bluewave

Model forecasts change which is nothing new. I was just pointing out to Liberty who enjoys the summer heat that the models were showing 85°-90° potential near JFK. Now they have a faster frontal passage so the forecast is for 80-85°. Still a warm late summer day with a dry downslope flow. Plus these warm downslope flow days usually beat guidance. So a few spots could still see some mid 80s. Back in August I was saying that the 90° potential probably wasn’t over for the warm spots in NJ which turned out to be correct this month. Maybe you should try posting some of your own ideas instead of being more concerned about trying to play gotcha games. I notice that you only chime on the few occasions that the warmest guidance doesn’t verify. But are usually silent when warmth beats guidance.

I posted yesterday that the heaviest rain would stay to our south due to the record blocking to our north which is still the case today. I didn’t mention any specific amounts since the models haven’t been very good recently in that regard beyond a few days out The big picture hasn’t changed much over most of the last year for precipitation. We have been drier than average with the heaviest amounts either completely missing our area or narrowly focusing in a small area like we have seen since May. The next few days look like more of the same. Some of the wetter models have the .50 line getting closer to NYC which would be nice. But not enough to end the drier pattern even if the wetter models closer to .50 verify. In my area along the CT Shoreline we had one of the warmest and driest summers. Vegetation has locally been on the brown side to the lack of rainfall.

You know it’s a dry pattern when the main interest is how close the .50 line gets to NYC.

The cold departures will be shrinking over the next few weeks. Looks warmer than average especially over the driest areas to our west. Whether the warm spots across the area see more mid 80s like the past several days will come down to wind direction. Data for September 11, 2025 through September 15, 2025 Click column heading to sort ascending, click again to sort descending. TETERBORO AIRPORT WBAN 90 TETERBORO AIRPORT COOP 90 SOMERSET AIRPORT WBAN 86 CALDWELL ESSEX COUNTY AP WBAN 85 HARRISON COOP 85 SUSSEX AIRPORT WBAN 84 TRENTON-MERCER AIRPORT WBAN 84 NEW BRUNSWICK 3 SE COOP 84 PENNSAUKEN 1N COOP 84 Trenton Area ThreadEx 84 New Brunswick Area ThreadEx 84

The Atlantic SSTs are still near the warmest on record. So this lull is more about the warmer waters further north across the oceans causing too much tropical stability. The Gulf SSTs are near the warmest on record also. So any system can get into the Gulf would have plenty of fuel. I am hoping that that area can catch a break from all the damage that has occurred the last decade. But the local residents can’t let their guard down. Since much of the activity has been backloaded into the late season there.

Happy Birthday. The models have an earlier frontal passage now on Friday. So the warmest 850s come through Thursday night. More like low 80s around Friday as the 850s are much lower now during the day than the older model runs.

Eric posted the record breaking temperature gradient a few months ago. It’s a little stronger than in 2022 which was the last year we finished below 100 ACE. So perhaps seasonal forecasts will incorporate this data during their July updates in the future when we get to the -4 to -5 sigma range.

This year has been defined by the sharp cutoffs to the heavy rainfall. The aerial coverage from most events hasn’t been very good. So this allowed MPO to go up 13.00” this year on the precipitation over FWN. Time Series Summary for SUSSEX AIRPORT, NJ Click column heading to sort ascending, click again to sort descending. 2025-09-15 20.02 17 Time Series Summary for Mount Pocono Area, PA (ThreadEx) Click column heading to sort ascending, click again to sort descending. 1 2025-09-15 33.40 1

Quite a big departure spread this month. The cooler spots have a shot at finishing the month with a small cold departure. But the warmer stations like EWR, HPN, and ISP could finish with a small warm departure. ISP….-1.2 HPN….-1.4 EWR…..-1.4 NYC…..-2.3 BDR……-2.5 LGA……-2.9

The source region to our west has been record dry since August 1st.

The lower ACE this season than last year wasn’t that much of a surprise. All our 161+ ACE years since 2010 have seen a steep decline the following years. This year the record mid-latitude SSTs and cooling tropics are the main features creating the more stable conditions like we have been seeing more frequently in recent years. So the direction lower this season for ACE is flowing the recent pattern. But magnitudes will be unique to each season. The amount of the decline can vary from year to year. ACE step down pattern following 161+ seasons 2024….161….2025….39.3 so far 2020….180….2021…145…2022…94.4 2017….224….2018….132

Record breaking rainfall with the impressive -IOD pattern. La Niña in the modern climate The Bureau of Meteorology has just changed the way it calculates sea surface temperature anomalies for monitoring La Niña (and El Niño). Traditionally, sea surface temperatures inside the Niño 3.4 region were compared to the long-term average of the 30-year period from 1991 to 2020. The difference between the current temperature and the long-term average temperature gave us the anomaly used for monitoring La Niña. However, rising global ocean temperatures caused by climate change have made this method ineffective. Put simply, Earth’s oceans are warming so quickly that the average ocean temperature of the past 30 years is cooler than the current global ocean temperature. This makes Niño 3.4 index values artificially warm when calculated using the traditional method. Instead of comparing the current state of the ocean to a baseline from the past climate, scientists have developed a new method that also incorporates the current average temperature of the global tropical oceans. This new method, with is called the relative Niño index, removes the climate change signal from the equation and makes it more useful in our rapidly warming climate.

Yesterday was the 4th day this month to reach 86° at SMQ. This has lead to the highs running +0.9 this month. Since it has been so dry, the minimums have been running -3.2°.

