bluewave

Especially 1991 with the record number on 90° days that spring. But the springs have been steadily getting earlier and warmer. It’s just that the warm up has occurred with more frequent spring -NAOs. The -NAOs can’t prevent the warming trend but they do shorten the warm ups when the -NAO is enough of a factor. So this spring has featured short 80°+ warm ups lasting a few days before the backdoors and onshore flow returns. Data for March 1, 1991 through May 31, 1991 Click column heading to sort ascending, click again to sort descending. State Name Station Type Number of Days Max Temperature >= 90 CT DANBURY COOP 11 NJ CRANFORD COOP 9 NJ PLAINFIELD COOP 8 NJ NEWARK LIBERTY INTL AP WBAN 8 NY NY WESTERLEIGH STAT IS COOP 8 NJ CANOE BROOK COOP 6 NY NY CITY CENTRAL PARK WBAN 6 NJ LITTLE FALLS COOP 6 NY PORT JERVIS COOP 5 NY NEW YORK AVE V BROOKLYN COOP 4 NY LAGUARDIA AIRPORT WBAN 4 NY MINEOLA COOP 4 NJ TETERBORO AIRPORT WBAN 3 NJ WANAQUE RAYMOND DAM COOP 3 NY WEST POINT COOP 3 NY JFK INTERNATIONAL AIRPORT WBAN 3

Yeah, spring is one of the the only seasons these -NAO patterns overperform. I am on the New England side of the backdoor with low clouds and mist. Like the cooler weather in general up here so far. Especially how quickly the temperatures fall due to much better radiational cooling after sunset. New Haven CLOUDY 55 54 96 S6 29.95F FOG

Yeah, still no extended 80° warm ups showing up just yet. We have been consistently getting a day or two of 80° plus from Newark east to here in Southern New England followed by backdoors. Looks like the Euro and GFS shift us back to a wetter pattern.

My guess is that climate change starts becoming so expensive for our economy to handle that we turn things around before we reach PETM levels of warmth. So an intermediate warmer climate state between what we used to have and prehistoric times. We will probably have to be on the move away from coastal areas that flood and areas where desertification occurs limiting agriculture.

Yes, weaker onshore flow along the immediate coastal beaches around the NY Bight can warm the SSTs at the beaches like we can see during the summer. But when you get further offshore this time of year persistent stronger easterly flow with clouds cools the SSTs. The record SSTs east of Newfoundland last summer were the result of sunny skies, high pressure, and light winds.

Upwelling from the easterly flow between the high to the north and 50/50 low which was displaced further south than usual. The spring has been one of our more reliable seasons for -NAO blocking. Almost like a rebound following the more +NAO winters.

Yeah, the easterly flow days in the mix will feel even cooler especially near the shore with the cold pool that has developed to our east.

There is always the opportunity for people to change their views once they make an honest evaluation of the data.

The first week of May will be a continuation of the April pattern. Warming back up to the 80s by Thursday before we get backdoored again heading into the weekend. The 50/50 low still remains strong.

The backdoor pattern prevented us from having a +4 to +5 month like areas around the Great Lakes got.

Classic backdoor pattern with 58° here at KHVN and 82° for Philly. New Haven CLOUDY 58 Philadelphia PTSUNNY 82

90° maxes west of the backdoor yesterday. Monthly Data for April 2024 for New Jersey Click column heading to sort ascending, click again to sort descending. Name Station Type Highest Max Temperature SOMERSET AIRPORT WBAN 90 PHILADELPHIA/MT. HOLLY WFO COOP 90 MILLVILLE MUNICIPAL AIRPORT WBAN 90 PENNSAUKEN 1N COOP 90 Belvidere Area ThreadEx 90 BELVIDERE BRIDGE COOP 90 CALDWELL ESSEX COUNTY AP WBAN 90 ESTELL MANOR COOP 90 SEABROOK FARMS COOP 89 EWING 3 WNW COOP 89 NEW BRUNSWICK 3 SE COOP 89 New Brunswick Area ThreadEx 89 FLEMINGTON 5 NNW COOP 89 PHILLIPSBURG-EASTON BRIDGE COOP 89 SOUTH JERSEY REGIONAL AIRPORT WBAN 89 SUSSEX AIRPORT WBAN 88 MOORESTOWN 4 E COOP 88 TRENTON-MERCER AIRPORT WBAN 88 Trenton Area ThreadEx 88 HARRISON COOP 88 FREEHOLD-MARLBORO COOP 87 CHARLOTTEBURG RESERVOIR COOP 87 TETERBORO AIRPORT COOP 86 Atlantic City Area ThreadEx 86 Newark Area ThreadEx 86 CAPE MAY 2 NW COOP 86 ATLANTIC CITY INTL AP WBAN 86 NEWARK LIBERTY INTL AP WBAN 86 TETERBORO AIRPORT WBAN 86 BOONTON 1 SE COOP 86

