bluewave

An October -AO followed by a +AO in November is usually something we see during an El Niño. I wonder if this unusual AO reversal for a La Niña is related to such a strong +PMM and slightly positive IOD? 2020 2.419 3.417 2.641 0.928 -0.027 -0.122 -0.412 -0.381 0.631 -0.072 2015 1.092 1.043 1.837 1.216 0.763 0.427 -1.108 -0.689 -0.165 -0.250 1.945 1.444 2009 0.800 -0.672 0.121 0.973 1.194 -1.351 -1.356 -0.054 0.875 -1.540 0.459 -3.413 2006 -0.170 -0.156 -1.604 0.138 0.156 1.071 0.103 -0.265 0.606 -1.029 0.521 2.282 2004 -1.686 -1.528 0.318 -0.409 -0.094 -0.236 -0.201 -0.720 0.855 -0.515 0.678 1.230

The big weather swings continue with all-time November warmth in Minnesota following the snowiest October on record.

Yeah, above normal winter temperatures have become the new normal since the super El Niño in 15-16. The main question is can we can get enough blocking intervals like 16-17 for a better snowfall outcome than the last two years?

Yeah, it was their 3rd coldest October temperature on record. Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Month of Oct Click column heading to sort ascending, click again to sort descending. Rank Year Lowest Min Temperature Missing Count 1 1976 30 0 - 1966 30 0 - 1962 30 0 2 1988 31 0 3 2020 32 0 - 2011 32 0 - 1974 32 0 - 1969 32 0 - 1965 32 0

Yeah, that looks close to the record for after the first week of November. JFK may have set the all-time November dew point record of 68° in November 2019. But that was earlier on the 1st. https://www.wunderground.com/history/daily/us/ny/new-york-city/KJFK/date/2019-11-1 11:51 PM 68 F 68 F 100 % S 40 mph 54 mph

With the exception of 77-78, the 70s were notorious for underperforming snow for the amount of cold we had. We don’t seem to get cold and dry winters anymore. Most of our cold winters since 2000 had 40”+ to 50”+ snowfall seasons.

This fall seems to be following the pattern since 2010. The years with an early freeze in October have had the warmest Novembers. Last year was the coldest November at Newark but didn’t drop below 40° in October. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Oct Click column heading to sort ascending, click again to sort descending. Year Lowest Min Temperature Nov Departure 2020 32 ? 2019 40 -4.0 2018 34 -3.1 2017 40 -0.7 2016 37 +2.9 2015 31 +5.2 2014 39 -2.9 2013 33 -2.4 2012 34 -3.5 2011 32 +4.1 2010 38 +0.5

Don recently posted a very informative paper on the topic. https://www.nature.com/articles/s41598-020-71945-4 Extreme weather events in Asia have been occurring with increasing frequency as the globe warms in response to rising concentrations of greenhouse gases. Many of these events arise from weather regimes that persist over a region for days or even weeks, resulting in disruptive heatwaves, droughts, flooding, snowfalls, and cold spells. We investigate changes in the persistence of large-scale weather systems through a pattern-recognition approach based on daily 500 hPa geopotential height anomalies over the Asian continent. By tracking consecutive days that the atmosphere resides in a particular pattern, we identify long-duration events (LDEs), defined as lasting longer than three days, and measure their frequency of occurrence over time in each pattern. We find that regimes featuring positive height anomalies in high latitudes are occurring more often as the Arctic warms faster than mid-latitudes, both in the recent past and in model projections for the twenty-first century assuming unabated greenhouse gas emissions. The increased dominance of these patterns corresponds to a higher likelihood of LDEs, suggesting that persistent weather conditions will occur more frequently. By mapping observed temperature and precipitation extremes onto each atmospheric regime, we gain insight into the types of disruptive weather events that will become more prevalent as particular patterns become more common Over Siberia they found a significant increase in the frequency and duration of warm spells and wet days, while central Asia saw more cold spells and wet days, and east Asia experienced more long wet spells. These results are consistent with an increased (decreased) prevalence of the pattern in node #1 (#12). They also found that warm, wet, and dry spells predominantly lengthened in most parts of Asia, suggesting a general increase in persistence. Another study14 analyzed output from several atmosphere-only models forced by sea-ice and ocean-temperature conditions consistent with a 2 °C warmer world. Similar to our results, they found significantly increased persistence of warm spells over northern and central Asia, as well as wet spells over northern and eastern Asia. In addition to supporting previous findings, our study demonstrates an increasing frequency of persistent large-scale circulation regimes and associated extreme weather events, especially since the mid-1990s when AAW emerged as a clear signal. As greenhouse gases continue to accumulate in the atmosphere owing to ongoing human activities, we find that patterns characterized by warming in high latitudes will occur more frequently while cold-Arctic patterns will decline. A higher percentage of days/year in any one pattern will increase the likelihood of multiple consecutive days occurring in that pattern, leading to more frequent persistent conditions. Moreover, we demonstrate that the predominant warm-Arctic pattern also exhibits a higher probability of long LDEs occurring relative to days belonging in a node, thus further augmenting the likelihood of persistent weather events. Three of the climate models participating in CMIP5 agree that warm-Arctic patterns will increase several-fold by the end of the century at the expense of cold-Arctic patterns, suggesting a substantial rise in the frequency of persistent circulation regimes and their associated extreme weather. The connections with changes in jet-stream characteristics, such as blocking and other cut-off circulation features, will be addressed in future work.

