GaWx

BAMwx (Michael Clark) brand new update: good update imho as it is well reasoned without the hype of last week’s super cold mid-Jan CFS based tweet. This is first public video update since Fri I believe. Last week he had you-tube updates on Wed and Fri and I had said those were pretty good presentations though I thought he had too much reliance on general CFS ideas on Wed. Today, like on Fri, he shows a better mix of multiple models rather than just focusing on CFS:

It’s way too early for me to have much of a feel, but I do think TSR is likely too optimistic going with near 1991-2020 averages considering how warm the Atlantic still is.

NG market up a whopping 8% since this time yesterday! Traders are seeing a general cooling on the EPS/GEFS in the E US for week 2, especially 12/20-24. Fwiw, the Euro-AI has been very cold on multiple runs although it is still mainly a cold outlier.

The newest BoM biweekly forecast for Nino 3.4 has cooled considerably. This is the prior one, which had -0.3 for Dec, -0.4 for Jan, -0.1 for Feb, and +0.2 for Mar: Here’s the newest one, which has -0.4 for Dec,-0.7 for Jan, -0.5 for Feb, and -0.1 for Mar: @snowman19

So for 2025 TSR is going for near average of 1991-2020 instead of anything close to hyper or anything close to 2024. I hope they are right, but I’ll still take this extremely early prediction with a humongous grain.

Thanks, Mitch. More specifically for N American 2 meter temperatures, here’s the link: https://charts.ecmwf.int/products/extended-anomaly-2t?base_time=202412100000&projection=opencharts_north_america&valid_time=202412230000

Per an analysis of cold ENSO cold first half of Dec analogs that I did today: -If current ensemble consensus of the lack of a cold dominated 2nd half of Dec. ends up verifying, analogs suggest strong likelihood of no return to cold domination in the first half of Jan although there’d still be a good chance for cold to dominate at some point later, favoring a portion of Feb. though last half of Jan would still have a shot. -However, if the current ensemble guidance is wrong and the 2nd half of Dec ends up cold dominated in the E US, then the analogs would suggest the chance for a cold dominated 1st half of Jan would rise substantially. -Fwiw since way out in fantasy range, weeks 5-6 of the Euro Weeklies (Jan 6-19) have neither a warm signal nor a cold signal. -The Euro op day 9-14 is quite cold but that is in low credibility fantasy range for an operational. It will very likely be warmer on upcoming runs since prior runs were significantly warmer and this run is a cold outlier amongst the models as a whole right now. However, it does show that a non-cold 2nd half of Dec is still too far out to be set in stone.

The new Euro Weeklies: -still no signal for anything close to major SSW (same for Dec 9 run of extended GEFS) -Lack of either warm or cold signal for E US persists for Jan 6-19. If last half of Dec ends up not cold, I’ll favor no dominant cold during this period per cold ENSO analogs as dominant cold would likely not return til later.

Keeping in mind the above post about the models having favored a not cold dominated 2nd half of Dec: The 12Z Euro *fwiw of course* is cold Dec 19-24. Since this is a cold outlier and that portion is out 9-14 days (largely fantasyland for an operational), it remains a low probability solution imho. But it does show that the fate of the 2nd half of Dec overall is still too far out to yet be set in stone.

Cold ENSO winters with cold dominating only the first half of Dec. in NE and SE and thus weren’t cold dominated in 2nd half of Dec: how did Jan and Feb turn out in the E US? These are 9 of them since 1874-5: -2007-8: cold didn’t return in Jan or Feb -2005-6: cold didn’t return to SE but did to NE in 2nd half of Feb -1954-5: cold 2nd half of Jan and 1st half of Feb -1949-50: cold 2nd half of Feb -1934-5: cold 2nd half of Jan and 1st half of Feb -1915-6: cold Feb NE and cold 2nd half of Feb SE -1898-9: historic cold 1st half of Feb -1893-4: cold 2nd half of Feb -1875-6: cold NE 2nd half of Feb; no more cold SE ——— Summary for these 9 cold ENSO winters with cold 1st half Dec and non-cold 2nd half Dec: -cold returned to NE within Jan and/or Feb in 8 of these 9 with only 2007-8 having no more cold -cold returned to SE within Jan/Feb 6 of these 9 -most frequent return of cold was (surprisingly to me) in Feb rather than in Jan with 1st half of Feb cold 4 of 9 NE and 3 of 9 SE -2nd half of Feb cold: 5 of 9 NE and 3 of 9 SE -2nd half of Jan cold: only 2 of 9 (1954-5 and 1934-5) -1st half of Jan cold: 0 of 9! ——————————— So, the above stats tell me that cold will very likely return in NE and pretty likely also in SE but that it would be highly unlikely in early Jan and most likely in Feb. The cold ENSO winters that were often cold in early Jan were cold in all of Dec rather than just in the 1st half of Dec. This is all assuming the models are right and that the 2nd half of Dec won’t be cold dominated. If that turns out to not be the case then chances of cold in early Jan would rise significantly. *When I say cold I mean cold domination for at least 1/2 a month.*

