bluewave

It looks like the ASOS may have undermeasured the actual liquid equivalent of the snow. The NWS has noted this at certain ASOS stations in the past during heavy snows. Other North Shore observers picked up nearly .50 of precipitation https://storymaps.arcgis.com/stories/96964b6457794d2196dff24d68d4688d Sometimes the Automated Surface Observing System (ASOS) can struggle to melt snow for liquid equivalent in heavier snowfall. Station Number: NY-QN-39 Station Name: Little Neck 0.3 SE Observation Date 1/7/2022 7:00 AM Submitted 1/07/2022 7:22 AM Total Precip Amount 0.49 in. Notes 27° snow reading 7:10 AM Taken at registered location Yes Snow Information New Snow Depth 7.8 in. New Snow Water Equivalent 0.49 in. Station Number: NY-NS-42 Station Name: Albertson 0.2 SSE Observation Date 1/7/2022 7:30 AM Submitted 1/07/2022 8:27 AM Total Precip Amount 0.44 in. Notes -- Taken at registered location Yes Snow Information New Snow Depth 7.5 in. New Snow Water Equivalent 0.51 in. Total Snow Depth 7.5 in. Total Snow Water Equivalent 0.51 in.

While the ratios were very high across the area, it’s possible that some of that some of that ratio calculation was a result of ASOS error. https://storymaps.arcgis.com/stories/96964b6457794d2196dff24d68d4688d Sometimes the Automated Surface Observing System (ASOS) can struggle to melt snow for liquid equivalent in heavier snowfall. This may have led to the 22:1 ratio, which is rare in this part of the country.

This new pattern for us emerged in January 2005 . We had one of the warmest first two weeks of January on record. Followed by a record high of 66° on the 14th and a KU on the 22nd. Seasons since 1950 when at least one station from Newark to Eastern LI recorded 40”+ and the NYC DJF average temperature. 35°+ average temperature seasons bolded 20-21….36.1 17-18….36.2 16-17….39.3 15-16….41.0 14-15…31.4 13-14…32.9 12-13…36.8 10-11….32.8 09-10…33.8 08-09…34.2 05-06…37.3 04-05…35.4 03-04…32.4 02-03…31.2 00-01….33.5 95-96…32.2 93-94…31.2 86-87….34.8 77-78….30.8 68-69….32.9 66-67….34.1 63-64…33.2 60-61….31.7 57-58…33.2 55-56…32.8 Last winter it was our best December snowstorm and -AO in years with bookend 60° days. May 2020 tied for our latest trace of snow following one of our warmest winters. 17-18 featured 30” of snow in March on Long Island after Newark hit 80° in late February. We had the blizzard in February 2017 a day after the 60s. 15-16 went +13.3 in December followed by the 30” snowstorm in January and new #1 NYC snowstorm. Even before the super El Niño, we were getting occasional patterns like this. Nemo in February 2013 following the very warm first few months of winter. The 11-12 lack of winter after the record snowstorm in late October. The February 2006 NYC #2 snow following one our warmest Januaries on record. The late winter 2005 snowstorms following one of the warmest first 2 weeks of January on record. This is a sea level version of spring in the Rockies where snow and warmth have often occurred together.

This is the only snowstorm in the area during the first week of January with a 60° high temperature. We saw the first 12”+ daily snow at ACY following a 60° day. This has been a common theme for us in recent years with record warmth and heavy snows close together. Time Series Summary for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Highest Max Temperature Jan 1 to Jan 7 Snow 2007-01-07 72 0.0 1950-01-07 66 0.0 1993-01-07 64 T 2000-01-07 63 0.0 1998-01-07 63 0.0 2012-01-07 62 0.0 1946-01-07 62 T 2008-01-07 61 T 1997-01-07 61 0.1 2022-01-07 60 8.4 2019-01-07 60 0.0 1966-01-07 60 T

This is the most dramatic December La Niña to January positive flip without a SSW. The SSW Januaries still maintained the La Niña background forcing state. This one is all by itself with the pronounced Nino-like forcing near the dateline and WWB pattern.

This may be the most extreme reversal of a La Niña pattern in December to a much more Nino-like one in January. The forcing near the Dateline and WWB would be impressive for a regular El Niño January. It will be interesting to see what type of pattern shows up in February.

Just measured 6” here in SW Suffolk.

The HREF max snowfall did a great job with the wider area of 6”+ than the other guidance. Also had the heaviest amounts going to our Northeast. The HREF also did very well with the summer flash flood events.

Yeah, the forcing keeps following where the strongest marine heatwaves are located. This month the record SSTs shifted closer to Dateline. There has been some cooling north of Australia where the convection was stalled out in December. Now the forcing forecast for a large part of January is more Nino-like near the Dateline.

SPC HREF has the best 6” potential where the banding sets up.

Yeah, the La Niña just became one of the most east based events on record. So Nino 4 has warmed back closer to neutral in recent weeks. This allows the forcing to stall closer to the Dateline for a while. That’s the key to maintaining more of a Nino-like +PNA.

Spots that get into the banding will have the best shot at reaching 6”.

The last several years have been famous for weather patterns that haven’t matched the ENSO background state. Competing marine heatwaves and MJO stalls have created some very wild patterns. The current very strong VP anomalies near the Dateline is much more El Niño-like. So it’s no surprise that the recent STJ pulse produced the record snows just to jour south like in an El Niño winter. The SE trough in the long range forecast would match with such strong forcing near the Dateline.

Hopefully, we can keep this pattern going for as many snow chances as possible. Euro has the -EPO/+PNA /south based Atlantic block continuing into the long range. Maybe the weeklies tomorrow will have some clues for what comes even later in January.

Looks like our Arctic shot early next weeks sets up an Atlantic wave breaking event. So we get some south based Atlantic blocking. This is followed by the well advertised +PNA spike. That will be another period to watch for snow in mid-January.

Just avoiding a 0.0 or T was a big win in December. The Pacific was so hostile in December, that even a better Atlantic wouldn’t have helped out. When we got the Atlantic blocking in late December, everything was shearing out and hitting confluence over SE Canada. So as the record low -PNA rebounded this month, there were record snows to our south and the snow event for our region on Friday. Just a little +PNA ridging can go a long way especially at the tail end of a -AO pattern.

New all-time December lowest monthly -PNA for the month at -2.56. So it’s no surprise that the December snowfall was so low around the area. The big rebound in recent days allowed record snows to our south. Plus our first accumulating snow potential of the season in few days. So this just goes to show how important getting a favorable Pacific is for snowfall from the mid-Atlantic to our area. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table 2021 0.19 -0.31 -0.97 -1.05 -1.35 0.67 0.56 0.95 0.44 1.13 0.72 -2.56

In addition to the first 60°+ day followed by a 12” snowfall day in ACY, the temperature drop tied the all-time January record for 42 hrs. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=169&network=NJ_ASOS&zstation=ACY&hours=42&month=jan&dir=cool&_r=t&dpi=100&_fmt=png

Yeah, that has been a well known bias along with the surface wind gusts. I know they seem to have reduced the wind gust error in the latest upgrade. The best storm track performance that I have seen from the Euro was Sandy and Nemo from the longer range. It may be that there is something about the model that handles phasing better than other models.

Yeah, overdoing precipitation and underestimating surface temperatures in strong WAA are a few if it’s biases. But changing over to a FV3 CAM based version may introduce whole new set of strengths and weaknesses. I know forecasters struggled through the recent GFS upgrades with all the new errors and biases that needed fixes.

The NAM usually does a pretty good job from around 24hrs out. That’s why I am not a big fan of replacing it with some FV3 based CAM. Not sure why they don’t just stick with the NAM and upgrade it regularly like Canada does with the RGEM. The NAM does a great job when dry air is involved like yesterday. It excels when there is a warm tongue between 900 and 750 mb. And when there is a legit very heavy snow threat like January 2016 it’s a strong performer also.

The source region for the Arctic shot next week is very cold.

Models just aren’t that good with East Coast winter storm events from more than a day or two out. The Euro had the same suppression bias with the storm on Monday as it had from before the upgrade. The CAMS did much better the day before with the dry air and sharp cutoff of the snow to the north. So the important details of this storm for us may not be known until Thursday.

LGA was our only station not to drop below 20° during a cold season. But all the other stations came close in 01-02. I can still remember joggers wearing shorts on the LB boardwalk during that lack of a winter. Time Series Summary for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Apr 30 Missing Count 1 2002-04-30 20 0 2 2021-04-30 17 0 - 2017-04-30 17 0 3 1998-04-30 16 0 4 2020-04-30 15 0 - 2006-04-30 15 0 - 2001-04-30 15 0 5 2012-04-30 14 0 - 2010-04-30 14 0 - 1975-04-30 14 0 Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Apr 30 Missing Count 1 2002-04-30 19 0 2 1975-04-30 15 0 - 1932-04-30 15 0 3 2021-04-30 14 0 - 2020-04-30 14 0 - 2017-04-30 14 0 - 2006-04-30 14 0 - 2001-04-30 14 0 - 1998-04-30 14 0 4 2012-04-30 13 0 - 2010-04-30 13 0 - 1937-04-30 13 0 - 1902-04-30 13 0 5 1983-04-30 12 0 - 1953-04-30 12 0

Yeah, we had the Feb 2017 blizzard a day after the record 60°+ warmth. https://www.weather.gov/okx/Blizzard_Feb92017 Blizzard conditions occurred over Long Island, Southern Connecticut, and coastal portions of the Lower Hudson Valley from after sunrise into the late afternoon hours on February 9, 2017. Snowfall totals ranged from 6" across portions of northeast New Jersey to around 10" in New York City to 12-16" across Long Island, southern Connecticut, and the Lower Hudson Valley. Thundersnow was observed across portions of Long Island and southern Connecticut. Snowfall rates range from 1 to 3 inches per hour with locally 4 inches per hour at times. The blizzard brought delays and cancellations to the regions transportations systems as well as numerous accidents on roadways. Approximately 2,000 flight cancellations and numerous delays occurred at the three major airports, Kennedy, Newark, and LaGuardia. The Long Island Railroad had systemwide delays and cancelled 20 trains. Multiple car accidents occurred on roads as well as several hundred rescues were performed by police/fire on Long Island. Other Facts A cold front associated with low pressure across southeast Canada moved across the region on Wednesday February 8. Behind the cold front, an upper level trough amplfied across the midwest. Energy within this trough acted on the cold front to develop a new low pressure across the Middle Atlantic. This low pressure rapidly intensified as it moved off the Delmarva coast the morning of Thursday February 9 and then to the south and east of Long Island later later that day. The southeast coast of Long Island including the eastern Hamptons and Montauk were warmer at the onset of the storm. Montauk was 41 degrees between 9 and 10 am in rain, before dropping to around 32 by 11 am in heavy snow. The day before the blizzard (Wednesday February 8), record warmth was observed across the Tri-State area. Record highs ranged from 62 at Central Park, NY to 65 at Newark, NJ. Temperatures dropped 30-40 degrees in 12-15 hours as readings were in the middle-upper 20s during the height of the blizzard.