These big weather swings have become the new normal.

You have to search for virtual lab gfs mos to get the new site. I only wish that that they also had ECMWF mos products. I believe the only access to that is on the NWS AWIPS in house system. https://vlab.ncep.noaa.gov/web/mdl/mos-products

Looks like 60s and 70s until further notice as the WAR pattern really locks in. KEWR GFSX MOS GUIDANCE 11/03/2020 0000 UTC FHR 24| 36 48| 60 72| 84 96|108 120|132 144|156 168|180 192 TUE 03| WED 04| THU 05| FRI 06| SAT 07| SUN 08| MON 09| TUE 10 CLIMO X/N 54| 38 61| 48 69| 52 70| 54 72| 55 72| 58 73| 56 68 40 56 KISP GFSX MOS GUIDANCE 11/03/2020 0000 UTC FHR 24| 36 48| 60 72| 84 96|108 120|132 144|156 168|180 192 TUE 03| WED 04| THU 05| FRI 06| SAT 07| SUN 08| MON 09| TUE 10 CLIMO X/N 52| 33 59| 47 65| 52 70| 51 68| 51 69| 53 70| 56 68 38 56

We could challenge the all-time November 500 MB positive height anomaly record this weekend. It looks like the record for the NYC area is 589 DM. The models all have values close to that level.

We broke the March cold streak this year so I guess it was only a matter of time before we had a warmer than normal November. These have been the only reliably cooler than average months in recent years. Getting more than 3 consecutive colder Novembers and Marches is just too much to ask from this warmer climate. NYC Nov 17...-1.1 Nov 18...-3.3 Nov 19...-3.8 Mar 17...-3.3 Mar 18...-2.4 Mar 19...-0.8 Mar 20...+5.5

The EPS weeklies are warmer than normal until further notice as the WAR pattern really locks in.

Gusting into the 40s along the coast. Jones Beach N/A 43 N/A N/A W30G43 N/A Wantagh N/A 41 28 60 W22G43 N/A Hempstead NOT AVBL Matinecock Pt N/A 43 N/A N/A NW33G46 N/A

Looks to be a very slow mover with such a strong blocking ridge to the north.

The coming warm up will get a boost from one of the most impressive WAR patterns we have seen during the month of November. The strongest ridge that I could find in the OKX soundings for November was 589 DM. The ensemble forecasts have the potential for a 588 DM+ ridge by the weekend.

New record lowest October average extent. There have been 10 new monthly lowest average extent records set since 2016. The only remaining monthly records are August and September 2012.

The last 3 Novembers in NYC were colder than average. But this year is starting out differently. The previous 3 years began the month warm and shifted colder by the 2nd week of the month. This year the coldest days for a while will be on the 2nd 3rd with a rebound back to the mild 60s. So it will be interesting to see if this means that we will finally see a milder than normal November. Nov....EWR...NYC...LGA 2019...-4.0....-3.8.....-3.7 2018...-3.1....-3.3....-2.7 2017...-.0.7....-1.1....-0.3 KNYC GFSX MOS GUIDANCE 11/01/2020 0000 UTC FHR 24| 36 48| 60 72| 84 96|108 120|132 144|156 168|180 192 SUN 01| MON 02| TUE 03| WED 04| THU 05| FRI 06| SAT 07| SUN 08 CLIMO X/N 56| 36 45| 39 51| 39 57| 51 67| 55 68| 56 68| 59 66 42 56

A record 11 consecutive warmer than average Octobers. Oct.......EWR...NYC...LGA 2020...+1.5...+1.0...+1.8 2019..+3.8...+3.0 ...+2.8 2018...+0.8...+0.8...+1.7 2017...+7.2...+7.2...+7.4 2016...+2.3...+1.9....+3.1 2015...+0.6...+1.1....+0.3 2014...+2.7...+2.7....+2.2 2013...+3.0....+3.3...+2.8 2012...+2.2....+1.1....+1.9 2011...+1.5...+0.2.....+0.2 2010...+1.7...+1.2....+2.1

It’s looks like those record warm SSTs off the West Coast and East Coast had a greater influence on our weather than the MJO. Notice how close the October pattern matched the +PMM. Those are the warmest SSTs off the West Coast that we have seen with such a strong La Niña. It’s probably why the October pattern was so different than we would expect from a La Niña.

Looks like the new shortest duration between 2 different seasonal T’s. May 9th to October 30th.

Yeah, the 5th coldest October minimum temperature on record for NYC. 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 3 1940 30 0 - 1869 30 0 4 1988 31 0 - 1975 31 0 - 1974 31 0 - 1969 31 0 - 1871 31 0 5 1972 32 0 - 1965 32 0 - 1933 32 0 - 1928 32 0 - 1917 32 0 - 1904 32 0 - 1889 32 0 - 1876 32 1 2020 32 0