During cold ENSO: I found 21 cases of a cold dominated Dec. 1-15 in the E US (including SE) back to 1874 (like 2024 may turn out): 2010, 2007, 2005, 2000, 1995, 1962, 1955, 1954, 1949, 1944, 1942, 1934, 1917, 1915, 1910, 1903, 1898, 1893, 1886, 1882, and 1875. So, 21 of ~70 cold ENSO Decembers. Of these 21 cold Dec. 1-15: -These were cold 1st half Jan: 2011, 2001, 1996, 1945, 1943 (NE only), 1918, 1904, 1887, and 1883. So, 9 of 21 NE and 8 of 21 SE. -These were cold 2nd half of Jan: 2011, 1963, 1956, 1955, 1945 (NE only), 1935, 1923, 1918, and 1904. So, 9 of 21 NE and 8 of 21 SE. -These were cold 1st half of Feb: 2011 (SE only), 1996, 1963, 1955, 1945, 1934, 1918, 1916 (NE only), 1904, and 1899. So, 9 of 21 NE/SE. -These were cold 2nd half of Feb: 2006 (NE only), 1963, 1950, 1916, 1904, 1894, and 1876 (NE only). So, 7 of 21 NE and 5 of 21 SE. - Only 2 of 21 had no return of enough cold to dominate half of a month in the NE in Jan or Feb: 2008 and 1911. So, this suggests 90% chance of at least another 1/2 month of cold domination in NE within Jan/Feb. - Only 5 of 21 had no return of enough cold to dominate half of a month in the SE in Jan or Feb: 2008, 2006, 1943, 1911, and 1876. So, this suggests 76% chance of at least another 1/2 month of cold domination in SE within Jan/Feb. - So, I’m expecting at least one 1/2 month of cold domination in the NE US and very likely also one in the SE within Jan/Feb. The lowest chance would be for this to be in the 2nd half of Feb. - 7 of 21 had at least two 1/2 months of cold dominating in both the NE and SE within Jan/Feb. And 8 of 21 had at least two in the NE. Thus, though unlikely, there’s a halfway decent chance for two cold dominated 1/2 months in Jan/Feb (a little moreso in NE). - 3 of 21 had at least three 1/2 months of cold dominating in both the NE and SE within Jan/Feb: 1963, 1918, and 1904. (Also, 1945 had three in just the NE while 2011 had three in just the SE. So, each region had 4 of 21 with three or more.) Thus, this is very unlikely. - 1 of 21 had cold dominating all four halves of Jan and Feb in both the NE and SE: 1904. Thus this is extremely unlikely. - Keep in mind that a half month not being cold could still be near normal as opposed to mild. - I plan to bump this post by the end of Feb.

1st 1/6 of E US met winter winner (projecting ahead to 12/15): cold We’ll see how the other 5/6 plays out. Hope we get another cold 1/6 at some point. Doesn’t seem like far fetched possibility, especially since there’s some tendency for cold in Dec to repeat in a portion of Jan and/or Feb. (more in Jan than Feb from what I recall, especially in La Niña).

Agreed. Per the map, these cities in the -3 to -6C shading were closer to the -6C than the -3C based on the location of the small areas of the next colder shading over NC and a small area in New England being significantly closer than the nearest locations of the next warmer shading. This implies to me that this Euro run was predicting ~-5C or -9F anomaly for these 4 cities, which is nearly twice as large an anomaly as what verified. Edit: Aside: However, down in my area (KSAV), it verified at -9.6F or about right fwiw.

