WPAC: CHANTHU - Post-Tropical

[Iceresistance]

This HAS to be between 120 & 140 mph because of that Pinhole Eye, there is no way it's only 90 mph . . .

[aspen]

The large band seen in the 9z pass is gone — only the compact core remains, with no sign of an EWRC in the next 12 hours or so.


Get ready for some stunning ERI imagery…and some more JTWC incompetency. Maybe they’ll do better later on in its life like Goni and Surigae.

[SouthDadeFish]

Truly remarkable rates of intensification ongoing right now. This is much stronger than 70 kt.

[aspen]

Now forecast to peak as a 130 kt Super Typhoon. Given how grossly underestimated Chanthu is, it’ll likely hit ST status a lot sooner.

[Yellow Evan]

CMG trying to wrap around. This is probably a Category 4 hurricane here.

[Hayabusa]

What a very interesting discussion

WDPN32 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (CHANTHU) WARNING NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 16.3N 134.6E
INITIAL INTENSITY: 70 KTS
GEOGRAPHIC REFERENCE: 720 NM SOUTH-SOUTHEAST OF KADENA AB
MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS
SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TY 19W IS UNDERGOING RAPID INTENSIFICATION AT THIS TIME. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY AT THE 1200Z HOUR SHOWED
THAT THE SYSTEM WAS CONTINUING TO INTENSIFY WITH STRONG CONVECTIVE
HOT TOWERS WRAPPING AROUND A WARM SPOT IN THE EIR IMAGERY. EIR
IMAGERY SUBSEQUENT TO THE 1200Z HOUR DEPICTED THE RAPID APPEARANCE
OF A WELL DEFINED, 10NM WIDE EYE, SUPPORTING THE ONSET OF VERY
RAPID INTENSIFICATION. THE INITIAL POSITION WAS PLACED WITH HIGH
CONFIDENCE BASED ON A 071107Z ASCAT-A BULLSEYE, WHICH ALIGNED
PERFECTLY WITH THE WARM SPOT IN THE EIR. THE INITIAL INTENSITY AT
THE 1200Z HOUR WAS HEDGED SLIGHTLY HIGHER THAN AGENCY SUBJECTIVE
AND AUTOMATED OBJECTIVE FIX DATA. INTERESTINGLY, WHILE SUBSEQUENT
UNOFFICIAL FIXES ARE AS HIGH AS T5.0, THE ADT HAS YET TO PICK UP ON
THE EYE AND REMAINS AT T3.5. AS EVIDENCED BY THE RAPID
INTENSIFICATION, TY 19W IS COCOONED IN A VERY FAVORABLE ENVIRONMENT
WITH LOW VWS, VERY WARM SSTS AND RADIAL OUTFLOW. OCEAN HEAT CONTENT
(OHC) IN THE AREA REMAINS VERY HIGH WITH VALUES BETWEEN 150-200
JOULES.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA FROM 071107Z.

CURRENT STEERING MECHANISM: DEEP SUBTROPICAL RIDGE TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T4.0 - 65 KTS
RJTD: T3.5 - 55 KTS
RCTP: T3.5 - 55 KTS
KNES: T4.0 - 65 KTS
CIMSS ADT: 57 KTS AT 071140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
VWS: 5-10 KTS
SST: 29-30 CELSIUS
OUTFLOW: STRONG RADIAL

ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TY 19W IS FORECAST TO TRACK WEST-NORTHWEST
THROUGH TAU 24, THEN TURNING GRADUALLY MORE NORTHWESTWARD THROUGH
THE REMAINDER OF THE FORECAST PERIOD AS THE STR REORIENTS SLIGHTLY
AND A WEAKNESS DEVELOPS IN THE RIDGE TO THE NORTH OF TAIWAN. AS
EVIDENCED BY THE ONGOING DRAMATIC IMPROVEMENTS IN THE EIR
APPEARANCE AND STRUCTURE, THE SYSTEM IS UNDERGOING A PERIOD OF VERY
RAPID INTENSIFICATION (RI). ENVIRONMENTAL CONDITIONS ARE EXPECTED
TO REMAIN VERY FAVORABLE FOR ADDITIONAL RI, OR EVEN EXTREME RI,
OVER THE NEXT 48 HOURS. THE SYSTEM WILL TRACK OVER VERY WARM, VERY
HIGH OHC WATERS FOR THE NEXT 24 HOURS, THEN MOVE INTO AN AREA OF
LOWER OHC. MEANWHILE THE VWS REMAINS LOW AND THE SMALL AREA OF
RADIAL OUTFLOW OVER THE SYSTEM REMAINS FIRMLY IN PLACE. THE RAPID
INTENSIFICATION PREDICTION AID (RIPA) CONTINUES TO BE TRIGGERED
THROUGH TAU 48. ANOTHER PERIOD OF INTENSIFICATION IS EXPECTED TO A
PEAK OF 130 KNOTS AT TAU 72 AS THE SYSTEM MOVES OVER ANOTHER AREA
OF HIGH OHC, WHILE THE OTHER PARAMETERS REMAIN FAVORABLE.
THEREAFTER, DECREASING SSTS AND OHC, AND INCREASING MID-LEVEL VWS
WILL OFFSET THE DEVELOPMENT OF A MODERATE POLEWARD OUTFLOW CHANNEL,
AND LEAD TO SLOW BUT STEADY WEAKENING THROUGH TAU 120. TS 18W
(CONSON) IS LOCATED 700NM TO THE WEST-SOUTHWEST. THE TWO SYSTEMS
ARE EXPECTED TO CLOSE WITHIN APPROXIMATELY 500NM BY TAU 72 BUT
THE PROBABILITY OF BINARY INTERACTION REMAINS LOW DUE TO THE
COMPACT NATURE OF THE TWO SYSTEMS.

MODEL DISCUSSION: NUMERICAL TRACK GUIDANCE HAS COME INTO BETTER
AGREEMENT SINCE THE PREVIOUS RUN. MODEL SPREAD IS 100NM AT TAU 48.
GFS REMAINS THE EQUATORWARD OUTLIER IN THE NEAR TERM, THOUGH
OVERALL IT HAS COME INTO BETTER AGREEMENT WITH THE REMAINDER OF THE
CONSENSUS MEMBERS. AFTER TAU 48, WITH THE EXCEPTION OF NAVGEM, THE
GUIDANCE NOW AGREES ON A TRACK ACROSS TAIWAN, INSTEAD OF THE
EARLIER GFS AND HWRF DEPICTIONS SHOWING A SHARP TURN NORTHWARD. GFS
AND HWRF STILL SHOW A NORTHWARD TURN, BUT NOW DO SO AFTER CROSSING
TAIWAN. SO THE RUN TO RUN INCONSISTENCIES STILL REMAIN, AND THUS
WHILE THE JTWC FORECAST TRACK REMAINS CONSISTENT, THERE IS LOW
CONFIDENCE IN THE EXTENDED FORECAST, THUS ONLY MEDIUM CONFIDENCE.
INTENSITY GUIDANCE IS MIXED, WITH ALL OF THE RAPID INTENSIFICATION
GUIDANCE TRIGGERED, WHILE GFS REMAIN LUKEWARM TO INTENSIFICATION.
THE JTWC FORECAST CLOSELY TRACKS THE RI GUIDANCE THROUGH TAU 48,
THEN REMAINS ABOVE ALL BUT THE COAMPS-TC THROUGH THE REMAINDER OF
THE FORECAST. CONFIDENCE REMAINS MEDIUM HOWEVER, IN LIGHT OF THE
EVEN FASTER RATE OF INTENSIFICATION BEING OBSERVED, AND THE
UNCERTAINTY IN THE TIMING OF LIKELY EYEWALL REPLACEMENT CYCLES.

FORECAST CONFIDENCE:
TRACK 0 - 72 HR: HIGH
TRACK 72-120 HR: MEDIUM
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
NNNN

[Yellow Evan]

TXPQ29 KNES 071415
TCSWNP
CCA

A. 19W (CHANTHU)

B. 07/1130Z

C. 16.3N

D. 134.8E

E. THREE/HIMAWARI-8

F. T5.0/5.0

G. IR/EIR/SWIR/SSMIS

H. REMARKS...CORRECTED FOR INTENSITY. SYSTEM IS EMBEDDED IN BLACK
RESULTING IN AN EMBEDDED CENTER PATTERN DT OF 5.0. THE 1105Z ASCAT PASS
BUILDS CONFIDENCE IN LLCC POSITION. ADDITIONALLY, THE 0940Z SSMIS 91 GHZ
PASS REVEALED INTENSE BANDING OCCURRING AROUND THE LLCC. THE EIR IMAGERY
DISPLAYED A ROBUST CDO FEATURE ON TOP OF THE LLCC WITH CMG THUNDERSTORM
ACTIVITY INDICATING THE SYSTEM IS DEEPENING. THE 24 HR TREND IS DEVELOPING
RAPIDLY. MET IS 4.0 AND PT IS 4.5. FT IS BASED ON DT.

