bluewave

We are following the decadal pattern since 2015 of NYC having the last freeze between March 20th and April 10th.

You can see what has been happening over the Pacific by looking at where the SSTs have been warming the fastest. The reason that we have been seeing more frequent La Ninas is due to the WPAC warming at a faster rate than the EPAC. So it causes stronger trade winds near the Dateline. This works against El Niño development. So when we finally tip the system back to El Niño it has to be very strong in order to develop against the very strong La Ninas background state. We saw the El Niño struggle to develop in 12-13 and 14-15 only to finally push through with the super El Niño in 15-16. Then again in 23-24. But something shifted in the spring of 2023 with the record warming in the EPAC. This warming off the South American Coast is continuing into April 2025. So the La Niña this winter was among the weakest we have seen since 1950 coming off such a strong El Niño. The rapid increase in global warming last 2 years may suggest that we have experienced a new type of Pacific shift. One in which the system is tilted more to El Niño development. If the EPAC warming persists into the summer, then it may inhibit the typical 2nd year La Ninas which has been the norm recently. So if any type of El Niño can push through from 25-26 to 26-27, then we me be in uncharted territory. But we will need more data going forward to confirm this new hypothesis. Ultimately, we will need to see a shift in the record Northern Stream of the Pacific Jet since 18-19 with the lowest cumulative 7 year snowfall on record from Philly to Boston for any snowfall improvement. This is very uncertain since the competing marine heatwaves in the North Pacific blur the distinctions between what we expect from a -PDO and +PDO. The next 5-7 years will probably be make or break as to whether this snowfall regime since 18-19 is a new climate feature or something that can shift a bit going forward. Long term we expect snowfall to decrease as the climate and the storm tracks warm. So using a linear understanding of the climate we could say that we get years of ups and others with more downs as the general trend line on snowfall is down. But if we see more of a non linear shift with the snow, then the decline could occur faster than then a general decrease along a linear path. Since snowfall measurement methodology shifted since the 1980s. From late 1800s into mid 1900s snowfall was under measured by today’s standards. So when the snowfall record is corrected higher from 1880 to 1980 or so, most areas will show a steady decline away from the Great Lakes snow belts with more frequent measurements these days than in the old days inflating the present totals.

Very steep low level lapse rates again today. Another day with NW gusts over 40 mph. So a continuation of our strongest average wind gust pattern since December. A few spots could see a stray snowflake later if the moisture doesn’t dry out coming over the mountains. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=140&network=NY_ASOS&station=LGA&syear=1900&sday=0101&eday=0407&varname=avg_wind_gust&w=none&thres=1&year=2025&_r=t&dpi=100&_fmt=png

It just wasn’t cold enough for much snow on the days that the precipitation fell due to the much warmer storm tracks. So NYC averaged 41.0° on the days with .25 or more of precipitation. While the overall average temperature including the dry days was 34.8°.

The first day of the year with a 60° average high is April 10th using the 91-20 climate normals.

+7 for the highs are still going to feel chilly in the early spring with the stronger winds, clouds, and rain.

The highs at places like JFK have been tied with 2012 and 2010 around 56.0°. Time Series Summary for JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending March 1 through April 6th high temperatures 1 2012-04-06 56.7 0 2 2025-04-06 56.3 0 - 2010-04-06 56.3 0 3 2016-04-06 54.9 0 - 1973-04-06 54.9 0 4 1985-04-06 54.8 0 5 2020-04-06 54.6 0

It’s been one of the warmest starts to spring we have seen. But even +6 to +7 for high temperatures is still going to feel cool with all the clouds,rain, and wind. We are just too close to the ocean to get a summer in March like they had in the Midwest back in 2012.

Those are the average high temperatures as 56.6° in NYC is the 6th warmest start to spring on record.

All the clouds, wind, and rain has made the 7th warmest start to average spring high temperatures feel much cooler. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending 03-01 to 04-06 warmest average high temperature 1 1945-04-06 60.7 0 2 1921-04-06 59.4 0 3 2012-04-06 59.3 0 4 1946-04-06 58.4 0 5 2010-04-06 57.8 0 6 2016-04-06 56.9 0 7 2025-04-06 56.6 0 8 2000-04-06 56.4 0 9 2020-04-06 55.9 0 10 1985-04-06 55.6 0 - 1903-04-06 55.6 0

