GaWx

 The MJO’s 3rd phase 8 period of the month ended on 12/20, when it went into phase 7.

So far this month there have been three phase 8 periods:

- Dec 3-7
- Dec 15
- Dec 17-19

Will there be more?

17 minutes ago, Jersey Andrew said:

Stunning changes to say the least. What is causing such large discrepancies?

I don’t know why the NAO and its influence has been underdone on the models, but these kinds of things make forecasting discussions so interesting. Just think if the models were all knowing. The discussion would be pretty boring.

 Look at how much Dec 29-Jan 4 has cooled vs 2 days ago on the EPS thanks to the stronger -NAO pushing back from the NE despite the strong Aleutian ridge remaining.

Two days ago:

Today:

Just now, wncsnow said:

It reminds me a little of January 2022 

Jan 2022 is an analog.

18 minutes ago, Carvers Gap said:

Just tagging on to @Matthew70's post...Here is the Euro Weeklies (ensemble) make from a week ago and compared to todays run for December 30th.  There is a PNA ridge which is likely just temporary.  There is a -NAO whose duration is TBD.  The Rex block relaxes.  This could easily flip back, but that is big change.  

Want to guess what caught the trend?  The Euro control of all things.  The extended version of the deterministic run possibly sniffed out out this cold front at full range(360 hours).

 

This is one of the biggest and most widespread changes toward colder on the EPS mean when going from 2 weeks out to one week out. In reality, most of the colder change has been just since the Friday runs! It’s all because the -NAO got much stronger and pushed back from the NE despite the strong Aleutian ridge remaining!

 Would snowman and MJO mind taking their constant arguing to PM? It’s cluttering up the thread with useless BS.

18 minutes ago, PhiEaglesfan712 said:

lol, January isn't coming close to 21 inches of snow. The snowiest January since the 2016 storm was 2022, and that was 15.3 inches, and 2018 is the only other year since then that has even topped 10 inches.

I'd be willing to bet that January ends up with less than 10 inches of snow and an above average temperature departure.

17 minutes ago, MJO812 said:

Another bold statement.  Some people haven't learned and its only December. 

 PhiEagles, please read my post again. I said 21” minimum for Jan+, alone. I didn’t say Jan, alone. In other words, I was not including Dec in my 21”+ prediction.

2 hours ago, donsutherland1 said:

Is is possible that these charts also have an algorithmic issue? Here's the GEFS from NCEP's site:

Even though I posted the WxBell charts, I admit that there are often discrepancies in their tele charts vs NOAA. For example, check out the initializations:

NOAA is -1.8 today (which is what’s actually listed for today) and it’s forecasted to rise to -1.5 tomorrow.

But WxBell has -2.5 today and with it headed down to -2.9 tomorrow!

 It seems like WxBell often has wider variations up and down among other things.

52 minutes ago, bncho said:

Central Park may hit 4+" for December with 12/23 and 12/26. That's a great signal for the rest of the winter over there.

It sure is. I already posted after the first storm a prediction of 21” minimum for Jan+, alone, on top of whatever Dec ends up with.

Look at how much the US population weighted HDD rose on the EPS mean from the 12/17 12Z run to the 12/22 0Z run for 12/28-31: 25 HDD (from 74 to 99)! This is from a way BN 74 to a NN 99. Normal is 100 HDD.

12/17 12Z HDD run in purple on left

12/22 0Z HDD run in purple on left

4 hours ago, Carvers Gap said:

Amplified patterns with an NAO and cold…definitely worth watching.  

Look at how much the EPS has cooled for the lows of Dec 30th in just 6 runs thanks to the pushback from the strengthening -NAO despite the Aleutian ridge not budging!
It has cooled this much from the Friday 12Z run, an amazing amount for an ensemble mean over such a short period:

- Roxboro, NC 12F from 38 to 26
- Charlotte 14F from 40 to 26
- CAE 14F from 43 to 29
- SAV 15F from 48 to 33
- ATL 18F from 45 to 27
- Chattanooga 19F from 41 to 22
- Nashville 19F from 42 to 23
- Birmingham 20F from 47 to 27
- Tupelo 19F from 48 to 29
- Chicago 13F from 30 to 17
- Tulsa 11F from 43 to 32

12Z 12/19 EPS:

0Z 12/22 EPS:

52 minutes ago, NorthHillsWx said:

The December 28 system has trended from the Canadian maritimes to the mid Atlantic due to blocking on the GFS over the last 4 runs. Definitely some volatility with unresolved strength of blocking over eastern Canada 

 Look at how much the EPS has cooled for the lows of Dec 30th in just 6 runs thanks to the pushback from the strengthening -NAO despite the Aleutian ridge not budging!
It has cooled this much from the Friday 12Z run, an amazing amount for an ensemble mean over such a short period:

- Roxboro, NC 12F from 38 to 26
- Charlotte 14F from 40 to 26
- CAE 14F from 43 to 29
- SAV 15F from 48 to 33
- ATL 18F from 45 to 27
- Chattanooga 19F from 41 to 22
- Nashville 19F from 42 to 23
- Birmingham 20F from 47 to 27
- Tupelo 19F from 48 to 29
- Chicago 13F from 30 to 17
- Tulsa 11F from 43 to 32

12Z 12/19 EPS:

0Z 12/22 EPS:

1 hour ago, MJO812 said:

Eps is now correcting with the blocking. Its hard to take these models seriously in the long range.

