bluewave

Strong HREF signal for locally 5”+ from the PRE next 48 hrs where the best training eventually sets up.

July 2024 has just set the new July all-time monthly +PNA record at +2.60. Very strong +PNA patterns began to become a feature with La Ninas in July starting in 1988. So nearly all the top 10 strongest +PNA patterns in July have been during La Ninas. It only took 2 years to beat the previous record set in. 2022. So we can use it as a marker of how strong the La Niña 500 mb pattern has already become after the very strong El Niño last winter. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table https://www.cpc.ncep.noaa.gov/data/indices/RONI.ascii.txt La Nina July +PNA and JJA…..RONI 2024….+2.60…?…………….1st place July +PNA 2022…..+2.54….-0.82…….2nd place July +PNA 2020…..+1.73…..-0.73 2017……+1.86…..-0.16 2007……+2.21….-0.54 1998……+2.24…..-1.07 1988……+2.16…..-1.49

This has been the 7th wettest summer through August 4th at Tweed New Haven just to my SW. Nearly 10.00” here since June 1st. This is even before we start seeing the heavy rainfall from Debby. Time Series Summary for NEW HAVEN TWEED AP, CT Click column heading to sort ascending, click again to sort descending. 1 2009-08-04 16.29 0 2 1972-08-04 15.58 0 3 2006-08-04 10.95 0 4 2013-08-04 10.88 0 5 2023-08-04 10.03 2 6 2008-08-04 10.02 0 7 2024-08-04 9.95 0 8 2003-08-04 9.79 0 9 1953-08-04 9.23 0 10 1971-08-04 9.13 0

Got really dark here and the streetlights had to come on at 5:30. Quick 1.46” and much wetter than yesterday but less wind. Another very dramatic sky before the storm. https://www.weather.gov/wrh/timeseries?site=khvn

The only way we can get cooler temperatures these days during the summer is through plenty of rain.

Parts of the region have the chance to surpass 100” of precipitation since last July especially if we can generate follow up tropical systems after Debby into September or October. Data for July 1, 2023 through August 4, 2024 NJ Click column heading to sort ascending, click again to sort descending. HIGHLAND LAKES 1SW COOP 82.37 MINE HILL TWP 0.4 NE CoCoRaHS 82.21 Data for July 1, 2023 through August 4, 2024 NY Click column heading to sort ascending, click again to sort descending. WEST POINT COOP 86.56 STONY POINT 0.7 NW CoCoRaHS 85.69 CARMEL 4N COOP 85.45 HIGHMARKET 2W COOP 84.97 SOUTH SALEM 0.8 N CoCoRaHS 84.37 THORNWOOD 0.7 NW CoCoRaHS 82.17 PEEKSKILL 0.4 N CoCoRaHS 81.65 PHONECIA 2SW COOP 80.78 SHRUB OAK COOP 80.59 Data for July 1, 2023 through August 4, 2024 CT Click column heading to sort ascending, click again to sort descending. COLUMBIA 2.6 S CoCoRaHS 94.27 BURLINGTON COOP 93.69 NEWINGTON 1.9 SSW CoCoRaHS 93.52 BRISTOL 2.8 NNE CoCoRaHS 92.77 BRISTOL 2.7 WNW CoCoRaHS 92.35 SOUTH WINDHAM 1.3 NNE CoCoRaHS 91.53 MOOSUP 1.7 NE CoCoRaHS 90.94 SALMON BROOK 4.9 WSW CoCoRaHS 90.55 MIDDLEFIELD 1.4 W CoCoRaHS 90.30 PROSPECT 1.9 ENE CoCoRaHS 90.22 Data for July 1, 2023 through August 4, 2024 VT Click column heading to sort ascending, click again to sort descending. AVERILL COOP 81.76 NASHVILLE 1 E COOP 80.53 STAMFORD 5.0 NNE CoCoRaHS 80.51 CABOT 3.9 ENE CoCoRaHS 80.00 RI Data for July 1, 2023 through August 4, 2024 Click column heading to sort ascending, click again to sort descending. COVENTRY 1.2 SW CoCoRaHS 89.65 NORTH CENTRAL STATE AIRPORT WBAN 89.27 CRANSTON 1.2 SSE CoCoRaHS 86.98 WEST WARWICK 3.3 SSW CoCoRaHS 86.83 GREENE 1.4 E CoCoRaHS 86.77 FOSTER 4.0 SSE CoCoRaHS 86.51

If we only get the PRE like the GFS and suppressed track then my guess is a 5”+ jackpot somewhere in the region. But if Debbie gives us a PRE and then tracks north like the Euro than a 10”+ jackpot for somebody. We probably won’t know for several more days yet. But it looks very wet either way.

