WPAC: DUJUAN - Post-Tropical

[1900hurricane]

It really shouldn't. JTWC's DT should have been 7.0. Still, for the reasons I mentioned above I would have hedged lower than an intensity corresponding to a 7.0, but higher than one associated with a 6.5. I highly doubt JTWC will go any higher than their FT though.

[Yellow Evan]

I'd go 135 knts at 6z if I was the JTWC based on appearance only due to lack of reliable intensity estimates. Don't feel comfortable thinking this is a Cat 5 without at least some sort evidence

[euro6208]

Latest forecast brings at least 60 mph to Taipei just outside of sustained typhoon winds. That could change...

[euro6208]

WDPN31 PGTW 270900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 21W (DUJUAN) WARNING NR 23//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 21W (DUJUAN), LOCATED APPROXIMATELY 320 NM EAST-
SOUTHEAST OF TAIPEI, TAIWAN, HAS TRACKED WEST-NORTHWESTWARD AT 08
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS THE EYE HAS ENLARGED TO 43 NM AS HIGHLY SYMMETRIC DEEP
CONVECTIVE BANDING WOUND TIGHTER INTO THE EYE. THE INITIAL POSITION
IS BASED ON THE EYE FEATURE AND EXTRAPOLATED FROM A WELL-DEFINED
MICROWAVE LOW REFLECTIVITY CIRCULATION CENTER IN THE 270507Z AMSU-B
PASS WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 125 KNOTS IS
BASED ON CONGRUENT DVORAK ESTIMATES FROM PGTW, KNES, AND RJTD. UPPER
LEVEL ANALYSIS INDICATES THE SYSTEM REMAINS IN A LOW (05-10 KNOT)
VERTICAL WIND SHEAR AREA WITH IMPROVED RADIAL OUTFLOW ENHANCED BY A
MICROSCALE ANTICYCLONE ALOFT. ADDITIONALLY, ALONG-TRACK SEA SURFACE
TEMPERATURES REMAIN CONDUCIVE AT 29 DEGREES CELSIUS. THE CYCLONE IS
TRANSITIONING TO A NEW STEERING SUBTROPICAL RIDGE (STR) CURRENTLY
ANCHORED OVER SOUTHEAST CHINA.
3. FORECAST REASONING.
A. NO SIGNIFICANT CHANGE IN THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TY 21W WILL MAINTAIN A WEST-NORTHWESTWARD TRAJECTORY AS THE NEW
STEERING STR BUILDS THEN FLATTENS OUT TO THE NORTH. THE
AFOREMENTIONED ENVIRONMENTAL CONDITIONS WILL PERSIST AND PROMOTE
FURTHER INTENSIFICATION OVER THE NEXT 12 HOURS, PEAKING AT 130 KNOTS.
AFTERWARDS, THE TYPHOON WILL GRADUALLY WEAKEN AS IT BEGINS TO
INTERACT WITH TAIWAN. THE RUGGED MOUNTAINOUS TERRAIN OF NORTHERN
TAIWAN WILL SIGNIFICANTLY ERODE THE SYSTEM BUT WILL STILL EMERGE AS A
MODERATE TYPHOON IN THE TAIWAN STRAIT BY TAU 36. TY 21W WILL MAKE A
FINAL LANDFALL IN CHINA SOUTH OF FUZHOU, THEN RAPIDLY DECAY MAINLY
DUE TO FRICTIONAL EFFECTS. BY TAU 72, THE SYSTEM WILL BE REDUCED TO A
30-KNOT DEPRESSION.
C. TY DUJUAN WILL WEAKEN TO BELOW WARNING CRITERIA AFTER IT
DEFLECTS NORTHEASTWARD TOWARDS THE YELLOW SEA NORTH OF SHANGHAI
BEFORE TAU 96. THIS IS IN RESPONSE TO A MID-LATITUDE TROUGH
APPROACHING FROM THE NORTHWEST. DYNAMIC MODEL GUIDANCE REMAINS IN
GOOD AGREEMENT UP TO LANDFALL INTO CHINA THEN SPREADS OUT
SIGNIFICANTLY. IN VIEW OF THIS, THERE IS HIGH CONFIDENCE IN THE JTWC
FORECAST TRACK ONLY UP TO THAT POINT.//
NNNN

[euro6208]

Eye temp is the warmest it's ever been +17.4C and tops remain very cold -73.1C.

