GaWx

For the SE US early next week, this is going to be quite the intense cold snap but also quick! Enjoy it while you can as that will probably be the last opportunity for very intense cold for quite awhile. It’s entirely possible it will end up the coldest of the season though there’s no way to know obviously.

Anthony, Thanks. Indeed, I realize that. The difference is that the one I posted is the official RMM that will go into the records together with all since 6/1/1974, the others that are already in the record book for folks like me to analyze. The ones you posted won’t. I’m not sure why they differ, but I prefer the Australian RMM. The ones you posted will be later essentially be forgotten by history.

Indeed, in Dec it is for the E US close to the worst, if not THE worst along with phase 6 as the image below shows. However, this is only a VERY weak phase 5 (not too far from the center of the circle) and thus isn’t nearly as bad on average as phase 5 is outside of the circle (it’s probably close to neutral):

Check this out. The official Australian RMM MJO for Dec 9th has already been released: after the Dec 3-7 phase 8 went surprisingly (to me) to Dec 8th’s very weak phase 6, Dec 9th comes in at very weak phase 5! Holy smokes! I still think it may retreat back to phase 8 later, but that remains to be seen:

1. For Dec, I recently counted the # of days that had weak MJO (amp <1) as well as strong MJO (amp of 2+) days 1974-2024: Avg # days <1/>2 MJO amp per Dec 70s: 14/1 80s: 16/1 90s: 10/3 00s: 12/7 10s: 12/5 20s: 8/7 Note how weak far outnumbered strong in the 1975-1989! And then note how the strong was almost up to weak in 2020-24! —————— 2. Jan: Due to time constraints, I just counted strong amp days 1975-2025: Avg # >2 MJO amp days per Jan 70s: 11 80s: 3 90s: 6 00s: 9 10s: 9 20s: 9 -Keep in mind that Jan has on average the strongest amp of any month, which seems intuitive. -Note that the 70s had the strongest, which may be due to randomness since there were only 5 years. - If you were to ignore the 70s, you’d see a notable progression to a higher # of strong amp days in Jan from the 80s to the 00s+. ————— 3. Feb: Like for Jan, I just counted strong amp days 1975-2025: Avg # >2 MJO amp days per Feb 70s: 4 80s: 4 90s: 5 00s: 5 10s: 9 20s: 6 One can see a slow increase of strong amp days in Feb as we move forward in time if we ignore the 2020s. ———— 4. DJF all combined shows the increase of strong amp days better: # of >2 MJO amp days per DJF 70s-80s: 11 90s-00s: 17.5 10s-20s: 23 So, per each DJF, 2010-25 had on average twice the number of strong amp MJO days as 1974-1989! Source for daily MJO amp: https://www.bom.gov.au/clim_data/IDCKGEM000/rmm.74toRealtime.txt

Today’s Euro Weeklies for 12/22-1/18 are even slightly uglier than yesterday’s ugly maps with a strong -PNA bringing warmer than normal for each week’s average for most of the US with the strongest warmth from the lower Midwest through the C/S Plains to the SW US, where it torches for part of the time in late Dec and early Jan. The E US is still clearly warmer than normal but like yesterday no torch dominates there. Hopefully, these maps fail miserably but I hate seeing them. But in case they were to not fail and before y’all jump off of a cliff, there is some good news for the first run with the new week (1/19-25): it transitions toward a -EPO/+PNA/-AO/-NAO. Maybe, this is a sign of better things to come by mid to late Jan? For 1/19-25: N America H5 Global H5: N America 2m temps: ahhhh with much colder than prior maps!

NG is down another 8% today and is now down a whopping 23% vs the high of one week ago! Here’s the ugly wx reason though it’s great news for future energy bills for the time being (actually NG marketers have lots of storage to draw from and thus the retail prices don’t vary nearly as sharply as one might think; also there are state price utility commission controls in some states): look on the left and that steep dive in EPS HDDs that flatline way below normal near 15/day for the purple 0Z run (today’s 12Z run wasn’t out yet on this…I think it came back slightly then to 16ish/day): @Stormchaserchuck1

As we all know, La Niña favors a weaker than average southern jet and we’re solidly into La Niña (per the MEI/RONI). So, this is totally expected based on ENSO. I wouldn’t be surprised if it averages weaker than normal the rest of the winter. That’s the best bet. But as is normal, there are usually short periods of increased S jet from time to time even in La Niña just like there are usually short periods of weak S jet in El Nino.

