bluewave

Top 10 warmest start to March across the region. Most spots are running +4 to +7. It’s just goes to show when we get a few months a little colder than average that the rebound warmer has been more impressive during recent years. SMQ…+5.4° FWN..+6.7° EWR…+5.8° NYC….+4.1° LGA…..+3.8° JFK……+6.1° HPN…..+4.4° BDR……+4.2° ISP…….+4.8° POU…..+5.1° BGM…+6.9° PHL…+5.8°

While we have had several epic snowfall seasons from the mid 1990s into the 2010s, earlier eras measured snowfall differently. So the seasons prior to this period undermeasured snow compared to the way we do now. So correcting these undercounts will show heavier snows from the late 1800s into 1980s. This would lead to a longer term decline snowfall when the earlier totals are raised. So places that don’t show any long term trend will show a decline when the measurements are standardized. And some areas which already have long term declines will show even steeper declines. Plus areas which show longer term increases may shift to not much trend when the earlier era snowfall is increased. https://news.ucar.edu/14009/snowfall-measurement-flaky-history As a hydrometeorological instructor in UCAR’s COMET program and a weather observer for the National Weather Service, I am keenly interested in weather trends. In this case, climate change is an important factor to explore, since we know that the heaviest precipitation events have intensified in many parts of the world (see related story: Torrents and droughts and twisters - oh my!). But when we turn to snowstorms in the Northeast, or elsewhere in the U.S., there is an additional factor at work when comparing modern numbers with historical ones. Quite simply, our measuring techniques have changed, and we are not necessarily comparing apples to apples. In fact, the apparent trend toward bigger snowfalls is at least partially the result of new—and more accurate—ways of measuring snowfall totals. Climate studies carefully select a subset of stations with consistent snow records, or avoid the snowfall variable altogether. Official measurement of snowfall these days uses a flat, usually white, surface called a snowboard (which pre-dates the popular winter sport equipment of the same name). The snowboard depth measurement is done ideally every 6 hours, but not more frequently, and the snow is cleared after each measurement. At the end of the snowfall, all of the measurements are added up for the storm total. NOAA’s cooperative climate observers and thousands of volunteers with the Community Collaborative Rain, Hail and Snow (CoCoRaHS), a nationwide observer network, are trained in this method. This practice first became standard at airports starting in the 1950s, but later at other official climate reporting sites, such as Manhattan’s Central Park, where 6-hourly measurements did not become routine until the 1990s. Earlier in our weather history, the standard practice was to record snowfall amounts less frequently, such as every 12 or 24 hours, or even to take just one measurement of depth on the ground at the end of the storm. You might think that one or two measurements per day should add up to pretty much the same as measurements taken every 6 hours during the storm. It’s a logical assumption, but you would be mistaken. Snow on the ground gets compacted as additional snow falls. Therefore, multiple measurements during a storm typically result in a higher total than if snowfall is derived from just one or two measurements per day. That can make quite a significant difference. It turns out that it’s not uncommon for the snow on the ground at the end of a storm to be 15 to 20 percent less than the total that would be derived from multiple snowboard measurements. As the cooperative climate observer for Boulder, Colorado, I examined the 15 biggest snowfalls of the last two decades, all measured at the NOAA campus in Boulder. The sum of the snowboard measurements averaged 17 percent greater than the maximum depth on the ground at the end of the storm. For a 20-inch snowfall, that would be a boost of 3.4 inches—enough to dethrone many close rivals on the top-10 snowstorm list that were not necessarily lesser storms! Another common practice at the cooperative observing stations prior to 1950 did not involve measuring snow at all, but instead took the liquid derived from the snow and applied a 10:1 ratio (every inch of liquid equals ten inches of snow). This is no longer the official practice and has become increasingly less common since 1950. But it too introduces a potential low bias in historic snowfalls because in most parts of the country (and in the recent blizzard in the Northeast) one inch of liquid produces more than 10 inches of snow. This means that many of the storms from the 1980s or earlier would probably appear in the record as bigger storms if the observers had used the currently accepted methodology. Now, for those of you northeasterners with aching backs from shoveling, I am not saying that your recent storm wasn’t big in places like Boston, Portland, or Long Island. But I am saying that some of the past greats—the February Blizzard of 1978, the Knickerbocker storm of January 1922, and the great Blizzard of March 1888—are probably underestimated. So keep in mind when viewing those lists of snowy greats: the older ones are not directly comparable with those in recent decades. It’s not as bad as comparing apples to oranges, but it may be like comparing apples to crabapples. Going forward, we can look for increasingly accurate snow totals. Researchers at NCAR and other organizations are studying new approaches for measuring snow more accurately (see related story: Snowfall, inch by inch). But we can’t apply those techniques to the past. For now, all we can say is that snowfall measurements taken more than about 20 or 30 years ago may be unsuitable for detecting trends – and perhaps snowfall records from the past should not be melting away quite as quickly as it appears

