bluewave

A weaker MEI isn’t such a great thing if it just means more forcing in MJO 4-7 or Niña influence like we are seeing now. We just swap out or combine 2 different forcing regions which are warm. Remember, doesn’t have to get anywhere near as warm as 15-16 to still be a warmer winter. We actually probably want a higher MEI to ensure that the warmer MJO 4-6 phases don’t interfere with the usual backloaded El Niño effect later in the winter. Hopefully, something resembling a backloaded El Niño emerges at least for snowfall prospects. Last winter 22-23 had the same average temperatures in the Northeast as 15-16. Both had strong forcing in slightly different warm regions for us. So while it would be tough to have two winters in a row so warm after last year, even half the departures of 22-23 and 15-16 would still be a warmer winter for us. Considering that we went +5 last winter in the Northeast against the warmer 91-20 means the same as the +5 in 15-16. So even a +2 to +3 winter this year would still be mild. So while the warmth in the WPAC to the Dateline is a warm signal, it’s always a wait and see approach what the exact warm departure will be.

Yeah, just pointing out a different evolution than 97-98 doesn’t mean necessarily a colder winter. The 97-98 winter had east based forcing. But we had very strong forcing near the Dateline in 15-16 and it was a warmer winter for us than 97-98. Plus last winter we had very persistent forcing in MJO 4-6 and it too was warmer than 97-98. Not saying this winter will be as warm as 15-16 or 22-23, but if forcing is strong and persistent enough in the MJO 4-7 regions and Nino 4, the risks are warmer than average and not colder. To what extent remains to be seen. We are currently seeing Nino 4 SSTs approach 15-16 levels. And the WPAC warm pool in the MJO 4-7 regions is also the warmest on record for and El Niño.

The November pattern saw the influence of the colder MJO phases for the Northeast. Plus we have had a decadal pattern of colder temperature trends in the Northeast. So two reasons for the colder temperatures in the Northeast. As for the MJO cancelling the whole winter, we just have to take things one step at a time. We know that we get warmer than average patterns when the MJO is in the 4-7 phases. And we know that record warmth in those regions slows the MJO in those phases. I don’t think anyone is canceling winter in December during an El Niño year when El Niños are mostly defined by what happens January 15th to February 28th. But if we continue to see MJO 4-7 activity ,then it could interfere with the typical backloaded El Niño winter response. Hopefully, the forcing focuses more in the regions near the Dateline allowing some semblance of a late winter El Niño pattern. So we are just going to have to be patient since that period is still pretty far out in time to have much confidence about.

Our sensible weather patterns rely heavily on tropical convection which drives the Rossby wave patterns. MJO and ENSO along with increasing marine heatwaves in the tropics and subtropics are another big factor. This understanding has been growing in recent years with numerous papers posted on the MJO slowing down and becoming more amplified in the warmer phases. The main culprit is the expanding WPAC warm pool. This has also been driving the increase in multiyear La Ninas referenced in other papers. We seldom miss an opportunity for warmth when the MJO slows in phases 4-7. There are also papers on favorable snow phases for the Northeast in the MJO 8-1-2 phases. It’s no coincidence that the greatest snowstorm over 30” in spots last March occurred with the strong MJO 8 passage. Unfortunately for us, we have been missing out on MJO 8 windows in recent years as the signal has frequently weakened or stalled before those phases. The MJO can also induce SSWs and cause the NAO to go positive or negative. Several well written and researched papers on that topic also. So as the science progresses, we are understanding the importance how the warming oceans are altering our climate. We also got a primer in recent years on how we need the Pacific on our side even we get a good -NAO -AO pattern. So we really can’t take for granted anymore that the -NAO or -AO will deliver for us without the Pacific backing off and cooperating.

Yeah, it’s been pretty tough waiting for MJO 8s in recent years only to get pushed back or not deliver. We have seen those P7 stalls or loops back missing out on 8. Or the actual MJO 8s like last March with the interior Northeast cashing in on record snows and nothing for the coast. Unfortunately, winters since 18-19 have been defined by unusually hostile Pacific patterns with a raging Pacific Jet into the West Coast dropping the trough in the West.

