bluewave

Sure it was. But people that pointed it out in these threads were labeled as being anti snow or overly pessimistic. The PNA flip snowstorm potential was being discussed as far back as December. This matched past climo when long -PNA or Western Trough intervals relaxed. As for this last week, that ocean storm was reliably modeled OTS. The trailing storm system to impact the area on Monday was too amped up with no blocking to hold the high pressure in place. So the OP runs did a great job indicating the cutter track. The GEFS low resolution showing a more easterly track were never designed to handle situations like this. So its always a matter of choosing the right forecast tool for the situation.

The long range pattern discussions have been doing very well this winter so far. Models were indicating a very warm and snowless December from as early as late November. This month we got a 6-10” snowstorm as soon as the Pacific flipped. While the 500 mb height anomalies for this last week were indicating cold, they never had the big classic snowstorm look for us. The PNA ridge was centered too far to the east indicating suppression potential for the ocean storm. The Monday cutter emerged due to the lack of blocking to hold the Canadian high in place over New England.

That wasn’t the point that I was trying to make. Models have been consistent in showing the Western Ridge pulling back to the Aleutians in early February. The EPS weeklies have been showing this for a while. Now the GEFS is picking up on the retrogression. This would allow the trough to return to the West. If this trough is too deep, then it just pumps the SE Ridge. This scenario would be a less favorable -PNA. The more favorable -PNA patterns for us in February involve a shallower trough over Western Canada with a flatter ridge over the SW US. A north based -PNA if you like. But the recent models are showing more of a deeper trough returning to the Western US in early February. But even that type of pattern could still allow for a small snow event like we got in February 2018.

A deep trough in the West is never a good pattern for us during any month from December to March.

The low of 10° in NYC is colder than the last two winters that didn’t drop below 14°. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Ending Date Lowest Min Temperature Oct 1 to Apr 30 Missing Count 2022-04-30 10 105 2021-04-30 14 0 2020-04-30 14 0 2019-04-30 2 0 2018-04-30 5 0 2017-04-30 14 0 2016-04-30 -1 0 2015-04-30 2 0 2014-04-30 4 0 2013-04-30 11 0 2012-04-30 13 0 2011-04-30 6 0 2010-04-30 13 0

That’s why we discuss the 500 mb patterns where the actual height anomalies are located. Raw teleconnection indices by themselves don’t tell you very much. Models are good at identifying the long range long wave patterns. These 500 mb patterns give a good broad sketch of what type of weather is possible within a certain domain. Back in December, the deep Western Trough that the models forecast from mid to late November was the dominant feature. So the lack of snow then was no surprise given the type of 500 mb pattern being shown. As soon as the trough began to lift out of the West in early January, we got the 6-10” snow event. This has matched the past climatology for our area following Pacific pattern changes.

It’s all about where the 500 mb anomalies line up. A ridge pulling back to the Aleutians could allow the trough to dig into the Western US in February. That scenario generally isn’t favorable for us since it allows systems coming east to pump the SE Ridge. That’s why we would want to make the most of our +PNA and -EPO interval while it lasts.

Let’s hope we can cash in in this +PNA -EPO while we have it in late January. The latest ensembles moved to the EPS idea of a pattern reversal in early February. The big ridge pulls back to the Aleutians allowing a more neutral to eventually -PNA in early February.

I said some of the models were showing colder potential in late January than we’ll see this weekend. But they have been back and forth in recent days on the magnitude of the cold. Temperatures around 10° tomorrow in NYC would be the coldest in 3 years. I mentioned that less cold suppression could be good for our snowfall prospects. We already have one January 6”+ snowstorm. It would be great to get another before the month is over. The last time we pulled of an early and late January multiple 6”+ snowstorms was 2014. Since 2003, we have had an early January snowfall peak followed by a mid-January lull like this year so far. If we can score a major snowfall event near or after the 20th, then it would match recent snowfall climatology. Snowiest January days since 2003 1-4….9.8 1-7….12.6 1-12…6.6 1-15…6.2 1-18…6.6 1-21…19.5 1-22…9.2 1-23…32.6 1-26…18.9 1-27….18.0 1-28….12.0

The suppression is today with the 959 mb ocean storm and Arctic outbreak right behind it into the weekend. The PNA ridge axis was just a little too far to the east. The Monday phase matches other very active patterns in recent years. Last December featured the big snowstorm followed by the much warmer system on Christmas. We seldom get big follow up snowstorms so soon following 6-10” snowstorms like we got last week. That’s why a winter like 10-11 was so rare to produce 3 KU events in a little over a month. Most years we are lucky to just get 1 KU event.

The models have backed off a bit on the magnitude of the cold they were showing for late January a few days ago. I am hoping this means less of a chance for storm suppression. This more Nino-like pattern has already produced a record STJ in South Florida.

Shallow cold air drain down the Hudson Valley gets NYC close to 10° tomorrow morning.