I. ADDL POSITIONS

07/0940Z 16.2N 135.1E SSMIS


...PATEL

[Yellow Evan]

TPPN11 PGTW 071454

A. TYPHOON 19W (CHANTHU)

B. 07/1430Z

C. 16.20N

D. 134.13E

E. ONE/HMWRI8

F. T5.5/5.5/D3.0/24HRS STT: D1.5/03HRS

G. IR/EIR

H. REMARKS: 05A/PBO IRREG EYE/ANMTN. DG EYE SURROUNDED BY W YIELDS
AN E# OF 6.0. ADDED 0.5 EYE ADJUSTMENT FOR W, TO YIELD A DT OF 6.5.
MET AND PT YIELDS 5.5. DBO PT.

I. ADDITIONAL POSITIONS:
07/1106Z 16.33N 134.77E WIND


RHOADES

Why based off PT?

[Hayabusa]

Eye now

2021SEP07 143000 3.6 988.6 57.0 3.6 4.0 6.0 0.5T/hour OFF OFF OFF OFF -31.67 -73.82 EYE 8 IR 2.3 16.25 -134.10 ARCHER HIM-8 20.5

[Hayabusa]

19W CHANTHU 210907 1200 16.3N 134.6E WPAC 85 974
19W CHANTHU 210907 0600 16.1N 135.7E WPAC 65 985
19W CHANTHU 210907 0000 15.6N 136.6E WPAC 50 995

[Hayabusa]

WTJP32 RJTD 071500
WARNING 071500.
WARNING VALID 081500.
TYPHOON WARNING.
TYPHOON 2114 CHANTHU (2114) UPGRADED FROM SEVERE TROPICAL STORM 980
HPA
AT 16.3N 134.1E SEA EAST OF PHILIPPINES MOVING WEST 10 KNOTS.
POSITION FAIR.
MAX WINDS 65 KNOTS NEAR CENTER.
RADIUS OF OVER 50 KNOT WINDS 30 MILES.
RADIUS OF OVER 30 KNOT WINDS 90 MILES.
FORECAST POSITION FOR 080300UTC AT 16.3N 132.6E WITH 35 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.
975 HPA, MAX WINDS 70 KNOTS NEAR CENTER.
FORECAST POSITION FOR 081500UTC AT 16.2N 131.2E WITH 50 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.
970 HPA, MAX WINDS 75 KNOTS NEAR CENTER.
JAPAN METEOROLOGICAL AGENCY.=

[Hayabusa]