That is probably rushing things. I think MJO 7 could linger on the VP anomaly charts until the 20th to 25th with such warm waters and forcing near the Dateline. Remember, there is a lag with the MJO and the pattern after it goes through the warm phases. So even if it can make to 8 by Christmas, it could take until early January to get a better pattern. That being said, it’s possible the MJO stalls in 7 and doesn’t make it fully into 8 like we saw several times in recent years. But that won’t be known for sure until we get later into December.

Not much difference since both they both have a warmer than average pattern here. Ridge extending into the Northeast with trough near the SW or near the West Coast. El Nino P 7 December General P 7 December

The RMM charts aren’t telling the whole story. The actual forcing in the 4-7 regions is going to be very robust. This is a warmer than average forcing signal through at least December 20th or 25th. This is why the models keep correcting warmer the closer in time we get. My early guess is that this means another close to 40° or warmer December for NYC.

The wave can’t speed through due to the record +30C SSTs in MJO 7. This is why the VP anomaly charts are more robust than than the RMMs. This is the bias of the of the RMM charts. Even if the RMMs show 8 in the longer range, some forcing still in 7 on the VPs won’t allow a true 8 to develop until the convection there can completely weaken. We see this every December. I think the pattern stays warm than through December 20th or 25th. Not sure about the last week of December yet. But we know from experience that it often takes longer than expected to cool a pattern down after an extended loop through the warmer phases. This is due to the MJO lag effect on the pattern which has been well described.

Exactly. Every December the models do the same thing and we end up lingering longer than expected in the warmer MJO phases. Currently have record SSTs near the MJO 7 region.

This is what we were talking about. The earlier RMM charts had a very weak MJO 4-6 signature while the VP anomaly charts said otherwise. Now the RMMs are showing a more robust MJO 4-7. The GFS often beats the Euro RMMs due to the Euro having issues with the barrier effect and MC convection. My guess is that we could see another stall near 7 which could persist up to the solstice or even Christmas with mild temperatures.

I don’t think that’s the case. We all know that those are departure maps and not absolute temperatures. So warmer departures at the start of December means highs in the 50s and lows in NYC in the 40s. Very tough to support a significant snow event at the coast with those temperatures. The NYC average split for the first week of December is 48°/37° the first week will average above that. Plus it’s very difficult to get a significant snow event at the coast with the current fast Pacific flow into the West Coast lowering heights out there and not letting a ridge lock in long enough out West.

You should never let someone else think for you. We have a great pool of talent on here. We turned out to be right about this not evolving like a typical east based event. Myself along with others were pointing out that the record WPAC pool was different than the way Paul was seeing this early on evolving like an El Niño before 1980. The structure of the OKC was also different. Whether this event tops at an ONI of of 1.8 to +2.0 or 2.0 to +2.2 is the least interesting aspect of this event IMHO. The big story is the record +30C warm pool from the Dateline back to the Maritime Continent. I can remember pointing out early on how the MJO 4-6 areas would rebound in temperature once the IOD peaked. There weren’t any tweets from Paul indicating that the WPAC would be so different from previous events. Instead we heard this this would be a classic pre 1980 El Niño. But none of those El Niños had the record WPAC warm pool and MJO 4-6 forcing to start December. Remember it’s not necessarily the exact ONI departures which count, but where the pool of +30C SST departures are located with the forcing which leads to our sensible weather. We are in a new era of marine heatwaves which provide competition to the ENSO. So instead of playing single El Niño notes, the atmosphere can respond like playing a chord with a mix of Nino and Niña notes. This will determine the Rossby wave and 500 mb pattern. The chart below is how much warmer the WPAC basin is than all other El Niños at the end of November.

