GaWx

The 18Z 12km NAM has the low further offshore than the 12Z.

Thanks. However, this map is from the GEFS rather than the GFS. You mentioned the GFS and it is colder. You had said: “12z gfs looks like nam-12km as well with 850s up in northern wake”

Do you have a 12Z GFS 850 mb map showing this? I’d like to see it. At 3 hour intervals (based on cross checking Pivotal), this TT GFS 850 map (hour 30) is the warmest at Wake and 0C is almost as far S as the S Wake border leaving RDU at -1C:

Today’s preliminary CPC PNA of +1.39 is the highest daily CPC PNA of this winter. And it will be rising further with a target near +1.75 ~Feb 21st. That would be the highest CPC PNA on any winter day since 12/7/2020! Per GEFS, I’m currently projecting a Feb CPC PNA of ~+1.60. That along with the +1.70 of Dec and +1.05 of Jan would give a DJF averaged CPC PNA of +1.45. The current highest DJF averaged CPC PNA (back to 1950-1) are the +1.43 of 2015-6 and the +1.41 of 1976-7, both El Niños. So, 2024-5 still has a shot at having the strongest DJF averaged CPC PNA on record (back to 1950-1). It will obliterate the current highest La Niña CPC PNA of +0.89 (2000-01). Note that I was careful to always call this the “CPC PNA” as opposed to just “PNA” due to Chuck and others questioning the CPC calculations of the CPC PNA in parts of late Jan and early Feb.

Check out how much colder is the 3 km vs 12 km 12Z NAM at RDU: 3 km: <0C at 850 at 4PM, similar to globals 12 km: >0C at 850 at 4PM, warmer than globals; it has a 2 mb stronger surface low and the low is quite a bit N of 3km position

Yes, the 12km 12Z NAM does have a good bit of sleet along with 850s getting above 0C. But the 3km is several degrees colder at 850/never getting above 0C. The globals are similar to the 12km NAM in that respect. I think some sleet is possible but no ZR and mainly snow is what I expect as of now in RDU.

I still don’t see much if any mixing of non-snow precip in the RDU area. This looks like a classic practically all snow Miller A there imo (maybe just a little sleet). 850s look to stay safely <0C from what I’ve been seeing. You may even get a little higher than 10:1 ratios of snow.

It would be pretty remarkable if early March is also cold with it being La Niña. That’s somewhat favored during El Niño, not La Niña. But this winter has been unusual overall with regard to ENSO. Also, the coldest periods with the TPV lobes bringing the E US cold during very strong/near record strong SPV periods has been anything but normal.

Is WXBell down for anyone else? It’s been that way for me for 1/2 hour+.

Have the weenies messed up WxBell? Meanwhile, the 12Z GFS was interesting with accumulating snow just west of ATL tomorrow near and soon after sunrise. But admittedly that’s likely overdone and is an outlier, regardless.

And Barney returns! I’d love for this to verify just for the cold. But it is just a fantasy range 12Z GFS op run which looks totally different from prior runs. So, this has no more than entertainment value, of course. It will likely be far different on the Happy Hour run.

Meanwhile, 12Z UKMET at RDU dropped back from the 2.1” of the 0Z run, to 1.5” on the 6Z and to 1.4” on the 12Z. The qpf on the 12Z is ~0.13”. It looks like to me that just about all of the precip at RDU will be snow per general model consensus.

0Z Euro: 2.5” Kuchera RDU from 0.25” qpf

Why are 0Z 12K NAM 850s 3-4C warmer than 3K NAM’s for RDU?

0Z UK for RDU: highest since 12Z of Sunday with 2.1” of pure snow from 0.2” of qpf.

At RDU, the qpf of 0.28” is ~same as the 12Z/6Z and the snow (actually a little higher at 3.1” on later map) is also similar. So, it has stabilized.

18Z Euro qpf/Kuchera: with 850s never above -1C; RDU gets 3.1” (edited) of pure snow from 0.28” qpf; 2m temps start 29 and drop to 25 most of the snow; higher ratio snows to the W/NW with 850s even colder

0.80” RDU but tight gradient

I just saw WB 12Z JMA update: the 850s do, indeed, stay just <0C at RDU through the entire event and qpf is 0.80”. Based on this, I’m going to retain my educated guess that this is giving RDU ~~6” of mainly wet snow with perhaps a small amount of sleet: 12Z JMA furthest N 850 0C line southern border of Wake county with -1C at RDU:

Are you saying that RDU got 3K NAM’d?

18Z NAM ZR ouch near RDU: 0.26”

18Z NAM has a good bit of ZR and less % that’s IP vs 12Z due to warmer atmosphere

RDU. There are no p-type maps or 2 meter temp maps for the JMA at either WB or TT. It is pretty much a given that 2m will be below 32. TT does have 850s at 24 hour intervals for today’s 12Z JMA allowing me to educatedly guess that RDU would be just about all snow (maybe a little sleet). I think that 6” of snowfall from 0.80” qpf would be doable but it is just an educated guess. Regardless, it would be a major hit. If it were mainly sleet (highly doubtful), it would still approach 3” of concrete. ***Edit: I’ll update this when it comes out on WB as they have 850s and qpf at 6 hour intervals through hour 72.

12Z JMA has was appears to be nearly all if not all snow at RDU due to 850s likely staying below 0C most if not the entire time along with ~0.80” qpf suggesting ~~6” of Kuchera snow. A 6” snowfall would be their 4th biggest in La Niña Feb-Apr back to 1886-7! The only larger than 6” were 8.0” on 3/10/1934, 6.9” on 2/6/1984, and 6.2” on 2/17-18/1989. 2/16/96 was very close with 5.6”. In contrast, there have been 8 snowstorms of 6”+ during El Niño Feb-Apr vs the 3 during La Niña at RDU.

Actually, the 12Z WB NAM output shows mainly snow (1.8”) and sleet (0.8”) with only .02” of ZR for RDU due to 850s only getting to barely above 0C for a portion and 925s being near 0C for only a short time before falling to -2 to -3 for most of the qpf: The globals keep RDU in near 100% snow.