GaWx

Today’s GEFS progs of -AO/-NAO aren’t as strong as those of yesterday (which can be seen in the quoted post): 1/5/23 GEFS AO prog: 1/15/23 has 80% >-3 vs 80% <-3 on the 1/4/23 run: 1/5/23 GEFS NAO prog: 1/15/23 has most >-1 vs most <-1 on the 1/4/23 run:

Actually, I think I’m largely in agreement with @so_whats_happening.Wouldn’t it make sense that there always (not just sometimes) is a lag (of however many days, which would vary from case to case) between what happens in the tropics/MJO and what happens in the middle latitudes (E US temperatures for example)? However, my agreement doesn’t mean that I shouldn’t still use those composite maps for concurrent. I think that’s where we disagree. It is tricky. So, for example, if we want to predict E US temperatures during an upcoming phase 8, I’d say going with BN makes sense based on the maps, which show concurrent US temperatures. That’s even though the BN temps were likely a result of a lag from phase 7.

I understand the concept of a lag from the MJO (tropics) to the mid latitudes. That makes perfect sense and thus I’m not disputing it. By the way, how many days is the average lag? But this is tricky imho. Check this out, the link to the MJO/US temperature composites that I look at: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/Composites/Temperature/ From that link, here are the DJF composites, for example: In the “Information” section linked below that goes along with these composites, it says nothing about lag between these composite maps and the respective phase noted for each map: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/Composites/Temperature/readme.shtml As I see it, these composites aren’t actually disputing that there is a lag. Rather, they are the after effects of a lag. For example, let’s look at phase 8. The concurrent temperatures average BN in the E US. But in reality, these BN temperatures have to have been a result of a lag from what was earlier initiated in the tropics (an earlier MJO phase) rather than from phase 8, itself. I’m educatedly guessing that this earlier phase is 7 in a large % of cases since the MJO typically rotates counterclockwise. Which phase in a particular case would be dependent on the number of days of the lag for it. If the lag for a particular case is, say, 5 days, we need to see where the MJO was 5 days earlier for that case. Let’s say it was in phase 7 five days earlier. Let’s say it was BN in the E US five days later. Thus it was in reality the phase 7 of five days earlier rather than phase 8, itself, that lead to the BN E US five days later, which happened to be during phase 8. So, as I see it, what resulted in the BN in the E US during phase 8 actually likely originated from what was happening earlier in the tropics during phase 7. So, even though these composites show concurrent E US temps during phase 7 to average AN, that AN is apparently actually a lagged effect from an earlier phase (say phase 6 in many cases). Phase 7, itself, is probably associated with a BN E US but due to lag the BN doesn’t occur til the MJO has moved into phase 8. So, the E US warmth during phase 4/5/6 is likely largely a lagged effect from phase 3/4/5. The E US cold during phase 8/1/2 is likely largely a lagged effect from phase 7/8/1, etc. The extreme cold of 12/23-7/2022, which occurred during phase 5, was likely a lagged effect of phase 4 since it was mainly in phase 4 during 12/8-22/2022.

That sudden increase in members with a major SSW near midmonth is still there on today’s (1/4/23) 0Z EPS (just something to follow as it could impact Feb):

The SE may very well not as snow is so unpredictable and there is a mix of factors. However, sometimes such a strong combo of -NAO and -AO will dominate enough to overcome the others. For example, the Jan 9-11, 2011, big winter storm had a moderate MJO phase 5-6 along with a neutral to slightly -PNA. It did have a potent -EPO, which may be in its forecast. Anyone have a GEFS EPO forecast?

Not necessarily. Last winter’s coldest (near Christmas) had a similarly strong MC MJO. Also, Jan 20-31 of 1978 had similar. MJO, just like most indices, tells us what usually happens as opposed to what nearly always happens. I should add that I haven’t seen a GEFS EPO forecast. Anyone see it? I suspect that might be negative, which would be favorable.

The 0Z GEFS is forecasting towards midmonth easily the strongest Jan -NAO since 2011 and 2010. Both of these times, ATL and other areas had measurable snow with 2011 being major in much of the SE US. It is also forecasting a very strong -AO. In addition, it is forecasting a strong MJO phase 4 and moderate -PNA.

The 0Z GEFS is forecasting easily the strongest Jan -NAO since 2011 and 2010: The 0Z GEFS is forecasting a very strong -AO along with it: Along with these, it is forecasting a strong phase 4 MJO and a moderate -PNA.

Some 0Z/6Z models like the 6Z GFS are suggesting a chance for a major SSW near midmonth like yesterday’s 0Z EPS was suddenly doing.

I’m talking strictly about averages. For example, for Corpus Christi based on 1991-2020, normals are 58 and under 12/27-1/20. On Feb 1, normal is up to 59.6 and it is 61.0 on Feb 15. I got this info from here: https://nowdata.rcc-acis.org/crp/ Choose daily normals and you’ll see the graph.

