bluewave

They are only universally inflated relative to the earlier era since the measurement methodology changed. https://www.wunderground.com/cat6/US-Snowfall-1900-2019-Decade-Decade-Look As anyone who has followed my blogs for WU over the past ten years has no doubt noticed, I am always interested in the actual data-derived records so far as weather events are concerned. In my previous post, I looked at record snowfalls for all the states and several cities for various periods of time (24 hours, monthly, etc.). In the conclusion to that blog, I wrote a bit on how climate change may be affecting snowfall in the United States. The basic conclusion was that no one really understands much about this. So, as a follow-up to that, I decided to look at how much snow has actually been measured decade by decade at 40 different cities/sites across the contiguous U.S. since 1900. I only included places that see winter snowfall regularly (i.e., in most years), meaning along and north of a line from North Carolina through Tennessee, Oklahoma and the mountainous regions of the West. A constraining factor in choosing the sites is that they must all have a continuous monthly snowfall record dating back to at least 1900, something that a surprisingly few do. There is no complete record for Nashville, Tennessee; Roanoke, Virginia; Sheridan, Wyoming; and Seattle, Washington, among other cities that would seem to be obvious choices. For instance, in the high mountain areas of the West there are virtually no sites with a continuous period of record (POR) back to 1900, aside from Flagstaff, Arizona; Donner Summit in the high Sierra of California; and Red Lodge, Montana (which I did not include because of its obscurity). Inherent problems with the data As noted in my previous blog, the methods of snow measurement in the U.S. have changed over time. An articleauthored by Matt Kelsch of NCAR/UCAR and official COOP observer for Boulder, Colorado, explains how in the oldest of snow records (mostly predating 1950) a simple 10-to-1 snow-to-liquid ratio was often used to estimate the snowfall (i.e., 1” of melted precipitation = 10” of snow). As it turns out, the average ratio for the contiguous U.S. is roughly 12:1 or 13:1, and that ratio can vary greatly from place to place and storm to storm, even within a single storm. At some point—and that point in time was different among the various weather observation sites—actual snowfall began to be measured using a stick-like ruler, with the snow measurements made either at the end of each snowfall or at one or more regular times each day (e.g., at 7 a.m. or 7 p.m.). At some point (and this is the problem with my data: that this “point” in time varied from site to site between the 1950s and 1990s), snowboards came into use (see Mr. Kelsch’s description of these in his writeup). The use of snowboards led to snowfall being more accurately measured, but it also increased the amount of snow attributed to any given storm. This is because snowfall measurements were now being made as often as every six hours (when the snow board would be cleared to make way for the next six-hour measurement) instead of just once or twice a day. Since deep snow settles as it falls, this method increases the amount of snow measured. As an observer who has used both techniques during his now-29-year COOP tenure in Boulder, Mr. Kelsch estimates that for extreme snowfalls the use of six-hourly snowboard measurements can result in snow totals that are 15 to 20 percent greater than what is actually measured on the ground. The potential for confusion became evident after New York’s official Central Park site reported a 24-hour snowfall of 26.8” on January 22-23, 2016, a new all-time record for New York City. That total was adjusted upward even higher, to 27.5”, after an NWS review found and corrected an error in the transmitted snow report. However, local weather-minded residents living near the site in Central Park (and there are many of those!) measured only 18” to 22” on the ground at the end of the storm. At Newark International Airport, observations from the same storm showed a preliminary record of 28.1”. That total was declared invalid by the NWS because the private contractor who measured the snowfall took snowboard measurements once per hour, as opposed to the standard six-hour interval. The revised total of 24.0” fell short of the record of 25.6” set on Dec. 26, 1947. Another example: The great Blizzard of March 1888 brought Central Park 2.10” of melted precipitation, resulting in the official 21.0” snowfall reported. Since temperatures during the height of the blizzard were in the low teens, it is likely that the ratio was much greater than 10 to 1, and thus the actual snowfall considerably more than the 21.0” officially reported. There is also the issue of observation sites moving from one location to another over time. This is one reason why Marquette, Michigan, is not in my list: their average annual snowfall almost doubled when the NWS office moved from the town to the hills several miles south. The bottom line is that comparing old snowfall measurements with new ones is comparing apples to oranges and, unfortunately, makes looking for historical trends (especially when talking about climate change) a hapless enterprise.

The recent issue with the Central Park snowfall measurements isn’t about 12 or 24 hour measurements like they did from the late 1800s into the mid 1900s vs more frequent measurements today. It’s that the warmer recent winters caused the snowfall to melt before the 6 hr measurements were taken. So they waited until several hours after the snow stopped to measure when some of it already melted. They should have at least measured when the snowfall stopped instead of waiting hours and hours to measure after when the temps went above freezing.

Probably correct since it looks the storm track returns to the Great Lakes right after.

4 days in a row with an easterly component to the winds will attempt to push back against the record westerly flow since December.

Not sure but New Haven probably would have had over 110” rather than the 95” report in 1779-1780 if they measured as frequently as today since the snowfall at the end of storms compacted 15-20% vs more frequent measurements of today. https://www.nps.gov/morr/learn/historyculture/hard-winter-news.htm A teacher in Yale College (New Haven, Connecticut) recorded approximately twenty days with snowfall, and a total of 95 inches of snow that winter. People walked across the Sound from Stanford, Connecticut to Long Island. Others walked from Rhode Island mainland to Block Island. Chesapeake Bay and the York River in Virginia froze over for the first time since Europeans settled there. Many people mentioned in letters that they could not remember a winter as bad.

The issue isn’t your experience with the measurements during recent times but how snowfall was measured before your time from the late 1800s to the 1950 to 1980 period.

Looks like a one-off as the long term EPS forecast bias has been cold especially day 11-15.

The Pacific Jet begins to relax in the spring allowing more STJ interaction.

It’s been a while since we had a 4 day nor’easter like the Euro has from Thursday into Sunday.

Nothing compared to the under-measurement during the blizzard of 1888. https://www.wunderground.com/cat6/US-Snowfall-1900-2019-Decade-Decade-Look Another example: The great Blizzard of March 1888 brought Central Park 2.10” of melted precipitation, resulting in the official 21.0” snowfall reported. Since temperatures during the height of the blizzard were in the low teens, it is likely that the ratio was much greater than 10 to 1, and thus the actual snowfall considerably more than the 21.0” officially reported.

Snowfall totals from the late 1800s to around 1980 in reality were in reality 15-20% higher using today’s measurement techniques. So while the snows during the 2010s were impressive, they would have been 15-20% lower using the old measurement standards. So in reality the 2010s were a transient decadal increase against a long term decline in snowfall. 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. Update • January 29, 2015 | Thanks to thoughtful feedback by several colleagues, this article has been updated. Paragraph 3 now includes a description of how climate studies handle the data inconsistencies. Paragraph 9 was added to describe the pre-1950s practice, no longer in wide use, of recording liquid water content only, and not snow depth.

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.