GaWx

No snakes today and a great walk with mid 60s temp and dewpoints near 38 along with a nice NW breeze.

Cool time lapse of the big mid-March snowstorm in Evergreen, CO, located at 7.2K ft 20 miles WSW of Denver or 10 miles SW of Golden: https://m.facebook.com/WeatherNation/videos/3-days-worth-of-snow-in-24-seconds/732334295379764/

On this date in 1892 - A winter storm in southwestern and central Tennessee produced 26 inches of snow at Riddleton, and 18.5 inches at Memphis. It was the deepest snow of record for those areas. (David Ludlum) Also on this date in 1892, Nashville got blasted with 17.0” of snow (17" on 3/17)! This was and still is the heaviest calendar day of snowfall on record there by a good margin. And it fell after 4.3” fell the prior two days! Chattanooga got 0.9” on 3/17 and 0.3” on 3/18. Knoxville got 3” though it was recorded on 3/18. Atlanta got 0.3” 3/17-18.

I’ve taken thousands of walks and until yesterday evening I had never seen three snakes in one walk. I don’t know if I’ve even seen two though I may have once or twice. 99% of the time I see none. So, seeing three yesterday was so ridiculously improbable! Two were poisonous and both apparently were Copperheads of different types. I’d post pics of them here but can’t due to attachment limits. Temperatures were in the 70s while dewpoints were in the 50s. The breeze was light.

There are some model hints that the period around 3/23-5 might include interesting wx in a good portion of the SE. Keep in mind that “interesting wx” and “winter storm” are not one and the same even though a winter storm is obviously interesting.

The models are near unanimous in showing a sub -20 mean 10 mb (strat.) wind at 60N on March 15th. That would be the 2nd most negative 10 mb wind in March since records started in 1959.

March of 1843 was truly amazing! From David Ludlum: Confirmation that the cold and snowy regime of March 1843 was widespread across the Southland came from a new observing post in southwestern Arkansas. In 1840 Nathan D. Smith of Washington; Hempstead County, near Texarkana, commenced a series of very good records which continued at least until the opening of the Civil War. The period from 1840 to 1859 was published in tabular form by the Smithsonian Institution in October 1860, and the record in manuscript is available until April 1861.° March 1843 (35.3°) was the coldest month in Dr. Smith's record save January 1856 (34.0°). His maximum of 70° came on the 30th, the minimum of +6° on the 16th. There were two 4-inch snowstorms, on the 15th and 24th-the same dates that Natchez received a like covering. On another occasion glaze formed on trees, and on another sleet fell.

Beautiful dry spring wx is expected again the next two days.

I just noticed that the unrounded ONI peak (NDJ) was revised down slightly from +1.97 to +1.95: https://www.cpc.ncep.noaa.gov/data/indices/oni.ascii.txt The RONI peak remained at +1.49 (OND)(border of moderate and strong): https://www.cpc.ncep.noaa.gov/data/indices/RONI.ascii.txt

Yesterday was quite nippy here in the ATL area with 50s and 20 mph winds. Today was beautiful and felt much warmer with 60s highs, much lighter winds, and sunshine. It was a great day for walking at the park I was at. The water was high due to last week’s 4-5” of rainfall. I saw several turtles on the lake’s edge.

Same with the 18Z GFS it appears. The Euro suites have generally been colder. We’ll see which comes closer.

Yesterday’s was the coldest Euro Weeklies map for 3/18-25 since the first one issued. See image below. That doesn’t equate to wintry precip. even if it were to verify. It means a cool period overall would be on the way, including frost and freeze potential. In the meantime a short cool period is on the way prior to then early next week. In addition, the last week of this month has been looking cool on each run though it wouldn’t be as cool per how it is on the run.

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.