A very backdoor April with LGA having the coolest averages relative to the means due to the easterly flow off the Long Island Sound. EWR….+1.7 NYC…..+2.0 LGA…..+0.1 JFK……+1.6 ISP……+0.7 BDR…..+0.8

The one way to avoid the higher property insurance and HOAs in Florida is to look into new construction which has better hurricane rated features not immediately at the shore. The average property insurance with a brand new roof and windows which are hurricane rated can be as low as 1500 a year. But properties with a roof older than 15 years can be very hard to insure with either outright rejections or rates over 6k. So if you live in an HOA the monthly fees reflect the master policy for the outside of the condos which has quadruped in some cases in recent years. So the key for buying a property down there is finding out exactly what your rates will be before you buy.

I can remember the big beach crowds before the season began. It gets really packed once the train crowds arrive from NYC. Gino’s is a goldmine with a line out the door as many people stop there first. It was my favorite pizza on Long Island. Now near New Haven it’s a pizza lovers paradise. Just had Modern pizza from New Haven over the weekend and it’s one of the best pizzas that I ever had.

https://judithcurry.com/2015/02/22/understanding-time-of-observation-bias/ At first glance, it would seem that the time of observation wouldn’t matter at all. After all, the instrument is recording the minimum and maximum temperatures for a 24-hour period no matter what time of day you reset it. The reason that it matters, however, is that depending on the time of observation you will end up occasionally double counting either high or low days more than you should. For example, say that today is unusually warm, and that the temperature drops, say, 10 degrees F tomorrow. If you observe the temperature at 5 PM and reset the instrument, the temperature at 5:01 PM might be higher than any readings during the next day, but would still end up being counted as the high of the next day. Similarly, if you observe the temperature in the early morning, you end up occasionally double counting low temperatures. If you keep the time of observation constant over time, this won’t make any different to the long-term station trends. If you change the observations times from afternoons to mornings, as occurred in the U.S., you change from occasionally double counting highs to occasionally double counting lows, resulting in a measurable bias. To show the effect of time of observation on the resulting temperature, I analyzed all the hourly temperatures between 2004 and 2014 in the newly created and pristinely sited U.S. Climate Reference Network (CRN). I looked at all possible different 24 hour periods (midnight to midnight, 1 AM to 1 AM, etc.), and calculated the maximum, minimum, and mean temperatures for all of the 24 hours periods in the CRN data. The results are shown in Figure 4, and are nearly identical to Figure 3 published in Vose et al 2003 (which was used a similar approach on a different hourly dataset). On average, observing temperatures (and resetting the minimum-maximum thermometer) in the early morning results in reading about 0.15 C cooler than if temperatures were observed at midnight. Observing temperatures in the late afternoon results in temperatures about 0.45 C warmer on average than if temperatures were observed at midnight. Switching from an afternoon time of observation to a morning time of observation would result in minimum, maximum, and mean temperatures around 0.6 C colder previously measured. What Would Happen to the Climate Reference Network if TOBs Changed? Another way to look at the impact of time of observation changes is to use the “perfect” Climate Reference Network (CRN) hourly data to see exactly what would happen if observation times were systemically changed from afternoon to morning. To do this I took CRN hourly data and randomly assigned 10 percent of stations to have a midnight time of observation, 20 percent of stations to have a 7 AM observation time, and 70 percent of stations to have a 5 PM observation time, similar to the U.S. Historical Climate Network (USHCN) prior to 1950. I then had 50 percent of the stations that previously had afternoon observation times shift to morning observation times between 2009 and the start of 2014. This is shown in Figure 5, and results in a time of observation shift quite similar to that of the USCRN shown in Figure 1, albeit over a 5 year period rather than a 50-year period. There is a cooling bias of about 0.5 C introduced to the conterminous U.S. temperature record from CRN data by shifting observation times from 5 PM to 7 AM in 50 percent of stations. Interestingly, there is a strong seasonal cycle in the TOBs bias, with the largest differences seen in February, March, and April, similar to what Karl et al 1986 found. This bias of 0.5 C is of similar magnitude in the minimum, maximum, and mean temperatures. It is slightly larger than the ~0.3 C TOBs adjustments made to USHCN data (shown back in Figure 2) for two reasons: first, the percent of stations shifting from afternoon to morning is slightly higher in my synthetic CRN data than what actually occurred in USHCN; second, not all observers actually record at 7 AM and 5 PM (they tend to range from 7-9 AM and 5-7 PM, and later morning and afternoon readings result in slightly less bias as shown in figure 4). It is clear that the shift from afternoon to morning observations in the United States introduced a large cooling bias of about 0.3 C in raw U.S. temperatures. As contiguous U.S. temperatures have risen about 0.9 C over the last century, not correcting for this bias would give us a significant underestimate of actual U.S. warming. While some commenters have hyperbolically referred to temperature adjustments as “the biggest science scandal ever”, the reality is far more mundane. Scientists are working their hardest to create the most accurate possible record of global temperatures, and use a number of methods including tests using synthetic data, side-by-side comparisons of different instruments, and analysis from multipleindependent groups to ensure that their results are robust. I’d suggest that those who doubt the efficacy of their approaches do what I did: download the data and take a look for yourself.

