WPAC: CHABA - Post-Tropical

[euro6208]

[Dave C]

Seems to be recovering nicely after a ragged appearance earlier. Outflow really expanding to the north.

[euro6208]

[euro6208]

Stronger on the latest 12Z GFS. 933mb barely a miss.

[euro6208]

WDPN32 PGTW 302100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 21W (CHABA)
WARNING NR 12//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 21W (CHABA), LOCATED APPROXIMATELY 809 NM
SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTHWESTWARD AT
09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY INDICATES A COMPACT, CONSOLIDATING LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH FRAGMENTED CONVECTIVE BANDING. THE
INITIAL POSITION IS BASED ON A LOW REFLECTIVITY CIRCULATION FEATURE
IN THE 301722Z MICROWAVE PASS WITH GOOD CONFIDENCE. THE INITIAL
INTENSITY OF 50 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF OBJECTIVE
AND AGENCY DVORAK ESTIMATES AND REFLECTS THE SLIGHT, ALBEIT MOMENTARY
DEGRADATION IN THE SYSTEM. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM
IS IN AN AREA OF LOW TO MODERATE (10-15 KNOT) VERTICAL WIND SHEAR
(VWS) AND GOOD RADIAL OUTFLOW. TS 21W IS TRACKING ALONG THE SOUTHWEST
PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TS CHABA WILL CONTINUE TO TRACK NORTHWESTWARD ALONG THE
SOUTHWEST PERIPHERY OF THE DEEP-LAYERED STR WHILE INTENSIFYING
STEADILY DUE TO OVERALL FAVORABLE ENVIRONMENTAL CONDITIONS. AFTER TAU
48, A MID-LATITUDE TROUGH APPROACHING FROM THE NORTHWEST WILL WEAKEN
THE STR AND CAUSE THE CYCLONE TO TRACK MORE NORTHWARD. TS 21W IS
EXPECTED TO PEAK AT 90 KNOTS NEAR TAU 72.
C. AFTER TAU 72, TS CHABA WILL ACCELERATE NORTHEASTWARD, MAKE
LANDFALL OVER SOUTHERN KYUSHU, JAPAN, AND DRAG ACROSS SOUTHERN JAPAN.
INCREASING VWS, IN ADDITION TO LAND INTERACTION, WILL RAPIDLY ERODE
THE SYSTEM; DOWN TO 40 KNOTS BY TAU 120. CONCURRENTLY, THE SYSTEM
WILL BEGIN EXTRA-TROPICAL TRANSITION. NUMERIC MODEL GUIDANCE IS IN
TIGHT AGREEMENT UP TO TAU 72 WHERE THE CONSENSUS MEMBERS
SIGNIFICANTLY DIVERGE IN BOTH DIRECTION AND SPEED. THEREFORE, THERE
IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST UP TO TAU 72, THEN LOW
CONFIDENCE AFTERWARDS.
NNNN

[1900hurricane]

Chaba's core is tiny. It could swing quickly in intensity either way very quickly.

[euro6208]

WDPN32 PGTW 010900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 21W (CHABA) WARNING NR
14//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 21W (CHABA), LOCATED APPROXIMATELY 692 NM
SOUTHEAST OF KADENA AB, OKINAWA, JAPAN HAS TRACKED NORTHWESTWARD AT
12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS A DEEPENING COMPACT CDO FEATURE OBSCURING
THE LOW LEVEL CIRCULATION CENTER (LLCC). DEEP CONVECTIVE BANDING
CONTINUES TO PERSIST ALONG THE EASTERN SIDE OF THE SYSTEM BUT
REMAINS DISCONNECTED FROM THE CDO. THE CURRENT POSITION IS PLACED
WITH GOOD CONFIDENCE BASED ON A 010535Z AMSU 89GHZ MICROWAVE IMAGE
SHOWING CURVED CONVECTION WRAPPING TIGHTLY AROUND THE WESTERN SIDE
OF THE LLCC. THE INTENSITY HAS BEEN INCREASED TO 55 KNOTS BASED ON
THE DEEPENING CORE STRUCTURE AND THE IMPROVED CONVECTION AROUND THE
LLCC IN THE MICROWAVE IMAGE. ADDITIONALLY, DVORAK INTENSITY
ESTIMATES FROM PGTW AND RJTD HAVE INCREASED TO T3.5 (55 KNOTS).
UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF LOW TO
MODERATE (10-15 KNOTS) VERTICAL WIND SHEAR (VWS) AND GOOD RADIAL
OUTFLOW. TS 21W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE
DEEP-LAYERED SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. THE STEERING STR WILL REMAIN THE DOMINANT STEERING MECHANISM
DRIVING THE SYSTEM NORTHWESTWARD OVER THE NEXT 48 HOURS AS IT
APPROACHES OKINAWA. AFTERWARDS, TS 21W WILL ROUND THE STR AXIS AND
BEGIN TO TURN TO THE NORTHEAST BY TAU 72. ALTHOUGH THE STORM HAS
CONTINUED TO STRUGGLE TO CONSOLIDATE AND INTENSITY HAS FLUCTUATED,
FAVORABLE ENVIRONMENTAL CONDITIONS WILL SUPPORT A STEADY
INTENSIFICATION. TS CHABA IS FORECAST TO REACH ITS PEAK INTENSITY OF
90 KNOTS NEAR TAU 48 AS AN APPROACHING MID-LATITUDE TROUGH PROVIDES
AN ENHANCED POLEWARD OUTFLOW CHANNEL. DYNAMIC MODEL GUIDANCE REMAINS
IN PRETTY GOOD AGREEMENT THROUGH THIS PORTION OF THE FORECAST WITH
THE MULTI-MODEL CONSENSUS REMAINING STABLE OVER THE PAST FOUR CYCLES.
C. IN THE EXTENDED FORECAST, TS CHABA WILL ACCELERATE
NORTHEASTWARD, MAKING LANDFALL OVER SOUTHERN KYUSHU, JAPAN.
AFTERWARDS, THE SYSTEM WILL TRACK ACROSS SOUTHERN JAPAN WHERE IT
WILL WEAKEN DUE TO INCREASING VWS FROM THE AFOREMENTIONED MID-
LATITUDE TROUGH AND LAND INTERACTION. CONCURRENTLY, THE SYSTEM WILL
BEGIN EXTRA-TROPICAL TRANSITION (ETT) AND IS EXPECTED TO COMPLETE
ETT BY THE END OF THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE
CONTINUES TO SHOW A SPREAD AFTER TAU 72 WITH TRACKS BOTH EAST AND
WEST OF MAINLAND JAPAN A POSSIBILITY. THE EVENTUAL TRACK WILL DEPEND
ON THE TIMING AND SPEED OF THE TROUGH THAT WILL PULL THE SYSTEM INTO
THE MID-LATITUDE WESTERLY FLOW. DUE TO THE MODEL SPREAD IN THE LONG
RANGE FORECAST, THERE REMAINS LOW CONFIDENCE IN THE JTWC TRACK
FORECAST.//
NNNN

