GaWx

With the MJO being difficult for the models to predict 3-6 weeks out, it’s almost anyone’s guess/way out in noise range. Even just 2 weeks out is often a challenge. The bc CFS (not a good MJO model) and 1/19 Euro Weeklies mean are saying it gets stuck within the top of the circle. But that’s merely the mean of members being all over the place. Being that I like to see it inside, near, or just outside the circle (especially LEFT side), I hope their means happen to verify well though. Could they be mainly in 8-1-2? It’s certainly possible. I just prefer that they be low amp. *Corrected typo…left not right side

To go along with the post above, here are the 18 3”+ RDU snow and/or sleet storms during moderate or stronger El Niños since 1889 that cover Feb 10th+: 2/21/1889: 10.0” 2/10-11/1912: 6.5” 3/3-4/1912: 3.0” 3/6/1912: 3.0” *2/13/1914: 3.8” *2/26/1914: 7.0” *3/22/1914: 3.0” *3/30-1/1915: 3.7” *4/3/1915: 10.0” 3/13/1926: 4.2” 3/24/1940: 7.0” *2/26/1952: 3.5” 2/15/1958: 3.0” 3/1/1969: 9.1” 2/10/1973: 4.5” *3/24/1983: 7.3” 2/16-17/1987: 5.0” 2/27/1987: 5.2” * No Dec/Jan measurable SN Dates: 2/10, 2/10-1, 2/13, 2/15, 2/16-7, 2/21, 2/26, 2/26, 2/27, 3/1, 3/3-4, 3/6, 3/13, 3/22, 3/24, 3/24, 3/30-1, 4/3 -9 during 2/10 through 2/27 -8 during 3/1 through 3/30-1 -1 on 4/3

The brand new 12 run CFS ens, similar to the new Weeklies, looks absolutely beautiful for the 3 weeks Feb 10th-Mar 2, especially Feb 17th-Mar 2, prime time climo for moderate+ Nino’s! So, once again the 3 main extended ensembles are in agreement on calling for about as favorable a pattern as one would want to see looking so far out. They’re still subtly suggesting a good chance for at least one Miller A/GOM low thanks to a characteristic El Niño moist split flow at 500 mb. These models are far from crystal balls and thus could end up being way off, but we like to hunt down potential well ahead of time in these forecast threads and I’d much rather see them than not! Also, keep in mind the nature of ensemble runs (these are the equivalent of 48 member runs (12 runs x 4 members)) tends to reduce the intensity of anomalies. Here are some of the latest 12 run CFS ens maps for the 2nd and 3rd weeks of the aforementioned 3 week period. Feb 17-24: chilly along with wet most of SE Feb 24-Mar 2: similar

I can’t help but love what the new Weeklies are showing for especially 2/12-26, which is similar to recent runs but even colder and wetter. There’s a clear pattern change to a +PNA/-AO/-NAO induced chilly SE along with near to AN precip. This happens to be during a prime time period for Nino winter storm climo. I mean what more can one ask for looking 3-5 weeks out. Man I hope this ends up verifying closely because the SE would be facing the potential of a memorable mid to late Feb (possibly going into early Mar). Week of 2/12-19: hint of Deep South Miller A low: Week of 2/19-26: similar

Based on the timing of recent extended models (besides the likely cool to cold 1/30-2/1), I’m looking to see the +PNA ridge start to repump ~2/12-3 along with the possible return of the -AO. Hopefully that will hold up. That would start showing up at the end of the 16 day GEFS/GEPS on ~the 1/27-8 runs and on the 1/28-9 EPS. I found this elsewhere for way out on 3/4 on yesterday’s weeklies fwiw:

1. 1/30-2/1 will be interesting to follow as it is on the 6Z gfs quite cold (though not as cold as current), but it is colder than any other recent run and is an outlier vs GEFS. Also, it is mainly dry other than mtn upslope and far NE NC/E VA as the cold mainly follows the precip. Regardless, this period offers a good chance for a break in the middle of the mild pattern with a cooldown to at least normal. 2. 1/28 on GEFS shows what could be a +2 NAO, which would be the highest for any day in met winter in over 8 years.