The latest last freeze over the past decade for NYC was 4-10-16. Frost/Freeze Summary for NY CITY CENTRAL PARK, NY Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. Minimum 03-01 (2020) 10-31 (2020) 218 Mean 03-27 11-19 236 Maximum 04-10 (2016) 12-09 (2016) 2024 03-24 (2024) 31 11-30 (2024) 30 250 2023 03-30 (2023) 31 11-25 (2023) 30 239 2022 03-30 (2022) 29 11-19 (2022) 31 233 2021 04-03 (2021) 32 11-23 (2021) 32 233 2020 03-01 (2020) 25 10-31 (2020) 32 243 2019 03-18 (2019) 32 11-08 (2019) 29 234 2018 04-09 (2018) 32 11-14 (2018) 32 218 2017 03-23 (2017) 23 11-10 (2017) 25 231 2016 04-10 (2016) 31 12-09 (2016) 29 242 2015 04-01 (2015) 32 11-24 (2015) 32 236

Looks like Wednesday will be the last freeze potential for NYC until next fall or winter.

Pretty impressive gradient to our south this morning with morning lows above 70° in Delaware. Those 850 mb temperatures just over+16C are close to the record. But with the front on the move south the strongest warmth will shift south this afternoon.

There has been a shift in the the tropical cyclone tracks since the 1990s. From the late 1930s into the early 1990s the hurricanes were being directed further up the coast due to the weaker ridge near and to the north of New England. This is why Hurricane Bob in 1991 was the last hurricane to cross the coast in New England. Also the reason the last hurricane to cross the coast on Long Island was Gloria in 1985. There hasn’t been a major hurricane landfall north of Florida or Georgia since 1996. All the major hurricane landfalls since 1996 have been in the Gulf and the East Coast of Florida. My guess is that the much stronger ridge east of New England which has resulted in the stronger summer onshore flow and higher dewpoints has been steering most of the tropical activity to our south. Even Sandy curved into SNJ instead of crossing the coast further north on Long Island or Eastern New England. So it will be interesting to see how much longer this steering pattern continues.

It will be interesting to see if we can actually get a slow moving coastal next weekend since that storm track has been almost nonexistent in recent years.

Who knows what the sky conditions will be that far out. But next week will be cooler before we warm up again for the 3rd week of April. JFK already had the 4th earliest 80 on record. So the warm ups continue to be more impressive than the cooldowns. First/Last Summary for JFK INTERNATIONAL AIRPORT, NY Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. 1990 03-13 (1990) 85 10-14 (1990) 82 214 2021 03-26 (2021) 81 10-14 (2021) 80 201 1998 03-27 (1998) 80 10-01 (1998) 80 187 2025 03-29 (2025) 82 - - - 1991 04-07 (1991) 81 10-03 (1991) 80 178 2010 04-07 (2010) 87 09-25 (2010) 87 170

Looks like a cooler pattern next week before the next warm up mid-April which has been correcting stronger in recent runs. New run next 70s+ warm up for mid-April Old run

Sunday looks like one of the biggest deviations between the surface and 850 mb temperatures that we have seen in a while. The 850 mb temperatures with full sun and SW to W flow would support highs near 90°. But the clouds, rain, and onshore flow will limit the high temperature potential.

As the atmosphere continues to warm, the 500mb heights have been increasing to record levels. So it leads to weather patterns getting stuck in place over extended periods of time. The trough areas have been shrinking also so we don’t see the really deep troughs like we used to get which were very cold. Even though we had impressive -EPO +PNA -AO blocking this past winter, the cold never was able to approach levels we saw during past winters with similar teleconnections.

Hopefully, January turns out to be the driest month of 2025 as we continue to see increased rain chances going forward in April.

Mid to upper 70s in parts of NJ where the sun is out.

Our dry months these days have mostly been the result of record 500mb ridges getting stuck in place like we saw in SEP, OCT, and JAN. But as soon as the blocks fade the rains return. In the old days the drier patterns were more a result of a cooler atmosphere holding less moisture. Now the atmospheric moisture is at record levels with serious flooding occurring in many locations like to our SW recently as the fast Pacific Jet encounters the Southeast Ridge.

The good news is that the NYC reservoirs to our north haven’t been low enough to require water restrictions since 2001-2002. The record dry pattern last fall occurred after one of the wettest periods preceding it. So the NYC reservoirs were OK. But some of the NJ reservoirs closer to the driest anomalies did fall pretty low. We have generally seen slow improvement in the drier conditions last few months. While this fast Pacific flow hasn’t been great for snowfall, it has remained wet enough overall to avoid anything approaching what we had back in the 1960s.

The 850 mb temperatures will be warmer than last weekend when we reached the 80s. But this time the flow will be more SW with clouds and the front nearby. If we were able to have deep westerly flow like last weekend with the forecast 850s, then it would support highs near 90°. So even with the clouds and more SW flow the 80s will make it to Central NJ on Sunday. More of a seabreeze this time around on Long Island.

2nd warmest March on record.