bluewave

My guess is that the uptick in tropical activity is related to the Atlantic warming in the last few weeks. Notice how the Atlantic was the warmest early in the season for Beryl and then dropped during the lull through August. Could be related to the lapse rates improving as the upper atmosphere differential probably wasn’t as great and the stability dropped. So we have a shot at finishing the season over 100 ACE which would be closer to average. We also had a lull during August 2022 and then an increase in September like this year. That year featured Ian in the Gulf during September and this year Helene. Warming surface decreased the delta from the upper levels to surface allowing more development.

I think the reason the warm front was a little further south than forecast yesterday was due to the models underestimating the influence of the high pressure in New England.

It looks like areas south of I-80 will actually do better for a change through Sunday morning with so much high pressure over New England.

My guess is it’s related to the record easterly flow this month giving LGA an unusual sea breeze influence. JFK always has a sea breeze influence while LGA usually doesn’t. So all the easterly flow resulted in the same temperature for LGA and JFK. It gave LGA a cool breeze off the Sound with a milder E flow at JFK from Central Nassau. Monthly Data for September 2024 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. NY PORT AUTH DOWNTN MANHATTAN WALL ST HEL ICAO 71.9 NJ NEWARK LIBERTY INTL AP WBAN 70.4 NY LAGUARDIA AIRPORT WBAN 70.2 NY JFK INTERNATIONAL AIRPORT WBAN 70.1 NY NY CITY CENTRAL PARK WBAN 69.4

The record Aleutian Ridge will continue into October as 500mb heights approach 600 dm east of Japan. There could be a near record PAC Jet extension out near the Bering Sea. We’ll have to see if models continue with the levels near 5 sd.

While it’s nice to be getting some light rain this morning, this is one of the narrower east-west rain bands we have seen in a while.

Late day warm front with 77° at Newark and 80° readings in Central NJ on the southerly flow.

I don’t think the model forecasts from yesterday were too far off. The warm front verified about 30-40 miles further south. The heaviest rainfall was still up closer to I-80 rather than down closer to the Driscoll Bridge 287 area. Models seldom get the exact location of the warm front down to the mile correct from even 24 hrs out around here. My guess is this is related to challenges of modeling the weather where the NJ bight meets the land areas which become hilly to mountainous so close to the coastal plain.

While the graph starts in 1982, there were never SSTs approaching these levels prior to that year in our modern record.

The Atlantic is back to all-time SST warmth after falling behind 2023 during the summer.

Newark only needs .06 to move out of 1st place for driest September. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Sep Click column heading to sort ascending, click again to sort descending. 1 2024 0.09 5 2 1941 0.14 0 3 2005 0.45 0 4 1951 0.95 0 5 1972 1.03 0 6 1948 1.14 0 - 1939 1.14 0 7 1931 1.19 0 8 1953 1.25 0 9 1964 1.30 0 10 1967 1.35 0

It was a record September nearly +500 meter Greenland block but it’s still linking up with the Southeast Ridge.

All we can say is that September 2024 is playing out in a roughly similar way to 2022. The 500 mb anomaly centers are in the same general locations. Strong Aleutian Ridge and Greenland Block. Plus a big September hurricane in the Gulf after a quiet August just like 2022. But that’s not to say that the rest of the pattern will play out in a similar way going forward. We will have to wait and see how the pattern progresses since there can always be new variability introduced which wasn’t present in a previous year with a similar pattern over the same time interval.

The one good thing about the Southeast Ridge correcting stronger today is that maybe the moisture from Helene will sneak further north into the weekend.

Tomorrow will be one of the few days this month with SSW flow so low 80s for the usual warm spots in NJ.

Really extreme ocean heat content in the Gulf out ahead of Helene.

The GFS is flexing stronger with the Southeast Ridge so heaviest goes north.

It’s interesting that this study came out in 2009 right before the next big step up in volatility over the last 10 to 15 years. We can also add the AO which overlaps with the NAO. It does seem like more of the volatility has been evident in the AO while the winter NAO seems to be becoming more positive. https://www.whoi.edu/press-room/news-release/study-links-swings-in-north-atlantic-oscillation-variability-to-climate-warming/ The research team found the variability of the NAO decade-to-decade (multi-decadal scale) has been larger, swinging more wildly, during the late twentieth century than in the early 1800s, suggesting that variability is linked to the mean temperature of the Northern Hemisphere. This confirms variability previously reported in past terrestrial reconstructions. “When the Industrial Revolution begins and atmospheric temperature becomes warmer, the NAO takes on a much stronger pattern in longer-term behavior,” said Goodkin. “That was suspected before in the instrumental records, but this is the first time it has been documented in records from both the ocean and the atmosphere.” The North Atlantic Oscillation is described by the NAO index, calculated as a weighted difference between the polar low and the subtropical high during the winter season. In a positive phase, both the low-pressure zone over Iceland and high pressure over the Azores are intensified, resulting in changes in the strength, incidence, and pathway of winter storms crossing the Atlantic. In a negative phase, a weak subtropical high and a weak Icelandic low results in fewer and weaker winter storms crossing on a more west-east pathway. The NAO index varies from year to year, but also exhibits a tendency to remain in one phase for intervals lasting more than a decade. An unusually long period of positive phase between 1970-2000 led to the suggestion that global warming was affecting the behavior of the NAO. “Anthropogenic (human-related) warming does not appear to be altering whether the NAO is in a positive or negative phase at multi-decadal time scales,” said WHOI paleoclimatologist Konrad Hughen. “It does seem to be increasing variability. Clearly, this has implications for the future.” “As temperatures get warmer, there’s potential for more violent swings of the NAO — the phases becoming even more positive and even more negative,” Hughen added. “If the NAO locks more into these patterns, intense storms will become more intense and droughts will become more severe.”

The most interesting part of this is the volatility of both the NAO and AO indices. We saw a record low Iceland 500mb height anomaly in August. Now this month one of the highest September daily 500mb height anomalies over Greenland near +500meters. This has been a theme in recent years with some of the greatest positive and negative swings over a relatively short period we have ever seen.

The landfall forecast was better than the ACE and total storms which were too high. It’s interesting that the Euro correctly forecast the more stable air over the tropics but missed on the ACE and number of storms. The summer temperature forecast did very well.

All 22 hurricanes of any intensity passing through that area moving NNE continued recurving to the NE and none bent back to the NW.

All previous major hurricanes taking the same track as Helene came NNE up along the coast or OTS. This will be the first time a major hurricane bends back toward the NW. Just goes to show how anomalous a blocking pattern we are in. All historical major hurricanes taking track close to forecast Helene Rare bend back to NW after landfall

Unfortunately, it wouldn’t be much help in 4 months if the Greenland Block continues linking up with the Southeast Ridge. Notice how the Southeast Ridge is correcting stronger for Thursday. So the models have pushed the heaviest rains north of I-78 from previous runs. We also get into SW flow which has been a rarity this month. So the usual warm spots in NJ could make it over 80° in what was originally forecast to be a cooler day. New run Old run

Should decrease more especially if we can sneak in some 80s later this week.