bluewave

7th wettest July for Cape May and 6th driest at SMQ. Time Series Summary for CAPE MAY 2 NW, NJ - Month of Jul Click column heading to sort ascending, click again to sort descending. 1 1959 10.52 0 2 1956 8.55 0 3 2000 8.38 0 4 2017 8.33 0 5 1945 7.99 0 6 1958 7.21 0 7 2024 6.85 4 8 1989 6.60 0 - 1926 6.60 0 9 1896 6.55 16 10 2001 6.17 0 Time Series Summary for SOMERSET AIRPORT, NJ - Month of Jul Click column heading to sort ascending, click again to sort descending. 1 2013 0.07 2 2 2003 0.10 25 3 1999 0.61 0 4 2022 0.86 0 5 2002 1.00 0 6 2024 1.64 1 7 2015 1.88 0 8 2001 2.19 0 9 2005 2.78 0 10 2011 2.90 0

You know you are in a very cold environment when such a warm departure is still so far below 0°.

It’s one of the few times of the year when MJO 5 is cold for us. With the record WPAC warm pool most other MJO 4-7 periods are warm. So November is the only real outlier month for us.

The only month in recent years we have been able to get something approaching regular cold departures has been November.

The last time the AAO dropped this low in late July and early August during a La Niña was in 2011. https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.aao.cdas.z700.19790101_current.csv 2011 7 28 -4.1244120597839355 2011 7 29 -4.727965831756592 2011 7 30 -4.49726676940918 2011 7 31 -4.067351818084717 2011 8 1 -4.2525835037231445 2011 8 2 -4.324845314025879

This looks like the greatest temperature gradient between JFK and Central New Jersey we have ever seen in July. Hightstown, NJ just set set their all-time July average high temperature of 91.8°. JFK has only averaged 84.3° which is well down the list at 20th warmest. So people on the South Shore got a real gift this July with the afternoon average highs so comfortable compared to NJ. But there is probably plenty of sand blown onto the streets especially near the beach with so many afternoons with this string of an Ambrose Jet. Time Series Summary for HIGHTSTOWN 2 W, NJ - Month of Jul Click column heading to sort ascending, click again to sort descending. 1 2024 91.8 6 2 2022 91.4 0 3 1955 91.2 0 4 2020 91.0 0 5 2010 90.2 0 6 2011 90.0 0 - 1999 90.0 0 7 1894 89.9 1 8 2023 89.8 0 - 2019 89.8 0 9 1910 89.5 0 Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Month of Jul Click column heading to sort ascending, click again to sort descending. 1 2010 89.0 0 2 2011 88.6 0 3 2022 86.9 0 4 1993 86.8 0 5 2019 86.7 0 - 1966 86.7 0 6 2013 86.5 0 - 1999 86.5 0 7 2020 86.4 0 - 1983 86.4 0 8 1949 86.2 0 9 2002 86.1 0 10 2012 86.0 0 11 2016 85.7 0 12 1963 85.5 0 13 2015 85.2 0 14 1994 85.1 0 15 1974 85.0 0 16 2023 84.8 0 - 2008 84.8 0 - 1955 84.8 0 17 1971 84.7 0 18 1968 84.5 0 19 1952 84.4 0 20 2024 84.3 1 - 1970 84.3 0 - 1961 84.3 0

No heatwaves yet at JFK this year since the Ambrose Jet continues to produce numerous days with gusts over 30 mph. JFK only has had 2 days reaching 90° due to the much stronger sea breezes this summer. This is the 3rd lowest count in record through July 29th. It’s nice that at least a very localized part of our area can have any record which even approaches the record cool summer of 2009. Kennedy Intl PTSUNNY 81 70 69 S25G36 Time Series Summary for JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending. 1 2009-07-29 0 0 - 1967-07-29 0 0 2 2014-07-29 1 0 - 2004-07-29 1 0 - 1985-07-29 1 0 - 1979-07-29 1 0 - 1960-07-29 1 1 - 1951-07-29 1 2 - 1948-07-29 1 198 3 2024-07-29 2 0 - 2007-07-29 2 0 - 1975-07-29 2 0 - 1958-07-29 2 1 - 1950-07-29 2 0

https://www.nrcc.cornell.edu/services/blog/2023/11/15/index.html#:~:text=The Northeast is getting wetter.&text=The Northeast has seen a,is also expected to continue. Northeast is getting wetter. Precipitation has increased annually and in all seasons (see figure above). The Northeast is expected to see more precipitation under all global warming scenarios. The Northeast has seen a roughly 60% increase in the number of days with extreme precipitation, the largest increase of all the U.S. regions. The intensity of these events has also increased. This trend, along with an increased risk of flooding, is also expected to continue.

The average July high temperature over the last 10 years at Harrison, NJ away from the sea breeze has been 89°. It has warmed up so much that a 90° day is pretty much the normal high temperature. As recently as the 2000s the average high was closer to 85°. So these days the more memorable heatwaves don’t really start until the warm spots reach 95°. Monthly Mean Max Temperature for HARRISON, NJ Click column heading to sort ascending, click again to sort descending. Mean 89.0 89.0 2024 90.4 90.4 2023 89.5 89.5 2022 91.0 91.0 2021 87.6 87.6 2020 90.3 90.3 2019 90.6 90.6 2018 88.6 88.6 2017 85.9 85.9 2016 88.9 88.9 2015 87.1 87.1 Monthly Mean Max Temperature for HARRISON, NJ Click column heading to sort ascending, click again to sort descending. Mean 85.6 85.6 2009 83.2 83.2 2008 87.5 87.5 2007 84.6 84.6 2006 88.5 88.5 2005 87.2 87.2 2004 83.0 83.0 2003 85.1 85.1 2002 89.7 89.7 2001 84.9 84.9 2000 81.9 81.9

The strength is relative to the other years in the multiyear La Niña event. 10-11 was stronger than 11-12. 17-18 was stronger than 16-17. And 20-21 was stronger than 21-22 and 22-23. So the 3 strongest years within the multiyear La Ninas were the coldest and snowiest. And the 3 weakest years of those groups relative to the others were the warmest and least snowy winters.