[mario_zxn]

CHABA IS A TY NOW.
WTPQ21 RJTD 011200
RSMC TROPICAL CYCLONE ADVISORY
NAME TY 1618 CHABA (1618) UPGRADED FROM STS
ANALYSIS
PSTN 011200UTC 17.6N 133.4E FAIR
MOVE NW 12KT
PRES 970HPA
MXWD 070KT
GUST 100KT
50KT 50NM
30KT 150NM
FORECAST
24HF 021200UTC 22.1N 129.6E 60NM 70%
MOVE NW 14KT
PRES 955HPA
MXWD 080KT
GUST 115KT
48HF 031200UTC 26.5N 128.1E 110NM 70%
MOVE NNW 12KT
PRES 950HPA
MXWD 085KT
GUST 120KT
72HF 041200UTC 31.3N 129.0E 220NM 70%
MOVE N 12KT
PRES 955HPA
MXWD 080KT
GUST 115KT =

[NotoSans]

Latest microwave imagery shows a closed eyewall. Both the JMA and JTWC upgraded it to a typhoon at 12Z, but I think the JMA estimate is closer to the reality.

[mrbagyo]

Is that a pinhole i'm seeing in the rbtop and rb loop or just a random warm pixel?
This typhoon has mad convection, if the warm spot is indeed an eye -- dvorak would surely skyrocket once it clears out.

[1900hurricane]

Looks like an enhanced V signature to me when looking at the rapid scan floater. You're right about the ridiculous convection though. With how much more symmetrical it has become over the center, there has to be some serious core building going on in there. Coupled with a robust poleward outflow channel developing (it actually looks a lot like Nepartak's), I think Chaba may be about to bomb out.

[euro6208]

65 knots.