JMA has this moving very close to Taipei with Iriomote and Isihigaki likely in the huge eye.

[Dave C]

It would have to move nw instead of wnw for the eye to reach those islands. The eyewall though could clip them on the north side.

[wxman57]

I've been conversing with Josh Morgerman over the past few days. He should be in Taiwan shortly. Josh was on a plane enroute Taiwan 5 hrs ago. He'll be heading down the east coast to intercept Dujuan. Should be quite a storm. Satellite loop indicates a westerly motion now. Could hit just north of the center of Taiwan. Taipei may not get hit too badly if that's the case.

[Dave C]

The western ridge taking over steering now, city of Hualien right at 24 deg. lat. looks to get raked by north eyewalls easterly winds but hopefully land interaction will knock it down some.

[1900hurricane]

Much more of the eye is in the warm medium grey than it was several hours ago, but isn't quite completely clear. Microwave and Japanese radar shows a little bit of weakness in the northern eyewall and this might be all it's taking to get the eye to completely clear. Dujuan still remains a very impressive typhoon.

[1900hurricane]

Uhhh...

TPPN10 PGTW 271510

A. TYPHOON 21W (DUJUAN)

B. 27/1432Z

C. 22.73N

D. 125.33E

E. FIVE/MTSAT

F. T6.0/6.5/D1.0/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 34A/PBO LARGE EYE/ANMTN. OW SURR BY BLK (+0.5 ADJ
FOR WHITE) YIELDS A DT OF 6.0. PT AND MET AGREE. DBO DT.

I. ADDITIONAL POSITIONS:
27/1304Z 22.62N 125.73E MMHS


MARTINEZ

I don't want to badmouth JTWC or anything, but just because it's a subjective Dvorak analysis doesn't mean you can do whatever you want. Even if the white doesn't meet the width requirement (i'm not sure it didn't), the eye is very clearly warm medium grey. It's not even a few isolated spots like it was yesterday.

[Yellow Evan]

That meets the width requirement and that eye is WMG. No offense to the JTWC, but these Dvorak analysis have been driving me nuts the way they've been done.

[NotoSans]

JTWC has a bad habit of classifying WMG eyes as OW ones.
I would place the intensity at 130 kt right now. Not really close to a 7.0 IMO.

[NotoSans]

JTWC back to T6.5 at 18Z. The white ring is not thick enough for a 7.0 though.

TPPN10 PGTW 271819

A. TYPHOON 21W (DUJUAN)

B. 27/1732Z

C. 23.03N

D. 124.90E

E. FIVE/MTSAT

F. T6.5/6.5/D0.5/24HRS STT: D0.5/03HRS

G. IR/EIR

H. REMARKS: 34A/PBO LARGE EYE/ANMTN. WMG EYE SURROUNDED BY B
(ADDED 1.0 FOR 24NM W RING) YIELDING A DT OF 6.5. MET AND PT
AGREE WITH DT. DBO DT.

I. ADDITIONAL POSITIONS:
27/1304Z 22.62N 125.73E MMHS


CHAPPOTIN

[Alyono]

remember, the rain is the big thing for Taiwan

[Yellow Evan]

It's really close. I've measured it through the SSD floater via a ruler and got a thick enough W to support T7.0. So, yes I have have gone with T7.0.

[1900hurricane]

Yeah, the white ring has shrunk in thickness a little. I wonder if it might have to do with what appears to be the beginning stages of a developing outer eyewall based on Japanese radar.

[NotoSans]

JMA kept the intensity at 100 kt at 18Z. They have also shifted the forecast track slightly northward, and Dujuan is now forecast to hit the Yonaguni Island directly. Perhaps we will get some valuable observations.