The first hint something unusual was going on was when NYC tied the all-time lowest August temperature at the end of the month of 50°. Several NW suburbs actually dropped into the upper 30s on August 31st. This was followed up by 2nd lowest October temperature of 29° in NYC. The locally colder spots were able to dip below 20. The historic cold continued with widespread single digits on December 3rd.This was the 2nd earliest single digits on record in NYC. So nothing like the climate of the early 2020s. Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Aug Click column heading to sort ascending, click again to sort descending. Rank Year Lowest Min Temperature Missing Count 1 1986 50 0 - 1982 50 0 - 1976 50 0 - 1965 50 0 - 1885 50 0 Monthly Data for August 1976 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. State Name Station Type Lowest Min Temperature NY WALDEN 1 ESE COOP 37 CT DANBURY COOP 38 NY PORT JERVIS COOP 38 NY CARMEL COOP 39 CT WESTBROOK COOP 39 CT MOUNT CARMEL COOP 39 NJ CANOE BROOK COOP 39 Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Oct Click column heading to sort ascending, click again to sort descending. Rank Year Lowest Min Temperature Missing Count 1 1936 28 0 2 1976 29 0 - 1925 29 0 - 1887 29 0 - 1879 29 0 Monthly Data for October 1976 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. State Name Station Type Lowest Min Temperature CT STAMFORD 5 N COOP 16 NY WALDEN 1 ESE COOP 17 NY PORT JERVIS COOP 18 Data for December 3, 1976 through December 3, 1976 Click column heading to sort ascending, click again to sort descending. State Name Station Type Lowest Min Temperature CT NORWICH PUBLIC UTILITY PLANT COOP 1 NY YORKTOWN HEIGHTS 1W COOP 2 NJ CHARLOTTEBURG RESERVOIR COOP 2 NY WALDEN 1 ESE COOP 3 NY BEDFORD HILLS COOP 3 NY PORT JERVIS COOP 4 CT STAMFORD 5 N COOP 4 CT DANBURY COOP 4 NY CARMEL COOP 5 CT MOUNT CARMEL COOP 5 CT GROTON COOP 5 NY MARYKNOLL COOP 5 NJ ESSEX FELLS SERVICE BLDG COOP 6 NJ CRANFORD COOP 7 NJ CANOE BROOK COOP 7 NY WESTCHESTER CO AP WBAN 7 NY SUFFERN COOP 7 NY MIDDLETOWN 2 NW COOP 7 NJ PLAINFIELD COOP 8 NJ LITTLE FALLS COOP 8 NY SCARSDALE COOP 8 CT WESTBROOK COOP 8 NY ISLIP-LI MACARTHUR AP WBAN 8 CT MIDDLETOWN 4 W COOP 8 NY DOBBS FERRY-ARDSLEY COOP 8 NJ JERSEY CITY COOP 9 NJ NEWARK LIBERTY INTL AP WBAN 9 NY NY CITY CENTRAL PARK WBAN 9

Yeah, 76-77 was the only winter I experienced with little ice age style extended cold. Time Series Summary for NY CITY CENTRAL PARK, NY - Dec through Feb Click column heading to sort ascending, click again to sort descending. Rank Season Number of Days Max Temperature <= 32 Missing Count 1 1976-1977 45 0 2 1917-1918 42 0 3 1880-1881 40 0 4 1903-1904 39 0 - 1884-1885 39 0 5 1935-1936 38 0 6 1919-1920 37 0 - 1904-1905 37 0 - 1892-1893 37 0 7 1977-1978 36 0 8 1887-1888 35 0 9 1878-1879 34 1 - 1872-1873 34 0 10 1933-1934 33 0 - 1874-1875 33 2 Time Series Summary for NY CITY CENTRAL PARK, NY - Dec through Feb Click column heading to sort ascending, click again to sort descending. Rank Season Number of Days Min Temperature <= 20 Missing Count 1 1917-1918 48 0 2 1880-1881 46 0 3 1976-1977 44 0 4 1935-1936 43 0 - 1919-1920 43 0 5 1933-1934 42 0 - 1903-1904 42 0 - 1874-1875 42 2 6 1884-1885 41 0 7 1872-1873 40 0 8 1892-1893 39 0 9 1906-1907 38 0 - 1887-1888 38 0 10 1993-1994 37 0 - 1871-1872 37 1

I would consider it snowy since it ended with the 950 mb benchmark blizzard. Probably the only time in the last decade that a truly cold pattern emerged during the last week of December. But we still got the warm up around the solstice.