Courtesy of another forum

This is a great GIF! Note that this major evolution of the EPS over this one week period of runs has occurred with the Aleutian ridge not budging but at the same time the -NAO gets stronger and forces the rise of the PNA/big colder E US change from the NE!

EPS NAO for late month as of one week ago: ~-1

EPS NAO for late month as of today: ~-2.5

37 minutes ago, MJO812 said:

Eps is now correcting with the blocking. Its hard to take these models seriously in the long range.

Courtesy of another forum

Look at how much the PNA has risen for a week from now:

From ~-2 as of 2 weeks out

GEFS:

EPS:

To ~0 one week out:

GEFS:

EPS:

 New video this evening from BAMWx (see link below) (I haven’t watched it yet)(don’t know why it shows twice but couldn’t fix it)

Summary from @bncho

Here were my main takeaways from this video:

1. Dec 29-31 will trend colder, like it has been for the past few days.
2. He thinks there'll be a big storm favoring NE for the first week of January; his top analogs like 1996 and 2000
3. Somewhere between the end of Dec and the start of Jan, he thinks that WWBs will happen, causing:
- the death of La Nina 
- -EPO by early Jan, but no +PNA
- MJO to move very quickly and finally get unstuck thru phases 2, 3, 4, etc., finally getting back into 7 by around Jan 15 (just in time for prime climo)
4. He likes the fact that the PV is on our side of the hemisphere, and he thinks it'll stay there
5. The models are not seeing the cold in the long-range

TL;DR: BAM WX believes that there will be a prolonged period of cold and stormy weather from Jan 15 to Feb 1. The first two weeks of January will likely offer shots of cold, but with relaxations in between.

 I continue to have a concern about certain WxBell maps being off. I’ve discussed the CFS being wacky and mainly too cold a number of times with@donsutherland1. But I also can’t figure out why their Euro Weekly (EW) maps are always colder than the ECMWF’s own EW maps! To me it just tells me that the WB EW maps are significantly too cold, period, which remains a concern. Why are they too cold? It’s definitely not due to climo base differences because if anything the in-house uses warmer climo (last 20 years), not colder, vs WB’s 1991-2020. Warmer climo means colder in-house anomaly maps, the opposite of reality! So, that makes the discrepancy even worse!

 Here’s examples from today’s EWs:

1. For Jan 12-18th:

ECMWF: AN ~80%, BN ~2% of US

WxBell: why do they have…

- AN in only ~1/3 of US vs 80% on in-house?

- BN ~25% of US vs only 2% on in-house?

————-
2. For Jan 19th-25th:

ECMWF: AN ~50%, BN ~ 3% of US

WxBell: why do they have…

- AN in only ~15% of US vs 50% on in-house?

- BN ~50% of US vs only 3% on in-house?

 MJO is in day 3 (12/17-19) of the 3rd phase 8 of this month:

11 hours ago, 40/70 Benchmark said:

January is going to be +PNA and the season will average -WPO....very strong statistical evidence. 

The models are pretty unanimous on continuing the -WPO into Jan and the strongly -WPOs in Dec strongly support a -WPO as we know. We also know that the -ENSO -PNA stats since 1983-4 suggest good support for a +PNA Jan. But both the Euro Weeklies and extended GEFS continue to show a -PNA throughout Jan (see images below). Are you saying these models are totally wrong and will correct toward +PNA? If so, why do you think they’re going -PNA? Persistence? (even though I’ve seen the EW predict PNA changes and do well).

57 minutes ago, LakePaste25 said:

Yeah and he even states this earlier. I’m not necessarily trying to call him out for being wrong but i’d like to know what has changed and is giving us a more canonical Nina. 

 

 
Today, I asked Eric to address his earlier thoughts about Feb having good prospects to go against the grain of warm Niña Febs should La Niña fade early. He implied that, regardless,

we’re not doing enough.

I then asked him, “What do you mean that we’re not doing enough? How’s ENSO looking to you for Feb?”

 His answer:

I would like to see a big and slow MJO event to go across the entire Warm Pool in January and I am not seeing that. 

These Convectively Kelvin Waves are moving us towards El Nino of course, but the westerly wind bursts from them aren’t as strong or sustained as I’d like them to be to zonally advect the warm pool eastward more quickly. 