WDPN32 PGTW 011500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 21W (CHABA) WARNING NR 15//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 21W (CHABA), LOCATED APPROXIMATELY 621 NM SOUTH-
SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTHWESTWARD AT
12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS A RAPIDLY CONSOLIDATING LOW LEVEL
CIRCULATION CENTER (LLCC) WITH A SYMMETRIC CDO CONTINUING TO DEEPEN
AND ENLARGE. A 010939Z SSMIS 91GHZ MICROWAVE IMAGE FURTHER SHOWS THE
VASTLY IMPROVED STRUCTURE WITH A CONVECTIVE RING NOW SURROUNDING
MOST OF THE LLCC. THE CURRENT POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON A 011208Z ASCAT PASS. THE INTENSITY HAS BEEN
INCREASED TO 65 KNOTS IN RESPONSE TO THE CONVECTIVE IMPROVEMENT IN
THE ABOVE IMAGERY AND IS SUPPORTED BY A T4.0 (65 KNOTS) DVORAK
INTENSITY ESTIMATE FROM PGTW. TY 21W IS TRACKING IN A FAVORABLE
ENVIRONMENT WITH STRONG DIFFLUENCE ALOFT, LOW (5-10 KNOT) VERTICAL
WIND SHEAR (VWS), AND VERY WARM SEA SURFACE TEMPERATURES. TY 21W IS
TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE DEEP-LAYERED
SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
A. THE RATE OF INTENSIFICATION AND PEAK INTENSITY HAS BEEN
INCREASED DUE TO THE RECENT RAPID CONSOLIDATION AND DEEPENING OF THE
CYCLONE. HOWEVER, NO SIGNIFICANT CHANGE TO THE FORECAST TRACK SINCE
THE PREVIOUS PROGNOSTIC REASONING BULLETIN.
B. THE STEERING STR WILL REMAIN THE DOMINANT STEERING MECHANISM,
DRIVING THE SYSTEM NORTHWESTWARD OVER THE NEXT 48 HOURS AS IT
APPROACHES OKINAWA. AFTERWARDS, TY 21W WILL ROUND THE STR AXIS AND
BEGIN TO TURN TO THE NORTHEAST. ENVIRONMENTAL CONDITIONS WILL REMAIN
FAVORABLE, ALLOWING FOR CONTINUED INTENSIFICATION OVER THE NEXT 48
HOURS. ADDITIONALLY, NEAR TAU 48, AN APPROACHING MID-LATITUDE TROUGH
WILL PROVIDE AN ENHANCED POLEWARD OUTFLOW CHANNEL. PEAK INTENSITY
WILL OCCUR NEAR TAU 60 WHEN THE TYPHOON IS AT THE STR AXIS. DYNAMIC
MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH THIS PORTION OF THE
FORECAST PROVIDING HIGH CONFIDENCE.
C. IN THE EXTENDED FORECAST, TY CHABA WILL ACCELERATE
NORTHEASTWARD, MAKING LANDFALL OVER SOUTHERN KYUSHU, JAPAN.
AFTERWARDS, THE SYSTEM WILL TRACK ACROSS SOUTHERN JAPAN WHERE IT
WILL WEAKEN DUE TO INCREASING VWS FROM THE AFOREMENTIONED MID-
LATITUDE TROUGH AND LAND INTERACTION. CONCURRENTLY, THE SYSTEM WILL
BEGIN EXTRA-TROPICAL TRANSITION (ETT) AND IS EXPECTED TO COMPLETE
ETT BY THE END OF THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE
CONTINUES TO SPREAD AFTER TAU 72, WITH TRACKS BOTH EAST AND WEST OF
MAINLAND JAPAN A POSSIBILITY. THE EVENTUAL TRACK WILL DEPEND ON THE
TIMING AND SPEED OF THE TROUGH THAT WILL PULL THE SYSTEM INTO THE
MID-LATITUDE WESTERLY FLOW. DUE TO THE MODEL SPREAD IN THE LONG
RANGE FORECAST, THERE REMAINS LOW CONFIDENCE IN THE JTWC TRACK
FORECAST.//
NNNN

[NotoSans]

SSD went with T5.0/5.0 in their latest fix, which seems fine to me. But I prefer using the embedded center pattern instead of the eye pattern as the warm spot does not look like a real eye at the moment.

TXPQ22 KNES 011513
TCSWNP

A. 21W (CHABA)

B. 01/1430Z

C. 18.2N

D. 133.2E

E. ONE/HIMAWARI-8

F. T5.0/5.0/D2.0/24HRS

G. IR/EIR/SWIR

H. REMARKS...DT=5.5 BASED ON WH EMBEDDED GRAY SHADE WITH WH EYE
SURROUNDED BY CDG. PT=5.0. MET=5.0. FT IS BASED ON CONSTRAINTS LIMITING
CHANGE TO 1.0/06 HRS. CONSTRAINTS NOT BROKEN DUE TO 6 HR MANUAL AVERAGE
DT OF 5.16.

I. ADDL POSITIONS

NIL


...SCHWARTZ

Meanwhile the JTWC is using the CCC Pattern. Doesn't make much sense to me.

TPPN11 PGTW 011442

A. TYPHOON 21W (CHABA)

B. 01/1430Z

C. 18.06N

D. 133.50E

E. FIVE/HMWRI8

F. T4.0/4.0/D1.0/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 55A/PBO CCC/ANMTN. CCC PATTERN YIELDS DT OF 3.5.
MET AND PT YIELD 4.0. DBO MET.

I. ADDITIONAL POSITIONS:
01/0939Z 17.18N 134.20E SSMS


HART

[mrbagyo]

1900hurricane, looks like you're correct, the feature is now gone in ir.
Those hot towers still indicate strengthening though.

[Dave C]

There's an upper low to the nw, I wonder if that will get out of the way as the typhoon slides towards it.

[mrbagyo]

[qscdefb]

A W eye has popped up in the past hour, embedded in CMG/CDG convection.
Meanwhile, JTWC gave Chaba 65kt winds as of 18Z.

[Cunxi Huang]

21W CHABA 161001 1800 18.5N 132.7E WPAC 65 987

JTWC is a joke. Noaa-19 composite shows a really thick and powerfull eyewall is forming.

[euro6208]

It's stronger than 65 knots. Dvorak lags behind big time from real recon data from Matthrew.

[euro6208]

hmm