GaWx

Making the CFS even wackier is when it is a WxBell version: -For one thing their versions almost always have an odd cold spot over Lake Michigan along with a warm spot to the NNE near the E UP of Mich. -The wackiest maps are the control runs (C) as opposed to ensemble mean (M) runs Here’s another example: cold spot over L Mich. (to -6C, which would be close to coldest on record) while there’s a warm spot of +4C over NE UP of Mich!

Today’s Euro Weeklies: 1. SPV: though there’s still a decent % with a reversal on 11/25, there actually was a notable drop in the % of SSWs on 11/25 in exchange for an increase in the % for that to be ~11/27-8: @MJO812@BlizzardWx Yesterday’s: 2. Today’s E US 2m temps are similar to yesterday’s run for Dec with a strong SE ridge early (mild again in the SE to lower Mid-Atlantic) that again slowly weakens through mid-Dec: 12/1-7: 12/8-14: 12/15-21: (12/22-28 similar) But yesterday’s extended EPS/GEFS were forecasting the MJO on 12/11-14 to reach phase 8, which is about the coldest phase on avg in the E US in Dec. with 60%/80% of them having been cold in Baltimore/RDU, for examples. Also, should the SSWE actually occur, the lagged cold may also start ~mid-Dec. So, should it actually get to phase 8 and the SSW occur in late Nov, I’d be looking for a very good chance for 12/15-21 and 12/22-28 to turn much colder in the E US on later runs as we get closer. That’s still a month out, an eternity for model accuracy and the ability for big changes to be seen. *Edit: In semi-windshield washer form, the 12Z EPS did turn back a bit colder in the SE US the last few days of the run vs the 0Z run due to a weaker SE ridge though it doesn’t look nearly as good to me as yesterday’s 12Z. Regardless, it is well after the end of the 2 week EPS that has the best prospects for cold for the 2 reasons I gave above. Patience would be helpful.

The 12/13 extended GEFS/EPS are both headed for phase 8 mid-Dec. For those wondering how often E US cold has been associated with phase 8 in Dec (whether well outside, just outside, near, or inside the circle), here’s the breakdown of 3+ day long phase 8 periods in Baltimore as a representative (centrally located) E US city: For 3+ day long phase 8 (includes inside circle): 23 periods (* La Niña) 12/20-22/1974: +1* 12/19-31/1975: -4* 12/14-17/1976: -2 12/10-15/1977: -6 12/16-18/1979: -5 12/26-28/1981: -2 12/8-10/1982: -6 12/19-23/1986: -3 12/2-6/1988: +1* 12/1-4/1989: -9 12/9-18/1989: -16 12/2-4/1990: +6 12/1-7/1991: +1 12/9-14/1991: +8 12/9-12/1992: 0 12/20-25/1995: -8* 12/15-17/2000: 0* 12/21-25/2001: -1 12/5-9/2002: -15 12/1-3/2007: -4* 12/6-9/2009: -4 12/20-22/2009: -7 12/21-24/2017: +5* ——— Before analyzing the temperatures, note how the frequency of 3+ day long Dec phase 8 periods has plunged since 2009: -During 1974-2009, there were 22 three+ day long phase 8s through the 36 Decs or a frequency of 0.61/Dec. -But during 2010-2024, there was only ONE 3+ day long period or a mere 0.07/Dec, which is a minuscule 1/9 as often as that for 1974-2008! -The longest drought during 1974-2009 was a mere 4 Decs. But during 2010-24, there have been two 7 Dec droughts!@bluewave -So, based on this, although I’m hoping the latest extended EPS/GEFS are correct in projecting a 3++ day long phase 8 this Dec, I’m taking it with a grain for now. —————— Now to analyze the Baltimore temps for the 23 three+ day Dec phase 8 periods 1974-2024: -# of periods: MB 4 (17%), B 10 (43%), NN 6 (26%), A 2 (9%), MA 1 (4%) -So, there have been nearly 5 times as many B/MB periods as A/MA periods! -The average daily anomaly was -4 over the 112 days. @donsutherland1