https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=161&network=NJ_ASOS&zstation=EWR&var=max_gust&dir=aoa&thres=35&month=jan&year=2025&_r=t&dpi=100&_fmt=js December tied for 1st place with the most days having 35KT or greater wind gusts at Newark. January was in first place with the most days with wind gusts at our above 35 KT at Newark and February was in 2nd place. So a very active Great Lakes cutter storm track with the very fast Northern Stream of the Pacific Jet. It’s why we got so little snowfall this winter despite the average temperatures close to long term average. Numerous seasons close to this 34.8° average temperature had significantly higher snowfalls. But on the 11 days with .25 of precipitation this winter NYC averaged 41° which is too warm for heavy snow. So this highlights the challenges of getting close to average or above average snowfall since 2018-2019 with such a fast Northern Stream and warm storm track pushed so far north.

2022 was just behind 2010 at Newark for 90° days in 2nd place. But the onshore flow held JFK to 6th place and LGA to 7th. SMQ finished in 1st place in 2022 with a shorter period of record beginning in 2000. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Jan through Dec Click column heading to sort ascending, click again to sort descending. 1 2010 54 0 2 2022 49 0 - 1993 49 0 3 1988 43 0 4 2021 41 0 - 2002 41 0 - 1991 41 0 5 2016 40 0 - 1983 40 0 - 1959 40 0 Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Jan through Dec Click column heading to sort ascending, click again to sort descending. 1 2010 32 0 2 1983 26 0 3 2002 21 0 4 1971 18 0 - 1949 18 0 5 2005 17 0 - 1991 17 0 6 2022 16 0 - 2012 16 0 - 1959 16 3 - 1955 16 2 Time Series Summary for LAGUARDIA AIRPORT, NY - Jan through Dec Click column heading to sort ascending, click again to sort descending. 1 2010 48 0 2 2018 38 0 3 2002 35 0 4 2020 34 0 - 1991 34 0 5 2016 32 0 6 1983 31 0 7 2022 30 0 - 2005 30 0 - 1953 30 0 Time Series Summary for SOMERSET AIRPORT, NJ - Jan through Dec Click column heading to sort ascending, click again to sort descending. 1 2022 46 1 2 2010 38 25 3 2016 37 0 4 2005 36 1 5 2024 35 0

2022 was our first drought summer with onshore flow. All the previous 4+ 100° day summers in NJ also had the 100° heat extending further east with westerly flow. So it shows that onshore flow can keep areas east of NYC cooler even during drought conditions if the winds stay onshore. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Jan through Dec Click column heading to sort ascending, click again to sort descending. 1 1993 9 0 2 1949 8 0 3 2022 6 0 - 1953 6 0 5 1988 5 0 - 1966 5 0 7 2011 4 0 - 2010 4 0 - 1955 4 0 - 1944 4 0

Local perceptions of what is considered cold are irrelevant to local climate records since they mostly form their perception based on recent years which have been much warmer. So recent perceptions will naturally lack the historical perspective of what cold winters used to be like. Fewer and fewer local areas are having historically cold winters any more just like the CONUS wider averages reflect.

Yeah, hopefully we can shrink those rainfall deficits heading into the summer. Since that’s when they can have a larger effect. NJ had a -9.00” deficit from February 2022 into August 2022 at peak seasonal heating and drying which resulted in 5-6 days reaching 100 in NJ that summer which was close to the record.

