raindancewx

I know I just made a huge post on the strongest landfalling Gulf Hurricanes, but it's not something I weight highly. It's more that given a choice between a year like 2010 without relevant Gulf hits, and a year like 1961, I'd pick 1961, if all other factors were equal. I do think it's interesting that the stronger La Ninas tend to not see major Gulf hurricanes though (2010, 1973, 1975, 1955, 1998, 1999, lack big hits).

This is how my analogs did last year for anyone curious. I was trying to create a +WPO La Nina based on how similar the Nino 3.4 data in 2021 was to 2007. But I also expected more blocking than that year, with the Apr-Dec NAO correlation (r-squared) around 0.2-0.3 in La Nina years. The -NAO in April was quite strong in 2020, like this year. It's freaking hard to get a major +WPO in a La Nina, but the tendency is that the WPO goes positive in the lowest sea ice extent years, and I knew that heading into last year.

I wasn't making some detailed observation based on any research, but I would bet on a relationship. Quite a few of the ten coldest Februaries in the past 90 years show up for sure (1933, 1936, 1949, 1989, 2019, 2021) for various spots of the US. Look at the fours / fives to hit the Gulf Coast since 1930. https://www.aoml.noaa.gov/hrd/hurdat/All_U.S._Hurricanes.html 1932, (1935), 1948, (1960), 1961, 1965, 1969, 1988 (Gilbert s. of TX), 2004, (2017), 2018, 2020 You can debate if 1935/1960/2017 (SW FL/Keys), 1988 (not US), should count, but you definitely have a lot of cold in those years of cat 4-5 Gulf landfalls. February 1936, February 2019, Jan 1970 are cold to stupid cold after the cat five hits (all El Nino / near El Ninos btw with the fives). Severe cold in Dec-Mar after a 4-5 landfall on the Gulf: December (8/12): 1932 (West), 1935 (East), 1948 (NW), 1960 (SE), 1961 (everywhere), 1965 (west coast), 1969 (east), 2017 (Lakes/NE). January (9/12): 1933 (West), 1936 (all but west), 1949 (west), 1961 (SE), 1962 (everywhere), 1966 (everywhere), 1970 (everywhere), 1989 (west), 2018 (SE) February (10/12): 1933 (West), 1936 (all), 1949 (West), 1962 (north), 1966 (everywhere), 1989 (everywhere), 2005 (sw), 2018 (N Plains), 2019 (Plains), 2021 (Plains) March (7/12): 1949 (West), 1962 (all but NE), 1970 (all but west coast, 1989 (N. Plains), 2005 (NE), 2018 (NE/Montana), 2019 (Plains) Summary of Severe Cold Signal: 1932-33: D-F (West) 1935-36: D-J (East), F (all) 1948-49: D-M (NW, then west) 1960-61: D-J (SE) 1961-62: D-J (all), F (N. US) M (all but NE) 1965-66: D (W), J-F (all) 1969-70: D (East), J (all) 1988-89: J (West), F (all) 2004-05: F (SW), M (NE) 2017-18: D (NE), J (SE), M (NE/Montana) 2018-19: F-M (Plains) 2020-21: F (Plains)

Severe cold snaps tend to occur within a year of the most powerful Gulf Hurricane landfalls. Typically after. Some periods in 1964-65, 1965-66, 1969-70, 1961-62 and 1967-68 are stupid cold in the Plains relatively near Hilda, Betsy, Camille, Carla, and Beulah. Similar to how you had stupid cold after Michael (2/2019) and Delta (2/2021) last year. We'll see how that goes. The other recent monster storm years like 2005 and 2008 and even 2012 had pretty severe cold at times (and snow too). It's just something with the MJO and how the subtropical highs setup in the Atlantic I think. The overall pressure pattern last year was kind of like a blend of 1959-60 (x2), 2007-08, 2008-09, to get the La Nina, warm North Pacific, super +WPO, and net -NAO. It's not an easy thing to replicate historically, but I sort of had the right idea in October with my blend of 1995-96, 2003-04, 2007-08 (x5), 2012-13 (x2), 2019-20. Point is, I'd look hard at the big Gulf years in the 1960s, and then some of the very weak and cold-Neutral years with the warm North Pacific. I already have some pretty solid analogs but nothing definitive yet.

