bluewave

You can see from this old NYT article how Central Park used to be warmer than LGA when the instruments weren’t under the trees. The ASOS at LGA is right on the water away from the main terminals and taxiways. So they can easily get wind flow off that western portion off the Sound-East River. https://www.nytimes.com/1977/07/22/archives/vandals-in-central-park-forcing-weather-service-to-seek-new-site.html

You are mixing several things together. First,Tony is correct that the city center is warmer than the airports. Philly is in a swamp next to the Delaware River. So it’s not the greatest representation of the actual temperatures in Philly. I am not a fan of rooftop sites, but it’s not necessarily that they are biased warm vs ground level. Just look at the warmest temperatures in the NYC micronet. The street level sites are often the same or even warmer than rooftop. Plus the higher the rooftop site, the cooler the temperatures. So high enough can be introducing a cool bias. Newark is not significantly warmer than say Harrison or Freehold. NYC is definitely too cold since it’s the only US observing site under a dense tree canopy which biases the highs 2-5 degrees too cool. This wasn’t the case when the site received direct exposure before the 1990s. This was when NYC was typically warmer than LGA as mentioned but the NWS at the time. Ever wonder why the heatwaves before the 1990s had Central Park near the leader for high summer temperatures? Go measure the highs out on the Great Lawn and you would see this cool bias of the trees disappear.

Consistent extreme dew points and heat indices didn’t really become more frequent around until July 1995. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=76&network=NY_ASOS&station=ISP&season=summer&varname=dwpf&agg=mean&year=1893&w=bar&hours=0-23&_r=t&dpi=100&_fmt=png

You don’t even need to look at any of the discussions from the various agencies. The raw data is freely available on the internet. Forcing continues to be centered over the WPAC which is driving the current amplification of the pattern ahead of Lee. Much more of a Niña-like pattern for early September. Record early September heat in the East and major hurricanes approaching from the east are also more Niña-like.

Those point forecasts can be off by 10-20 miles in determining where the max sets up around Philly. So the upper 90s maxes around Philly have been spot on in the city center. Same goes for NJ. The coarse model resolution often shows the max temperatures 20-30 miles SW of Newark and Harrison. But the maxes are usually further NE. So I take the Euro NJ state temperature max and adjust it closer to the urban corridor around Newark.

We wouldn’t be seeing the strong Atlantic hurricane activity if the El Niño was having a big influence on the actual pattern.

We still haven’t seen a full coupling of the atmosphere when the trade winds and clouds are factored in. Also note how the forcing is struggling to make it east of the Dateline for another month. http://www.bom.gov.au/climate/enso/ while trade winds and Pacific cloudiness have not yet demonstrated sustained El Niño patterns. Overall, atmospheric indicators suggest the Pacific Ocean and atmosphere are not yet consistently reinforcing each other, as occurs during El Niño events.

95 at Philly international and 96 at Northeast Philly. So downtown Philly near the Franklin Institute was probably 97-98. But it can sometimes take time for the downtown Philly OBS to become available. When I go to the site, downtown Philly is only updated through July. That site runs a few degrees warmer than the airports. Monthly Data for July 2023 for Pennsylvania Click column heading to sort ascending, click again to sort descending. Name Station Type Highest Max Temperature HARRISBURG CAPITAL CITY AP WBAN 99 BRADDOCK LOCK 2 COOP 97 BIGLERVILLE COOP 97 Philadelphia Center City Area ThreadEx 97 PHILADELPHIA FRANKLIN INSTITUTE COOP 97 LANCASTER AIRPORT WBAN 96 SHIPPENSBURG COOP 96 CASHTOWN 1S COOP 96 CARLISLE WATER PLANT COOP 96 WILLIAMSPORT 2 COOP 96 LANDISVILLE 2 NW COOP 95 MIDDLETOWN HARRISBURG INT'L AP WBAN 95 CHARLEROI LOCK 4 COOP 95 PHILADELPHIA INTL AP WBAN 95 SAFE HARBOR DAM COOP 95 CONNELLSVILLE 2 SSW COOP 95 NORTHEAST PHILADELPHIA AIRPORT WBAN 95

The timing of the historic warmth that month matched the MJO 4-6 passage very well. The record warmth began to emerge around the 10th and lingered through the 27th. Plus it coincided with the very positive NAO and AO that month. We can often see lingering effects several days past the warmest MJO phases. Which lead to the 70° warmth around Christmas. Go to December 2015 in menu. https://www.nrcc.cornell.edu/regional/narrative/narrative.html

The mid-December MJO 4-6 forcing completely overpowered the whole Dateline forcing pattern leading to the historic SE Ridge and +13 temperature departures. The WPAC warm pool actually muted a super El Niño at least for a month. That’s what we have been dealing with to some extent with every El Niño attempt since then.

Newark on track for the first time since 1983 of having the warmest annual temperature without a tie in September. Monthly Highest Max Temperature for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Year Apr May Jun Jul Aug Sep Oct Season 1953 77 91 100 99 102 105 80 105 1993 82 93 102 105 100 100 82 105 1983 85 84 96 98 97 99 84 99 2018 84 94 96 98 96 98 82 98 2015 82 91 93 98 97 98 81 98 2010 92 95 98 103 98 98 79 103 1980 75 90 94 101 95 98 79 101 1989 79 89 96 99 97 97 80 99 1944 80 94 95 98 102 97 88 102 2013 85 94 96 101 91 96 89 101 1964 85 96 99 99 94 96 80 99 1931 71 93 96 96 96 96 86 96 2023 93 90 91 96 91 95 M 96

Yeah, the summer has seen increasing blocking which may be linked to the decreasing late spring snow cover in North America according to the paper. While winter has seen a decline, we have had some of the best winters for Greenland blocking since 2009 along with some of the lowest blocking seasons. So a much higher range.

Based solely on the historic Atlantic SSTs, we would finish the season with 200-250 ACE units. So if this Nino continues to have trouble coupling, we may approach those levels. It will be interesting to see how things turn out.

They have a nice tweet out today on the topic.

It’s all about the progression of model forecasts and seasonal trends. Always a bit uncertain as to when a seasonal trend will end and we go back to the long term pattern. I will give new AI model forecasts at ECMWF credit from a few days ago for seeing the stronger WAR ahead of the OP. Tomorrow may be the first time in a while that the warmest temperature of the year occurs in September. Someone in NJ could hit 100° which would be one of the latest instances in the season if they could pull it off. AI models at ECMWF brush the Cape this run. https://charts.ecmwf.int/catalogue/packages/ai_models/

Yeah, the AI versions of the Euro have come further west also due to the stronger WAR than forecast. Figures the WAR would wait until September to finally put in a cameo this year. Plus any UL to our west could tug the storm even further west in later runs. Now we are back to the forecast bias of underestimating he WAR longer range only to correct stronger the closer in we get. This has been out pattern for years after a brief break over the summer. Figures it would be so difficult to sustain that for long with the record SSTs offshore. New run stronger WAR Old run weaker WAR

That 30 day period was in effect a super modoki El Niño. Nino 4 was the warmest on record near +30 C heading into winter. Greatest snowstorm on record in NYC around 30” and a below zero Valentine’s Day. So a greater snowstorm than all of the previous winter and a lower winter minimum temperature. But the extended cold and snow cover of the previous season was absent due to the higher background warmth following the ridiculous December 2015. I enjoyed the snowstorm quality in January 2016 more than any individual storm in 14-15. While there were numerous lows in 14-15 below 10° around NYC, It took until 2016 to actually dip below 0° for the first time since 1994. If the December rare MJO 4-6 didn’t happen, could have been a super El Niño with more extended snow and cold than any other.

There has been something off with every El Niño development since the super La Niña +13 pattern in December 2015. Heck, you can even go back to the El Niño that was supposed to develop in 2012-2013 which fizzled around Labor Day. But at least Nemo in February fulfilled the hoped for back-loaded El Niño pattern.

It looks another case of the WPAC warm pool slowing down the MJO from progressing past the Dateline this month.

You wonder what the magic number necessary these days is for a robust El Niño atmospheric response when +1.5 in Nino 3.4 hardly moves the needle.

Very weak event so far in regard to typical developing El Niño atmospheric response.

Most of the dynamical ENSO guidance are just repeater models. They exaggerate the conditions going forward that they were initialized at. When was the last time any of those models successfully forecasted a change from the state that they were initialized under until later in the game when it became obvious?

The GFS caved to the Euro on the NJ record September 100° heat on Thursday.