The 0Z EPS is the coldest run yet for the E US in mid January. Thus, I expect today’s Euro Weekly for 1/15-22 to be the coldest yet for that week in the E US. After that week, we’ll see if 1/22-29 is colder than yesterday. With the midmonth cold extending into the SE, that may turn out to be one of (if not) the best shots at significant wintry precip in much of the SE of this winter with some chance of that even deep into the SE. Interestingly, this would likely be when the MJO is in or near phase 4, often a warm phase. But often doesn’t mean always. Consider Christmas of 2022 for example.

The 0Z EPS is the coldest run yet for the E US in mid January. Thus, I expect today’s Euro Weekly for 1/15-22 to be the coldest yet for that week in the E US. After that week, we’ll see if 1/22-29 is colder than yesterday. Interestingly, 1/15-22 would likely be when the MJO is in or near phase 4, often a warm phase. But often doesn’t mean always. Consider Christmas of 2022 for example.

Actually, early to mid Jan has the coldest climo/longterm daily averages) by a small margin for areas like yours and mine. Further north into the NE US, the coldest climo of the year extends into early Feb.

Yeah, I’d much rather there be a wind reversal/major SSW than not. But would it actually be crucial for 2-4+ weeks later? Nobody knows. I just think it helps the odds.

I didn’t mean that 1/22-29 is colder than 1/15-22 on the run as 1/15-22 is the coldest. I meant that 1/22-29 is the week that cooled off the most of any week vs what the prior run had. I’m not about to try to make a prediction of whether or not 1/15-22 will be the coldest of the entire winter. However, it will be during/near the coldest climo for many. So, should it end up as cold as what the EPS has, it would have a good shot at being the coldest week of the winter.

I go by the unrounded ONI peaking at +2.00+. Others may define it differently.

-The ONI for OND came in at +1.94, not quite super. -The RONI for OND came in at +1.51, barely strong. -Dec ERSST came in at +2.07 vs the Dec OISST of +1.99. So, ERSST continues to come in slightly warmer than OISST, which may be significant going forward as we see whether or not unrounded NDJ ONI comes in at +2.00+, which would give us a super. -Nov ERSST was +2.02. So, to get a super for NDJ, Jan ERSST only needs to be +1.91. With the slightly cooler OISST now up at +2.10, I consider that chance to be high as of now.

The Euro Weeklies for today are colder in the E US vs yesterday for all of the weeks covering 1/15-2/12. The week 1/22-29 is especially colder. Perhaps this is related to the weaker mean SPV at mid-month. It is somewhat surprising because the EPS MJO today is much stronger in phase 4 at midmonth.

What the? The EPS mean for 1/17-18 fell sharply from yesterday’s +14 to today’s +6. There are ~~20% of members with a major SSW 1/15-19 vs only 5% yesterday. We know that the EPS has been strongly biased to the too weak side in recent weeks. So, I’m going to assume this is just a burp, especially with the other 0Z ensembles not showing this:

The 0Z EPS (bc) forecasted mid Jan mean phase 4 MJO amplitude has increased significantly since yesterday, not what I wanted to see for midmonth: Yesterday’s (1/2) EPS had ~1.00 (right on circle and then going inside it) phase 4 amp for 1/17: Today’s (1/3) EPS has a well outside the circle ~1.65 phase 4 amp for 1/17 (hoping this is just a burp):

The period starting near the end of the 8-14 looks to be when the cold moves SE into the E US per the last several EPS runs. There are indications of an Arctic high plunging down into the N Plains ~1/16-7. And that interestingly enough looks to be when the MJO is in the MC phases. Note though that the EPS and CMC have only a weak/near or inside COD MC, which would allow for a better chance for cold then. OTOH, the GEFS is much warmer then in the E US, not surprising since it has a very strong MC MJO: Note also that the GLAAM is per this CFS rising to a + soon afterward:

Correct as early Feb is near normal.

Today’s Euro Weekly for Jan 15-22 is still the coldest week:

Latest WCS PDO up to -0.63, highest since late October:

The 1/1 Euro Weeklies have an even stronger SPV late Jan/early Feb with the ensemble mean right at climo then (see below). (Look in my quoted post to see how much weaker was the SPV on the 12/26 run.) The last two weeks of the run, 1/29-2/5 and 2/5-12, warmed notably in the E US vs yesterday’s run (connection to stronger SPV??). OTOH before that, the week of 1/15-22 on the 1/1 Weeklies got even colder in the E US with BN temps nearly everywhere (see below). This is now the coldest week of the run in the E US as a whole! Also, keep in mind that this is during about the coldest climo of the winter for many. Interestingly, the models are suggesting that the MJO will then be in the MC though hopefully weak. Last winter’s coldest E US was when it was in the MC. Though it appears there might then be a moderate -PNA, there looks to then be a strong -NAO/-AO largely running the show. The run for 1/15-22 from just 6 days earlier (12/26 run posted in my quoted post) had AN temps for most of the E US!