WPAC: HAISHEN - Post-Tropical

[euro6208]

I would love to see a list of atlantic systems that exceeded dvorak/satcon/adt that were stronger because of recon. I bet many of them than ones that were weaker or similiar.

Looks don' matter. No mention of Cold Medium Gray, Cold Dark Gray, White Thick, Spiral, CCC, CDO pattern etc LOL

If the dvorak scale is so widely used, then why does the atlantic ignore it most of the time?

Because RECON///

[NotoSans]

Haishen is still pulling off a full W ring and a >+19C eye. If it can hold this for just a few more hours, perhaps the JTWC will upgrade it to a Cat 5 at 18z.

I've noticed that on some storms lately, including Maysak, they seem to wait until after it's peaked and starting do weaken to upgrade it to peak intensity for some reason

They did that with Bualoi as well, which they horribly underestimated. It was easily a Cat 5 like Haishen and probably got up to 150 kt (according to a well-timed SMAP pass). The JTWC assessed peak appearance — a 19C eye with a very thick W ring — as a 120 kt Cat 4, and once an EWRC was clearly taking its toll, they upgraded it to 125 kt.

For Bualoi it depends on what type of conversion factor you are using because SMAP’s raw data is 10-minute sustained winds.

Using a 0.93 conversion factor as recommended by WMO would yield 140kt, but a more conservative 0.88 yields 148kt.

But yes I’d argue Bualoi is a category 5.

[NotoSans]

Note that latest AMSU only comes at 925mb/126kt which would further drag down SATCON value, so it seems unlikely for JTWC to upgrade to category 5 for the time being.

Irma’s highest AMSU is 910mb/158kt. For Dorian it’s 910mb/145kt. Remote sensing techniques performed very well for Irma but not so much for Dorian.

[euro6208]

Note that latest AMSU only comes at 925mb/126kt which would further drag down SATCON value, so it seems unlikely for JTWC to upgrade to category 5 for the time being.

Irma’s highest AMSU is 910mb/158kt. For Dorian it’s 910mb/145kt. Remote sensing techniques performed very well for Irma but not so much for Dorian.

Many typhoons were also higher AMSU than Best Track.

Don't you think maybe because of recon, the readings were incorporated into the estimates?

[NotoSans]

Note that latest AMSU only comes at 925mb/126kt which would further drag down SATCON value, so it seems unlikely for JTWC to upgrade to category 5 for the time being.

Irma’s highest AMSU is 910mb/158kt. For Dorian it’s 910mb/145kt. Remote sensing techniques performed very well for Irma but not so much for Dorian.

Many typhoons were also higher AMSU than Best Track.

Don't you think maybe because of recon, the readings were incorporated into the estimates?

No.

[aspen]

Note that latest AMSU only comes at 925mb/126kt which would further drag down SATCON value, so it seems unlikely for JTWC to upgrade to category 5 for the time being.

Irma’s highest AMSU is 910mb/158kt. For Dorian it’s 910mb/145kt. Remote sensing techniques performed very well for Irma but not so much for Dorian.

AMSU did do well with pressure estimates of both Irma and Dorian; it was spot-on with the latter. Maybe this means the actual pressure of Haishen is in the low to mid 920s.

[Highteeld]

TPPN10 PGTW 041532

A. SUPER TYPHOON 11W (11W)

B. 04/1450Z

C. 23.11N

D. 133.09E

E. ONE/HMWRI8

F. T7.0/7.0/D1.5/24HRS STT: D0.5/03HRS

G. IR/EIR

H. REMARKS: 05A/PBO IRREG EYE/ANMTN. WMG EYE SURROUNDED BY W
YIELDS AN E# OF 6.0. ADDED 1.0 EYE ADJUSTMENT FOR W, TO YIELD A
DT OF 7.0. MET AND PT AGREE. DBO DT.

I. ADDITIONAL POSITIONS: NONE


YOUNG

[euro6208]

Ooo 140 knots now?

TPPN10 PGTW 041532

A. SUPER TYPHOON 11W (11W)

B. 04/1450Z

C. 23.11N

D. 133.09E

E. ONE/HMWRI8

F. T7.0/7.0/D1.5/24HRS STT: D0.5/03HRS

G. IR/EIR

H. REMARKS: 05A/PBO IRREG EYE/ANMTN. WMG EYE SURROUNDED BY W
YIELDS AN E# OF 6.0. ADDED 1.0 EYE ADJUSTMENT FOR W, TO YIELD A
DT OF 7.0. MET AND PT AGREE. DBO DT.