I'll be quite surprised if there isn't at least one storm to track mid-Feb on. I have a feeling that the mid Feb MJO and beyond position will be pretty crucial though it is just one factor even if often a major one. Consider that for the 2nd winter in a row that intense SE cold is occurring during strong "warm" phases thanks to high latitude blocking.

Most indications suggest that the next ~3.5 weeks will be mainly burned. That’s what we have to work with as it looks now. So, I’ve accepted that as likely and have already moved on instead of dwelling on it. Thus, now the hope is for what happens afterward. Regardless of what will end up happening prior to ~Feb 12th, the potential from that point on remains as high as ever based on a combo of the extended models and analogs. Arguably, it is even higher for mid-Feb onward as snowless Dec/Jan analogs are hinting at. All it takes is one big snow and the season could easily be AN for most in the SE. Thus a mid-Feb pattern change could easily still be early enough to make it an AN snow winter in much of the SE.

When I click on the link, it won’t let me see the actual tweet. It instead goes to a page asking me to sign-in. But I don’t have an account. I don’t get it because I normally can view a linked tweet despite not having an account. Are you able to embed this tweet in your post? The extended 1/18 GEFS fwiw agrees with the average of the last 12 CFS ensemble runs in having a pattern change to significantly colder in the SE that first occurs ~2/12-15 and extends through late Feb due to a combo of a solid +PNA/Aleutian low (SE 500 mb hts go BN) and -AO. SE precip anomalies hint at a mid or late Feb GOM low, with a nice ST jet/split flow likely helped by El Niño. Yesterday’s Euro Weeklies also agree. But before mid-Feb, all 3 agree on mild to warm dominating late Jan through early Feb. Thus the end of the two week models might continue to look ugly for another ~10 days. So, I’m hoping for and leaning toward an abrupt pattern change near mid-Feb that is similar to some other Nino winters that I showed yesterday (1914, 1919, 1924, 1952). We’ll see whether or not 2024 ends up to be similar. I’m optimistic but none of us have a crystal ball. And keep in mind that in the SE it often only takes one big storm to make it a snowy winter.

But with it being a strong El Niño, the equivalent of Tom Brady is fortunately in at QB!

Fwiw hot off the press this is the average of the last 12 CFS 4 member ens runs for 2/22-2/29: this follows a mainly pretty mild first half of Feb; then sustained significantly colder first comes in near midmonth and intensifies; strong +PNA and -AO 2nd half of Feb; also a weak -NAO

At Raleigh, these four moderate or stronger El Niño winters had no measurable SN Dec and Jan but soon afterward the pattern abruptly changed between Feb 6 and Feb 14: 1913-14: - After an even shorter and less intense cold snap in mid Jan than the current one, the 3.5 week long period Jan 15-Feb 7 averaged 6 AN, which included 5 highs between 66 and 73 Jan 28-Feb 4. Then suddenly they plunged to average 10 BN Feb 8-Mar 23 with freezes on 26 of 44 days and 4 significant winter storms, which included 17.2” of SN. 1918-9: - 5 AN Jan 14-Feb 8 including 6 highs of 65-70 Jan 19-31 - 3.3” SN fell Feb 9 1923-4: - After 3 days of highs of 66-68 Feb 3-5 and AN Jan 29-Feb 5th, Feb 6th-29th averaged 7 BN along with 2.4” of SN. Another 2.1” fell in March. 1951-2: - 5 AN Dec 29-Feb 13 including 6 highs in 70s - 5 BN Feb 14-Mar 18 with 4.7” SN https://www.weather.gov/wrh/Climate?wfo=rah

Indeed. Here was the Dec 26th Euro Weeklies run for Jan 15-22, warmer than normal in most of the E half of the US just 20 days in advance of what’s in reality a very cold week for most of the country:

Look no further than how warm the Dec 26th run of the Euro Weeklies had for the week of Jan 15-22 (2-7 F WARMER than normal in most of the E US) vs current progs of 10-20 F COLDER than normal in most of the same areas) for a perfect example of how far off it was just 20 days prior! So, the Dec 26th run’s Jan 15-22 will end up ~12-27 F too warm! Twenty days from now is only Feb 7th. So, for those who feel confident about mid Feb and beyond, keep this in mind as regards the severe limits of our abilities to accurately forecast out just 3 weeks. Also, keep in mind moderate+ Nino climo, which often favors Feb 15th and beyond for the best stretch of the winter. Due to limits on attachments (I hate them) and thus instead of reposting them here, here’s the link to my post about this along with the Euro Weeklies maps in the TN Valley forum:

I assume you realize that you turned out to have the right idea with Knoxville's actual low being 0 and Tri's actual low being +3 vs yesterday's 12Z GFS progging -14/-13. I counted at least the four prior runs as well as the 18Z having something similar. However, interestingly in case you didn't see it, the subsequent 3 runs starting with the 0Z suddenly warmed ~10 and thus were much closer to reality. We agree that it takes near perfect radiational conditions for the GFS to be close in these situations when it's extremely cold. That may have happened in some cities of TN from what I've read. If anyone could be more specific about these cities and post the 1/16 12Z GFS prog compared to what verified, please let us know. But most of the time, extreme GFS runs like that 12Z run you noted for Knoxville and Tri seem to end up quite a bit too cold. I first learned about this cold bias over fresh snowcover from a pro met whom I know. I see that the -14 progged Knoxville low was a whopping 44 BN! So, the actual low of 0 was a "mere" 30 BN.

Indeed! Here was the Dec 26th run of the Euro Weeklies for Jan 15-22: Right after this, the Euro Weekly runs for Jan 15-22 progressively got much colder. Just one week later (Jan 2), there was this for the same period: And here’s the final map for the same period, which was released two days ago (Jan 15th): So, in hindsight, the Weeklies map released on Dec 26th ended up a humongous warm bust and it was issued only 20 days prior to the start of the very cold week! When combined with the tendency for somewhat of a warm bias on the Weeklies, there’s no telling what mid Feb+ will bring.

More on these 9 (moderate or stronger Nino with no measurable snow Dec and Jan): -Even though 1/3 of them had less snow than climo Feb 15+, the 9 together still averaged almost a normal full season just for Feb 15 through April with 5.4”. This compares to an average of 3.6” for Feb 15+ for the 22 moderate+ Nino seasons that had measurable SN in either Dec or Jan. So, keep the snow away til Feb lol. -Keep in mind that even the 3.6” is ~1” snowier than climo for all years for just Feb 15+. So, the 5.4” for Feb 15+ for the 9 years is double climo. -Feb/Mar temp anomalies for these 9: 1903: +1/-3, 1914: -6/-6, 1915: +1/-9 1919: -3/+1, 1924: -4/-3, 1941: -6/-7 1952: 0/-3, 1983: -4/-1, 1992: +1/-1 Avg of the 9: Feb -2/Mar -4

OISST for 3.4 has been dropping quite a bit meaning a super is still not yet a lock even if still likely:

Twice for non measurable: -1948-9, 1949-50 -1990-1, 1991-2 -11 seasons without measurable -So, 2 of 11 seasons w/o measurable had no measurable the subsequent winters https://www.weather.gov/wrh/Climate?wfo=rah

RDU had no measurable snow in both Dec and January during 9 of the 31 moderate or stronger El Niños since 1888-9. Here’s how much measurable they got Feb+: 1903: 0” 1914: 17.2” 1915: 14.3” 1919: 3.3” 1924: 4.5” 1941: 1.8” 1952: 4.7” 1983: 11.8” 1992: 0” So, 3 of the 9 had big late winters. In the list above, 1914’s 17.2” is the snowiest Feb+ of the 31 moderate+ Nino winters on record while 1915’s 14.3” is 2nd snowiest of the 31. 1983’s 11.8” is 4th snowiest. So, 3 of the 4 snowiest Feb+ moderate+ Nino winters had no snow in both D & J. OTOH, 2 of the 9 were shutouts (1903 and 1992). (Of the 31 total, 7 had no snow Feb+.) The average Feb+ for the 9 Dec-Jan shutouts was 6.4” or near the longterm average. Most of this (average of 5.4”) occurred Feb 15+. So, 2024 may very well be a very long season. But as shown above, the average is derived from a wide range from 1/3 of them being very big late seasons and 2/9 of them being shutouts. It will be interesting to see where 2024 ends up.

