vortex95

No season prior has had two very close passes to any of the islands w/ both at hurricane-strength. All areas "pay the piper" sooner or later when it comes to hurricanes. HI now, FL 2004 and other years, New England 1938-1960, the GA coast in the 1890s (3 hurr landfalls, 2 in one season!), etc. Why is Hawaii generally not favorable for TCs most of time? Gt this write-up some years ago. Very strong El Nino disrupts the typical flow/circulation regime, and makes it more favorable. ----- A TC approaching the Hawaiian Islands will often get sheared due to strong upper southwesterlies putting too much stress on the vertical structure of a TC moving westward in the slower but more dense trade flow over only marginally warm water. The shape and size of the NPAC basin means that, particularly in summer w/ the shorter wavelengths of the upper westerlies, there is usually room for more than one ridge or one trough in the middle and higher latitude flow. The Gulf of AK therefore often becomes home to a strong vertical high pressure cell, while troughing may prevail farther to the W near the coast of Asia and Japan. The rounded shape of the Gulf of AK fits well w/ the shape of the high w/ the high usually centered close to 45N latitude. A strong high at that latitude over the oceans can be considered a type of blocking high of great vertical extent. A strong blocking high tends to induce a cutoff low centered 15 deg S of the high center, which would place the low at 30N. This low pressure circulation in the weaker flow of summer is often not easy to detect in the surface flow except for a slight cyclonic shear w/ the easterlies increasing going northward and a slight curvature in the isobars along w/ increased clouds and showers. The longitude of these pressure features w/ the high at 45N and the low at 30N is usually near 160W. Thus, by extension, over the Hawaiian Islands still farther to the S and SE at 20N between 155W and 160W, this area experiences during this very common flow pattern of summer and fall a broad band of southwesterlies aloft, which is detrimental to TCs.

Some EPS members are bullish on the medicane (see attachment). Why they refuse to call these for that they are is perplexing, They have been documented since the 1940s, and some clearly have become fully tropical in nature. Like this one from 2020 (strongest medicane on record I think). https://en.wikipedia.org/wiki/Cyclone_Ianos Contrary to what this post says (link below), medicanes are not extremely rare, not are they rare, not when you go back and look history of them. There have been 92 systems documented since the 1940s, and counts prior to 1990s are likely too low. https://x.com/MatthewCappucci/status/2098869390833807409 /

Excellent point and observation. It shows 2024, for instance, when it was so suppressed during the peak, wasn't just fluke. It now has happened 2 more times, all in a row? That is non-trivial, and definitely warrants a lot of study. And all 3 seasons w/ the peak squashed, it all has been for different reasons. Are the more reasons why this could happen? Not necessarily happens again next year, but what is the true range of possibilities here? I would argue there are more. This all goes into understanding TCs and environments more, and eventually leads to better forecasts!

What part of an ocean basin is warmer or cooler than avg is a factor for TC b/c it impacts the general atmospheric circulation, and I bet for each tropical basin, it is a different configuration that aids or knocks down TC development/maintenance! Yes, the El Nino is very impressive, but I would be a bit reserved as to "El Nino is the strong on record, that means everything associated w/ it as to regional sensible wx is made more intense or worse." The atmosphere does not work on a linear curve, and unexpected deviations in parts of the globe occur more often that it is thought, but many focus on the more "classic" impacts historical and run w/ that. Given we are in uncharted territory, that may mean atypical results in certain cases.

I do not think it works that way, at least in a linear fashion. OHC is dissipated by other means in the season transition. All the OHC in the world is meaningless for TCs if the atmosphere does not cooperate. Look how how things were leading up to the 2024 season, and yes, it was active, but far from the 220+ ACE forecast (161 for the season). The peak climo of the season was taken out big time by unusually warm mid-level temps in the MDR along w/ the lack of instability, and the ITCZ unusually far N which negated robust tropical waves off Africa. Failure mode can come from things outside the traditional wind shear/TPW/SST when it comes to TC seasons, so using a single parameter or two will give limited forecast skill. Also, 1982-83 was a very strong El Nino year, and 1982 was suppressed, and 1983 was even more suppressed (lowest # of NS in the satellite era w/ 4). So would caution thinking next season is "all set."

