Based on the GEFS chart’s PNA mtd as well as the 0Z GEFS 14 day PNA prog, we have a chance to break the all-time record (since 1950) +PNA for a non-Nino Dec. I estimate based on dailies that the (tabular equivalent) MTD is ~~+1.8. The prog avg (tabular equiv) for the next 2 weeks is near that meaning the progged MTD through Dec 27th is ~~+1.8. *Keep in mind that the tabular equivalent is ~~twice the dailies.* Also, keep in mind that the 10 day GEFS progs have verified significantly too low since late Nov as they’ve averaged only ~half as high as verifications.
Current highest tabular Dec +PNA for non-Nino:
2020: +1.58
1960: +1.46
1985: +1.39
2005: +1.38
2000: +1.23
Highest tabular Dec +PNA for El Nino:
2006: +1.86
1969: +1.84
1963: +1.77
2002: +1.59
1986: +1.37
0Z GEFS prog through 12/27 and mtd: ~+1.8:
Based on the GEFS chart’s PNA mtd as well as the 0Z GEFS 14 day PNA prog, we have a chance to break the all-time record (since 1950) +PNA for a non-Nino Dec. I estimate based on dailies that the (tabular equivalent) MTD is ~~+1.8. The prog avg (tabular equiv) for the next 2 weeks is near that meaning the progged MTD through Dec 27th is ~~+1.8. *Keep in mind that the tabular equivalent is ~~twice the dailies.* Also, keep in mind that the 10 day GEFS progs have verified significantly too low since late Nov as they’ve averaged only ~half as high as verifications.
Current highest tabular Dec +PNA for non-Nino:
2020: +1.58
1960: +1.46
1985: +1.39
2005: +1.38
2000: +1.23
Highest tabular Dec +PNA for El Nino:
2006: +1.86
1969: +1.84
1963: +1.77
2002: +1.59
1986: +1.37
0Z GEFS prog through 12/27 and mtd: ~+1.8
Tabular monthly PNA 1950+:
https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table
Next post will explain why this progged strong Dec +PNA favors a +PNA continuing through Jan….
As stated above, the 5 highest tabular Dec +PNAs for non-Nino on record (2024 progged to have good chance to be new highest):
2020: +1.58
1960: +1.46
1985: +1.39
2005: +1.38
2000: +1.23
Where were the subsequent Jan tabular PNAs for these non-Nino high +PNA Dec?
2021 +0.19
1961 +1.41 (4th highest on record for non-Nino)
1986 +0.97 (tied for 7th highest on record for non-Nino)
2006 +0.43
2001: +1.51 (3rd highest on record for non-Nino)
Avg Jan for these 5: +0.90
So, a +PNA in Dec tends to carryover into Jan for non-Nino. Three of the 5 did strongly and one weakly. The other (2020-1) went to neutral. So, none even went to a weak -PNA.
Further followup:
So, the above suggests a good shot at a +0.75+ PNA in Jan. The following 9 non-Nino Jans since 1950 had a +0.75+ PNA (all cold ENSO except RONI neutral 1961 and 1981):
Year/PNA/E US temps
1961 +1.41 cold
1981 +2.42 cold
1984 +0.97 cold
1985 +1.63 cold
1986 +0.97 normal
2001 +1.51 normal
2011 +1.29 cold
2014 +0.97 cold
2022 +1.01 cold
So, the current cold and strongly +PNA Dec has totally changed my thinking for Jan using the Dec to Jan analog method to a good shot at much colder than I originally thought based on models.
Wonderful thread, Larry.
I actually look at this index, as well as others every day but didn't realize that we were near a record. I would say that the record for the month of December is mainly from the extraordinary persistence/sustained +PNA for an unusually long period with ZERO dips.
See below.
You're PNA graph did not copy for the last month, Larry.
https://www.marketforum.com/forum/topic/83844/#83856
Arctic Oscillation Index, North Atlantic Oscillation Index, Pacific North American Index.
https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.shtml
https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.shtml
https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/pna.shtml
This +PNA has been part of the ridge/west-trough east couplet mentioned frequently the past several weeks.
Here it is peaking with the 500 mb anomalies of this next cold wave during the 6-10 day period.
Awesome discussion by this guy:
