bluewave

Near record upper low off of Southern California matches with the extreme east based forcing leading to the ridge shifting into the East later in October.

My new spot here gets pretty impressive radiational cooling inversions unlike back on the Long Island South Shore. One of the more interesting effects on a handful of occasions was the marsh gasses getting trapped under the inversions. Probably the most pungent smell that you can imagine. As my area has a great wetlands habitat which transitions into rolling hills with in less than a mile.

The BOM RONI values in the East getting close to +6 are more in line with the ONI numbers.

The modoki-style forcing out near the Dateline following the shutdown of the MJO 5 forcing which drove the record warmth in December. The hand-off of the forcing from the MC to the DL caused the whole pattern to invert from December to January. This allowed the NP low to back off in the Pacific from late January into early February.

The latest first freeze for LGA which is the UHI capital was 1-4-16. NYC snuck one in on 11-24-15. The average first freeze for LGA since then has been 11-30 and NYC 11-20. Frost/Freeze Summary for LAGUARDIA AIRPORT, NY Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. 2015 03-29 (2015) 27 01-04 (2016) 15 280 2001 03-28 (2001) 31 12-23 (2001) 32 269 1998 03-22 (1998) 31 12-22 (1998) 24 274 2021 04-02 (2021) 29 12-19 (2021) 31 260 Data for November 24, 2015 through November 24, 2015 Click column heading to sort ascending, click again to sort descending. NY MONTAUK AIRPORT WBAN 37 NY SETAUKET STRONG COOP 35 NY LAGUARDIA AIRPORT WBAN 33 NY NY CITY CENTRAL PARK WBAN 32 NY JFK INTERNATIONAL AIRPORT WBAN 31 Frost/Freeze Summary for LAGUARDIA AIRPORT, NY Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. Minimum 03-01 (2020) 11-08 (2019) 226 Mean 03-25 11-30 249 Maximum 04-06 (2016) 01-04 (2016) 281 2025 03-23 (2025) 32 12-04 (2025) 25 255 2024 03-24 (2024) 32 11-30 (2024) 32 250 2023 03-30 (2023) 32 11-25 (2023) 32 239 2022 03-30 (2022) 30 11-19 (2022) 32 233 2021 04-02 (2021) 29 12-19 (2021) 31 260 2020 03-01 (2020) 26 12-08 (2020) 32 281 2019 03-13 (2019) 32 11-08 (2019) 31 239 2018 04-02 (2018) 32 11-15 (2018) 30 226 2017 03-23 (2017) 26 11-10 (2017) 27 231 2016 04-06 (2016) 32 12-09 (2016) 32 246 2015 03-29 (2015) 27 01-04 (2016) 15 280 Frost/Freeze Summary for NY CITY CENTRAL PARK, NY Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. Minimum 03-01 (2020) 10-31 (2020) 218 Mean 03-28 11-20 236 Maximum 04-10 (2016) 12-09 (2016) 250 2025 04-09 (2025) 31 11-29 (2025) 32 233 2024 03-24 (2024) 31 11-30 (2024) 30 250 2023 03-30 (2023) 31 11-25 (2023) 30 239 2022 03-30 (2022) 29 11-19 (2022) 31 233 2021 04-03 (2021) 32 11-23 (2021) 32 233 2020 03-01 (2020) 25 10-31 (2020) 32 243 2019 03-18 (2019) 32 11-08 (2019) 29 234 2018 04-09 (2018) 32 11-14 (2018) 32 218 2017 03-23 (2017) 23 11-10 (2017) 25 231 2016 04-10 (2016) 31 12-09 (2016) 29 242 2015 04-01 (2015) 32 11-24 (2015) 32 236

Centered right under Nino 3 at +4.47 now. Starting to see a +30C warm pool bridge develop from Nino 3.4 over to the coast of Central America. Matches up with the record east based forcing for so early in an event.

Looks like as we head into late October the expression of ENSO becomes more of split North Pacific low between the Bering Sea and Southern California. It will be interesting to see if these centers can eventually merge into one giant low as we head into November and December. If some semblance of a split remains, then it would be indicative of the background 500mb pattern which has been keeping the PDO negative instead of leading to a +2.00 PDO.

Which has been the case this year so far leading to much warmer than expected conditions across the CONUS than we typically see from such strong El Niños.

February 2025 was the exception when the Southeast Ridge verified much stronger right around storm time leading to the record snows ending up near Toronto.

It will be interesting to see if the new PBC EPS weeklies actually can do better than just defaulting to climatology after 15 days.

We are just going to have to wait until we get through December and January to see what happens in February. The issue with the seasonal models is that they default to an El Niño climatology package in February which incudes many weaker events. 2023-2024 and 1997-1998 didn’t necessarily follow the typical February climatology. This event is much stronger than both of those so we should probably keep expectations low and if we do better than those two years in February it’s a nice surprise.

These October Ural to Scandinavian blocks have become the new normal especially in October in the low Arctic sea ice era since 2007.

These strong Scandinavian-Ural blocks have become fairly common post 2007 with the record low Arctic sea ice state. We also saw this late October into early November SPV weakening and bounce back pattern in 2021 and 2022. But as always it’s the Pacific which has the final say.

Beyond 15 days the weeklies have been defaulting to El Niño climatology. The forecast from the start of October illustrates this point. Hopefully, they start releasing the new bias corrected versions of the weeklies to the public so we can see how much skill they have compared to uncorrected version. Notice how more of a spilt low pattern between the Aleutians and California developed than the default to October El Niño climatology. New October 19 to 26 forecast Old forecast defaulted to October El Niño climatology

Just remember that a weaker SPV was also a feature with the 1997-1998 event. There was also an impressive area of stratospheric warmth above the Urals to Barents region. It’s the overpowering Pacific which is the main feature when east based El Niños get this strong. So it’s not uncommon to see this during super El Niño events as we also had something similar with the weaker 2023-2024 super El Niño.