bluewave

We started to see a change during the 10-11 and 11-12 multiyear La Niña. 10-11 was one of our strongest La Ninas and best winters. The weaker 11-12 was much warmer and less snowy. Before this the weaker La Ninas were colder and snowier and the stronger ones warmer and less snowy.

Looks like 2nd highest dew point at SMQ on the hourly updates since records started in 1999. Not sure if those off hour 5 min higher obs at 81° were considered official. The chart below is only for hourly updates. https://www.weather.gov/wrh/timeseries?site=KSMQ&hours=72 https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=155&network=NJ_ASOS&zstation=SMQ&var=max_dwpf&w=all&threshold=100&hour=12&sdate=0101&edate=1231&month=jul&_r=t&dpi=100&_fmt=png

The weaker ONI La Ninas over the last decade have been warmer than the stronger ones. Not sure if we get a continuation of this theme going forward. But it will be interesting to see how things turn out.

SMQ is becoming the new Miami with dew points in the upper 70s again after last weekend. Somerville PTSUNNY 87 78

If the -PDO and marine heatwaves in those areas continue to be this strong going into the fall and winter, then it would probably mean a highly amplified Aleutian ridge. You can see the last frame of the Euro showing this. The recent CANSIPS was also moving toward this look in its recent update. So a very strong La Niña background state even if the ONI is only in La Nada to weak La Niña territory.

The Euro is similar to the SPC HREF next few days. Mid to upper 70s dew points and the potential for locally heavy downpours. Looks like the sea breeze boundaries and pre frontal trough will be the focus for convection and high dew point pooling.

I am guessing that the weaker Nino 3.4 and stronger -PDO are related to the current global record SSTs. We are just coming off a borderline super El Niño event so it naturally takes longer for Nino 3.4 to cool. This is what happened during the 16-17 La Niña following the 15-16 super El Niño. It took until the following season in 17-18 for the La Niña SSTs and ONI to drop lower. So the Euro rushed the cooling of Nino 3.4 from the forecasts issued back in the spring. The same way it tried to weaken the current marine heatwave east of Japan and south of the Aleutians. So both SST areas are now warmer in the recent forecast issued about an hour ago. The current record -PDO is allowing a much stronger La Niña atmospheric response than expected from just using the official ONI SSTs. As per the MJO details, we usually have to wait until at least October to get some hints as it’s usually less amplified during the warm season. New Euro run stronger marine heatwave south of Aleutians and east of Japan continuing to drive the stronger -PDO heading into fall Older run weaker marine heatwave south of Aleutians and -PDO and stronger La Niña cooling in Nino 3.4

It will be interesting to see if we can get some remnant moisture from Beryl next weekend.

Those are just the RMM plots which are usually less amplified this time of year. But the main forcing as per the VP anomalies since June 20th has been MJO 3-6. It’s forecast to continue into July as the convection slowly travels east. So we are getting a very strong La Niña atmospheric response based on the ongoing marine heatwaves west of the Dateline in the tropics and east of Japan.

Today looks like the beginning of our dominant July pattern next few weeks as high dew points and PWATS result in convection chances most days. Big WAR to our east and trough over the Midwest. So the daily focus for convection once the convective temperatures are met should be near the area.

First time that both May and June had monthly -PDO readings under -3.00. So it appears that the -PDO is delivering a very strong Niña-like atmospheric response. Notice how the VP anomalies are similar to what we would see during a very robust La Niña in July. This means the actual La Niña SST values east of the Dateline may not matter as much as long as this -PDO continues at record low values. The record SST warmth east of Japan and in the MJO 4-7 regions are carrying the La Niña signal even though the official La Niña regions east of the Dateline are slower to cool after such a strong El Niño. https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat

That 111° record at Phoenixville in July 1936 looks like another obvious error which wasn’t corrected. There has never been another instance of Phoenixville running 7° warmer than Philadelphia during a July heatwave with Philadelphia reaching 101° or higher. All other occasions of Philadelphia reaching 101° in July when Phoenixville temperatures were also available were within a 0 to 3° difference. July…1966 Philadelphia…104° Phoenixville…104° July….1936 Philadelphia……104° Phoenixville…....111° July….2010 Philadelphia….103° Phoenixville…..103° July……1995 Philadelphia…..103° Phoenixville…..100° July……1930 Philadelphia…..103° Phoenixville…..106° July…..1988 Philadelphia……102° Phoenixville……99° July…..1954 Philadelphia….102° Phoenixville…..104° July…….1917 Philadelphia…..101° Phoenixville……99°

That ridge over the Atlantic may approach a new record this time of year around 600 dam. If it was right in top of us it would mean more 100° heat. But there is enough of a trough to our west for clouds and convection give us a break from 100° heat. But the very high dew points could give us 100° heat indices instead.