It looks like the pattern is becoming wet enough that the 100° heat and warmest part of the summer is behind us now.

This chart goes back much further and shows how the recent warming of the WPAC is unprecedented. Remarkable Changes in the Dominant Modes of North Pacific Sea Surface Temperature https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101078 The second PC is mostly positive from 1990 to 2021 and strongly positive from 2014 to 2021 (Figure 6b), reflecting the positive SSTa across much of the North Pacific that EOF 1 alone does not capture. The weak negative lobe in the second EOF lessens the warming near the coast of North America. As EOF 2 describes less of the variance than EOF 1, it might be expected that its shape is more variable when calculated over different time periods, interestingly, the positive lobe in EOF 2 has grown steadily when calculated over successively longer time periods (Figure 6b, x-ticks). The positive lobe of EOF 2 filled up 98% of the North Pacific when calculated over the period 1950–2018 and similarly for HadISST data at 93% (Figure S1.6 in Supporting Information S1). While EOF 2 has not been invoked as often as the PDO as a measure of SST variability, the robust evolution since 2014 is still worthy of note. Figure 6 Open in figure viewerPowerPoint (a) The second EOF of SST over the PDO region for the entire time series (1950–2021). (b) The principal component for the second EOF is shown on the left y-axis using colored bars. The right y-axis (x symbols) shows the percentage of data points greater than zero in the second EOF from 1970 to 2021. 5 Conclusions The fundamental result of this study is that the first EOF of SST in the North Pacific has changed starting in 2014. For more than 20 years, the PDO has been used to describe the state of the North Pacific. However, since the marine heatwave of 2014, there have been remarkable changes to the dominant mode of SST in the North Pacific. The spatial pattern of the first EOF of SST from 1950 to 2021 is notably different from the PDO, suggesting that though the PDO served as a useful metric of SST variations until 2014 (Johnstone & Mantua, 2014), it may no longer be as effective a climate index for the North Pacific. From 1950 until the 2014 MHW, the first EOF remained consistent in its proportion of positive and negative regions with both taking up roughly half the area of the North Pacific (and with the positive region taken to be the eastern Pacific). When EOFs are calculated from 1950 to endpoints after 2014, the first EOF has a maximum positive region covering 77% of the North Pacific, with a PC indicating the largest anomalies on record. These changes to the first EOF/PC of North Pacific SST are nothing short of remarkable. In concert with these changes, the second EOF/PC of SST has also undergone profound evolution since 2014. This second EOF now accounts for approximately 18% of the variability, growing from 13% during the 1950–2013 period. The spatial structure of the second EOF now is positive over almost the entire basin, with a PC that has grown strongly positive in the last several years. Thus, the second EOF/PC describes warming over much of the Pacific not in the positive lobe of the first EOF. A relevant aspect of our analysis is that we did not remove a trend from the data before calculating the EOFs and PCs. This is consistent with the original calculations of EOFs in the North Pacific (Davis, 1976) and more recent analysis by Johnstone and Mantua (2014), but inconsistent with the definition of the PDO which did have a global mean trend removed (Mantua et al., 1997; Zhang et al., 1997). Whether or not a trend was removed had little effect on the first EOF, and thus the PDO, until 2014. Two of our results lead to this conclusion: first, our first PC calculated between 1950 and 1993 agreed with the PDO with a correlation coefficient of 0.97; and second, our first EOF calculated with successively longer time series did not change in shape until 2014. There are many approaches to removing a trend from time series (Deser & Phillips, 2021; Frankignoul et al., 2017; Solomon & Newman, 2012). We investigated two of these approaches: first we removed a least-squares fit of a line to the global average temperature as in the original definition of the PDO (Figure S2 in Supporting Information S1), and second, we removed a least-squares fit of a line from each grid point in the North Pacific (Figure S3 in Supporing Information S1). In each case the EOF analysis reproduced the PDO spatial pattern and index, suggesting that the PDO remains a good measure for the variability relative to the trend. In general, removal of a trend (as by least-squares fitting of a line, e.g.,) tends to deemphasize the ends of a record. In our analysis, the inclusion of the trend highlights the fact that the warming in the eastern Pacific has increased notably in recent years, a fact that would be obscured if a linear trend had been removed. The PDO is recognized to be a result of many processes that may cause temperature variability (Newman et al., 2016) rather than any singular phenomenon. The many processes that affect SST have apparently combined to create both this era of frequent marine heatwaves beginning in 2014 and a fundamental change to the first mode of SST. The persistence of the marine heatwaves was studied by Di Lorenzo and Mantua (2016) who also invoked a number of interacting processes, suggesting that the variance described by the PDO would increase in a warmer climate. Di Lorenzo and Mantua (2016) explicitly removed a trend before calculating the EOFs of SST, so that their EOFs described variance relative to the trend. The PDO is based on a constant spatial pattern defined by the EOF that described the most variance of SST through the mid 1990's. However, there is no guarantee that the EOFs of SST will remain constant as climate change continues. This concern about indices based on EOFs applies also to the North Pacific Gyre Oscillation (Di Lorenzo et al., 2008), which describes variance in sea surface height. The PDO is widely used as a measure of temperature in the eastern boundary upwelling system along the west coast of North America (e.g., Weber et al., 2021). The period of persistent marine heatwaves since 2014 has made the PDO less useful as an index of temperature in this region because it does not reflect the recent increase. In general, using PCs from a basin-wide analysis as indices of temperature for specific regions may be problematic because the influences from distant parts of the basin affect the PCs. Options moving forward may include: (a) updating the definition of the first mode of temperature variability, as we have done here, (b) explicitly accounting for the trend in addition to the PDO for a measure of temperature, or (c) defining a new temperature metric in a specified area in the region as is done for the various measures of El Niño (Trenberth, 1997) or more recently as in the NEP index (Johnstone & Mantua, 2014). Interestingly, the NEP was first published just before the recent period of MHWs, and the value of the approach championed in Johnstone and Mantua (2014) has only increased. The wide-ranging effects of the recent period of MHWs are likely to be seen in continuing studies of the eastern North Pacific. thunderbolt 1