The natural gas (NG) mkt opened this evening up higher a whopping 6.5% vs the Fri afternoon close. During winter NG opening on Sun evening up that sharply the vast majority of the time means the next couple of weeks look significantly colder in the E US vs how it looked on Fri afternoon on the EPS/GEFS, which we’ve already been discussing. From a few minutes ago by Mike, a Midwest pro met. who follows this market closely: “The ridge/west-trough east couplet mentioned yesterday has amplified a bit but the biggest deal is more cross polar flow into Canada from Siberia on the last run which introduces a MUCH cold source region for the cold when cold fronts come south from Canada. The NWS week 2 products were still VERY bearish/mild but the market knows better. When was the last time you saw a huge gap higher in December with a forecast like this? Regardless, there is a great deal of uncertainty and model runs are likely to change a great deal for the previous runs.”

The 12Z EPS is also colder in the E US vs prior runs for 12/20+. As I said elsewhere: with the last few days of trending colder 12/11-14 as well as new colder trends for 12/20-3+, it may become difficult for Dec as a whole to not end up pretty solidly BN in much of the E US.

The new Euro weeklies means are similar to recent days with NN temps in the E US in early to mid Jan when averaged out. So, neither a strong warm signal nor a strong cold signal as of yet. It of course may mean the bulk of the E US ends up averaging out pretty close to normal from a mix of warm and cold periods. Or it could be that we are still way too far out for a clearcut signal (warm or cold) to emerge that perhaps will later reveal itself. With the warmer globe and few areas showing BN vs numerous areas showing AN, I’m quite content to see the NN dominance persist. For illustration, look at these two weeks of global views of 2m temps and note that the NN in much of the US and Canada is actually easily the largest non-AN land area in the N Hem: Week 5 (1/6-12): Week 6 (1/13-19):

You can add the 12Z EPS to the 12Z GEFS that is cooler in the E US 12/21-3. Along with the 12/11-4 cooldown: if this keeps up the E US is going to have a hard time not ending up with a pretty solidly BN Dec as a whole.

This is the kind of thing that has been common over the last 8 years (things backing up NW as forecasting time decreases probably largely related to the MC warm pool). I hope this isn’t a sign of things to come the rest of this winter for the E coast although I fear this is a realistic possibility. But it may be good for most of you guys.

Note the animation below in this TN Valley subforum post. This is the kind of thing that has been common over the last 8 years (things backing up NW as forecasting time decreases probably largely related to the MC warm pool). This is an illustration of what causes the cold bias of most models in the E US. I hope this isn’t a sign of things to come the rest of this winter although I fear the realistic possibility: @bluewaverefers to this tendency often

In terms of mean zonal 10 mb winds at 60N, the gold standard for measuring the weakness of the SPV, I’m not currently seeing a rapid weakening on either the Euro Weeklies or the extended GEFS.

Regarding the bolded, is it ever really clear in advance how it’s going to turn out? I don’t recall a winter here without widely varying feelings. If it were clear, these forecasting threads would be pretty boring. Nobody ever knows for sure. It is the uncertainty that makes for great forecasting discussions. Long range forecasting is a crap-shoot in that way and it really takes high skills to have a good chance to do well consistently. Even the very best models like the Euro are often fooled just a couple of weeks out!

Note that the spread of members’ amplitude on the GEFS’ MJO forecast is quite wide:

I’m one who has for a long time preferred lower amp MJO (just outside, near, or inside circle) based on it being associated with colder in winter (especially Jan) than higher amp in the E US as well as being more favorable for major winter storms in the SE, especially ZR/IP in N GA, based on several decades worth of stats. However, I do wonder if that relationship still exists to the same extent due to the MC warm pool being so dominant the last 8 or so years.

These three are suggesting that the CFS’ forecast of going strong on the top of the diagram is likely out to lunch. That’s not surprising as the CFS has often had too strong an amplitude and isn’t at all reliable. Only the CMC agrees with the CFS.

At KSAV over the same 97 year period, 2024’s 1st week of Dec ranks as tied for 2nd with 1944 behind only 2000 (assuming I didn’t miss any colder ones…I’m pretty sure I didn’t). But when taking relevant climo of each period into account, 2024 is 2nd coldest, alone. When taking into account warming climo back to 1874, 2024 looks like it is the 3rd coldest 1st week in Dec anomalywise behind only #1 1876 and #2 2000!