GaWx

Most of the ATL area got well over 2” of rainfall for the event ending yesterday and a similar amount is likely for Fri-Sat. Flood watches are already up.

I thought this thread and others similar to it are supposed to be for forecast discussion of any aspect of wx that any poster wants to post about rather than being restricted to just discussion of wx a particular member reading the posts wants. Am I mistaken? Anyway, whether or not any particular member wants or cares about potentially the coldest period in 2 months near and just after St. Patrick’s Day, I’m going to continue to post about it, regardless, whenever I have the chance and feel like it. Otherwise, why does this thread even exist? I find many aspects of wx interesting.

No change from the above. Ups and downs with a short chill early next week and a potentially longer and colder period starting around St. Patrick’s Day. The St. Patrick’s cold could be intense for mid to late March. Hard freezes in much of the SE wouldn’t be a shock as we will have a very weak SPV through the rest of the month favoring -NAO/-AO and mid to late March El Niños of 1881, 1885, 1906, 1914, 1915, 1926, 1940, and 1983 had hard freezes. This obviously could be overdone but the 12Z Euro (AI) has 850s WAY BN even based on 1981-2010 climo with below 0C well down into FL! Will stupidity become a reality? We could very well see the coldest (in the absolutes, not just in the anomalies) since Jan 21st-22nd! Stay tuned ITT for further updates as they become available.

Model consensus is suggesting a short chilly period in one week and a potentially colder period in about two weeks (near/just after St. Patrick’s Day).

Keep in mind that if one were to go by RONI or MEI peaks, 2023-4 was a moderate rather than a strong El Niño.

The very inaccurate extended models fwiw suggest stupid cold vs late March normals to occur in the SE after midmonth similar to El Niños of 1881, 1885, 1906, 1914, 1915, 1926, 1940, 1983. This would be 2-3 weeks after the upcoming strongest of season strat 10 mb wind reversal. The SE is way overdue for Nino late Mar stupidity. Look how often it occurred through 1940. As the great philosopher once said, winter ain’t over til it’s over.

ACE level is never close to a foregone conclusion.

This is about the most impressive widespread cold rain of the season to date for the main CAD regions with many areas in the upper 30s, including here in much of the northern half of Atlanta metro. Definitely feels like mid-winter! Moderators, please pin this. TIA

https://en.m.wikipedia.org/wiki/Accumulated_cyclone_energy Top 10 ACE years/snowfall following cold season 1933 NYC: 52.0”; BOS: 62.7” 2005 NYC: 40.0”; BOS: 39.9” 1893 NYC: 39.2”; BOS: 64.0” 1926 NYC: 22.3”; BOS: 41.1” 1995 NYC: 75.6”; BOS: 107.6” 2004 NYC: 41.0”; BOS: 86.6” 2017 NYC: 40.9”; BOS: 59.9” 1950 NYC: 9.3”; BOS: 29.7” 1961 NYC: 18.1”; BOS: 44.7” 1998 NYC: 12.7”; BOS: 36.4” AVG NYC: 35.1” vs 28.5” mean (23% above mean) all years since 1868-9; 1 MAN, 5 AN, 0 NN, 2 BN, 2 MBN; 60% above median AVG BOS: 57.3” vs 43.1” mean (33% above mean) all years since 1890-2; 2 MAN, 3 AN, 4 NN, 1 BN, 0 MBN; 70% above median If you get a chance, calculate the mean/median for these same 10 years for Detroit. Each season’s snowfall can be obtained here: https://www.weather.gov/wrh/Climate?wfo=dtx I’m curious to see what you find. Also, DC folks can go here for their snow: https://www.weather.gov/wrh/Climate?wfo=lwx

Went through a line of severe thunderstorms S of ATL near McDonough a little while ago during a trip to ATL. The line had gone through ATL, itself, a little earlier. The temp is only 56, about 20 colder than before the line. That’s a sharp cold front!