I. ADDITIONAL POSITIONS: NONE


YOUNG

[euro6208]

When was the last time a 7.0 atlantic system occurred and upgraded to a 5 WAY BEFORE recon?

Usually they are upgraded when only at 6.0 or 6.5...

Hard truth.

[NotoSans]

When was the last time a 7.0 atlantic system occurred and upgraded to a 5 WAY BEFORE recon?

Usually they are upgraded when only at 6.0 or 6.5...

Hard truth.

Igor'2010 was T7.0 from both subjective agencies (TAFB and SAB) but NHC held it at 135kt due to ADT. No recon during peak.

Again, Atlantic has a very small sample of category 5 which cannot yield any significant conclusion even from a statistical perspective. Katrina and Rita are also two category 5s which run very close to Dvorak.

[galaxy401]

When was the last time a 7.0 atlantic system occurred and upgraded to a 5 WAY BEFORE recon?

Usually they are upgraded when only at 6.0 or 6.5...

Hard truth.

When was the last time you discussed about a storm without throwing excuses of "recon" and "Atlantic"? You just throw in any Atlantic hurricane that reached Cat 5 as a scapegoat. All you have been doing is spamming the same posts constantly without actually contributing to the topic at hand.

Every time you give an intensity estimate, we can probably lower it by 10-20 kts to get the actual intensity. No way this storm is 155 kts. Is it a Cat 5? Probably, but comparing it to those very strong WPAC typhoons isn't reasonable yet (unless Haishen intensifies more).

[NotoSans]

To be fair there are researches supporting the claim that Dvorak underestimates storms at higher intensities. Knaff 2010 studied the bias of Dvorak - for T6.5 it is -4kt and for T7.0 it is -8kt.

But the study is based purely on Atlantic samples, so the researchers did not calculate biases for T7.5 or T8.0 (since there are simply no samples).

It may be that Dvorak just does poorly in Atlantic storms (one theory is that the tropopause temperature is higher in the Atlantic, therefore storms find it more difficult to produce cold convection). Or Dvorak does have a systematic bias.

But the bias is not significant to the point that Dvorak systematically underestimates storms by 10kt or above.

And we have more remote sensing techniques in recent year (not adjusted by recon data - I would like to see concrete evidence proving the opposite). Some storms underestimated by Dvorak did well in remote sensing. Some were the opposite.

Link to the research:
https://journals.ametsoc.org/waf/articl ... d-Tropical

[NotoSans]

Latest JMA forecast track brings Haishen very close to Minamidaito so we may see some valuable surface observations. Any track wobble affects whether the island will be hit by the eye/eyewall. Haishen should have weakened some by the time it reaches the islands, but any ground truth (even a pressure reading) is better than nothing.
 https://twitter.com/homosapieninhk/status/1301944801089081344

[Cunxi Huang]

CURRENT ESTIMATE
Date (mmddhhmm): 09041620
SATCON: MSLP = 917 hPa MSW = 138 knots
SATCON Member Consensus: 134.0 knots
Pressure -> Wind Using SATCON MSLP: 124 knots
Distance to Outer Closed Isobar Used is 205 nm
Eye Size Correction Used is -2.1 knots Source: IR

[Highteeld]

11W HAISHEN 200904 1800 23.3N 132.7E WPAC 135 916

[aspen]

11W HAISHEN 200904 1800 23.3N 132.7E WPAC 135 916

Jeez, they refuse to upgrade this. And they did so well with its RI phase yesterday, only for them to drop back down to typical JTWC underestimating.

[NotoSans]

11W HAISHEN 200904 1800 23.3N 132.7E WPAC 135 916

Jeez, they refuse to upgrade this. And they did so well with its RI phase yesterday, only for them to drop back down to typical JTWC underestimating.

SATCON members are tightly clustered at 135kt (ATMS at 136kt, AMSU at 137kt and ADT at 132kt; SATCON final estimate is 138kt), and even Dvorak is not a clear-cut 7.0 (JMA is at 6.5; JTWC is at 6.5 FT although CI remains 7.0).

So this is really a borderline case where both 135kt and 140kt are justifiable.

[galaxy401]

So this is the third typhoon to move to the Korean peninsula in the last couple weeks. They're still doing a search and rescue for the crew ship that sunk in the previous typhoon and now they have this storm to cause more problems.

[weeniepatrol]

[Hayabusa]

Major models still have some deepening in the next 24 hours and JMA still calling for a 915 mb 110 kt/violent peak in the same timeframe, I don't know if that's even likely to happen.