cbmclean

Merry Christmas to my foster weather family.

Could be worse. Imagine if you were in that tiny area of central Illinois with no snow. Somebody there pissed off Santa.

Is there a 50/50 low in any of those packages?

Learned that the hard way this month.

Got down to 1 F last night in Old Fort. Man if that snow storm had actually occurred as it been depicted imagine the records that would have been shattered.

And finally, unrelated to my recent posts, I remember some discussion about whether or not the GEFS had been updated to run on the "new" GFS dynamic core. I stumbled across this article while looking for more reanalysis data. Apparently GEFS went to FV3 way back in Sept 2020. https://journals.ametsoc.org/view/journals/wefo/37/6/WAF-D-21-0112.1.xml The Global Ensemble Forecast System (GEFS) is upgraded to version 12, in which the legacy Global Spectral Model (GSM) is replaced by a model with a new dynamical core—the Finite Volume Cubed-Sphere Dynamical Core (FV3). Extensive tests were performed to determine the optimal model and ensemble configuration. The new GEFS has cubed-sphere grids with a horizontal resolution of about 25 km and an increased ensemble size from 20 to 30. It extends the forecast length from 16 to 35 days to support subseasonal forecasts. The stochastic total tendency perturbation (STTP) scheme is replaced by two model uncertainty schemes: the stochastically perturbed physics tendencies (SPPT) scheme and stochastic kinetic energy backscatter (SKEB) scheme. Forecast verification is performed on a period of more than two years of retrospective runs. The results show that the upgraded GEFS outperforms the operational-at-the-time version by all measures included in the GEFS verification package. The new system has a better ensemble error–spread relationship, significantly improved skills in large-scale environment forecasts, precipitation probability forecasts over CONUS, tropical cyclone track and intensity forecasts, and significantly reduced 2-m temperature biases over North America. GEFSv12 was implemented on 23 September 2020.

And that's all I could at this link: https://psl.noaa.gov/cgi-bin/data/narr/plotmonth.pl. It says that plots are only available for data going back to January 1979. From the previous post it looked like someone has data goign back to at least 1950. Anyoen have any idea where I can get that?

December 1995. Crazy east trough although mostly off-shore. Definitely no WAR. Western ridge is also displaced east. Actually from the North American view this doesn't look like a massive -AO. Maybe the other side of the artic was high?

December 2000 will always have a fond place in my memory. HGad just went off to college where I really blossomed after a difficult high school experience. And the late fall/early winter was memorably chilly.

Dec 2009 Quite different. No mean E trough at all. Instead negative anomalies centered over the great plains.

Well start going backwards in time. Dec 2010. Eastern trough is centered rather south compared to the composite and a good bit off shore. No mean western ridge.

11 F in Old Fort

I'm at the inlaws for Xmas so hopefully I'll have some time to play this evening

True, but there is the strong eastern trough signal as well as a weaker but less robust trough off the west coast. I'm just surprised to not see a similar consistent signal in the western conus. The patterns are complex and many-faceted, and sometimes defy easy characterization

I was more referring to the lack of positive anomalies in the western CONUS. Surprised to see that with troughing to the east and the west. ETA: I am referring to the bottom composite.

Also interesting that the WAR doesn't show up on this year. It just appeared when it counted I guess.

Interesting that the strong troughs in the east in the bottom pic are not reflected by a strong ridge in the west. How is that possible?

Every model in history has overestimated the speed of cold air going through the mountains. It's just something that has to be manually corrected for. Not sure why they can't get those physics right. But overall this front seems to have been well-modeled from range.

The truth shall set us free...free of snow.

Anyone with access to the long range EPS, is it showing similar hope, or is it to depressing to even mention?

Definite retrograding of the AK vortex. Lets hope this look continues to move forward in time.

Looking at the TNH temp correlation, there doesn't seem to be much for the eastern seaboard. Is it something that affects snowfall more than average temperature here?

Not very familiar with the TNH teleconnection. Reading up on it a bit at the CPC site. From their write-up its not really clear which phase is better for the eastern CONUS. From https://www.cpc.ncep.noaa.gov/data/teledoc/tnh.shtml The positive phase of the TNH pattern is associated with below-average surface temperatures throughout the western and central United States, and across central and eastern Canada. It is also associated with above-average precipitation across the central and eastern subtropical North Pacific, and below-average precipitation in the western United States and across Cuba, the Bahama Islands, and much of the central North Atlantic Ocean. The negative phase of the TNH pattern is often observed during December and January when Pacific warm (ENSO) episode conditions are present (Barnston et al. 1991). One recent example of this is the 1994/95 winter season, when mature Pacific warm episode conditions and a strong negative phase of the TNH pattern were present. During this period, the mean Hudson Bay trough was much weaker than normal and shifted northeastward toward the Labrador Sea. Additionally, the Pacific jet stream was much stronger than normal and shifted southward to central California, well south of its climatological mean position in the Pacific Northwest. This flow pattern brought well above-normal temperatures to eastern North America and above-normal rainfall to the southwestern United States.

Thanks. Seems like puke in is faster than puke out.

Can't check ensembles. Anyone know if anymore hints of AK vortex retrograding?