In addition to the extra-tropical W Pac, look at how much colder WB’s CFS map is vs the TT CFS map off the SE US, E of Australia, and in the W Atlantic off Argentina. All 4 of these areas have below normal/blue shades on the WB map and above normal/red shades on the TT map even though they’re both from the same model for the same month (November). I agree about the importance of the dissipation of that marine heatwave off Japan.

Thank you for the maps! WB results for E 1/3 of US winters: 1. 2019-20: much too cold everywhere 2. 2020-1: excellent Mid-Atlantic to N. Eng to Michigan; too warm SE/TN Valley; much too warm lower Gulf states to Gulf coast 3. 2021-2: excellent N. Eng to Mich; slightly too cold Mid-Atlantic to Ohio Valley; too cold SE/TN Valley 4. 2022-3: much too cold everywhere 5. 2023-4: much too cold everywhere except only moderately too cold deep SE/pretty close FL In summary for these 5 winters: -never too warm Mid-Atlantic to New England to Michigan to Ohio Valley -too warm once SE/TN Valley/Gulf coast states -much too cold most or all areas 3 of 5 -did very well New England to Michigan twice My source for actual: https://psl.noaa.gov/data/usclimdivs/ ——————————————- *Edit to include three added later: 2016-7: much too cold everywhere 2017-8: excellent overall/best of the 8; most areas excellent though SE slightly too cold 2018-9: much too cold everywhere except only moderately too cold Mich and only slight misses New England So, updated summary for all 8: -good to excellent most of New England to Michigan 4 of 8: kudos! -too warm one of 8 SE/TN Valley/Gulf coast states -virtually none of Mid-Atlantic to New England to Michigan to Ohio Valley too warm even once -combined with much too cold most or all areas 5 of 8 times suggests cold bias

I just noticed that the 2/25 and 2/26 extended GEFS runs are colder for 3/10-14 vs earlier runs and that the 2/26 run is significantly colder than earlier runs for 3/20+ fwiw. Perhaps this is the very weak SPV having a say so but who knows? And the extended models can’t be trusted regardless.

Regarding JB’s wondering about a possible +PDO next winter, I now think I know where he got that from. If interested, read this post I just made in the Mid-Atlantic forum, where they were also talking about it:

For winter: -2014-5 and 2015-6 were solid +PDOs. -2016-7 and 2017-8 averaged pretty much neutral -2018-9 was only modestly -PDO -Strong to very strong -PDO since https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat

Now I see that he appears to be getting the +PDO forecast idea from the WB CFS SSTa prog for Nov. based on 10 days of runs with a 1981-2010 base: look how cold it has the IO, the area between Japan and Hawaii, the S Pacific from E of Australia out several thousand miles, the strip from off the SE US to the N Atlantic, and the SW Atlantic to just off S. America. These 5 areas are mainly BN with coldest of -2 to sub -3! Then note the warmth off W N. America with as warm as +2 off Baja. That does look like a moderate +PDO being progged on the WB map for Nov: But compare the WB prog to TT’s CFS SSTa for Nov. (below), which is based on 3 days of runs with a 1984-2009 base: the IO’s coldest is -1.2 (vs -WB’s -2) and the other 4 areas areas are mainly warmer than normal with much of it +0.8 to +2.5 (vs WB’s mainly BN with coldest of -2 to sub -3)! In addition, the area off Baja that has its warmest of +2 on WB is only +1.0 at its warmest on the TT map and is cooler than most of the area from there to off Japan, making it a -PDO being forecasted on the TT Nov map: How can they be so different? Any opinions? The bases aren’t that different and I don’t see for relatively stable SSTa’s how 10 days worth of runs would make much difference vs 3 days of runs. I think the main problem may be with WB’s algorithms.