The latest MJO forecast is a mix with GEFS not looking as good but the Euro still looking good: 11/14 GEFS further right with it hung up in middle of 6 rather than 6/7 border: But Euro is still all systems go to 7/8: 11/14 Euro ~same as yesterday with progression into 7: 11/13 extended Euro (they run a day later) continues to look very nice with it again getting to the often cold in the E US phase 8 mid-Dec (can’t ask for better for then): And yesterday’s extended GEFS also heads to phase 8 mid-Dec:

But they for much of Dec actually have a stronger SE ridge than prior runs even though they show it weakening through the month: these, which are from the ECMWF site, itself, are definitely not showing persistent cold in the E US, especially Mid-Atlantic and more especially in the SE. Heart of the cold is Chicago W and SW. Dec 1-7: significantly warmer than prior runs thanks to SE ridge Dec 8-14: slightly warmer than prior runs Dec 15-21: Dec 22-28:

Tell me about it, Ray! For those not knowing about or seeing what we’re talking about, check this craziness out: not a single day in the entire DJF 1995-6 for the 10 mb zonal mean wind at 60N to be below the 1958-2022 mean and with most of Jan/Feb above the 70th percentile:

The avg SPV strength of a winter is by no means anywhere close to an end all be all factor as many of us know. For example, these winters had an SPV on the strong side but still had cool to cold in much of the E US (a bit counter-intuitive): -1980-1 DJ -1983-4 -1995-6 -2013-4 -2024-5 DJ https://acd-ext.gsfc.nasa.gov/Data_services/met/ann_data.html

No worries, Don! Very easy to do. I sometimes get them mixed up. Actually, at first, I didn’t see what I noticed with a second look.

Thanks for the link! From there: Nov/Dec 1983: SPV not even weak ————- Nov/Dec 1989: SPV actually pretty strong ——————- Nov/Dec 2000 no reversal but SPV quite weak with low ~+4 late Nov: So, none of Novs/Decs 1983, 1989, and 2000 had a major SSW (reversal) though 2000 had a weak SPV. @snowman19

Thanks as always, Don. The weakest zonal winds/wind reversal on your bottom chart (Euro zonal wind forecast for 12Z on 11/22/25) actually are within 60-90N (blue shades) rather than south of 60N. For 60N at 10 mb, this actually shows a very weak wind of a mere +5 on 11/22 (and is dropping) and that’s still ~3 days before the EPS mean drops to 0.

Today’s 2 week GEFS and EPS MJO progs are in very good agreement on the MJO being hung up near the 6/7 border with moderate intensity: GEFS: EPS: Here’s yesterday’s (11/12/25) extended EPS (these always come out at this site a day later): after the near 2 week long stall near the 6/7 border, it crawls through 7 and then barely into 8 with a trajectory that suggests it might collapse into within the circle/weak amplitude soon afterward. But keep in mind that should it actually occur, a weak amplitude doesn’t at all necessarily mean mild in the E US as weaker MJO on the left side is often associated with cold based on analyses I’ve done and posted here plus charts I’ve seen from others: just outside the circle phase 8 in Dec like this shows has sometimes been associated with quite cold in the E US:

I’m still looking for strat. zonal wind data for 1983 and 1989. In the meantime, I did find the following graph, which is of 65N to 90N zonal mean temperatures at 10 mb in 1988 and 1989. Look on the far right: although there was no major SSW in any of the tables I look at (meaning no reversal of zonal winds at 10 mb), you can see there still was a bit of a stratospheric warming spike centered on ~Dec 1st of 1989 to near a record high for that date: https://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/archive/10mb9065_1989.gif —————— This is even more evident further up at 5 mb and at 2 mb: 5 mb: 15C spike warming centered near 12/1/1989: https://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/archive/05mb9065_1989.gif ————— 2 mb: 15C spike warming centered near 12/1/1989: https://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/archive/02mb9065_1989.gif

Ray, You have to go to the bottom of this and then choose the winter: http://arctic.som.ou.edu/tburg/products/realtime/strat/ Unfortunately, one can go back only to 1990-1 from this source for some reason even though graphs exist back at least to 1958-9.