Yeah, nice looking shelf cloud at the start. The ASOS at HVN to my SW had a gust to 48 mph. I estimated around 30 mph by me. The downpour wasn’t as impressive as recent weekends only around .30 rain estimated. Strongest part of storm was to my west.

Radar estimates in excess of 2.00” near Pearl River.

2nd day in a row with flooding north of I-80.

The common denominator is that the NW Atlantic warm pool and attendant 500 mb height and temperature records are much more impressive than the colder records from south of Greenland to Northern Europe. tps://www.nature.com/articles/s41558-021-01159-7.epdf?sharing_token=_FVaOVyABkcD2Hudkuy4HdRgN0jAjWel9jnR3ZoTv0O_gxR6rgaJtPXjMaI-B_Efht4SyFms8mqqnoqmB-1adVBLGM5Ox8NTZgYnk58C8f_MqmRXlgMUKAvhPoz3ntaVpIMcZZ9PrSyXcXowWePIeqVtKWaAjhHN6qpaUvjsKJPMu2-ItgHqBkpP-ekBm2TbTkyKT4Ld921Svm7C1wJQmod5-Am_0W6rnLf3GjdTJ9U%3D&tracking_referrer=www.theguardian.com Abstract The northeastern United States (NEUS) and the adjacent Northwest Atlantic Shelf (NWS) have emerged as warming hotspots, but the connection between them remains unexplored. Here we use gridded observational and reanalysis datasets to show that the twentieth-century surface air temperature increase along the coastal NEUS is exceptional on the continental and hemispheric scale and is induced by a combination of two factors: the sea surface temperature (SST) increase in the NWS associated with a weakening Atlantic Meridional Overturning Circulation (AMOC), and atmospheric circulation changes associated with a more persistent positive North Atlantic Oscillation. These connections are important because AMOC slowdown and NWS warming are projected to continue. A survey of climate model simulations indicates that realistic SST representation at high spatial resolution might be a minimum requirement to capture the observed pattern of coastal warming, suggesting that prior projection-based assessments may not have captured key features in this populous region.