The bar naturally gets lower when discussing how cold it feels since recent winters have been warming so fast. This winter was actually cold in some regions during January and February. But overall it was a pretty mild winter collectively across the entire CONUS. Since the geographic footprint of the Arctic air coverage has been shrinking over the years. So it’s harder for a cold month in one geographic region to be expansive enough to be a cold one in another region.

Heaviest rains have been finding a way to favor closer to coast since last summer but all areas have been very dry.

The actual temperature rankings for the entire CONUS finished the winter on the warmer side since 1895. Since recent winters were so much warmer, this winter felt very cold in comparison. The CONUS had 6 winters since 15-16 finish within the top 22 warmest of all winters. But the last time the CONUS had a 22nd coldest winter was back in 09-10. Have to go back to the late 70s for a top 10 coldest winter. So you can see how using departures in a rapidly warming climate fails to provide an accurate perspective. December 24…..4th warmest January 25………33rd coldest February 25……..48th warmest DJF 24-25……….27th warmest 23-24…..1st warmest winter 15-16….. 2nd warmest winter 19-20…..7th warmest winter 16-17…..9th warmest winter 22-23…18th warmest winter 21-22….21st warmest winter 78-79…..1st coldest winter 77-78…..7th coldest winter 76-77…..12th coldest winter 83-84…..18th coldest winter 84-85…..20th coldest winter 09-10….22nd coldest winter

Another 70° day in the warm sector away from the marine influence.

For the Northeast it was -1.2° using 1991-2020, -0.3 using 1981-2010, +0.5 using 1971-2000, and +1.8° using 1961-1990.

Onshore flow here and record warmth to the north has become very predictable with the strongest 500mb anomaly over Nova Scotia instead of to our south.

Another over the top warm up with the record warmth going to our north.

Yeah, that was 3-13-90. We used to get flatter ridges over the Southeast with strong westerly flow warm ups. So the warmest temperatures were directed right in to the area. Now the over the top warm ups have become the norm going into Canada first. So this leaves room for more backdoors and onshore flow.

I remember you posting an article on the Nino 1+2 very early warming into the spring of 2023. Wondering if this new PCC pattern they discovered in the Pacifc may be related to the faster warming last few years. We have noticed how these WWBs and warming have been very impressive in the EPAC since the spring of 2023. The WWBs actually set a February record last month with the warming which has occurred there last few weeks. They don’t seem to know very much yet about this but I think it could possibly be related to why the warming suddenly increased beyond all past cases related to ENSO. https://lamont.columbia.edu/news/climate-change-signal-tropical-pacific

It’s been very common in recent years. Very strong ridging into Southeast Canada turns the flow more onshore during our early spring warm ups these days. Back in the old days we could get deep westerly flow in the early spring so mid 80s would extend across Long Island like in March 1990. Monthly Data for March 1990 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. NJ CRANFORD COOP 86 NJ NEWARK LIBERTY INTL AP WBAN 86 NJ PLAINFIELD COOP 85 NY NY CITY CENTRAL PARK WBAN 85 NJ ESSEX FELLS SERVICE BLDG COOP 85 NY WEST NYACK COOP 85 NY MINEOLA COOP 85 NY JFK INTERNATIONAL AIRPORT WBAN 85 NY PORT JERVIS COOP 84 NJ TETERBORO AIRPORT WBAN 84 NJ LITTLE FALLS COOP 84 NY DOBBS FERRY-ARDSLEY COOP 84 NY WESTBURY COOP 84 CT STAMFORD 5 N COOP 84 CT IGOR I SIKORSKY MEMORIAL AIRPORT WBAN 84 NJ CANOE BROOK COOP 83 NY NEW YORK AVE V BROOKLYN COOP 83 NY LAGUARDIA AIRPORT WBAN 83 NJ LODI COOP 83 NY PATCHOGUE 2 N COOP 83 NJ CHARLOTTEBURG RESERVOIR COOP 82 NY SUFFERN COOP 82 NY SCARSDALE COOP 82 NY DIX HILLS COOP 82 NY WESTCHESTER CO AP WBAN 82 CT NEW HAVEN COOP 82 CT MOUNT CARMEL COOP 82 NY ISLIP-LI MACARTHUR AP WBAN 82 NJ WANAQUE RAYMOND DAM COOP 81 NY WEST POINT COOP 81 NY WALDEN 1 ESE COOP 81 NY MIDDLETOWN 2 NW COOP 80 NY YORKTOWN HEIGHTS 1W COOP 80 CT COCKAPONSET RANGER STA COOP 80 NY RIVERHEAD RESEARCH FARM COOP 80 CT NORWICH PUBLIC UTILITY PLANT COOP 80

