Reanalysis questions

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bg1
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Re: 1966-1970 HURDAT reanalysis project

#381 Postby bg1 » Wed Jan 19, 2022 10:20 am

Iceresistance wrote:
bg1 wrote:I'm a bit confused about the unnamed hurricane AL091968. It looks like it was classified as subtropical while it had hurricane-force winds if I'm reading the report correctly and I thought only fully tropical cyclones could be called hurricanes if strong enough (and subtropical cyclones would still be called "subtropical storms")

Wikipedia is saying that this is a 'Subtropical Cyclone'

I see that... Personally I would go with that nomenclature too
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Re: 1966-1970 HURDAT reanalysis project

#382 Postby Hurricanehink » Wed Jan 19, 2022 1:23 pm

Add 1970 to the list of storms with a pre-season and a post-season storm, given the recent addition of a late-November storm.
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Re: Reanalysis questions

#383 Postby GSBHurricane » Wed Jan 19, 2022 1:56 pm

1966-1970 is now out for those who are interested.
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Re: 1966-1970 HURDAT reanalysis project

#384 Postby AlphaToOmega » Wed Jan 19, 2022 3:01 pm

bg1 wrote:
Iceresistance wrote:
bg1 wrote:I'm a bit confused about the unnamed hurricane AL091968. It looks like it was classified as subtropical while it had hurricane-force winds if I'm reading the report correctly and I thought only fully tropical cyclones could be called hurricanes if strong enough (and subtropical cyclones would still be called "subtropical storms")

Wikipedia is saying that this is a 'Subtropical Cyclone'

I see that... Personally I would go with that nomenclature too

I could be wrong on this, but I believe the nomenclature is that "hurricane" refers to any tropical/subtropical cyclone with sustained wind speeds of at least 64 knots.
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Re: Reanalysis questions

#385 Postby tolakram » Wed Jan 19, 2022 4:08 pm

Topics merged, this is the original reanalysis thread. Carry on :)
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Re: Reanalysis questions

#386 Postby DorkyMcDorkface » Wed Jan 19, 2022 7:45 pm

tolakram wrote:Topics merged, this is the original reanalysis thread. Carry on :)

Didn't see it, thanks
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Re: Reanalysis questions

#387 Postby Iceresistance » Thu Jan 20, 2022 11:06 am

With 1966-1970 done, when is 1971-1975 coming out?
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Re: Reanalysis questions

#388 Postby CrazyC83 » Thu Jan 20, 2022 1:07 pm

I think 1971-75 is still at least a couple years ago. Checking out the new findings now.
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Re: Reanalysis questions

#389 Postby Shell Mound » Thu Jan 20, 2022 1:26 pm

CrazyC83 wrote:I think 1971-75 is still at least a couple years ago. Checking out the new findings now.

One interesting case that the recent reanalysis covered is that of Debbie (1969). On 18 and 20 August 1969 Project STORMFURY, as is well known, seeded Debbie with silver iodide, and the metadata indicate that Debbie apparently underwent or commenced eyewall replacement cycles on those two dates. The aircraft recorded a 31% decrease in Debbie’s MSW on 18 August and an 18% decrease on 20 August, respectively. While the reanalysis suggests that the ERCs were the responsible for these changes, what is still unclear is whether the seeding had any impact on the initiation of the ERCs themselves. A close look at the metadata suggests that the seedings did not have much of an effect.

Per aircraft radar, on 18 August the diameter of Debbie’s eye increased from ~24 n mi at 11:55 UTC to ~40 n mi at 17:52 UTC. Debbie’s eye maintained a ~40-n-mi diameter through 12:02 UTC on 19 August. The eye subsequently shrank to ~20 n mi by 18:36 UTC on the same date. On 20 August the diameter of Debbie’s eye fluctuated between ~20–30 n mi throughout the day, but the very last reconnaissance fix, at 23:43 UTC, on that date indicated inner and outer eyewalls whose diameters were ~17 and ~35 n mi, respectively. The first ERC took about a day to complete and the latter started little more than a day later than the first’s completion.