Since 1950, there is no ENSO event where Nino 3.4 has fallen by more than 1.0C from September to Dec-Feb. Keep your eyes on the September readings in Nino 3.4. First few days are 26.5C on the weeklies (centered on 9/1). You need 26.0C in DJF just for a La Nina (-0.5C v. 1951-2010 average of 26.5C).

Happy one year anniversary for the great 9/8-9/8 snow storm. We had snow down to Santa Fe last year. High was 47 in Albuquerque, unbelievable cold for that early in the year.

La Nina? La Not-a. Basically no meaningfully cold water in the 120-170W, 5N-5S zone yet.

The years with the highest Atlantic ACE tend to have active MJO pulses in the right phases during Summer for fun and games later on, when it gets cold. I haven't looked, but I'd expect that the increased frequency of hurricanes in some La Ninas corresponds to different strength for the subtropical high in winter, and can lead to more volatile conditions on the Atlantic side, instead of just the Pacific volatility that often shows up in La Nina winters. The strongest storms hitting the Gulf Coast (1886, 1900, 1932, 1961, 1965, 1969, 2018, 2021 as examples) also tend to occur when the Atlantic flips from AMO phase to another, and that is linked to more pronounced periods with blocking in some of the research.

ACE is pretty correlated to total snow in NYC/Philly, less so in Baltimore/DC/Boston in La Ninas. r-squared is around 0.3 in some spots in around 30 winters. Almost impossible since 1930 to get a big winter for snow without a high ACE total in a La Nina. Not a guarantee, but La Nina goes from ~0% odds for a great winter (+20-30% snow v. average) to 50% if the ACE is high enough. Look at the 11 winters for snow I listed for Baltimore above, and compare them to the lower ACE (<150) years to see it.

PNA has never really correlated that well to December or Fall ENSO values, whether you use Nino 3.4 ssts like I do, MEI, ONI, SOI, whatever. PNA correlation to Nino 3.4 December is 0.1 according to CPC. Very weak. https://psl.noaa.gov/data/correlation/table/corr.table_dec.txt

ACE is sustained winds in every named tropical storm measured every six hours, in knots. That number is squared and divided by 10,000. Each 6-hour ACE value for each storm is summed for the season. So sustained winds of 115 mph (category three) give 100 knots. That value would 100*100 / 10,000, i.e. 1 point. If the storm was 130 kts six hours later, it would 130 * 130 / 10,000. The ACE figures I referred to are for the Atlantic. The six hour time frame for measurement is used because it corresponds to old ship reports and things like that pre-satelite era.

Yep. Especially in the Fall. If you rank Nino 3.4 by month for "coldness", the event last year was most impressive in the Fall. October and November 2020 were both top ten cold ENSO events since 1950. The later/earlier periods were no where near that. These are your coldest ever Novembers in Nino 3.4, using a constant baseline (CPC uses a sliding baseline) of 26.49C. Top ten sounds real strong out of 71 years right? Problem is only like 23 or 24 of the years are La Ninas. So the peak is really only slightly above the middle of the pack for a La Nina, and then it was weaker in winter Spring. 1955 -2.24 1973 -2.16 1988 -1.84 1975 -1.44 2010 -1.43 1999 -1.37 2007 -1.32 1998 -1.25 1964 -1.23 2020 -1.21

That look on the Euro is somewhat similar to at least one of the cold ENSO (non-La Nina) years in the 1960s. Can't remember if it's 1960-61, 1961-62, 1962-63, or 1967-68 but I think at least one of those is similar. The warmth by Indonesia with another big IOD phase is not something I was looking at a few weeks ago.