[euro6208]

WDPN31 PGTW 272100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 21W (DUJUAN) WARNING NR 25//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 21W (DUJUAN), LOCATED APPROXIMATELY 220 NM SOUTHEAST
OF TAIPEI, TAIWAN, HAS TRACKED WEST-NORTHWESTWARD AT 10 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
SHOWS THE SYSTEM HAS MAINTAINED A LARGE 44-NM EYE AND CONTINUES TO
HAVE HIGHLY SYMMETRIC DEEP CONVECTION WRAPPING TIGHTLY INTO THE EYE.
THE INITIAL POSITION IS BASED ON THE EYE FEATURE WITH HIGH
CONFIDENCE. THE INITIAL INTENSITY OF 125 KNOTS IS BASED ON DVORAK
ESTIMATES FROM PGTW, KNES, AND RJTD. UPPER LEVEL ANALYSIS INDICATES
THE SYSTEM REMAINS IN A LOW (05-10 KNOT) VWS AREA WITH EXCELLENT
DIVERGENCE. THE CYCLONE IS CURRENTLY TRACKING ALONG THE SOUTHERN
PERIPHERY OF A STR EXTENSION.
3. FORECAST REASONING.
A. NO SIGNIFICANT CHANGE IN THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TY DUJUAN WILL MAINTAIN A WEST-NORTHWESTWARD TRAJECTORY
THROUGH TAU 48 AS THE SYSTEM REMAINS UNDER THE STEERING INFLUENCE OF
THE STR AND THE EXTENSION SLOWLY RETREATS TO THE EAST. EXPECT TY 21W
TO BEGIN TO DECREASE IN INTENSITY DUE TO LOW OHC AND SOME LAND
INTERACTION IN TAU 12 AS WELL AS COMPETING WITH THE MOUNTAINOUS
TERRAIN OF TAIWAN AND LOWER SST VALUES OF THE TAIWAN STRAIT BY TAU
24. MAKING LANDFALL IN CHINA BEFORE TAU 36, TY DUJUAN WILL CONTINUE
TO DECAY AS FRICTIONAL FORCES WILL CAUSE THE SYSTEM TO COMPLETELY
DISSIPATE BY TAU 72. ADDITIONALLY, AN APPROACHING MID-LATITUDE
TROUGH WILL FORCE THE SYSTEM TO TURN MORE POLEWARD AT THE END OF THE
FORECAST PERIOD. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGHOUT THE FORECAST PERIOD LEADING TO HIGH CONFIDENCE IN THE
JTWC FORECAST WHICH IS LAID CLOSE TO THE MULTI-MODEL CONSENSUS.//
NNNN

[Yellow Evan]

TPPN10 PGTW 272111

A. TYPHOON 21W (DUJUAN)

B. 27/2032Z

C. 23.15N

D. 124.41E

E. FIVE/MTSAT

F. T6.5/6.5/D0.5/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 34A/PBO LARGE EYE/ANMTN. WMG EYE SURROUNDED BY B
(ADDED 1.0 FOR 28NM W RING) YIELDS A DT OF 6.5. MET AND PT
AGREE WITH DT. DBO DT.

I. ADDITIONAL POSITIONS: NONE


CHAPPOTIN

Wow, so close.

[Yellow Evan]

TXPQ22 KNES 272114
TCSWNP

A. 21W (DUJUAN)

B. 27/2032Z

C. 23.1N

D. 124.4E

E. ONE/MTSAT

F. T6.5/6.5/D0.5/24HRS

G. IR/EIR

H. REMARKS...SYSTEM GAS MAINTAINED WARM EYE AND STRONG CORE FOR PAST
24HRS. DT=6.5 BASED ON WARM MEDIUM GRAY EYE EMBEDDED IN BLACK AND
SURROUNDED BY WHITE RING. MET=7.0 BUT PAT=6.5. FT IS BASED ON DT.

I. ADDL POSITIONS

NIL


...SWANSON

Why no addition for BF?