bluewave

My dew point dropped 10° in a hour. Areas just to my north are in the upper 20s. So a continuation of the very dry theme with RH near only 20%. Meriden SUNNY 74 29 19 NW18G31 29.88R New Haven SUNNY 75 37 25 N17G30 29.88S https://www.weather.gov/wrh/timeseries?site=khvn https://www.weather.gov/wrh/timeseries?site=kmmk

It’s really impressive how strong and persistent the Aleutian Ridge had become this year. The ridge keeps driving this record breaking -PDO pattern. 500 mb heights have been at record levels for an extended period.

Yeah, I get some nice radiational cooling inversions here just to the east of KHVN. It’s a change from living on the South Shore of LI where it was tough to get any radiational cooling. It’s neat how quickly the temperature falls off once the sun sets under good radiational cooling conditions.

Yeah, a very sharp cutoff to the warmth somewhere near your area especially on the higher res guidance where the warm front stalls out.

Euro really struggling lately as we saw with several of those Milton runs which were too far north. We are back to getting warm sectored on Sunday now. So the 80° highs should push further north in NJ. A continuation of the northern and eastern sections doing better on rainfall. New run Old run

We are getting a very strong October La Niña atmospheric response with a record 500mb +EPO Alaskan vortex for October producing the winds to 100 mph in Alaska.

The 91-20 means have gotten so warm that a small +0.6 SEP departure at Newark still ranks within the top 20 warmest monthly average temperatures. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Sep Click column heading to sort ascending, click again to sort descending. 1 1961 74.5 0 2 2005 73.5 0 3 2015 73.4 0 4 2021 72.5 0 5 2016 71.8 0 - 1971 71.8 0 6 2010 71.6 0 7 1959 71.5 0 8 2018 71.4 0 9 2023 71.2 0 - 2011 71.2 0 10 1973 71.0 0 - 1931 71.0 0 11 2017 70.9 0 12 2019 70.8 0 - 1980 70.8 0 13 1968 70.7 0 14 1983 70.6 0 - 1970 70.6 0 15 2002 70.5 0 16 1998 70.3 0 17 1985 70.2 0 18 2007 70.1 0 19 1989 69.9 0 20 2024 69.8 0 - 2014 69.8 0 - 1972 69.8 0

We saw the same left of track averaged model forecast bias at play with Hurricane Charley in 2004. It was originally forecast to come closer to Tampa Bay. Some of the models had more of a bias than others as you mentioned. https://www.nhc.noaa.gov/archive/2024/

I have noticed that the model forecasts which the official forecasts are based on have had too much of a left of track bias with the major hurricanes near the Southwest and Central Florida Gulf coast in recent years. Not sure if this is somehow related to frictional effects of the hurricane circulation encountering the FL west Coast or another factor? In any event, this has worked out for Tampa Bay since they never want to see the RFQ of a major hurricane landfall. So the storm was about 25-30 miles to the right of some of the earlier forecasts. Ian and Irma followed a similar forecast evolution pattern but were a little further right. Perhaps related to the longer land interaction?

At least May 2020 delivered.

We recently had 6 sigma jet max out near the Aleutians but that wasn’t in a great spot for CONUS rainfall outside the hurricane landfalls.

We are nearly tied with 2016 for ACE. That was one of the only other times there was more ACE in October than August and September combined along with 1970. So the backloaded nature of this season is in the top 3 along with 2016 and 1970.

That was very close to the maximum surge there. https://waterdata.usgs.gov/monitoring-location/02299861/#parameterCode=00065&period=P7D&showMedian=false

The surge at Sarasota came in around 10 feet. Unfortunately, that part of Florida doesn’t have a good coverage of tide gauges. So it’s quite possible the highest surge will have to be estimated based on water marks in buildings.

22-23 had a record -AO in December and a good follow up in March but the hostile Pacific and Southeast Ridge linkage kept the best snows up into Central and Northern New England.

Volatility continues to be the big NAO story as we are going to see a near record NAO reversal heading into mid-October.

We went into this season recognizing that the Atlantic SSTs were at all time highs and it was a developing La Niña summer. So the model forecasts such as the Euro were indicating that there could be closer to 25 named storms and 225+ ACE. As of the time when Beryl went Cat 5 so early those very high numbers seemed plausible. But as the summer went on the dry air, increased stability, warmer 250 mb temperatures , and ITCZ shift into the Sahara were holding the ACE down into September. My guess is that the burst of activity the last few weeks was helped by the SSTs increasing enough to overcome the initial warmer upper levels so the lapse rates and instability were able to improve. It’s also possible the upper levels began to cool in the last few weeks. The favorable MJO was part of it. But the previous favorable MJO in early August underperformed vs past periods that time of year with higher SSTs. Its interesting that the Euro did show the drier air issues but it wasn’t reflected in its tropical storm and hurricane forecasts. Even if the total ACE came in under forecast, it doesn’t in any way take away from the recent weeks which picked up where Beryl left off although there was a large gap in the middle. So I would say the Euro seasonal added great value since it correctly implied what could happen if all the ducks lined up like we have seen last few weeks. But it may be that the models need to be upgraded to incorporate the influence to the pattern of all these competing marine heatwaves and interactions with the upper levels around 250mb. Absent that activity gap during midseason, we would most likely be over 200 ACE and 25 named storms if the rate of development last few weeks was uninterrupted going back to July. But the most important major hurricane forecast numbers were pretty close to the forecast centers issuances back in the spring. So the real world impacts of the last few weeks were well telegraphed ahead of time.