The tree growth over the ASOS has become so dense that Central Park hasn’t made it over 98° since 2012 which is a new record. Number of Consecutive Days Max Temperature < 99 for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Run Length Dates Period of record: 1869-01-01 to 2024-04-28 1 4302 2012-07-19 through 2024-04-28 2 4022 1966-07-14 through 1977-07-17 3 3260 1885-07-22 through 1894-06-24 4 2844 1903-09-19 through 1911-07-02 5 2212 1911-07-11 through 1917-07-30 6 1786 2005-08-14 through 2010-07-04 7 1763 1983-09-12 through 1988-07-09 8 1761 1957-07-23 through 1962-05-18 9 1476 1919-07-05 through 1923-07-19 10 1475 1944-08-12 through 1948-08-25 https://www.foxweather.com/weather-news/new-york-city-arguably-has-the-most-unique-weather-observations-in-america 1920 2021

The usual warm spots from around Philly NE into NJ should get very close to 90° ahead of the backdoor this afternoon.

Much cooler April than last year as we had a strong blocking pattern which muted the influence of the perma-ridge south of the Aleutians. Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Apr Click column heading to sort ascending, click again to sort descending. Rank Year Mean Avg Temperature Missing Count 1 2010 57.9 0 2 2023 57.6 0 3 2017 57.2 0 4 1941 56.8 0 5 2002 56.1 0 - 1981 56.1 0 - 1921 56.1 0 6 1969 55.9 0 7 2006 55.7 0 - 1991 55.7 0 8 1994 55.6 0 - 1945 55.6 0 9 2019 55.5 0 - 1985 55.5 0 - 1910 55.5 0 10 2005 55.1 0 - 1974 55.1 0 11 2008 55.0 0 - 1976 55.0 0 - 1968 55.0 0 - 1952 55.0 0 12 2012 54.8 0 13 2021 54.6 0 14 2009 54.5 0 - 1986 54.5 0 - 1980 54.5 0 15 2024 54.4 3 - 1915 54.4 0

We’ll probably need better climate models in the future to give us that answer. https://www.nature.com/articles/s41612-022-00301-2 This work must be open to the idea that climate models, as currently formulated, may be deficient in their representations of past and future changes in tropical Pacific climate. Until this issue is resolved, many aspects of future projections that are strongly influenced by the tropical Pacific – including future regional climate, teleconnected climate risks, and the oceanic uptake of CO2 – will be highly uncertain.

While it’s a bit early for me to start thinking about next winter, the winter warmth since the 15-16 super El Niño has been simply astounding. There had never been a sustained 9 winter period in our modern instrumental period back to the late 1800s this warm before in the Eastern US. My guess is that the shift is related to dramatic warming in Western Pacific which began back in 2014. This is in concert with more frequent and higher amplitude MJO 4-7 phases. Even with the El Niño this winter the Aleutians ridge near the Dateline was unusually strong. This has been a repeating theme since 15-16. It also works to amplify the ridge and warmth in the East. All the seasonal model winter forecasts since 15-16 have been significantly too cold. This is probably related to the models not having the capability to factor in the historic SST changes since 2014 in the Pacific when they have been making their seasonal forecasts. So it will be interesting to see if this pattern keeps repeating in coming winters or something happens to shift away from this persistent 9 winter pattern. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101078 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.

Next few days we could see some localized pockets over .50 with the warm front.

I guess this is to be expected given the acceleration of ocean warming as per this recent study. But the timing of this most recent spike will probably need some further investigation. It would be interesting to know which specific variables were involved so we could forecast these individual temperature jumps more successfully.

It will be interesting to see what is causing the the global SSTs to peak a month later than average continuing at record levels.

You know spring is progressing when we stop getting afternoon highs in the 40s with rain behind the backdoor cold fronts. Looks like most areas away from the immediate shore will reach the 80s by Monday. Then a weak backdoor for Tuesday with highs still in the 60s and 70s eastern sections.