NYC has had many issues with tree growth on top of the equipment due to neglect when the NWS moved out to Upton back in 1993. So the new ASOS was installed in 1995 under a dense canopy leading to artificial cooling on sunny days. While this artificial cooling is exaggerated when the trees leaf out since 1995, they do get some artificial cooling in winter due to the taller trees and lower sun angle. So it’s no longer a reliable first order site for temperatures in our area last 30 years. I used JFK since its Liberty’s main station that he follows since it’s closer to his home station than the other sites are.

For JFK December was warm and wet finishing +0.9° with 4.44” of precipitation. January was near normal and dry at +0.2 and only 0.65” of precipitation. February was warm and wet finishing at +2.7 and 3.17” of precipitation.

Even JFK has a shot at 85-90° next Friday as the models have a warm downslope flow now.

It didn’t work out for the 2019-2020 winter since the rest of the Pacific was so warm with the record IOD reversal which supercharged the SPV during the fall when it was so positive.

The low volume is why it was so much easier to reach the North Pole this summer. Extent is only a one dimensional measurement of where the edge of the ice field is. But now there is so much open and thin ice behind that edge that it’s losing its relevance as a useful metric for describing the state of the sea ice. Since in the old days there was solid MYI older ice behind the edge of where the ice was. The Barents Observer ‪@thebarentsobserver.com‬ Follow "What struck me most: the ease of access through what used to be a far more ice-covered region", expedition leader Jochen Knies tells us, "We had been sailing through open water at 6–8 knots, something unthinkable three decades ago." See our report straight from the North Pole! #climatechange “I didn’t hear the usual grinding of ice” When a Norwegian vessel reached the North Pole this week, the scientific team made an alarming discovery. www.thebarentsobserver.com September 4, 2025 at 7:09

The volume is close to the lowest on record for this time of year since the ice is so thin due to the record MYI melt over the years. This allows the big disparity between extent and area. As the concentration is also near record lows. Zack Labe ‪@zacklabe.com‬ Follow ⚠️ While extent will not be setting any annual minimum records this year, the average thickness of #Arctic sea ice is actually at historic lows for this time of year (in the dataset by PIOMAS). Thinner ice is younger and usually more fragile. More graphics of volume: zacklabe.com/arctic-sea-i... ALT September 10, 2025 at 8:07 AM Everybody can

MPO made it down to 41° at the end of August which was the coldest since 2000. But not really that cold prior to 2000. The drier conditions allowed them to make it to the 11th coldest reading for August. The warmth back in June was more impressive. It was their first June 93° maximum temperature. Time Series Summary for Mount Pocono Area, PA (ThreadEx) - Month of Aug top 10 lowest temperatures Click column heading to sort ascending, click again to sort descending. 1 1986 31 0 2 1965 32 0 - 1907 32 0 3 1987 33 4 - 1941 33 0 - 1940 33 0 4 1982 34 0 - 1976 34 0 - 1942 34 0 - 1923 34 0 - 1910 34 0 - 1908 34 0 - 1904 34 0 5 1979 35 0 - 1921 35 0 - 1916 35 0 6 1972 36 0 - 1971 36 0 - 1968 36 0 - 1934 36 0 - 1927 36 0 - 1912 36 0 - 1911 36 0 7 1992 37 4 - 1989 37 6 - 1988 37 5 - 1963 37 0 - 1947 37 0 - 1946 37 0 - 1922 37 0 - 1915 37 0 - 1909 37 0 - 1905 37 0 - 1903 37 0 8 1981 38 0 - 1977 38 0 - 1930 38 0 - 1924 38 0 - 1919 38 0 9 1969 39 0 - 1964 39 0 - 1949 39 0 - 1944 39 0 - 1935 39 0 - 1906 39 0 - 1902 39 0 10 2000 40 0 - 1974 40 0 - 1966 40 0 - 1962 40 0 - 1952 40 0 - 1950 40 0 - 1936 40 0 - 1929 40 0 - 1917 40 0 11 2025 41 0 - 1984 41 0 - 1983 41 0 - 1958 41 1 - 1957 41 0 - 1954 41 2 Time Series Summary for Mount Pocono Area, PA (ThreadEx) - Month of Jun warmest maximum temperatures Click column heading to sort ascending, click again to sort descending. 1 2025 93 0 2 1952 92 0 - 1933 92 0 - 1914 92 0 3 2011 91 0 - 1911 91 0 4 2012 90 0 - 1964 90 0 - 1957 90 3 - 1956 90 0 - 1953 90 0 - 1908 90 0 5 2021 89 0 - 2008 89 0 - 1944 89 0 - 1943 89 0 - 1934 89 0 - 1925 89 0 6 2024 88 0 - 2023 88 0

Much easier to get a strong -WPO with a relaxed Pacific Jet not constantly eroding the ridge.

The ridge axis was centered just off the West Coast during the 13-14 winter on the wettest storm days for NYC leading to that much snowier outcome than last winter. But the Pacific Jet was significantly weaker. So it allowed the 500mb ridge to remain in place and not get weakened and undercut by such a fast Pacific Jet. The lack of kickers coming into the West Coast during 13-14 with the weakened Pacific Jet allowed the colder storm track just southeast of NYC with numerous BM redevelopers. The Southeast ridge was much weaker and further east than recent years. 18 storm days for NYC DJF 13-14 with .20+ of precipitation

I have been discussing this for a while now. The rapid expansion of the mid-latitude ridging has been altering the way that the higher latitude teleconnections have been occurring relative to the past. We have also been seeing a much faster Pacific Jet with the record mid-latitude SSTs under these expanding ridges.

It was mostly that the +PNA was getting undercut by the very fast Pacific Jet. The composite below is for the heaviest precipitation days last winter from Philly to Boston. The energy diving into the trough to our west during the storms pumped the Southeast ridge allowing the wettest storms to cut to our west.