JTWC has amended the 12Z forecast and discussion

WDPN32 PGTW 071500 AMD
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (CHANTHU) WARNING NR 006A
AMENDED//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 16.3N 134.6E
INITIAL INTENSITY: 85 KTS
GEOGRAPHIC REFERENCE: 720 NM SOUTH-SOUTHEAST OF KADENA AB
MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS
SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
THE 1200Z FORECAST HAS BEEN AMENDED TO REFLECT THE ONGOING EXTREME
RAPID INTENSIFICATION OF THE SYSTEM. ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY AT THE 1200Z HOUR SHOWED THAT THE SYSTEM
WAS CONTINUING TO INTENSIFY WITH STRONG CONVECTIVE HOT TOWERS
WRAPPING AROUND A WARM SPOT IN THE EIR IMAGERY. EIR IMAGERY
SUBSEQUENT TO THE 1200Z HOUR DEPICTED THE RAPID APPEARANCE OF A
WELL DEFINED, PINHOLE EYE, SUPPORTING THE ONSET OF EXTREME RAPID
INTENSIFICATION. THE INITIAL POSITION WAS PLACED WITH HIGH
CONFIDENCE BASED ON A 071107Z ASCAT-A BULLSEYE, WHICH ALIGNED
PERFECTLY WITH THE WARM SPOT IN THE EIR. THE INITIAL INTENSITY AT
THE 1200Z HOUR WAS HEDGED SLIGHTLY HIGHER THAN AGENCY SUBJECTIVE
AND AUTOMATED OBJECTIVE FIX DATA AND SUBSEQUENTLY INCREASED FAR
ABOVE THE 1200Z FIXES, AND NOW SET AT 85 KNOTS. THE KNES 1200Z FIX
HAS BEEN CORRECTED TO T5.0. INTERESTINGLY, WHILE SUBSEQUENT 1500Z
FIXES WERE AS HIGH AT T5.5 (PGTW) WITH HIGHER DATA T-NUMBERS, THE
ADT HAS YET TO PICK UP ON THE EYE AND REMAINS AT T3.5. AS EVIDENCED
BY THE RAPID INTENSIFICATION, TY 19W IS COCOONED IN A VERY
FAVORABLE ENVIRONMENT WITH LOW VWS, VERY WARM SSTS AND RADIAL
OUTFLOW. OCEAN HEAT CONTENT (OHC) IN THE AREA REMAINS VERY HIGH
WITH VALUES BETWEEN 150-200 JOULES.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: DEEP SUBTROPICAL RIDGE TO THE NORTH.



AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T4.0 - 65 KTS
RJTD: T3.5 - 55 KTS
RCTP: T4.0 - 65 KTS
KNES: T5.0 - 90 KTS
CIMSS ADT: 57 KTS AT 071140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
VWS: 5-10 KTS
SST: 29-30 CELSIUS
OUTFLOW: STRONG RADIAL
OTHER FACTORS: WHILE THE RADIAL OUTFLOW IS STRONG, IT IS LIMITED
IN EXTENT DUE TO THE SMALL OVERALL STRUCTURE OF THE SYSTEM.

ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS FORECAST IS AMENDED TO INCREASE
THE INITIAL INTENSITY AS WELL AS THE FORECAST INTENSITY.

FORECAST DISCUSSION: TY 19W IS FORECAST TO TRACK WEST-NORTHWEST
THROUGH TAU 24, THEN TURNING GRADUALLY MORE NORTHWESTWARD THROUGH
THE REMAINDER OF THE FORECAST PERIOD AS THE STR REORIENTS SLIGHTLY
AND A WEAKNESS DEVELOPS IN THE RIDGE TO THE NORTH OF TAIWAN. AS
EVIDENCED BY THE ONGOING DRAMATIC IMPROVEMENTS IN THE EIR AND THE
DEVELOPMENT OF A PINHOLE EYE, THE SYSTEM IS UNDERGOING A PERIOD OF
EXTREME RAPID INTENSIFICATION (ERI). ENVIRONMENTAL CONDITIONS ARE
EXPECTED
TO REMAIN VERY FAVORABLE FOR ADDITIONAL RI, OR EVEN ERI,
OVER THE NEXT 36 HOURS, EXPECTED TO PEAK AT OR ABOVE 130 KNOTS BY
TAU 36. THE SYSTEM WILL TRACK OVER VERY WARM, VERY HIGH OHC WATERS
FOR THE NEXT 24 HOURS, THEN MOVE INTO AN AREA OF LOWER OHC.
MEANWHILE THE VWS REMAINS LOW AND THE SMALL AREA OF RADIAL OUTFLOW
OVER THE SYSTEM REMAINS FIRMLY IN PLACE. THE RAPID
INTENSIFICATION PREDICTION AID (RIPA) CONTINUES TO BE TRIGGERED
THROUGH TAU 36. THEN IT IS LIKELY TO EXPERIENCE AN EYEWALL
REPLACEMENT CYCLE WHICH WILL DECREASE THE INTENSITY SLIGHTLY NEAR
TAU 48. ANOTHER ROUND OF INTENSIFICATION IS EXPECTED AFTER TAU 48,
TO A PEAK OF 130 KNOTS AT TAU 72 AS THE SYSTEM MOVES OVER ANOTHER
AREA OF HIGH OHC, WHILE THE OTHER PARAMETERS REMAIN FAVORABLE.
THEREAFTER, DECREASING SSTS AND OHC, AND INCREASING MID-LEVEL VWS
WILL OFFSET THE DEVELOPMENT OF A MODERATE POLEWARD OUTFLOW
CHANNEL, AND LEAD TO SLOW BUT STEADY WEAKENING THROUGH TAU 120. TS
18W (CONSON) IS LOCATED 700NM TO THE WEST-SOUTHWEST. THE TWO SYSTEMS
ARE EXPECTED TO CLOSE WITHIN APPROXIMATELY 500NM BY TAU 72 BUT
THE PROBABILITY OF BINARY INTERACTION REMAINS LOW DUE TO THE
COMPACT NATURE OF THE TWO SYSTEMS.