The pattern started on January 1st and we have already had a 6”+ snowstorm. Since our snowier era began in 2003, only two Januaries had two 6”+ events. Four years had single events that went over 6”. So it would be great if we could get another event to go over 6” by late January or early February. We are already ahead of snowfall expectations in January during a La Niña that gave us under an inch in December. La Niña years bolded Monthly Total Snowfall for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Year Dec Jan Season 2011-2012 0.0 3.4 3.4 2006-2007 0.0 1.9 1.9 2001-2002 0.0 3.3 3.3 2018-2019 T 0.6 0.6 2015-2016 T 28.8 28.8 1999-2000 T 10.5 10.5 1994-1995 T 0.3 0.3 1986-1987 T 16.3 16.3 1972-1973 T 0.9 0.9 1971-1972 T 2.2 2.2 1965-1966 T 9.3 9.3 1953-1954 T 13.1 13.1 1943-1944 T 5.5 5.5 1941-1942 0.1 3.0 3.1 1996-1997 0.2 3.1 3.3 1978-1979 0.2 6.0 6.2 1954-1955 0.2 2.4 2.6 1977-1978 0.3 16.6 16.9 1988-1989 0.4 6.4 6.8 1974-1975 0.4 1.8 2.2 1992-1993 0.5 2.2 2.7 2021-2022 0.6 9.7 10.3 2012-2013 0.9 1.0 1.9 1985-1986 0.9 2.8 3.7 1940-1941 0.9 9.5 10.4

The latest EPS weeklies continue the cold -EPO +PNA for the rest of January. The model begins to shift back to a more Nina-like pattern in early February. Moves the current Nino-like forcing from the Central and EPAC back to the Maritime Continent. So the temperatures begin to moderate then. Any delay in the La Niña forcing to return would keep the colder pattern going a while longer. Plenty of time to check the actual status of the tropical convection once we get to the beginning of February. Jan 17-24 Jan 24-31 Jan 31-Feb 7

Both the EPS and GEFS give us a classic MJO 8 look in late January as the forcing shifts to the EPAC.

The BNL tower temperatures show how quickly the shallow colder radiational cooling temperatures near the surface can rise with a southerly flow off the Atlantic in the upper 40s.

The big reversal may be related to the recon mission and dropsondes over the EPAC giving the models more information since yesterday. https://www.nco.ncep.noaa.gov/status/messages/ SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE NWS NCEP CENTRAL OPERATIONS COLLEGE PARK MD 0300Z TUE JAN 11 2022 00Z GFS is running on time. UPDATED 00Z RAOB RECAP... 91348/PNI - Purged temp/moisture 812-767mb...wet bulb effect. 70414/SYA - TTBB missing. 72357/OUN - 10148. 72632/DTX - 10142. 72403/LWX - No report for NAM. Available for GFS. 27 dropsondes were available for GFS ingest in support of the Atmospheric River recon over the Eastern Pacific. Liddick/SDM/NCO/NCEP SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE NWS NCEP CENTRAL OPERATIONS COLLEGE PARK MD 0305Z WED JAN 12 2022 00Z GFS is running on time. UPDATED 00Z RAOB RECAP... 76225/CUU - Purged spurious wind data at 867mb. 91334/TKK - Purged temp/moisture 483-415mb...wet bulb effect. 70414/SYA - 10145. 72357/OUN - 10148. 72632/DTX - 10142. 78384/GCM - 10142. 72582/LKN - TTAA missing for NAM. Full report for GFS. 72202/MFL - No report for NAM. Available for GFS. 21 dropsondes were available for GFS ingest to support Atmospheric River Recon in the East Pacific. Liddick/SDM/NCO/NCEP

The first -10 or lower temperature departure day in NYC since the July 4th and Memorial Day weekends. CLIMATE REPORT NATIONAL WEATHER SERVICE NEW YORK, NY 443 PM EST TUE JAN 11 2022 ................................... ...THE CENTRAL PARK NY CLIMATE SUMMARY FOR JANUARY 11 2022... VALID TODAY AS OF 0400 PM LOCAL TIME. CLIMATE NORMAL PERIOD 1991 TO 2020 CLIMATE RECORD PERIOD 1869 TO 2022 WEATHER ITEM OBSERVED TIME RECORD YEAR NORMAL DEPARTURE LAST VALUE (LST) VALUE VALUE FROM YEAR NORMAL ................................................................... TEMPERATURE (F) TODAY MAXIMUM 24 1248 AM 69 2020 39 -15 37 MINIMUM 15 1058 AM 3 1968 28 -13 28 AVERAGE 20 34 -14 33

This Arctic shot came in on a NW flow across the Great Lakes which were still very warm from December. You can see how the Arctic air moderated crossing SE of the lakes. The models did a good job with the big spread between the 850 mb temperatures and the surface. The next Arctic front will come through Friday night. This one will have more of a NNW flow avoiding the warmer lakes. So while the 850s won’t be as cold, the 2m low temperatures could be several degrees colder than today. More NNW flow for early Saturday NW flow moderating across the lakes today

Past dramatic December to January La Niña flips usually occurred with a SSW event. This year we did it without a SSW. The current reversal is being driven by the convection shift from the Western to Central Pacific. Plus we already have much more snow in early January from Atlantic City to NYC Metro than in the past La Niña years. That being said, the favorable patterns in those years lasted into the first week of February. More La Niña-like patterns made a return by the 2nd week of February. So it will be interesting to see how we can keep this pattern going.

Yeah, the ridge along the West Coast into Alaska is still going strong at the end of the EPS run on January 26th.

Yeah, the models have a very strong Alaskan blocking pattern mid to late January. Starting to see some long range runs even colder than this week into the weekend. While the long range CFS has its accuracy issues, it’s now continuing the late January pattern into early February. I have noticed that these very strong Alaska blocking patterns can take longer than the models forecast to begin to break down. So just something to watch as we approach the start of February. New run Old run

Yeah, Saturday morning looks like it will be colder than today. Both GFS and Euro drop NYC to near 10°. The next Arctic shot will come a with more NNW flow which doesn’t pass over the warmer Great Lakes like today. Models have below zero readings for the interior.

Yeah, the continued forcing near the dateline is keeping that strong Alaskan blocking pattern going.

That’s why we like to look at where the actual 500mb anomalies are located. Plus the vendors have their own custom teleconnection indices which differ from the CPC official values that we are all familiar with. The Alaskan blocking signal is so strong for week 2, that it will probably hold into the last week of the month.