I hear your frustration since CNJ has been a localized dry spot. But model output especially when convection is involved isn’t generally able to do INMBY forecasts. It can provide a heavy rain signal for someone in the region which has been working out. But unfortunately the technology can’t pinpoint whether Somerset or Sussex jackpots like we saw yesterday. So the 2.60” jackpot was to your north. Wantage NJ 2024-08-02 SafetyNet 84 68 94 60 29.97 29.81 2.60 27

Heaviest rain was north of 80 again with Wantage coming in at 2.60” https://www.njweather.org/data/daily/3588

Hillsborough only .11 rain since July 20th so the drier vegetation probably helping them out away from sea breeze influence. https://www.njweather.org/data/daily/3572

My guess is that it’s an additive process. When El Niño and subtropical marine heatwaves combine it has greater warming potential for the global temperatures. Then as we head into La Niña the cooling is less impressive since the marine heatwaves in other areas are ongoing. So El Niño and La Niña are having to compete with marine heatwaves in other areas. Notice how this was the first borderline super El Niño with so much SST warmth from 20°to 60°N. It’s much more pronounced than it was after the 15-16 super El Niño. One theory is that it’s a reduction in shipping aerosols but there are many competing papers on the topic. May take a while for some type of consensus to form on the exact cause of the accelerated warming.

This was a new type of global temperature response during an El Niño. It was the first time the global temperatures rose before the El Niño fully developed like we saw last spring. Now the warming is lingering past the Nino peak which was during the winter. May be related to the ongoing marine heatwaves outside the traditional ONI SST regions.

CNJ has been dry with wetter areas both north and south.

May be the first time since 1993 that the state of NJ has recorded 100° readings in June, July, and August. Monthly Data for June 2024 for New Jersey Click column heading to sort ascending, click again to sort descending. NEWARK LIBERTY INTL AP WBAN 100 HARRISON COOP 100 SOUTH JERSEY REGIONAL AIRPORT WBAN 100 Newark Area ThreadEx 100 Monthly Data for July 2024 for New Jersey Click column heading to sort ascending, click again to sort descending. TETERBORO AIRPORT WBAN 101 HARRISON COOP 101 TETERBORO AIRPORT COOP 101 HIGHTSTOWN 2 W COOP 100 Monthly Data for August 2024 for New Jersey Click column heading to sort ascending, click again to sort descending. NEWARK LIBERTY INTL AP WBAN 100 Newark Area ThreadEx 100 Monthly Data for June 1993 for New Jersey Click column heading to sort ascending, click again to sort descending. NEWARK LIBERTY INTL AP WBAN 102 Newark Area ThreadEx 102 Monthly Data for July 1993 for New Jersey Click column heading to sort ascending, click again to sort descending. PENNSAUKEN 1N COOP 106 Newark Area ThreadEx 105 NEWARK LIBERTY INTL AP WBAN 105 TUCKERTON 2 NE COOP 104 TOMS RIVER COOP 104 WAYNE COOP 104 BELLEPLAIN STA FOREST COOP 103 LITTLE FALLS COOP 103 LODI COOP 102 ATLANTIC CITY INTL AP WBAN 101 WOODSTOWN PITTSGROV 4E COOP 101 LAKEHURST NAS WBAN 101 Atlantic City Area ThreadEx 101 TETERBORO AIRPORT WBAN 101 ESTELL MANOR COOP 101 MILLVILLE MUNICIPAL AIRPORT WBAN 100 SEABROOK FARMS COOP 100 INDIAN MILLS 2 W COOP 100 PEMBERTON COOP 100 EWING 3 WNW COOP 100 LAMBERTVILLE COOP 100 CANOE BROOK COOP 100 Trenton Area ThreadEx 100 Monthly Data for August 1993 for New Jersey Click column heading to sort ascending, click again to sort descending. NEWARK LIBERTY INTL AP WBAN 100 WAYNE COOP 100 Newark Area ThreadEx 100

My guess is the only way we can avoid a repeat of the last 2 winters is for some type of mismatch between the La Niña background state in at least one of the winter months and like we got in January 2022 when the MJO went into phase 8. But short term shifts in the forcing like that probably won’t be known until the period in question gets much closer. So something that can’t really be known months out in a seasonal forecast. The only other clue would be the early MJO indicator in October. But years with a weaker La Niña SST ONI response like 16-17 had a weaker MJO 5 response in October and a very warm winter. Unfortunately we don’t have that more +PDO to work with this time.

The persistent record marine heatwave near Japan continues to set all-time records.

Tomorrow almost has the look of a quasi-PRE from the future Debbie although it probably wouldn’t meet the formal definition. The closed low opening up over the Great Lakes shares the same deep tropical moisture plume. So my guess is that some localized spot in the wider region has a shot at going over 3” in the convection. I am hoping the crew in CNJ can finally get lucky. Will check the 0z and 12z coming HREF runs for clues.