Overall, the progression of the posited ERCs seems to have been fairly normal, so the effects of the seedings, if any, appear to have been rather minimal.
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Re: Reanalysis questions

#390 Postby CrazyC83 » Thu Jan 20, 2022 2:14 pm

Gerda 1969 puzzles me. It had a pressure of 980 mb, yet was considered (and maintained as) a category 3 due to a reading by the Nantucket Lightship southeast of Cape Cod. I have to believe that reading was erroneous (i.e. questionable instrumentation). Combined with reasonable land data later, I'd have knocked the peak intensity all the way down to 75 kt (a drop from cat 3 to cat 1) and disregarded that reading.
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Re: Reanalysis questions

#391 Postby galaxy401 » Fri Jan 21, 2022 2:51 am

So 1969 got a nerf while 1970 was buffed. 1969 had two major hurricane downgrades and two Cat 2s were actually just Cat 1s.

Not surprised about the Inez upgrade. I remember hearing a couple years back that it was going to be upgraded to a Cat 5.

Don't forget that Doria in 1967 got upgraded to a Cat 2 as well.

Biggest surprise was the Azore hurricane in 1970. In addition to the upgrade in the Azores, it also was a tropical storm when it was in the Caribbean. Another unnamed hurricane was upgraded to a Cat 2. How were there so many unnamed hurricanes that year?
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Re: Reanalysis questions

#392 Postby Shell Mound » Fri Jan 21, 2022 7:37 am

CrazyC83 wrote:Gerda 1969 puzzles me. It had a pressure of 980 mb, yet was considered (and maintained as) a category 3 due to a reading by the Nantucket Lightship southeast of Cape Cod. I have to believe that reading was erroneous (i.e. questionable instrumentation). Combined with reasonable land data later, I'd have knocked the peak intensity all the way down to 75 kt (a drop from cat 3 to cat 1) and disregarded that reading.

Additionally, the metadata indicate that satellite imagery at the time showed a sheared system, so the anemometer was probably faulty.
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Re: Reanalysis questions

#393 Postby MHC Tracking » Sat Jan 22, 2022 6:31 am

List of major changes made by the HURDAT team for 1966-70:
Alma 1966: 110->100 kt
Becky 1966: 65 kt->75 kt
Celia 1966: 70 kt->65 kt
Dorothy 1966: 65 kt->75 kt
Faith 1966 had 54 hours of TC points cut
Inez 1966: 130 kt->145 kt
Kendra re-added as a TS, previously was a low after being operationally called a TS
Other new TS added to 1966
2 unnamed TS added in June 1967
TD upped to TS in September 1967
7 TDs removed from 1967
Beulah 1967 now 110 kt at both the Yucatan and Matamoros landfalls, up from 95 and down from 140 respectively
Doria 1967 forms 4 days earlier, up from 75 kt to 85 kt
Fern 1967: 75 kt->65 kt
Brenda 1968: 65 kt->70 kt
Dolly 1968 analyzed as a TS 42 hours earlier than before, peak upped to 75 kt from 70
Unnamed S1 in 1968: 70->75 kt
Gladys 1968: 70->85 kt
TS added in September 1968
A bunch of "TD"s removed
TD 01L 02L, 04L 1969 removed
Blanche 1969 now formed 12 hours earlier
Camille now intensifies much more rapidly
Francelia 1969: 100 kt->85 kt
Gerda 1969: 110 kt->105 kt, landfall: 95 kt->70 kt
10L, 11L and 14L 1969 removed
18L 1969 removed
Inga 1969: 100 kt->95 kt
Kara 1969: 90 kt->75 kt
Laurie 1969: 85 kt->75 kt
Unnamed November 1969 hurricane: 65 kt->75 kt
Martha's landfall in Panama: 60 kt->40 kt
TD added in August 1969
Other TD removed
Celia 1970: 110 kt->120 kt
TS 8 1970: Extended by 8 days, peak upped from 60 kt to 70 kt
August 1970 TD now TS
TD 15 1970: Initial TD phase now TS twice, new portion added where it regenerates into a STC and peaks at 75 kt in the subtropics
1970 "Canada Hurricane": 90 kt->85 kt
Unnamed October hurricane 1970: 65 kt->85 kt
2 new peak season TDs added, 1 post-season TS added to 1970
Multiple TDs removed
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Re: Reanalysis questions

#394 Postby Hammy » Sun Jan 30, 2022 6:23 am

Added/upgraded systems:

1966
Image

1967
Image
Additionally, seven depressions were removed entirely.

1968
Image
Additionally, ten depressions were removed entirely.

1969
19 depressions removed entirely, no new storms added.

1970
Image
Additionally, six depressions were removed entirely.
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Re: Reanalysis questions

#395 Postby Hammy » Sun Jan 30, 2022 6:27 am

Tracks of #4 and #10, both extended and found to have reached hurricane intensity

Image

Image
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