There are no official Nov or Dec major SSWs based on reversals at 10 mb for any of 1983, 1989, and 2000. To be fair if you read this closely, BAMwx isn’t explicitly saying that there was an early major SSW in any of those 3 years (if they were they’d be wrong): A few of these years were absolutely blockbuster in December. Chances to replicate the intensity of cold in years like 2000, 1989 and 1983 are unlikely, but there is strong support notable cold the first half of December setting up. That’s not to say that the SPV wasn’t weak. Despite no reversal, 2000 was quite weak mid-Nov through Dec with a low of +4 to +5 m/s in late Nov as per the chart below: (I don’t have these charts for 1983 and 1989….does anyone else have a link to them?):

Snowman, I don’t see an SSWE at any point in Nov or Dec of 1989. Where are you seeing that? https://www.researchgate.net/figure/The-SSW-and-SFW-event-onset-date-year-and-type-identified-in-the-NCEP-NCAR-dataset-The_tbl1_267063738

There are 5 major SSW events on record between Nov 24th and Dec 7th:-1958-1965-1968-1981-1987Here’s the Dec temp. anomaly map: E US mainly 1-2 F BN Here’s the Jan temp. anomaly map: E US mainly 2-4 BN, which incorporates extreme cold in places during 1966 (late), 1982 (mid) and 1988 (early): Here’s the Feb temp. anomaly map: E US NN: So, the coldest month regarding E US anomalies was Jan and the warmest was Feb. Feb. might have been even warmer (warmer than normal) had 4 of these 5 winters not been during El Niño, which tends to favor cold in the 2nd half of winter vs La Nina’s colder 1st half. All of this is telling me that should the late Nov major SSW actually occur, the coldest month could easily be Jan rather than Dec, which makes sense considering an assumed several week lag. But, of course, that would remain to be seen especially considering La Niña often favoring Dec as the coldest anomalywise. https://www.researchgate.net/figure/The-SSW-and-SFW-event-onset-date-year-and-type-identified-in-the-NCEP-NCAR-dataset-The_tbl1_267063738

I just saw it. Right you are and by a good margin!! Mean minimum down to ~0:

Thanks. But to his credit, he backs it up well! Some on the other side don’t back it up as well. As far as myself, I clearly prefer cold and root for it. However, I do my best to post as objectively as possible and not let my preferences affect my posts. So, whereas I enjoy posting about cold, if I see a model that looks warm I won’t be afraid to post it to protect my objectivity. I post whatever I see, cold, warm, neither, etc.

He’s just trying to be funny. It’s good to laugh at yourself. I do that all of the time! I’m my own best comedian when I laugh at myself as I have so much material! Geez, all I have to do is to look in a mirror. Come on, man, we all know that you enjoy pushing mildness in winter when you can back it up well (which to your credit you do), and that there are more that do the same on the opposite end sometimes without good evidence.

Are you thinking we have a good chance to get a strong+ El Niño per RONI? If so, are you thinking a mainly mild result in the NE US?

