bluewave

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.

This was the first time ACY had a 60°+ day before a daily snowfall of 12”+. Day before high temperature and daily snowfall of 12”+ Maximum 1-Day Total Snowfall for Atlantic City Area, NJ (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Value Ending Date Period of record: 1945-01-31 to 2022-01-03 1 35° 18.4 2010-12-26 2 27° 16.6 1979-02-19 3 32° 16.0 2003-02-16 4 40° 14.6 2010-02-06 5 23° 14.3 1987-01-26 6 32° 13.2 2018-01-04 7 62° 13.0 2022-01-03 8 29° 12.9 1964-01-13 9 32° 12.7 1996-01-07 10 38° 12.3 1989-02-24

That forecast Arctic shot for early next week looks like it will be colder than anything NYC has seen in the last 2 winters. Time Series Summary for NY CITY CENTRAL PARK, NY - Jan through Dec Click column heading to sort ascending, click again to sort descending. Year Lowest Min Temperature Missing Count 2021 14 0 2020 14 0 2019 2 0 2018 5 0 2017 9 0 2016 -1 0 2015 2 0 2014 4 0 2013 11 0 2012 13 0 2011 6 0 2010 13 0

More spring in the Rockies record warmth near record snow like we have seen in recent years. RECORD EVENT REPORT NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1257 AM EST MON JAN 03 2022 ...RECORD HIGH TEMPERATURE TIED AT GEORGETOWN DE... A RECORD HIGH TEMPERATURE OF 68 WAS TIED AT GEORGETOWN DE YESTERDAY. THIS TIES THE OLD RECORD OF 68 SET IN 2000. Public Information Statement National Weather Service Mount Holly NJ 359 PM EST Mon Jan 3 2022 ...UPDATED SNOWFALL REPORTS FOR MONDAY JANUARY 3RD... Location Amount Time/Date Provider ...Delaware... Sussex County... Georgetown 12.0 in 0346 PM 01/03 Trained Spotter

The Euro is back to being stronger with the Arctic outbreak next week. 12z January 11th

The 500 mb pattern with the ridge bridge near Alaska to Greenland can work for us with the right storm track. We also have another +PNA spike over the Rockies. So this may be our best shot of the season so far if things work out. While it’s not a perfect match, the Euro 500 mb pattern on Friday almost has a Feb 14 type look. Hopefully, we can put something together.

Starting to get some very light snow here in SW Suffolk.

I sure hope a model like that doesn’t replace the NAM. https://vlab.noaa.gov/web/environmental-modeling-center/fv3-convective-allowing-forecast-system NAM development was frozen after the March 2017 upgrade, and RAP/HRRR development with the WRF-ARW model will cease after the RAPv5/HRRRv4 upgrade in 2020. However, operational execution of these modeling and associated DA systems will continue until comparable FV3-based systems are able to give similar performance.

Yeah, we’ll need a further north track like the Euro to moisten up the lower layers. The 18z hi res NAM still further south. But it shares the very dry lower layer. This may come down to nowcast time.

This GFS forecast sounding highlights the uncertainty of where the northern snow cutoff from the dry air sets up.

Yeah, the 10° dew point line sets up near the I-78 corridor on the 12z Euro.

Looks like it will be the first time that ACY has so much snow on a day in January following a 60°+ day. We pulled this off during the 16-17 winter. But big January ACY snowstorms usually have the cold in place before the storm. So a very spring on the Rockies vibe. Biggest January snowstorms and day before high temperature Maximum 1-Day Total Snowfall for Atlantic City Area, NJ (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Value Ending Date Period of record: 1945-01-31 to 2022-01-01 1 14.3…23° 1987-01-26 2 13.2….32° 2018-01-04 3 12.9….29° 1964-01-13 4 12.7…..22° 1996-01-07 5 10.1…..37° 2016-01-23 6 8.3….37° 2000-01-25 7 8.0….47° 1961-01-19 8 7.7…36° 2011-01-08 9 7.6…..27° 2010-01-30 10 7.4….42° 1958-01-07

The 12z guidance would put ACY in top 10 snowiest January day range. Maximum 1-Day Total Snowfall for Atlantic City Area, NJ (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Value Ending Date Period of record: 1945-01-31 to 2022-01-01 1 14.3 1987-01-26 2 13.2 2018-01-04 3 12.9 1964-01-13 4 12.7 1996-01-07 5 10.1 2016-01-23 6 8.3 2000-01-25 7 8.0 1961-01-19 8 7.7 2011-01-08 9 7.6 2010-01-30 10 7.4 1958-01-07

This will have a very sharp cutoff line for snowfall in some parts of region with such low dewpoints nearby. KPOU GFS MOS GUIDANCE 1/02/2022 0600 UTC DT /JAN 2 /JAN 3 /JAN 4 / HR 12 15 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 00 06 X/N 53 17 32 10 37 TMP 48 48 51 48 39 31 24 19 17 26 29 29 22 18 15 14 14 25 34 30 27 DPT 46 42 34 28 23 19 15 12 9 12 10 6 6

I don’t mind waiting until the day before a storm for the models to settle on snowfall amounts. This seems to be common for us. But it’s more of a problem when the day before forecast is way off. The NAM was the model that got the January 2016 record snowfall event correct the day before while the Euro was too suppressed. January 2015 was a disappointment for most areas west of Suffolk based on forecasts the day before. So it doesn’t pay to get invested in snowfall amounts beyond a day or two.