GaWx

I forgot to mention that there’s a dedicated thread for today’s storm. For documentation purposes, you may also want to post your results in there: Today here I just got an invigorating walk in with low 40s and just enough breeze to give it a nice bite. Today’s high of only 51 (normal is 65) means that every day so far this month has had a high only in the 50s. We already had had the first time in recorded history (back to 1874) of no high reaching 60 for Dec 1-7. Now it’s also the first time for that for Dec 1-8 and tomorrow is going to make it the first time for Dec 1-9! Rainfall so far this month is over 2”, which is way above the normal of 0.75” for Dec 1-9. For the first time since at least Thursday we had no rain.

How often has your area received 6” or more from a single storm?

For the record regarding the main indices for today’s wintry event: - The prior -PNA rose to the more favorable neutral PNA (-0.1) - AO -1.9, one day after a short-term minimum of -2.2 was hit - NAO -1.2, one day after a short-term minimum of -1.3 was hit - MJO likely was inside the circle phase 8 (probably won’t know for sure for a couple of days) - +EPO - -WPO

Good points. But if there were a clearly identified long time model bias, adjusting for that would obviously make sense.

The questions are whether or not and, if so, how long these same model misses will continue. It isn’t black and white. Nobody knows including you and me.

Today’s Euro Weeklies for week 3+ are still lacking cold domination to return to most of the E US south of the N tier with a solid -PNA dominating through mid Jan along with no -NAO or -AO. If this verifies, it would likely be pretty mild in much of the E US and nothing like we’ve been experiencing the last 2 weeks. However, models the last 3 weeks have been too warm in the E US with too much SER and missing much of the -NAO and -AO. Also, Midwest snowcover is well above avg, there’s the potential lag effects from the 11/28/25 SSWE, and the MJO remains favorable for E US cold. Are the weeklies/models finally getting their act together or are they going to continue with the same errors? Opinions?

A big reason the models have been much too warm in the E US are the horrible NAO/AO progs with this one from just 11 days ago having it go + just 1 week later: 11/28 AO prog for today: ~+1 Today’s AO verified way down at ~-2 (strong -AO) meaning a +3 miss: There was a similar big miss for the NAO: 11/28 NAO prog for today slightly positive (~+0.2): Today’s NAO verified way down at -1.2 (strong -NAO), meaning a +1.4 miss:

OTOH: The natural gas market, which is down sharply (6%) currently feels the prospects for a warmer pattern Dec 16th and beyond have increased. Check out the 0Z EPS HDD, which is on left chart, as it shows HDD plunging from mainly AN through 12/14 to BN 12/16-21 along with a trajectory suggesting more BN HDD (meaning warmer than normal E US). We’ll have to see whether or not this will finally verify well as the EPS has been too warm for the last 3 weeks as it has continually been correcting colder as the periods get closer:

Related to this is the -PNA Dec to +PNA Jan transitions for -ENSO that have been happening during the last 40 year period. That transition has been strongest when the Dec -PNA was strongest. Examples of cold Jans were during these winters: 1983-4, 1984-5, 2008-9, 2010-1, 2013-4, and 2021-2 where Jan was cold though not always colder than Dec.

Indeed, and look at the trend of just the last 3 GEFS for 12Z on 12/18: E trough deepening/W ridge strengthening. It’s important to keep watching these trends as the models in general have been much too warm in the E US since the runs starting 3 weeks ago though at some point this trend is likely to end at least temporarily:

I’ll give him the benefit of the doubt and assume he’s not counting weak phase 8 (inside circle). But even so, these had outside the circle phase 8 in Dec since 2001: 2017: 2009: 2007: 2002: @mitchnick

There’s no question that the CAD wedge has been the big winner in the SE US so far this month. My area has had almost every day mainly cloudy, rain on most days, and every day 12/1-7 has had highs only in the 50s! That’s very hard to do on every day for a week in early Dec with normal highs 10 degrees warmer. As a matter of fact, it’s so hard that this is the first time on record that it has happened with records going all of the way back to 1874! Interestingly, the highs have ticked down each day this month: 59, 58, 55, 54, 53, 52, and 50. I see that GSO has had all highs only in the 40s Dec 1-7. I wonder if that’s ever on record happened there. Anyone know? Edit: If that’s not enough, the forecast is calling for 2 more days of 50s highs, which will make it Dec 1-9! Same idea for GSO with 2 more sub 50 highs for Dec 8-9! Edit: I just checked GSO. Only once on record back to 1903 did they have not get out of the 40s Dec 1-7: 1910. However, they did get to 50+ on Dec 9th, So based on the forecast, Dec 1-9th, 2025 will be the first on record not having even one day get out of the 40s at GSO!

Which are y’all going with for Saturday’s (12/13) low? The GFS sticks out as much colder than the others at ATL with upper teens there, which tells me it’s likely too cold there. It has had a cold bias over snowcover in recent years (which is well above average in the Midwest). That’s probably a factor as I don’t know that that has been fixed. 6Z GFS: pipe busting cold with upper teens ATL/RDU: likely too cold 0Z Euro: slower with the cold and thus is much warmer on Sat AM with upper 30s: likely too warm though it has 20s the subsequent few days 0Z ICON: mid 20s RDU to upper 20s ATL: looks like a reasonable middle-ground 0Z CMC: coldest at RDU with mid teens (CMC has a well-known cold bias) though only down to mid 20s ATL 0Z UKMET: only down to low 30s though it has a warm bias/very likely too warm though it is headed for 20s on Sunday

I’m not using Dec 2022 as a heavily weighted analog because of snowcover. On this date in 2022, there was only 1% snowcover in the Midwest: Compare that to today’s 46%, the 3rd highest only to 2013’s and 2007’s 53% and just ahead of 2005’s 45%. The 2003-24 average is only ~15% meaning today’s is ~3 times the average for Dec 7th: @donsutherland1you may want to keep this in mind for your forecasts. https://www.nohrsc.noaa.gov/nsa/index.html?region=Midwest&year=2025&month=12&day=7&units=e

I created a new thread for tomorrow’s wintry event in mainly NC/VA: