2026 C and E Pacific tropical activity

[vortex95]

On 9/9/2026 at 10:01 PM, GaWx said:

Thanks for that info.

 It seems that this has been a really bad year for Hawaii! When was the last season as bad as this? And the season is far from over!

-H Lala: extreme rainfall and very strong winds to H force in some cases

-TS Moke: additional heavy rains along with gusty winds only a week after Lala thus hampering recovery efforts

-H Lowell: lots of damage from sustained TS force/gusts to H force W islands, significant storm surge, and very high waves 

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?  Got this write-up some years ago.  Very strong El Nino disrupts the typical flow/circulation regime, and makes it more favorable.

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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.
 

[vortex95]

The HI area had some sig activity 1993 and 1994. 

Polar image attached from Aug 15, 1993, showing annular HU Fernanda to the E and HU Keoni to the SW.

And in 1994, the CPAC was very active.  HU Emilia became the strongest CPAC HU (140 kt) up to this time in mid-July.  Then a week later, Gilma attained peak intensity roughly the same as Emilia in the CPAC.  Then in Aug, HU John  peaked at 150 kt to again break the CPAC record for the strongest storm, and became the longest-lived TC globally until 2023.

The three Cat 5s in 1994 all passed well S of HI, so no direct impacts, but to have that kind of activity is remarkable.  SSTs were running about 2.5 C above avg in the region as mdt El Nino was in taking shape.  Another item that stood out during this time was a very large area of dry air on WV in the central southern Pacific in the tropics/subtropics, so subsidence here implies rising motion synopticly on the other side of the equator in at similar latitudes.
 

[NorthHillsWx]

12 hours ago, vortex95 said:

The HI area had some sig activity 1993 and 1994. 

Polar image attached from Aug 15, 1993, showing annular HU Fernanda to the E and HU Keoni to the SW.

And in 1994, the CPAC was very active,.  HU Emilia became the strongest CPAC HU (140 kt) up to this time in mid July.  Then a week later Gilma attained peak intensity roughly the same as Emilia in the CPAC.  Then in Aug, HU John  peaked at 150 kt to again break the CPAC record for the strongest storm, and became the longest- lived TC globally until 2023.

The three Cat 5s in 1994 all passed well S of HI, so no direct impacts, but to have that kind of activity is remarkable.  SSTs were running about 2.5 C above avg in the region as mdt El Nino was in taking shape.  Another item that stood out during this time was a very large area of dry air on WV in the central southern Pacific in the tropics/subtropics, so subsidence here implies rising motion synopticly on the other side of the equator in at similar latitudes.
 

That’s a stunning storm east of Hawaii. Great grab, could fit the entire big island in the eye 

[vortex95]

HU Polo is in an RI phase now, and it would not surprise me if it over-performs and gets to high-end (150-160 kt).  This tends to occur in very strong El Nino.  We had Patrica in 2015 and Linda in 1997. 

Linda never has a recon in when it was intense, sot its 160 kt peak is estimated, but it is likely it was higher than that.  Look at this VIS image of Linda on 9/12/97.  It was not as small as Patrica, but look at its CDO and very sharp subsidence ring around it.  That is tell-tale sign of high-end intensity!  Probably closer to 170 kt for a peak, but as I noted, NHC does not go above 160 kt for a TC in the absence of recon or other in situ data.  The uncertainty when you get this intense is just too high, but one can say it was highly likely it was at *least* 160 kt!
 

[vortex95]

One other item concerning Polo.  

The only thing that may prevent record territory here is its slow, meandering movement in the next 24 hr.  Yes, NHC notes the high OHC, however, when talking absolute records, everything typically has to be near ideal.  The deep-layer 31 C SSTs, if that "only" falls to 30 C due to upwelling, that can be a factor.  Still very intense, but 1 C difference in SST can be significant, in a relative sense, in this case, again when you are talking record territory.

[vortex95]

Another item on Polo.  It is rare you see a hurricane in the deep tropics in the NHEMI bodily move SE like Polo has for the past 12 hr.

No evidence of a trochoidal eye wobble yet.

I hope there is a recon soon.   Would be a shame to miss it peak intensity!

[Windspeed]

Another item on Polo.  It is rare you see a hurricane in the deep tropics in the NHEMI bodily move SE like Polo has for the past 12 hr.

No evidence of a trochoidal eye wobble yet.

I hope there is a recon soon.   Would be a shame to miss it peak intensity!

Recon should be nailing Polo at or near peak. Also, I concur, no real trichoidal motion yet. The tiny eye is just moving with the subtle low-level westerly flow. There appears to be enough motion that the small eyewall should avoid significant upwelling prior to any internal structural change, which most likely will begin within 24 hours due to the very intense outter concetric banding structure that is developing. I can't see Polo not undergoing an EWRC outside of 24 hours given this appearance. I'll say recon finds an intense Category 5 hurricane of around 155 kts.

[Windspeed]

It is interesting to note that the official intensity estimate by the NHC is outpacing ADT numbers. Raw T# right now is 7.5 but it is important to note that dvorak doesn't always handle tiny eyes well within such an explosive CDO pattern such as this, and I am sure the met on duty that just upgraded Polo is well aware even if we won't get the discussion and explanation until the next package. That being said, numbers are skyrocketing up. Recon should be there by midday. I have little doubt Polo will be a Category 5 and an intense one at that.

[vortex95]

Regarding recons in the EPAC, they were hardly ever done prior to early 2000s, even for very intense systems.  CPAC has always had them for those systems that were threatening HI.

[Windspeed]

Regarding recons in the EPAC, they were hardly ever done prior to early 2000s, even for very intense systems.  CPAC has always had them for those systems that were threatening HI.

Did we not work out something with Mexico with regard to potential threats? Granted, Polo likely avoids landfall, but it will pass close enough to cause problems (i.e. flooding).

[Windspeed]

Polo's eye has warmed dramatically. Also, lightning data has erupted with a distinctive ring that we find on the most intense eyewalls. Also, recon is en route.

[Chinook]

1 hour ago, Windspeed said:

Polo's eye has warmed dramatically. Also, lightning data has erupted with a distinctive ring that we find on the most intense eyewalls. Also, recon is en route.

Marco

[Chinook]

Just now, Chinook said:

Marco

Polo

[olafminesaw]

3 hours ago, Windspeed said:

3 hours ago, vortex95 said:

Regarding recons in the EPAC, they were hardly ever done prior to early 2000s, even for very intense systems.  CPAC has always had them for those systems that were threatening HI.

Did we not work out something with Mexico with regard to potential threats? Granted, Polo likely avoids landfall, but it will pass close enough to cause problems (i.e. flooding).

 Not sure but it makes sense to just go ahead and do a mission for training and research purposes in a dead quiet hurricane season. 

[olafminesaw]

Not sure we're getting that ERC anytime soon after all

[Windspeed]

Not sure we're getting that ERC anytime soon after all

Looks good for today. But you will notice those are some intense outer bands. I'd say a concentric eyewall will most likely develop by tomorrow given that banding structure.

[nycwinter]

would not upwelling be a issue if the storm moves at 2 mph.

[vortex95]

3 hours ago, Windspeed said:

3 hours ago, vortex95 said:

Regarding recons in the EPAC, they were hardly ever done prior to early 2000s, even for very intense systems.  CPAC has always had them for those systems that were threatening HI.

Did we not work out something with Mexico with regard to potential threats? Granted, Polo likely avoids landfall, but it will pass close enough to cause problems (i.e. flooding).

We may have.  The first time I recall a scheduled recon into a EPAC system was Linda in Sep 1997 b/c it was originally fcst to recurve and hit srn CA!  Other than that, it was just the occasional NOAA research mission. 

It may be if the TC is fcst to get intense and is close to Mexico, they do recons.