MODEL DISCUSSION: NUMERICAL TRACK GUIDANCE HAS COME INTO BETTER
AGREEMENT SINCE THE PREVIOUS RUN. MODEL SPREAD IS 100NM AT TAU 48.
GFS REMAINS THE EQUATORWARD OUTLIER IN THE NEAR TERM, THOUGH
OVERALL IT HAS COME INTO BETTER AGREEMENT WITH THE REMAINDER OF THE
CONSENSUS MEMBERS. AFTER TAU 48, WITH THE EXCEPTION OF NAVGEM, THE
GUIDANCE NOW AGREES ON A TRACK ACROSS TAIWAN, INSTEAD OF THE
EARLIER GFS AND HWRF DEPICTIONS SHOWING A SHARP TURN NORTHWARD. GFS
AND HWRF STILL SHOW A NORTHWARD TURN, BUT NOW DO SO AFTER CROSSING
TAIWAN. SO THE RUN TO RUN INCONSISTENCIES STILL REMAIN, AND THUS
WHILE THE JTWC FORECAST TRACK REMAINS CONSISTENT, THERE IS LOW
CONFIDENCE IN THE EXTENDED FORECAST, THUS ONLY MEDIUM CONFIDENCE.
INTENSITY GUIDANCE IS MIXED, WITH ALL OF THE RAPID INTENSIFICATION
GUIDANCE TRIGGERED, WHILE GFS REMAIN LUKEWARM TO INTENSIFICATION.
THE JTWC FORECAST IS ABOVE ALL THE GUIDANCE INCLUDING THE RI
GUIDANCE THROUGH TAU 36, THEN TRACKS CLOSEST TO THE COAMPS-TC
THROUGH THE REMAINDER OF THE FORECAST. CONFIDENCE REMAINS MEDIUM
HOWEVER, IN LIGHT OF THE EXTREMELY FAST RATE INTENSIFICATION BEING
OBSERVED, AND THE UNCERTAINTY IN THE TIMING OF LIKELY EYEWALL
REPLACEMENT CYCLES.

FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
TRACK 72-120 HR: LOW
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: LOW

4. JUSTIFICATION FOR AMENDMENT://
NNNN

[mrbagyo]

Can Chanthu be classified as a midget typhoon.
the cloud cover is so tiny, what's its ROCI.

[Sciencerocks]

115 knots???

[zzh]

19W CHANTHU 210907 1800 16.3N 133.6E WPAC 115 949

Cat 4

[ElectricStorm]

This might be one of the all time fastest ERI's right here if this keeps up. Eye is clearing. At this rate it'll be a super typhoon by this evening and a Cat 5 by morning unless something crazy happens.

[Iceresistance]

12z GFS would warrant the retirement of 'Chanthu' from the basin . . .

[Yellow Evan]

This might be one of the all time fastest ERI's right here if this keeps up. Eye is clearing. At this rate it'll be a super typhoon by this evening and a Cat 5 by morning unless something crazy happens.

This might be a super typhoon right now. JTWC is playing catch up here though they seem aware of what is going on.

[cycloneye]

19W CHANTHU 210907 1800 16.3N 133.6E WPAC 115 949

[CryHavoc]

This might be one of the all time fastest ERI's right here if this keeps up. Eye is clearing. At this rate it'll be a super typhoon by this evening and a Cat 5 by morning unless something crazy happens.

This might be a super typhoon right now. JTWC is playing catch up here though they seem aware of what is going on.

It absolutely looks like a super typhoon. In fact, I would put money toward it being closer to cat 5 strength than a 115mph storm.