Our only ticket out of this crap mid to late winter is to push the warm pool east enough to extend the pacific jet to a point where we get a +PNA/+TNH/+NAO pattern instead of a -PNA/+TNH/+NAO. That seems less likely to me than say a month or so ago given how the Warm Pool has behaved to this point

@40/70 Benchmark

 FFC is forecasting 4 days of 70s highs in ATL: 12/24-7 with 12/28 in the mid 60s. As has been said, the 4 days of 70+ in late Dec would be pretty historic although not as high as a few years that had 5-6 days of 70+ in late Dec.

5 hours ago, 40/70 Benchmark said:

I don't understand why he feels as though the warm pool needs to shift to allow for +TNH??? We have had intervals of it in this regime previously both last year and in 2022 ...

The data indicates that -WPO this severe in December is very likely to yield a -WPO in the seasonal mean moving forward, furthermore, we haven't had sn issue establishing -EPO ridges in this west warm pool regime.

 Looking at strong -WPO Decembers since 1950 verifies your statement for a -ENSO that’s in Dec and continues through JF per RONI.

 I count 10 strong -WPO Decembers during -ENSO winters. Here’s how the subsequent WPO ended up for JF averaged out:

2013-14: -WPO

2010-11: -WPO

2005-6: +WPO

1995-6: -WPO

1983-4: neutral WPO

1964-5: neutral WPO

1962-3: -WPO

1961-2: -WPO

1956-7: -WPO

1955-6: -WPO


 So, the tally for the JF avg is 7 -WPO, 2 neutral WPO, and 1 +WPO. So, these 10 strong -WPO Decembers during -ENSO decently favored -WPO for the average of JF fwiw. Both are favored to be -WPO but Jan is the most strongly favored for that.

 Out of these 10, 7 Jans had BN temps in the SE. The ones that didn’t were 1965 (NN), 2006 (AN), and 1957 (AN). But Feb leaned AN, which isn’t surprising with -ENSO.

21 minutes ago, michsnowfreak said:

Yesterday's weeklies were the warmest and they corrected cooler again today. The weeklies past 2 weeks, if they are correct, are like the old "broken clock is right twice a day" saying.

Indeed, the warmest Euro Weeklies run so far this season is still yesterday’s as todays is slightly less warm during several weeks in the E US overall. So, slightly better than yesterday but still ugly overall for cold lovers in the E US overall. It doesn’t look as good as two runs ago that were all NN to slightly BN throughout the E US 1/12-2/1. Todays for that period is mainly AN in most of the E US for that 3 week period. Consistent with that, today’s doesn’t show signs of a building +PNA in the means like the run from 2 days ago showed.

 A year ago at this time the EW were quite cold for much of Jan, which got me so excited and verified very well.

 As always when it’s warm, I’ll continue to hope it busts badly.

4 hours ago, gtg947h said:

We're closing on a house just south of Atlanta Jan 2nd... I don't need that

You can relax now. The 12Z Euro has no storm, which was fully expected due to the 0Z coming out of nowhere in semi-fantasyland and with hardly any EPS support. But the 12Z does look solid cold as early as the PM of 12/29 and lasting through 12/31 fwiw. However, its E US trough is stronger than other 12Z ops and is thus currently an outlier for the cold. Regardless, the colder trend seems to be there. So, we’ll see. 
 

 Edit: The 12Z EPS has no support for a synoptic scale SE snowstorm as they support a mainly dry shot of cold.

4 hours ago, bluewave said:

This has to be the most extreme -WPO +EPO dipole that we have seen in December. Lead to the unusually strong ridge out West with the -PNA for such a strong -WPO. Record Pacific Jet and historic flooding in the Pacific Northwest. 
 

Strong December -WPO 500 mb composite more -EPO snd weaker Western U.S. ridge 

 Indeed, this combo has been a rarity in at least Dec. Looking at history for Dec, I looked to see the last time there was a strong -WPO dominating with a neutral or +EPO. It looks per the current December’s numbers that there will end up a strong -WPO while there will probably be a weak +EPO average (with the 3 +EPO periods averaging longer than the 3 -EPO periods).

 The last half month+ long period within Decs when there was anything similar was the first half of 1995 (extreme -WPO and weak +EPO), the first half of 1966 (very strong -EPO and neutral EPO), and Dec 7-23, 1956 (extreme -WPO and moderate +EPO).

 Over a shorter timeframe, Dec 1-10 of 2012 had a very strong -WPO while there was a moderate +EPO.

56 minutes ago, gtg947h said:

We're closing on a house just south of Atlanta Jan 2nd... I don't need that

 The roads from this highly unlikely 0Z Euro still in semi-fantasyland (mainly Dec 30th there) snow out of nowhere (and only one of the 50 EPS members (#30) has anything like this) would be fine by Jan 2nd per the same run. So, you’d just be left with beautiful scenery for your closing.

 If this were to somehow happen though, there’d be many very upset members NC/TN north. They’d be giving @suzookand @dsaura hard time! So, maybe it’s better it not happen lol. I don’t think they’ll need to worry about this occuring.