In the large picture, it just goes to show there is a *lot* more to TC genesis than low wind shear, high TPW, and warm SSTs. The 3 alone are not enough. Some questions, the larger circulations that modulate things, like the MJO, Walker Circulation, subtropical high, and Hadley Cell, as some examples. Small deviations in these can mean big for sensible wx as far as TCs go, and they are not all fully understood esp. how they interact w/ each other, and alongside the most dominate cycles/circulations El Nino/La Nina. We know why the MDR is shutdown now, but outside of there? I do not think there have been much study as to cycles/more or less favorable for the subtropics and mid-latitudes. There have been some Atlantic seasons not nearly as suppressed as this one, and atypically large amount of ACE for the season is from TCs that form outside the tropics.

That quite impressive for Sep. Major dust outbreaks are usually done by early August in more typical seasons. Throw this in w/ wind shear?

We now have the lowest Atlantic ACE season-to-date -- 4.4 units as of 9/6. This is the lowest in the satellite era, and prior, since 1941. Given TC records are more incomplete as you go further back, this record today is even more outstanding, as historical seasonal ACE, prior to the satellite era especially, is too low.

Want to see an unexpected large-scale difference from other years going into a very strong El Nino? The area above 80N barely got above freezing this summer. See here: https://ocean.dmi.dk/arctic/meant80n.uk.php No other summer since records began in 1958 has been this cold, and I looked at other very strong El Ninos, and all got to a mean of 1 C at least for the summer. Since this is an avg over large area, 1 C is a significant in this case. So this begs the question, how could this impact things as to what we typically expect in a very strong El Nino? Such as <gasp!> the upcoming winter for the CONUS? Is the AO, and by extension, the NAO, impacted? I often wondered if we could get a wicked -NAO during very strong El Nino, what would come out of that? @CoastalWx likely would come up w/ this scenario. "Well, we saw what happened in the epic -NAO in 2009-10. Hmm, since the Mid-Atlantic got crushed, and much of New England missed out, maybe that means the STJ active and warmth pushed N, and the cold pressing more S, that would make SNE in "snow weenie heaven!!!!" I could also add in @ineedsnow here as to thinking that! Also, since I am not an uber winter weenie, is there any actual difference between the AO and NAO? You look at NOAA here, and I don't see anything. The graph looks a lot like NAO phases. https://www.climate.gov/news-features/understanding-climate/climate-variability-arctic-oscillation

That's good historical info. The only item I would as in, is "how strong was El Nino in those years?" Strength of El Nino can be a big factor. And the presence of El Nino is not always a "slam dunk." The type of El Nino is important. Modoki El Nino, which has the highest SST anomalies in cntrl tropical Pacific rather than the ern, that can lead to an epic season, like 2004! Want to see an unexpected large-scale difference from other years going into a very strong El Nino. The area above 80N barely got above freezing this summer. See here: https://ocean.dmi.dk/arctic/meant80n.uk.php No other summer since records began in 1958 has been this cold, and I look at other very strong El Ninos, and all got to a mean of 1 C at least for the summer. Since this is an avg over large area, 1 C is a significant in this case. So this begs the question, how could this impact things as to what we typically expect in a very strong El Nino? It might make no difference overall, but what about on more regional levels? And I am not just talking about Atlantic TCs later season, but other things like the upcoming winter for the CONUS? Is the AO, and by extension, the NAO, impacted? How that sets up or its phase in a given winter has big implications for NAMR!

Another "dud season" record. 4.4 ACE units through 9/6 for the Atlantic is the lowest season-to-date ACE in the satellite era, and prior, going back to 1941. Given TC records are more incomplete as you go further back, this record today is even more outstanding, as historical seasonal ACE, prior to the satellite era especially, is mostly too low.

I had never heard of lantern files until now. Are they endemic to New England? Worse than stink bugs?

@CoastalWx rejoicing?

For the next generation GOES satellites (2032), the plan is to have hyperspectral sounding capabilities onboard. This is far better than the current GOES sounder sensor, and I think will revolutionize mesoscale forecasting, and may make RAOBs obsolete. In a 512x512 km area, it is said it can take over 16,000 soundings every 11 sec!

Not good, but I do find GFS MOS is ok, better than the NAM MOS of the time. NAM does do better in CAD situations though. But the RRFS is coming, much to @CoastalWx's dismay! LOL. Which reminds me, does MOS exist in any form for the HRRR/ECMWF and other models?