December 2025 OBS and Discussion

[MJO812]

40 minutes ago, eduggs said:

The last two GFS op runs are well east of the GEFS mean days 5 through 6 with the shortwave and SLP in the east. The GEFS mean shows precipitation primarily in the lower MS valley while the op GFS shows it along and off the east coast. Discounting the op runs for now though an eastward trend is noted in the other mid-range op models. The GEFS seem to be somewhat of a compromise between the 12z EPS and GEPS. The GEFS would put us right on the edge of both significant precipitation and marginal temperatures for wintry precipitation. 

18z AI Euro ticked northwest. Gives the coast and Inland some accumulations.

[MJO812]

Anyone looking at the 0z gfs ? Nice snowstorm next week.

[bncho]

ka ching on the GFS

[eduggs]

Can't complain about the 0z GFS. We haven't had a widespread coastal snowstorm like that in a while. Gorgeous ouput! CMC, ICON, ECM, and ensembles close enough for interest. Hopefully no big swings from here on out (doubtful)... Small, incremental improvements would be ideal. We are still almost a week out, so it's still going to be tough to pull this off I think.

[MJO812]

4 minutes ago, eduggs said:

Can't complain about the 0z GFS. We haven't had a widespread coastal snowstorm like that in a while. Gorgeous ouput! CMC, ICON, ECM, and ensembles close enough for interest. Hopefully no big swings from here on out (doubtful)... Small, incremental improvements would be ideal. We are still almost a week out, so it's still going to be tough to pull this off I think.

Gfs is  active and cold . Nice to see.

[eduggs]

The UK is also an excellent run at 0z (both surface and aloft). Supports the GFS - maybe slightly better even.

[eduggs]

6 minutes ago, MJO812 said:

Gfs is an active and cold run. Nice to see.

The 0z GFS is an absolutely filthy glutton for snow. I'm going to pretend I didn't see the extended run and keep my personal focus on the mid-range.

[MJO812]

Just now, eduggs said:

The 0z GFS is an absolutely filthy glutton for snow. I'm going to pretend I didn't see the extended run and keep my personal focus on the mid-range.

Nice ridge out west and plenty of cold. What a turnaround from the models.

[eduggs]

1 minute ago, MJO812 said:

Nice ridge out west and plenty of cold. What a turnaround from the models.

The GFS retrogrades the CA ULL west into the Pacific. If that doesn't happen, the longwave flow across the US would be significantly altered. Our downstream weather is extremely sensitive to the modeled evolution of the western trof over this period. Could still end up balls cold or periodically torched days 6-15.

[MJO812]

Ukie is also on board with the storm along the front.

[eduggs]

0z GEFS is slightly drier/south compared to 18z. So the GFS and GEFS moved towards each other this run.

[Snowlover11]

[NEG NAO]

2 hours ago, MJO812 said:

Anyone looking at the 0z gfs ? Nice snowstorm next week.

The important feature is the strong enough cold enough HP in southeast Canada staying PUT long enough to keep feeding the cold enough air in and storm track is perfect Benchmark because of this

[NEG NAO]

The OZ UKMET looks to be a closer to the coast track as the HP in southeast Canada is not as strong - starting at least as Frozen in the metro - the Canadian and the Euro AI are offshore tracks

[NEG NAO]

The 0Z Euro starts as frozen in the metro BUT that HP does not stay anchored like in the GFS run so there is a change over to rain - still to early to predict the outcome except to say the storm chances are increasing and a frozen to rain scenario is favored right now IMO