0Z AO forecasts for 2/13-20 2/6: GEFS -3.5; EPS: -3.2 2/7: GEFS -3.0; EPS: -2.8 2/8: GEFS -3.2; EPS: -2.5 2/9: GEFS -2.7; EPS: -2.5 2/10: GEFS -2.2; EPS: -2.1 2/12: GEFS -1.2; EPS: -1.1 Actual for 2/13-20: -0.6 Although both did horribly, the EPS was slightly less horrible. I’d go F for GEFS (avg miss -2.0) and F+ for EPS (avg miss -1.8)

Yep, 95-96 would be an obvious bet for him if the PDO were to switch to positive just like that La Niña winter’s PDO switch. And then if he were to give up on the PDO switching, he could still fall back on 2010-1 with its strong -PDO Niña. Got to keep business going strong!

It would be good for the E US overall, but I’ve seen no evidence whatsoever that the PDO will flip. That’s especially the case with La Niña likely coming. As speculated at another subforum, Bastardi is probably trying to drum up business because he already said a -PDO/La Niña next winter would probably mean a warm one. So, now he seems to be backtracking a bit with this very highly speculative +PDO talk. This isn’t surprising because warm E US winter forecasts don’t work well for business.

Absolutely. He’s done this in the past in giving early hints about a warm winter forecast only to backtrack by trying to find a reason to go colder or at least sow doubt about warmth. When was the last time he went warm throughout the E 1/3 of the US and stuck with it? I can’t even recall anything resembling that. His cold bias for the E US is awful.

I was curious about Bastardi saying something about the PDO possibly flipping for next winter. So, I just looked at the SSTa progs from the CFS, CANSIPS, and NMME for as far as the models go out (Nov to Jan). Anyone can do this easily and quickly. Whereas they all clearly show La Niña forming, none show anything even remotely suggesting a change to +PDO. If anything, they show a restrengthening of the -PDO with the very warm waters from Japan eastward through most of the Pacific persisting and the waters off our W coast cooling some.

I was curious and for that reason at TT I just looked at the SSTa progs for the CFS, CANSIPS, and NMME for as far as the models go out (Nov to Jan). Anyone can do this easily and quickly. Whereas they all clearly show La Niña forming, none show anything even remotely suggesting a change to +PDO. If anything, they show a restrengthening of the -PDO with the very warm waters from Japan eastward through most of the Pacific persisting and the waters off our W coast cooling some.

We finally reached the coldest normal mean of any day in the Arctic, Feb 25th. Compare that to mid to late Jan for a good portion of the US, including the SE. For about the next two weeks, the daily normals only very slow warm and are still only near Jan normals. Only afterward (after Mar 10) the warming of normals accelerates. There have been many winters when the coldest Arctic day was in Mar, especially recently.

We finally reached the coldest normal mean of any day in the Arctic, Feb 25th. Compare that to mid Jan for much of the SE. For about the next two weeks, the daily mean normals only very slow warm and are still only near Jan normals. Only afterward (after Mar 10) the warming of normals accelerates. There have been many winters when the coldest Arctic day was in Mar, especially recently.

Since long term models are so accurate , I looked at them closely: -Euro Weeklies warmest yet through 3/24 -Recent CFS ensemble runs about coldest yet for 3/10-17 along with AN precip. -So, for 3/10-17, the Euro Weeklies have gone from cold a few days ago to NN now. That compares to recent CFS ens being BN to MBN. -So, huge disagreement mid March. Whereas I’d love for the CFS to be right, I’m for now going for the Euro to be closer based on how this winter has gone. But I’m going to watch the forecasted strongest major SSW of the season that’s predicted ~Mar 3 along with the PNA/NAO/AO possibly going +/-/- by 3/10 to hopefully cause the Weeklies to bust too warm in mid March. -Whereas Mar 3-9 is a high confidence period to average mild in the SE, Mar 10-17 is an extra low confidence period for whatever. And don’t forget that Mar 1 could have a bit of a wintry surprise for some of the CAD areas.