I meant unexpected with regard to the main model MJO projections we follow. None of them on any day’s run had it going into 6 though it likely will leave quickly.

There’s been an ~3 day lag time in getting the official MJO phase/amp. As it turns out, the initial phase 8 lasted only 5 days (12/3-7) as it went into phase 6 on 12/8 (per 1st image), which was totally unexpected. I’ll keep following this closely to see if it re-enters phase 8, which I think has a very good chance but we’ll see. Regarding this initial phase 8 (12/3-7), here are some E half of US anomalies: - Boston: -8 - NYC: -8 - Baltimore: -7 - RDU: -8 - Atlanta: -7 - Birmingham: -7 - Tulsa: -7 These are on the border of B and MB normal: Below are the average anomalies for NDJ, which I believe are in degrees F. These average anomalies were well exceeded even if these are in degrees C: Thus, this was a colder than average phase 8 in the E US based on these 7 cities. Source for daily temperatures: https://www.weather.gov/wrh/climate

Today’s Euro Weeklies, after the current cold domination ends, are similar in the big picture to yesterday with a stout -PNA and mildness dominating much of the E US, especially the further south you go, into mid Jan though Jan 12-18 is slightly cooler than yesterday. That last week’s PNA is less negative. The NE US is again near normal on most maps. Mid-Atlantic is mainly mild til the last week.

He’s been trolling AmericanWx for years. You may not be familiar with his posts.

Hey troll, I didn’t say these were anywhere near historic. The record lows for 12/15 at RDU/ATL are way down at 8/11. But these are ~18 BN.

The 12Z model consensus is coming in for Mon lows at ~20F for ATL and ~17-20F for RDU.

It was about a week in advance when the models suddenly got colder for the period starting a few days before Thanksgiving. We’re now about a week before the progged big warmup in the E US. Just saying although I’m not saying that will likely happen again. But it’s good to stay grounded due to the inaccuracy of models more than a week out.

It also got down to 29 at KSAV, which was a few degrees colder than the forecasted lower 30s. But it didn’t quite get down to the coldest yet this season, which is the incredible 28 of Nov 11th.

Per yesterday’s Euro Weeklies, it’s overall looking to average mild from the Mid-Atlantic-OH Valley-lower Midwest south for most of the 4 week long period 12/22-1/18. Could it end up verifying well? Of course, especially the earliest portion, when statistically there’s more skill. Will it? Nobody could possibly know, obviously. Notwithstanding the poor performance for the 3 weeks from just before Thanksgiving through mid Dec, the Euro Weeklies have been just good enough at foretelling general trends that they shouldn’t be ignored by any means. But could they largely end up failing, especially for the Jan portion? Obviously they could.

1. No teleconnection even comes close to guaranteeing anything. Anyone who says it does is overrating it. But most have notable tendencies that make them helpful for forecasting. They’re useful tools, including the MJO, but they’re not crystal balls as the atmosphere is much too complicated for any one index to be reliable. I’d argue the MJO is about as good a tool as any of them, but like any tool it needs to be used correctly. 2. I recently did an analysis of 3+ day long Dec phase 8 at RDU and found a whopping 78% of them to have been colder than normal: # of periods: MB 5 (22%), B 13 (57%), NN 0 (0%), A 2 (9%), MA 3 (13%) So, there have been nearly 4 times as many B/MB periods as A/MA periods at RDU for Dec phase 8 periods lasting at least 3 days. 3. Regardless, of what may come and in what phase, what about prior to that period? The period 12/3-16, most of which is forecasted to be in phase 8, is forecasted to end up with all colder than normal days at RDU and in much of the SE and to be at least in the top 5 cold for that period of the last 50 years! That would be 90 percentile cold. 4. I plan to average out the temperature anomalies for whatever days end up in phase 8 later this month.