Great stuff, Don! Since I had seen similar results in looking at the following for RDU big snows, I figured you and others might find this interesting: 21 RDU 6”+ snowstorms since 1950 (Niña or -neutral ENSO bolded)1/19/1955 Niña neut PNA, neut AO, moderate -NAO12/11/1958 mod +PNA, neut AO and NAO3/2-3/1960 mod -PNA, neut AO and NAO3/9/1960 weak -PNA, strong -AO, neutral NAO2/26/1963 -neutral strong +PNA, mod +AO, neutral NAO1/26/1966 neut PNA, strong -AO and -NAO2/9/1967 -neutral mod +PNA, weak +AO, moderate +NAO3/1/1969 strong +PNA/-AO, moderate -NAO1/7-8/1973 weak +PNA, neut AO, strong -NAO2/18-9/1979 neut PNA/AO/NAO3/1-2/1980 neut PNA/AO, moderate +NAO3/24/1983 mod +PNA/-AO, neutral NAO2/6/1984 -neutral mod +PNA/+AO, strong +NAO1/7/1988 mod +PNA, neut AO, weak +NAO2/17-8/1989 Niña neut PNA, strong +AO/+NAO1/24-5/2000 Niña mod +PNA, neut AO, moderate -NAO1/2-3/2002 -neutral strong +PNA, neut AO, moderate -NAO2/26-7/2004 neut PNA, strong -AO, weak -NAO12/26/2010 Niña weak -PNA, strong -AO, moderate -NAO1/17/2018 Niña neut PNA, weak +AO, strong +NAO12/9-10/2018 mod +PNA, neut AO, moderate +NAO—————————For the 21 storms-11 (52%) +PNA, 7 (33%) neutral PNA, 3 (14%) -PNA-7 (33%) +NAO, 6 (29%) neutral NAO, 8 (38%) -NAOSo, whereas 52% had a +PNA vs only 14% with a -PNA, 38% had a -NAO vs 33% with a +NAOSo, whereas there were almost 4 times as many with a +PNA vs a -PNA, -NAO vs +NAO has been much more balanced.————The above is for all ENSO.What about for just -ENSO?-5 (56%) +PNA, 3 (33%) neutral PNA, 1 (5%) -PNA-4 (44%) +NAO, 1 (11%) neutral NAO, 4 (44%) -NAOSo, whereas 56% had a +PNA vs only 5% with a -PNA, 44% had a -NAO vs 44% with a +NAOSo, whereas there were 5 times as many with a +PNA vs a -PNA, -NAO vs +NAO has been totally balanced. ————— I found similar results for Greensboro and Atlanta. Bottom line: in the SE US, a +PNA is a bigger driver of big snowstorms than is a -NAO.Daily PNA link: https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.pna.index.b500101.current.ascii Daily NAO link: https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.index.b500101.current.ascii ———— *Edit: Interestingly, looking back at big storms at RDU and GSO, the last 5 (2014-18) were all with a moderate to strong +NAO! So, there hasn’t been even one 6”+ snow at either RDU or GSO with a -NAO (even a weak one) since way back on 12/26/2010! This could, of course, be from randomness. But I’m not sure about that considering what @bluewavehas said about -NAO ridges tending to hook up with SE ridges more often than in the past. Hmmmm…. Edit #2: I just noticed this for the 21 RDU big snowstorms for the AO:5 +AO, 11 neutral AO, 5 -AOSo, neutral has been favored.

My best explanation is that the heart of the cold was aimed more toward your SW. Consider that GSP had 22, Macon had 25, and SAV/JAX had historic 28s! But from your area to the NE US, there was little (or no) record cold.

We do way down here, Anthony. Suppression is our winter bread and butter. Therefore, I love +PNAs! Nothing is more beautiful on a wx map than a very tall western N American ridge.

Allan Huffman going with a cold January in the E US. I wonder if this is because of a prog for a very early SSWE followed by a lagged cold effect in Jan: I’d be more than happy with this. I’d love another cold Jan! Not having a warmer than normal La Niña winter in the majority of the SE including another cold Jan would be a victory!

Thanks for posting this. I wonder if Alan’s cold Jan is largely because of a prog for a very early SSWE followed by a lagged cold effect in Jan. I’d be quite content with this. Not having a warmer than normal La Niña winter in the majority of the SE including another cold Jan would be a victory!