Interesting what happened yesterday with that afternoon coastal trough and the flash flooding on Long Island. For the last few days models had this feature more to the SW over NJ. But I mentioned how these features can often be fickle. This one followed the past pattern and wound up across Long Island instead of NJ. During the winter these IVTs or coastal local instability troughs often end up in areas other than forecast. The most extreme instance of one of these during the warm season was with Henri a few summers ago. The main system looped back into CT and the coastal trough wound up right through NYC with the flash floods. But the CAMS had the main axis further SW in NJ or Delaware. So these often become nowcast specials. At least the HFREF got the heavy rain potential correct both times. But the placement was way off.

The first thing I do during a La Niña is see how amplified the MJO 5 is during October. For some reason the weaker La Ninas since 10-11 have all had weaker MJO 5s during October. This was followed by a stronger MJO 4-7 rebound in December. It’s why the weaker La Ninas since 10-11 have had warmer winters and the stronger La Ninas colder. Our best winters were 10-11, 17-18, and 20-21, which were stronger and colder ONIs and RONIs than the other grouped La Nias like 11-12, 16-17, and 22-23. But every La Niña since 11-12 has been warmer than average. The magnitude of the warmth was stronger during the weaker La Ninas. The stronger La Ninas had stronger MJO 5s in October and weaker MJO 4-7s in December. This relationship doesn’t work for stronger coupled El Niños or uncoupled El Niños since 15-16. The long range guidance always seems underestimate the MJO 4-7 forcing since 15-16 in any ENSO state coupled or uncoupled.The marine heatwaves in this area tend to focus the forcing here. Last winter also had a competing record marine heatwave in a MJO 2 leading to the colder pattern for a time out West in January. This increased to record MJO 4-7 forcing has resulted in an unprecedented 9 consecutive warm to record warm winters in a row for the Northeast.

Yeah, just like the PNA.

I like the Greenland Blocking Index which is like a combination of the AO and NAO. https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/gbi.mon.data

Very impressive departures there with the big drop in the AAO.

I guess it can get a little confusing at times when people discuss blocking on the Atlantic side. Most blocks in recent years in this sector have been registering as -AOs rather than -NAOs. That’s why I like looking at the 500mb height anomalies to get a better read on the situation. In the past we would get the -NAO to fall in tandem with the -AO. But these days during the winters it has been more -AO dominant. Plus we have the more frequent south based blocks during the 2020s linking up with the Southeast ridge. While in the past this often wasn’t the case. Probably related to the record warming of the Gulf Stream and Atlantic.

Yeah, it’s being driven by the continuing record marine heatwave near Japan.

Maybe as soon as next spring?

That’s pretty much to be expected from the NAM since it hasn’t been upgraded since March 2017. Over 3.00” now on Eastern LI. This is where the signal for the heaviest rains have been from most models since its closest to the subtropical low. NAM development was frozen after the March 2017 upgrade, and RAP/HRRR development with the WRF-ARW model will cease after the RAPv5/HRRRv4 upgrade in 2020. However, operational execution of these modeling and associated DA systems will continue until comparable FV3-based systems are able to give similar performance.

The East End of Long Island is currently getting very heavy downpours with 1.50” estimated in the last hour.

CT Shoreline the big winner again with over an inch the further east you do. Daily Precipitation Report Station Number: CT-NL-46 Station Name: Mystic 3.4 NW Observation Date 7/29/2024 7:00 AM Submitted 7/29/2024 7:08 AM Gauge Catch 1.23 in. Notes @19:00 =0”, OVC. <> @07:00.OBS: 1.23” overnight, 63°F, moderat

The cooler pattern over the last 10 days allowed Newark to fall back away from the lead in 90° days. So Newark dropped from 3rd place down to 8th. A bit unusual to get a cooler pattern in what is typically one of the warmest 10 day periods of the year. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 1 2010-07-18 26 0 2 2021-07-18 24 0 - 1993-07-18 24 0 3 2024-07-18 23 0 - 1991-07-18 23 0 Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 1 2010-07-28 36 0 2 1993-07-28 31 0 3 2022-07-28 29 0 - 1987-07-28 29 0 4 1994-07-28 28 0 5 2021-07-28 27 0 - 1991-07-28 27 0 6 2011-07-28 25 0 7 2024-07-28 24 0 - 2012-07-28 24 0 - 1999-07-28 24 0 - 1952-07-28 24 0 - 1949-07-28 24 0

Depends on the MJO. Frequent MJO 4-7s will get you -EPO/- PNAs at times when the Aleutian ridge becomes more poleward. A -EPO/-PNA is a warm pattern with a La Niña in the Northeast. This is when we hit 80° back in February 2018. In order to get it cold in the Northeast we need a -EPO +PNA like we got from December 2017 into early January 2018. But that required a MJO 8 pattern.

The latest HREF mean has one area of heavier rain further east closer to the low and a secondary area in NJ with the IVT-like feature similar to the GFS.