Yeah, looks like the onshore flow and backdoor season has officially begun. So plenty of onshore flow going forward. West of the Hudson will be favored for the best warmth over the next week.

We are beginning to shift into the spring pattern was has much less westerly flow than the winter did. Yesterday was the first day with stronger easterly flow. Every warm up will have to compete with onshore flow. So the 70° warmth will probably line up west of the Hudson on the warmer days. And the onshore flow will be very noticeable especially near the coast. We will probably have to wait a week for our next stronger westerly flow event behind one of the cuttters.

Part of it is that the drought peaked in mid-April 2002 with all the record heat and some spots approaching 100°. It started getting rainy in late April so we didn’t get the peak drought conditions during the summer like in 1995. Plus we didn't have the high winds in the spring of 2002 like we have been getting this year. So hopefully we can start getting wet again by mid to late spring so we avoid a drought peak during the summer with all that would entail. Monthly Data for April 2002 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. NJ HARRISON COOP 98 NJ ESSEX FELLS SERVICE BLDG COOP 98 NJ PLAINFIELD COOP 97 NJ CRANFORD COOP 97 NJ NEWARK LIBERTY INTL AP WBAN 97 NJ CANOE BROOK COOP 96 NY NY CITY CENTRAL PARK WBAN 96 NJ LITTLE FALLS COOP 96 NJ MIDLAND PARK COOP 96 NY DOBBS FERRY-ARDSLEY COOP 96 NY BRONX COOP 96 CT STAMFORD 5 N COOP 96 NJ TETERBORO AIRPORT WBAN 95 NJ CALDWELL ESSEX COUNTY AP WBAN 95 NJ WANAQUE RAYMOND DAM COOP 95 NY WEST POINT COOP 95 NJ TETERBORO AIRPORT COOP 95 NY OCEANSIDE COOP 95 CT DANBURY COOP 95 NY YORKTOWN HEIGHTS 1W COOP 95 CT MERIDEN MARKHAM MUNICIPAL AP WBAN 95 NY SETAUKET STRONG COOP 95 NY MOUNT SINAI COOP 95

It has been the 2nd driest late August to mid-March on record in NYC. The actual rainfall has been similar the same as the 2001-2002 drought. So those departures are legit since they match the actual amounts. There has only been 14.73” since August 23rd. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. 1 2002-03-13 14.25 0 2 2025-03-13 14.73 1 3 1947-03-13 15.23 0 4 1932-03-13 16.08 0 5 1966-03-13 16.10 0 6 1880-03-13 16.64 0 7 1954-03-13 16.87 0 - 1876-03-13 16.87 0 8 1905-03-13 17.05 0 9 1897-03-13 17.07 0 10 1992-03-13 17.12 0

Part of the challenge in conveying that these winters just aren’t as cold as the used to be is making the bar lower for what constitutes a cold winter. Updating the climate normals every 10 years normalizes how much warmer the winters are getting. The NOAA NCEI should probably settle on a baseline from before the rapid increase in temperatures prior to 1980 like NASA, Berkeley Earth, and other centers do for determining the global temperatures.The record winter warmth in recent years made this winter seem like a cold one in comparison. But the actual temperature rankings place this winter closer to the old average or even warmer.

March has become too warm for much snow around NYC during the 2020s. Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Mean 0.1 0.1 2025 0.0 0.0 2024 T T 2023 0.1 0.1 2022 0.4 0.4 2021 T T 2020 T T

Every weather event that occurs is in some way influenced by the average global temperatures around the time of the event. You wouldn’t expect the real world weather events to be the same during an ice age as they were during the PETM. So the background climate temperatures during each era sets the parameters or range of possibilities for the individual weather events.