That bath water by Indonesia seems way more important to the global pattern at the moment than the weak little cold-Neutral look we have. Still a lot of light blue / white (-0.4C to +0.2C waters v. 1981-2010 averages) in the 120-170W, 5N-5S Nino 3.4 zone.

Nino1+2 Nino3 Nino34 Nino4 Week SST SSTA SST SSTA SST SSTA SST SSTA 28JUL2021 22.1 0.8 25.1-0.4 26.7-0.4 28.7-0.1 04AUG2021 21.7 0.7 25.1-0.2 26.7-0.3 28.6-0.2 11AUG2021 20.9 0.1 24.8-0.4 26.5-0.4 28.6-0.2 18AUG2021 20.5-0.1 24.4-0.6 26.0-0.9 28.6-0.2 25AUG2021 20.6 0.0 25.0-0.0 26.5-0.3 28.5-0.3 01SEP2021 20.3-0.2 24.7-0.3 26.5-0.3 28.4-0.3 29JUL2020 20.1-1.2 24.7-0.8 26.3-0.8 28.4-0.5 05AUG2020 19.8-1.3 24.6-0.7 26.3-0.7 28.4-0.4 12AUG2020 19.9-0.9 24.8-0.4 26.4-0.6 28.3-0.5 19AUG2020 19.5-1.1 24.3-0.7 26.0-0.9 28.4-0.4 26AUG2020 20.0-0.6 24.2-0.8 26.1-0.7 28.6-0.2 02SEP2020 18.9-1.7 23.6-1.4 25.8-0.9 28.4-0.4 For this week, +1.4C in Nino 1.2, +1.1C in Nino 3, +0.7C in Nino 3.4, and even in Nino 4 compared to 2020. Last year, conditions were solidly La Nina by now. This is not that. Nino 3.4 is 120W-170W. You have some warm water below the surface at 160W and west. The waters below the rest of Nino 3.4 are somewhat cold but not incredibly. You also have some warmth way at depth which diminishes the totality of the cold signal quite a bit.

It doesn't work reliably in Baltimore/DC and south, but in La Nina years, ACE over 150 is almost a pre-requisite Summer trait for the big NE snowy winters. Pretty sure there are no La Ninas more than +20% or +30% for NYC/Philly snow totals since 1930 when ACE is not at least 150. I know you guys don't live up there, but if you hit 150 ACE in the Summer, you at least have a shot at a lot of Nor'easters with blocking. The big ACE La Nina years since 1931-32 are these, in order of highest ACE: 1933, 2005, 1995, 2017, 1950, 1998, 2020, 1999, 2010, 1955, 1964. If you use Baltimore, the 11-year average snowfall is (44.6+19.6+62.5+15.4+6.2+15.2+10.9+26.1+14.4+18.1+18.6)/11 --> 22.9, and essentially a coin flip for near-normal to snowy conditions using the 1991-2020 snow average. 1933-34, 2005-06, 1995-96, 1999-00, 1955-56, 1964-65 are all near average to snowy using the most recent 30 years. 2020-21 and 2010-11 would probably be snowy patterns too with less bad luck.

All months since March this year have at least resembled the 1961 look nationally, although the placement/extent of the cold matching 2021 has not been perfect. You can see the Summer finished too cold in 1961 compared to this year. My view is you can't treat weak La Ninas in the old days like weak La Ninas today. They tend to be surrounded by warmer waters in the Pacific now. But the old cold-Neutrals years often had that. So that's why a lot of those years are working well as analogs right now. Locally, there is something of a signal in the temperature matches for a very cold December followed by a much warmer late winter. The monsoon in my exact spot has not been strong, but it has been quite consistent for southern NM and Arizona this year. Those areas won't need any cold/extra moisture in winter to remain above average...so my guess is they won't be cold or wet. Here we've been dry with near average temps which is a more mixed signal. The hottest driest cold-ENSO Summers tend to be colder/wetter winters here (1954, 2007, 2011, 2012, 2016, 2020) while the wettest/coldest cold-ENSO Summers tend to be warmer/drier winters here (1933, 1999, 2005, 2008, 2013, 2017). Not quite sure what to do with a Summer with below average hot days and rain yet. Last year had ~88 days hit 90, with ~40% below average rain in Summer. This year is more like 25% below average rain. As of yesterday, only 55 days have hit 90 - fewest since 2008 (64 is average for a year).