The relationship exists only when the ACE is at extremely high levels like the La Niña years 95-96, 05-06, 17-18, and 20-21. I would say it’s more a marker than necessarily a cause and effect. In that there was a greater underlying pattern at play those years in which the ACE and other factors were part of. Other significantly lower La Niña ACE years from those very high peak years weren’t indicative of a positive or negative winter outcome just that they weren’t necessarily top tier La Ninas for snow and cold.

ACE hasn’t traditionally had much relationship with the winter pattern outside the really high La Niña ACE years over 180 like 95-96, 05-06, 17-18, and 20-21. Accumulated Cyclone Energy - Atlantic [14] Season ACE TS HU MH Classification 1933 258.57 20 11 6 Extremely active 2005 245.3 28 15 7 Extremely active 1893 231.1475 12 10 5 Extremely active 1926 229.5575 11 8 6 Extremely active 1995 227.1025 19 11 5 Extremely active 2004 226.88 15 9 6 Extremely active 2017 224.8775 17 10 6 Extremely active 1950 211.2825 16 11 6 Extremely active 1961 188.9 12 8 5 Extremely active 1998 181.7675 14 10 3 Extremely active 1887 181.26 19 11 2 Extremely active 1878 180.85 12 10 2 Extremely active 2020 180.3725 30 14 7 Extremely active

The easterly flow resulted in numerous stations approaching their warmest September monthly minimum despite the average monthly temperature closer to normal. The effect was most obvious at JFK which set a new record warm minimum for September at 56°. Westchester only made it down to 49° which was 2nd warmest. Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Month of Sep Click column heading to sort ascending, click again to sort descending. 1 2021 53 0 2 2015 52 0 3 2018 51 0 4 2024 50 0 - 2023 50 0 5 2017 49 0 Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Month of Sep Click column heading to sort ascending, click again to sort descending. 1 2024 56 0 - 2015 56 0 3 2021 54 0 - 2018 54 0 - 2017 54 0 - 2002 54 0 - 1994 54 0 - 1968 54 0 Time Series Summary for WESTCHESTER CO AP, NY - Month of Sep Click column heading to sort ascending, click again to sort descending. 1 2018 51 0 2 2024 49 0 3 2008 48 0 - 2002 48 0 - 1999 48 2 - 1968 48 0

The chart below really shows how there is something else going on with the current record global temperature jump compared to past El Niño years.

Yesterday was the 2nd latest first 40s of the season at ISP. This was due to the record easterly flow keeping the minimums up in September. This surface pressure pattern is finally reversing allowing some NW flow with the cooler temps. Now that that big high over New England has relaxed for a while it will allow a SW to W flow warm up later in October which we didn’t see much of over the summer due to all the onshore flow. The expanding drought to our West could allow highs on a few days to approach 80° which is near record levels in late October on some days at Newark like we saw last October. First/Last Summary for ISLIP-LI MACARTHUR AP, NY Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. 2018 06-12 (2018) 48 10-12 (2018) 49 121 2024 05-13 (2024) 42 10-08 (2024) 47 147 2023 06-08 (2023) 47 10-08 (2023) 47 121 2015 05-23 (2015) 48 10-02 (2015) 49 131 2021 06-01 (2021) 49 10-01 (2021) 49 121

Most major hurricanes which make landfall on the Florida Gulf Coast travel through the Florida Straits or up from the Western Caribbean. So they have tended to track toward either SW Florida like Ian and Charley or the Panhandle and Big Bend like Michael or Helene. It’s extremely rare to get in intense hurricane form near the BOC like Milton and strengthen while tracking eastward. Most storms which had been on more of an eastward heading toward the Central FL Gulf Coast near Sarasota or Tampa have been weaker systems. So this area hasn’t had something this strong since before it was so heavily developed.

Yeah, Aug 76 into Jan 77 was the last time we had something resembling a LIA late summer into winter. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending Aug to Jan avg temp 1 1918-01-31 46.8 0 2 1888-01-31 47.0 0 3 1881-01-31 47.1 0 4 1884-01-31 47.2 0 5 1977-01-31 47.8 0 6 1877-01-31 47.9 2 - 1872-01-31 47.9 0 7 1883-01-31 48.5 0 - 1873-01-31 48.5 0 8 1904-01-31 48.7 2 - 1893-01-31 48.7 0 9 1887-01-31 48.9 0 10 1875-01-31 49.1 3

Yeah, the coastal development has been very high in those areas.