Indeed, that swing in Feb-Mar of 2021 of nearly 11 in just 29 days was amazing. About the only comparable swing I’ve seen is this one: 2/15/56: -4.6 3/2/56: +4.7 This one was a swing of 9.3 in just 16 days. Arguably, this one may be even more amazing.

There have been only 6 -NAO winters during the last 44 (only 14% of them) since 1979-80. The prior 30 winters included 16 -NAO (53%) winters! OTOH, the % of summers with a -NAO has gone up sharply. From 1950-2006, there were only 15 (26%) -NAO summers. But just since 2007, there have been 12 (71%) -NAOs during summer! Something significant has changed at both the winter and summer seasonal levels to affect the NAO in opposite ways. This isn’t just from randomness. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table

If we weren’t in a strong El Niño, I might agree. However, based on the RDU average snow strictly for moderate or stronger El Niños (31 of them…so a large sample), I have to respectfully disagree about Valentine’s Day being a crucial day this year: Nov: 0.2” Dec: 0.9” Jan: 2.0” Feb 1-14: 1.0” Feb 15-28(9): 1.4” Mar: 1.7” Apr: 0.4” So, during these winters, the 2nd half of Feb (the month with the most snow on average despite it being the shortest month) actually averaged more than the 1st half. It may even be the most active half month of the entire winter. And then there’s still March, a pretty active month, itself.

Looking at the daily indices during 6”+ RDU snowstorms since 1950: whereas a +PNA was fairly common (though far from being required), a -NAO actually wasn’t. The average NAO was actually pretty close to zero with a fairly even mix of -NAO, neutral NAO, and +NAO. So, whereas a -NAO helps with SE cold, itself, it doesn’t seem to be associated with big SE (at least RDU) snowstorms. That was a surprise to me when I complied the stats a few years back.

Per met Alan Huffman's surface compilation of major RDU snowstorms (not talking about ice or sleetstorms meaning sig CAD not necessary) -best bet is for an Arctic high center, preferably strong and sprawling, to come down into the Dakotas as opposed to further west, which allows for cold enough air to soon after reach the SE in advance of potential precip. -as opposed to waiting longer for more modified/stale cold first coming into the W, which also often has trouble getting over the Apps -as opposed to a plunge of the high down into TX/AR/LA, which is often the coldest option but is also usually too dry to allow for moisture return into the lower levels prior to a warmup; high plunges like these often result in extreme cold/dry followed by too rapid a warmup due to warming on the backside of the high -and then for the large Dakotas high to move SE, ESE and then E through the Ohio Valley thus hopefully still keeping it cold enough in the SE at least as high as 850 mb (with or without significant CAD) -at the same time you want moist WSW to SW 500 mb flow over the top of the lower level cold in the SE US while the Arctic high is still in/near the Ohio Valley. If the 500 mb flow over the SE is instead WNW or even W, it usually is too dry in the SE for a big storm if any storm at all -timing is obviously crucial being that big SE snows are infrequent -best bet at 500 mb is for a split flow of the N stream bringing down but not plunging the Arctic high combined with a moist S stream simultaneously bringing in plentiful moisture from the Pacific and especially Gulf over the top of the S extent of the Arctic high -more specifically, a +PNA with a 500 mb trough centered near the Mississippi River is what I look for -Most of the memorable major SE snowstorms are associated with a weak to very weak GOM surface low that doesn't go too far inland, if inland at all other than over FL. These are usually Miller As.