Thanks. Our areas had a freezing fog advisory late last night, which I believe is quite rare:309 AM EST WED DEC 10 2025 ..PATCHY FREEZING FOG THIS MORNING AREA OBSERVATIONS, SATELLITE IMAGERY, AND WEB CAMS INDICATE THAT PATCHY DENSE FOG IS IMPACTING PORTIONS OF SOUTHEAST GEORGIA AND SOUTHEAST SOUTH CAROLINA EARLY THIS MORNING. MOST OF THE PATCHY FOG IS SHALLOW, BUT IS PRODUCING VISIBILITIES OF A QUARTER OF A MILE OR LESS IN ISOLATED AREAS. MUCH OF THE FOG IS FORMING AS STEAM FOG NEAR WATERWAYS INCLUDING RIVERS, STREAMS, TIDAL CREEKS, AND MARSHES. TEMPERATURES ACROSS THE AREA HAVE FALLEN BELOW FREEZING AND INTO THE UPPER 20S IN MANY LOCATIONS. FREEZING FOG WILL OCCUR, EVEN PRODUCING LIGHT RIME ICE ON ELEVATED AND EXPOSED SURFACES. WHILE LOW VISIBILITIES COULD IMPACT TRAVEL, ESPECIALLY WHERE VISIBILITIES CHANGE SIGNIFICANTLY OVER SHORT DISTANCES, RIME ICE FROM FREEZING FOG IS NOT EXPECTED TO PRODUCE ANY IMPACT ON TRAVEL CONDITIONS. TEMPERATURES WILL RISE ABOVE FREEZING, AND ANY LINGERING FOG WILL DISSIPATE, BETWEEN 8 AND 9 AM THIS MORNING. PRECAUTIONARY/PREPAREDNESS ACTIONS... IF DRIVING, SLOW DOWN AND LEAVE EXTRA DISTANCE AHEAD OF YOU IN CASE A SUDDEN STOP IS NEEDED.

A half hour ago I finished walking at the park in 35 invigorating degrees. To sort of borrow a phrase from DT, yes, I was the only sick, twisted cold wx freak out there walking. But I was bundled up and had extra energy giving me an extra spring in my step. Winds were calm with clear skies allowing for Gainesville, FL-like ideal radiation. I could even see some cool looking steam fog over water. Dewpoints were only a couple of degrees lower. Today’s high was only 45, which is 20 below normal.

Today is the 9th day in a row of highs below 60 at SAV and below 50 at GSO, extending the record! Before this SAV had never even had this for Dec 1-7 going back to 1874. GSO had had a 7 day period one other time.

Today’s Euro Weeklies for the 4 weeks Dec 22nd through Jan 18th continue to look bad (mild) especially in the SE and MidAtlantic. There’s no way to sugarcoat it. The hope is that they’re just pain wrong. But that’s just a hope: 12/22-28: 12/29-1/4: 1/5-11 1/12-18:

There’s a college football thread for those who don’t know and are interested that could use more discussion like this:

After a big drop yesterday of 7%, natural gas prices are again sharply lower today (down 5% for a 2 day total of 12%) on warmer E US prospects for at least late this month. It’s very rare for NG to drop that much in early winter with cold looking to dominate for the foreseeable future, which as we know is not at all the case after about a week of intense E US cold per model consensus. Week one’s intense cold is already built into the price. It’s usually changes in prospects for week 2 into early week 3 that drive daily changes in NG prices. That’s because week one is normally already priced in and typically doesn’t jump around too much. And beyond early week 3 is usually too far out in fantasyland/too little forecasting skill that far out to have too much impact.

1. Where’s “Star” located? 2. No index ever even comes close to guaranteeing anything. That’s nothing new to us. 3, However: The period Dec 3-17, which is prior to the days his maps are showing, is currently looking to end up much colder than normal in the majority of the E US, including a top 3-5 coldest of the last 50 years in many places. That would jibe well with phase 8’s cold E US tendency.