CAPE

December threads started a third of the way into November will tend to have plenty of long range model discussion/speculation.

I am always 'cautious' when guidance advertises a NA block, for obvious reasons. Looks likely that there will be a period of blockiness at this point. Remains to be seen how long it persists. I haven't looked at the MJO forecasts for a couple days- last I looked it was forecast to move into the COD then perhaps emerge at a low amplitude, maybe in phase 1 or 2. The GEFS seems to be moving in the right direction overall in the LR on the Pac side and with heights building in the EPO region. Most recent runs of the EPS are showing some signs too. Time will tell. We just can't know.

I was looking at the ensemble runs and discussing what they are depicting for the first week in Dec. I try to keep the LR discussion in this thread, because that's what it is by definition lol. December is still 10 days away, and this has been an active thread for at least 10 days now. But yeah the op runs are useful for the early next week time frame.

The question is how long it lasts. It appears to break down pretty quickly on the EPS, while the GEFS at least keeps a neutral look towards the end of the run. Signs of some improvement on the Pac side and in the EPO domain, more so on the GEFS. Could be a warmish period ahead if/when the positive heights break down in the NA, and at the same time the Pac remains less favorable. Before that(should it occur), maybe there will be a chance or 2 at something the very end of Nov into the first few days of Dec with the favorable looks.

Might be time for me to change my profile pic to the Dec 2009 one. On second thought, I did that last year around this time..

Absolutely. But at the same time, there is clearly a correlation, in the same way we evaluate 500 mb heights and make reasonable assumptions about the mean temperature in the column below that point, as well as using it as a general (pretty accurate) indication of surface pressures and temps.

Ofc it's also important to realize that the AO and NAO phases are determined by surface pressure measurements(difference in pressures in the case of the NAO) in specific regions.

12z EPS has the AO and the NAO crossing neutral then heading into + territory around Dec 3-4th. GEFS strongly disagrees. This is obviously something to monitor considering the importance (particularly the AO) to a favorable pattern for cold and snow here. Also the weeklies/climate/seasonal guidance are almost unanimously insistent on a +AO/NAO as we move into December, so there is that. Personally I am not concerned at this point given the beating the PV has taken and is forecast to continue taking going forward.

UK weather here the past few days. Mostly cloudy, a bit of rain, temp range 37-45.

Seems to align with the continued disruption of the PV the GEFS is advertising.

If this depiction is legit, SPV might be singing some Nelly.

Predominate -AO/-NAO an easy guess

Been monitoring the AO/NAO teleconnections on the EPS and GEFS. Previous runs had both the AO and NAO hitting neutral by Dec 1. Current runs have both indices projected to still be negative and heading towards neutral maybe by the 5th or 6th. Not a major revelation, but seeing the LR ens pushing back the possible shift in phase is a good sign.

The 6z run looks even better than 0z. Pumps the EPO ridge and has more widespread cold over the lower 48.

The weeklies are typically so ambiguous it ends up being up for interpretation. Glass half full or half empty. Certainly it could be worse, but that is not a great look imo. And yes, it's the weeklies and they really offer little value. I'll stick with the LR ens guidance and not worry about what may happen beyond that window.

Not a bad way to roll. Seems pretty reasonable the beginning of Dec could suck.

@Bob ChiII EPS weeklies H5 anomalies a week beyond the end of the 0z EPS. Fwiw, 2m temps look average. I would say the look is pretty crappy overall, but ofc it's the weeklies. Always overly smoothed and ambiguous.

Yeah its hard to make a call for a cold December around here. It happens every so often. Still can get a frozen event even if overall the month is 'warm' as long as the pattern isn't hostile, and with climo becoming more favorable moving forward.

Stay out of the tangled webb they weave.

GEFS currently has the MJO forcing moving briefly into phase 2, then into the COD by early Dec. Who knows what happens beyond that. Looks like it may do a loop in the COD, but it could reemerge in a favorable phase or stay neutral. If early Dec is going to be on the mild side, I am not sure the MJO state will be a primary reason. As for the Nino correlation, well we don't really have Nino conditions currently. Do we typically have warmish Decembers when ENSO is warm-neutral?

This is what I am doing for the most part, but given this is the December thread and it is in sight on the LR now, worth a peak- especially given what the seasonal models are advertising.

I will gladly take this look to start the month of Dec. GEFS looks very similar.

There is that baseball team in Baltimore...they call em the Os.

Ok Eagles. WTF? You can't stumble, bumble, and fumble and beat the Pats. Get it together.

From what I have seen(and I don't go out of my way to read any of these dudes on twitter) he never wastes any time when it comes to sounding the bells for a "bad" pattern.