If you included the necessary prior conditions to the immediate trigger for the recent flooding, you'd have Henri and all the other flash flood events from the near record wet Summer in Boston and NYC in there, and I'd expect you'd end up a lot closer to 400.

The surface observations are much warmer than last year in Nino 1.2, but also warmer in Nino 3, 3.4 and 4. Have to catch up to last year before we have any chance to surpass it. Aug 2021 v. Aug 2020 at the surface Nino 1.2: +0.76 Nino 3: +0.17 Nino 3.4: +0.14 Nino 4: +0.15

I'm absolutely convinced that those of you in the Northeast are only capable of posting in this thread when unusual things happen in the wide wide world of not-New Jersey. At the end of the day 3 inches of rain in an hour is way more impressive than the west beating old highs by a small amount for five minutes a day whether you want to admit it or not.

Nora remnants provided a nice widespread area of rains out here. I think we have a shot at 1-3 more dying hurricanes helping out through 10/31. Some of my analog matches on US temps/precip show a very wet October for the SW.

The relatively strong intensity of the flooding and tornado activity in the Northeast is reminiscent of Allison - another storm that wouldn't see it's upper dynamics completely destroyed by landfall. I've mentioned previously that I'm looking at 2001 as an analog for seeing similar Nino 3.4 conditions to both winter 2020-21 and July/Aug. After Ida hit, I noticed that the intensity in millbars was near identical to Carla in 1961, an extraordinary powerful hurricane, famous for damaging or destroying something like 60,000 buildings in Texas. The flood threat with Carla was extensive too. You can see the spread was similar in breadth to Ida, just further west due to land falling to the west. If you look nationally, the US weather pattern for temperatures has been very close to 1961 since March. You had incredible heat in the NW for instance in June. Locally, the Jan-Aug high temperatures in 2021 are an incredible match to 1961. Third closest match to 2021 in the past 90 years in 1961. Can't be easy to get this level of heat in the NW in a cold ENSO year given the Earth has warmed in 60 years. So the 1961 June heat is impressive.

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/index/heat_content_index.txt 100-180W subsurface was -0.83 in Aug 2021, compared to -0.80 in Aug 2020. More rain for me today. A rare, long-lasting light rain courtesy of the death of Nora. Monsoon has now matched last year locally, still a month to go.

I like to compare the old footage to the new footage for hurricanes in similar areas. Ida: Carla: Lots of electrical grid damage here - Hurricane Hilda: Hurricane Betsy: - the modern levee system was designed to prevent another Betsy. Kinds of a legendary storm. Hurricane Beulah: Another amazing system Hurricane Camille:

The clustering below of big bad storms reminds of me some periods in the 1930s and 1960s. Carla (1961), Hilda (1964), Betsy (1965), Beulah (1967) Camille (1969) for some comparable Gulf monsters to the recent four. That period from 1964-1969 was pretty rough down there. Freeport (1932), 1933 - several Gulf Coast hits and a nasty stronger Isabel too for the NE, Hurricane "1" in 1934 is kind of legendary in some ways, 1935 had the five in the Keys, and then 1938 had the New England hurricane and a hurricane hit the central Gulf. 1933 is a nuts season, but 1932 doesn't really get it's due. Carla: 1961 (931 mb right before Landfall, similar spot to Laura, likely similar to Laura for winds too) Hilda: 1964 (950 mb at landfall) - stronger Oct 1964 version of Delta in October 2020 (970 mb) Betsy: 1965 (942 mb, hit right near Houma like Ida) Beulah: 1967 (950 mb landfall S. Texas, lots of floods and tornadoes) Camille 1969 (900 mb just around landfall - 175 mph winds based on observations)