to sneak in for the Christmas 2020 flood cuttter a few days later which caused the flood damage to the ski resorts and they lost the whole snowpack of 40” from a few days earlier.

The last time that raging Pacific Jet was tamed to some extent was way back in January 2022. But it was still a little too strong combined with the +AO so the best snows that January ended up east of NYC rather further west. The storm track was just a little too far east along the East Coast for areas in NJ to do as well as Suffolk County did on Long Island. It was the result of the brief MJO 8 shifting the pattern. But that December 2021 had one of the fastest Pacific Jets and DFW went +13. Then in February it was back to the regularly scheduled fast Pacifc jet programming. In all my years tracking the weather I haven’t seen as hostile a stretch for fast and dominating Pacific flow as we have seen from 18-19 through 23-24. It was like someone flipped a switch after the November 2018 snowstorm.