GaWx

All 0Z ensembles are much colder in the E US 12/13-17 vs earlier runs.

New weeks 3-4 outlook makes sense since it’s similar to the Euro Weeklies. But hopefully they will end up too warm:

Chicago per model consensus is on track for a top tier cold Dec 1-20. Here are the 15 coldest Dec 1-20 at Chicago of the last 75 years (top 20 %) in reverse chronological order: 2016, 13, 10, 08, 05, 00, 89, 85, 83, 76, 72, 63, 58, 56, 50 2025 appears at this time like it might compete with many of these.

At 1PM, there was a whopping 26F diff. between Valdosta’s 76 and Tifton’s 50. Tifton is a mere 45 miles N of Valdosta!

The yucky rainy pattern continues here. Luckily during a short break in the light rains yesterday evening, I squeezed in a walk. Today so far has been different. The rains at times have been heavy, with my measurements suggesting ~0.75”. There’s been enough to be wary of hydroplaning if going too fast. This is the heaviest I’ve seen in several months. Thus, it’s the first minor test of my completed yard drainage projects as well as the city’s redug nearby street drainage ditch project. But it’s still not yet a complete tear as I need even heavier rains. Regardless, there will be more on and off rains through Sunday. My temps have been mainly in the mid to upper 50s after dipping to the rain cooled upper 40s last night. Temps are 12 warmer in Brunswick 75 miles to the S.

9 of the last 11 of the Jans following -PNAs in Dec for -ENSO were either cold or pretty close to normal. You’ve been harping on the only two warm Jans of the 11. Feb will more than likely be mild. It’s not necessarily Jan and Feb being similar as you’ve been thinking. This indicator suggests that’s unlikely as of now.

I’ll be rooting for a strong -PNA this month. Why? For -ENSO: Strongest -PNA Decs since 1983-4: -2021-2: -2.56; Jan was +1.01/cold -2010-11: -1.78; Jan was +1.29/cold -1984-5: -1.60; Jan was +1.63/cold -2008-9: -1.41; Jan was +0.61/cold ——— The Euro Weeklies continue with a pretty strong SER/-PNA in the first half of Jan. But it’s recently been correcting to a weaker one in late Nov/early Dec.

Agreed. But also keep in mind that the 15 days on that model (0Z EPS) preceding the map you showed are very cold in the NE 1/4 of the US and suggest one of the coldest 1st 19 days of Dec anomalies on record in the NE 1/4 of the US: Days 1-10: Days 11-15:

Today’s 2 week ensemble MJO forecasts: -12/5 EPS steady as a rock with a 17+ day long phase 8, second (back to 1974-5) only to the 18 days of 1975-6: a cold E US weenie couldn’t place it any better though keep in mind that the MJO, itself, is only one index of many despite it having notable tendencies: 12/5 GEFS: though not steady like EPS with only a 5 day phase 8 followed by 3 days of weak phase 1 (which also is often cold in Dec) followed by 5 more days in phase 8 and then 4 days barely in phase 7, this is on the whole still favoring dominating cold in the E US: Related to the very cold Dec forecasts, natural gas is up a whopping 6% today, alone! Knowledgeable NG investors don’t normally go long NG in winter unless the forecast is for a cold E US.

I still feel that Jan and Feb should be analyzed separately for the NE US. Since 1983-4 as regards -PNA Decs: -3 times as many -ENSO -PNA Decembers were followed by cold Jans as mild Jans including the recent Jan of 2022. In addition, there were cold Jans in 2014, 2011, 2009, 1985, and 1984. Related to this, 9 of 11 of these Jans were either cold or pretty close to normal. -But OTOH there were 6 times as many mild Febs vs the only cold Feb (2014) of these analogs in the NE.

I don’t feel 1989-90 is an -ENSO analog to 2025-6. That’s because: -Dec was slightly +ENSO per RONI (+0.09) and only a hair -ENSO per ONI (-0.01). -Jan was already a solid +ENSO per RONI (+0.39) and slightly +ENSO per ONI (+0.11). -Feb was +0.31 to +0.34.

Back to 1995-6, lowest SOI plunges -ENSO/lagged NYC wx -52 on 2/17/17: MB 3/10-18 and 9.7” -49 on 12/10/12: B 12/26-1/3 and 0.4” -47 on 12/19/95: MB 1/2-12 and 25” -47 on 2/2/13: B 2/7-10 and 11.4” -44 on 12/4/25 (due to strong compact Tahitian low) ??? -39 on 12/14/01: 12/30-1/2 MB/0” -34 on 1/19/17: 2/9-10 B/9.4” -31 on 11/7/22: 11/14-21 MB/0” The above tells me that IF there’s possibly any partial correlation of a strong -SOI during -ENSO to cold and/or snow at NYC, it’s not until 1-4 weeks afterward. A period of very heavy snow and/or MB temps occurred 1-4 weeks after 6 of the 7 sub -30 cases. This could easily just be random considering the small sample size and that this is pretty spread out (1-4 weeks afterward).

It’s been a semi-raw cloudy day here today with only low 50s most of afternoon and with occasional very light rain. Steadier not as light rain is about to start, which is just the beginning of Mon and off rainy period through Sunday. This should evap cool temps down into the high 40s soon. It’s going to be hard to get walks at the park in but I’ll try my best during any breaks.

Just like yesterday, the GEFS and EPS disagree on how long the MJO will stay in phase 8: GEFS: only 6 days though it returns for rd 2 on 12/18: But the EPS, which recently has been much steadier and has been verifying better than GEFS since phase 7, once again is going with a very long phase 8 (16+ days, longest in 50 years): you can’t place an MJO better than this in Dec for E US cold lovers (and it looks to be cold the next 10 days per models though one must remember that there are always other factors to consider due to the complexity of the atmosphere):

Or will Jan be cold like in 1984, 1985, 2009, 2011, 2014, and 2022? Or will Jan be within a few degrees of normal (in the NE at least) like 1997, 1999, and 2013? So, Jan has had 3 times as many cold vs warm for the analogs since 1983-4 that I’m looking at. OTOH, Feb has a better chance to torch in the NE imho as only 2014 of the analogs I’m looking at was solidly cold there vs 6 being cold in Jan. In Feb, these were mild: 1984, 1997, 1999, 2009, 2017, and 2023. So, in Feb, 6 times as many were mild vs cold. That compares to 3 times as many cold vs mild in Jan. Two very different months on average.