Looks like a Florida pattern has we head into the extended July 4th weekend. PWATS over 2.00” and 75°+dew points. So as soon as we reach convective temperatures each day the thunderstorms will pop up.

We can use the ESRL data as a proxy for the RMM plots. This year had the most convection for such a strong El Niño in the WPAC with the warmest SSTs in that region. It resulted in much stronger forcing in the WPAC than usual for such a strong El Niño. Also notice how much stronger the Aleutian ridge was than in the other El Niños. The heights were also higher than average over Mexico. So this was more of a hybrid ENSO event made up of a borderline super El Niño and Niña-Like -PDO and MJO forcing.

Our last two strong to super El Niños in 15-16 and 23-24 had much weaker troughs along the Southern Tier than in the 97-98, 82-83, and 72-73 El Niños. My guess is it’s related to the record MJO 4-7 activity. It looks like the unusual ridge over Mexico for such a strong El Niño was a precursor to the record heat this spring into early summer there.

72-23 was a much colder winter across the entire CONUS with a historic Southeast snowstorm. https://www.weather.gov/ilm/Feb1973Snow

It reminds me of what monsoonal climates often experience. They have their warmest summer temperatures early followed by the heavier rains. 2021 was an example of this here. Newark made it to 103° in June which was followed by the heavier rains for the rest of the summer into September. It will be interesting to see if 100° stands as the warmest or Newark make makes amither run later on. These are the June to September monthly maximum temperatures for Newark and the rainfall. Monthly Highest Max Temperature for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 2024 100 M M M 100 2023 91 96 91 97 97 2022 96 102 101 93 102 2021 103 97 99 91 103 2020 93 96 94 89 96 Monthly Total Precipitation for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 2024 1.75 0.00 M M 1.75 2023 2.66 6.26 4.27 8.31 21.50 2022 2.40 0.55 1.92 3.73 8.60 2021 4.36 8.91 7.19 10.50 30.96 2020 2.89 11.22 3.19 4.06 21.36

Much wetter pattern starting to show up now that the models have a cutoff low to our west in early July. Interesting how most times in recent years following 100° heat it has turned wet. So not much chance in the immediate future of seeing a repeat of the 100° heat in late June. The high dew points and active convection pattern should be the big story.

In a sea of record warmth across the globe, the warming hole is one of the few places to register a daily record low as July begins. Several locations across the region recorded their wettest June on record. Springfield, IL just recorded their 2nd coldest July temperature on record. Time Series Summary for Springfield Area, IL (ThreadEx) - Month of Jul Click column heading to sort ascending, click again to sort descending. 1 2013 48 0 - 1975 48 0 - 1972 48 0 - 1971 48 0 - 1967 48 0 2 2024 49 30 - 1996 49 0 - 1891 49 0

Looks like the 2012 record low extent could be safe for another year. Latest CPOM UCL forecast for September average extent is around 4.1 million sq km. This forecast has been close every year over the last decade. It’s a statistical model based on May melt ponding. While their full forecast discussion isn’t available yet in the link, they probably observed the melt ponding back in May to be less extensive than 2020 and 2012. 2024…..4.10…Forecast 2023…..4.37 2022….4.87 2021……4.92 2020……3.92…2nd lowest 2019……4.32 2018…...4.71 2017……4.87 2016……4.72 2015…..4.63 2014…..5.28 2013…..5.35 2012…..3.60….lowest 2011……4.61 2010…..4.90 2009….5.36 2008….4.67 2007…..4.28 https://www.arcus.org/files/sio/main/June_2024_SIO_Report_Corrected.pdf

With the convection in the forecast for next weekend, we will keep the measurable rain on weekend theme going. Only 1 weekend since the beginning of March without at least a trace of rain. Many spots had more rain than Newark did yesterday. Newark Jun 29-30….0.39 Jun 22-23…..0.04 Jun 15-16……0.0 Jun 8-9……….T Jun 1-2……….T May 25-25…..T May 18-19…..0.04 May 11-12…0.38 May 4-5…..0.31 Apr 27-28…0.11 Apr 20-21…0.05 Apr 13-14…0.04 Apr 6-7…….T Mar 30-31…0.01 Mar 23-24….3.10 Mar 16-17…..T Mar 9-10….1.46 Mar 2-3…..1.31