On the few occasions we do get extended cold like 13-14 or 14-15 it has been very snowy. Cold and dry really hasn’t happened here since the 70s and 80s. Walking to the bus stop in January 1977 was probably the closest I have experienced to what life was like during the little ice age. Luckily the next season was one of our greatest on record for snowstorms and the cold relaxed a bit. One of the worst on record for cold and dry was the -10 December 1989. Things seemed promising after the snowy Thanksgiving but cold suppression reigned in December.

Success in any endeavor is a careful balancing of science,art, persistence,and intuition. The skillful use of data can suffice when traditional notions of sample size seem too small. You don’t have to wait 100 years when seasonal forecasts which employed these methods have done very well recently.

It’s really contingent on the strength of the weather or climate signal that we are dealing with. When a signal is very strong a smaller sample size may be sufficient. But when the signals are weak there may never be a large enough sample size. There has been an extremely strong Western Pacific and Western Atlantic warm signal since the super El Niño in 15-16. This is why seasonal forecasts which have used some of these elements such as strong SE Ridge or WAR have been so successful. It was rare to be able to do this before the last decade when seasonal forecasts were more of a crapshoot due to weaker climate signals. So we were usually deprived of a large enough sample size unless the signal was so overwhelming like a super El Niño or very strong La Niña. Or a very strong temperature signal in one season which continued to the next.

I think Paul’s charts are similar to Allan’s MJO 7 El Niño December 500 mb composites. But that may be a little fast for phase 7 with convection still lingering further west into mid-December. We may eventually get to that look as the month progresses. We’ll see. https://www.americanwx.com/raleighwx/MJO/MJO.html

Yeah, a mild low 50s pattern to start the month with the warmer minimums dominating. While the highs aren’t that much above normal, the fast Pacific Jet is working against the -NAO influence. We may have a shot at 55-60° by mid-December as we lose the -NAO and the Pacific Jet continues on steroids.

November continues to be one of the few months of the year that is able to reliably produce colder departures at times. The monthly temperature increases from 81-10 to 91-20 have been more pronounced during certain months. Newark and Islip are compared below. The +1.0 or warmer months for either station were bolded. ……….EWR…..ISP Dec…+1.5….+1.5 Jan….+1.2…+1.3 Feb….+0.5….+0.5 Mar….+0.4….+0.6 Apr….+0.5…..+0.6 May...+0.6….+0.9 Jun….+0.3….+0.6 Jul…..+1.4…..+1.1 Aug...+0.6….+0.9 Sep….+1.0….+1.3 Oct…..+0.9..+1.4 Nov….+0.2..+0.5

Using the 850 mb temperature anomalies in recent months has been deceptive since the 2m temperatures have been running warmer across the CONUS. On top of that, raw model 2m temp anomalies forecasts have been running cooler than the actual temperatures and the MOS on the colder days. But most weather map providers don’t have MOS corrected 2 m temperatures. There has been very little cold in Eastern Canada this fall.

If you are adhering to the rules of sample size purism, then very few posts in this thread using El Niño winter composites have a large enough sample size. The possible subcategories this winter include questions of coupling, strength, location of warmest ENSO SST anomalies, record WPAC warmth for an El Niño, negative phase of PDO, early MJO 4-6 phases, competing marine heatwaves for forcing with ENSO, along with other factors. So there are going to be a naturally small number of past years which match this year. But that doesn’t mean we can’t try to use even a smaller sample size than we would probably want to to look for clues. Sometimes in forecasting we have to try and follow the spirit of the law so to speak when the letter of the law may be out of reach.

I picked a total of 7 El Niño years since 2000 which showed similarities in fall patterns to winter. A similarity doesn’t mean an exact carbon copy. Plus the increasing number of multiyear La Ninas may naturally create a larger sample pool of events to draw from than El Niños. We could probably reduce what officially counts as an El Nino by including coupling issues in years like 18-19 along with El Niños with -PDOs. Competing marine heatwaves may eventually result in a large enough sample size to change our expectations of ENSO events relative to climatology from earlier eras when these extreme marine heatwaves weren’t as prevalent.