WPAC: KOPPU - Post-Tropical

[dexterlabio]

Usually we've seen intense typhoons weakening just before landfall. This does not seem to be the case with Koppu which is still trying to form a visible eye. On the latest IR imagery you can see a band of deep convection south of the center wrapping around the eye. Microwave images aren't bad.

[mrbagyo]

Koppu is moving westward at a crawling phase, affording it much time to gather strength in the energetic Philippine Sea, that also gives it a bigger chance to clear that eye before it strikes land.

Usually we've seen intense typhoons weakening just before landfall. This does not seem to be the case with Koppu which is still trying to form a visible eye. On the latest IR imagery you can see a band of deep convection south of the center wrapping around the eye. Microwave images aren't bad.

I remember a similar case that happened before - Nesat '11 just before landfall
That's certainly not a pinhole eye...

[mrbagyo]

CATEGORY 3
24W KOPPU 151017 0000 15.7N 124.3E WPAC 105 944

[dexterlabio]

Agreed it's not a pinhole eye. It looks like one because the eye is still clearing out and it appears squinted.

[supercane]

As posted above, the 03Z JTWC advisory raised Koppu's winds to 105kt with a peak of 120kt forecast in 12hr.
WTPN51 PGTW 170300
WARNING ATCG MIL 24W NWP 151017010226
2015101700 24W KOPPU 017 02 260 06 SATL 010
T000 157N 1243E 105 R064 045 NE QD 040 SE QD 040 SW QD 045 NW QD R050 055 NE QD 060 SE QD 070 SW QD 075 NW QD R034 105 NE QD 105 SE QD 130 SW QD 135 NW QD
T012 158N 1230E 120 R064 040 NE QD 040 SE QD 040 SW QD 040 NW QD R050 055 NE QD 060 SE QD 070 SW QD 070 NW QD R034 105 NE QD 110 SE QD 125 SW QD 110 NW QD
T024 159N 1220E 110 R064 045 NE QD 045 SE QD 035 SW QD 040 NW QD R050 065 NE QD 065 SE QD 040 SW QD 045 NW QD R034 115 NE QD 115 SE QD 060 SW QD 080 NW QD
T036 164N 1213E 085
T048 170N 1211E 065
T072 180N 1213E 045
T096 196N 1219E 040
T120 212N 1226E 050
AMP
SUBJ: TYPHOON 24W (KOPPU) WARNING NR 017
1. TYPHOON 24W (KOPPU) WARNING NR 017
<rest omitted>

The following forecast from JMA shows a peak of 85kt.
WTPQ50 RJTD 170000
RSMC TROPICAL CYCLONE ADVISORY
NAME TY 1524 KOPPU (1524)
ANALYSIS
PSTN 170000UTC 15.8N 124.5E FAIR
MOVE W 06KT
PRES 940HPA
MXWD 085KT
GUST 120KT
50KT 80NM
30KT 210NM SOUTHWEST 180NM NORTHEAST
FORECAST
24HF 180000UTC 16.2N 122.0E 70NM 70%
MOVE W 06KT
PRES 950HPA
MXWD 080KT
GUST 115KT
48HF 190000UTC 16.9N 121.4E 110NM 70%
MOVE ALMOST STATIONARY
PRES 985HPA
MXWD 050KT
GUST 070KT
72HF 200000UTC 17.8N 121.4E 220NM 70%
MOVE ALMOST STATIONARY
PRES 985HPA
MXWD 050KT
GUST 070KT
96HF 210000UTC 18.8N 121.6E 240NM 70%
MOVE N SLOWLY
120HF 220000UTC 19.8N 121.8E 260NM 70%
MOVE N SLOWLY =

WTPQ30 RJTD 170000

RSMC TROPICAL CYCLONE PROGNOSTIC REASONING
REASONING NO. 9 FOR TY 1524 KOPPU (1524)
1.GENERAL COMMENTS
REASONING OF PROGNOSIS THIS TIME IS SIMILAR TO PREVIOUS ONE.
POSITION FORECAST IS MAINLY BASED ON NWP AND PERSISTENCY.
2.SYNOPTIC SITUATION
NOTHING PARTICULAR TO EXPLAIN.
3.MOTION FORECAST
POSITION ACCURACY AT 170000 UTC IS FAIR.
TY WILL MOVE AT THE SAME SPEED FOR THE NEXT 24 HOURS THEN DECELERATE.
TY WILL RECURVE WITHIN 36 HOURS FROM 170000 UTC.
TY WILL MOVE WEST FOR THE NEXT 24 HOURS THEN MOVE GRADUALLY TO NORTH.
4.INTENSITY FORECAST
TY WILL KEEP PRESENT INTENSITY FOR NEXT 24 HOURS.
TY WILL WEAKEN BECAUSE LANDFALL IS EXPECTED WITHIN 24 HOURS.
FI-NUMBER WILL BE 5.0 AFTER 24 HOURS.=

However, looking at JMA's website shows a peak of 100kt at T+12H.

[Yellow Evan]

Yea def not a pinhole, my bad earlier.

[supercane]

From this abstract on pinhole eyes in tropical cyclones, "pinhole eyes are defined as those eyes with a diameter smaller than 10 n mi, representing less than ten percent on the eye size measurements available in aircraft reconnaisance fixes." 10 nmi = 18.5 km. While this definition is not universal, it appears to be a fair starting point for discussion, and at least earlier, Koppu did not have a pinhole eye, though it may be getting there.

[Darvince]

To me this thing looks 115 to 125kt.

Saved loop:

[supercane]

WDPN31 PGTW 170300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (KOPPU) WARNING NR 17//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 24W (KOPPU), LOCATED APPROXIMATELY 202 NM EAST-
NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 06 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
SHOWS THE SYSTEM HAS DEVELOPED A 13-NM EYE AS DEEP CONVECTIVE BANDS
WRAPPED TIGHTER INTO THE EYE. THE INITIAL POSITION IS BASED ON THE
EYE FEATURE WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 105 KNOTS
IS BASED ON DVORAK ESTIMATES FROM PGTW, KNES, AND RJTD AND REFLECTS
THE INTENSIFIED STATE OF THE TYPHOON. UPPER-LEVEL ANALYSIS INDICATES
THE SYSTEM REMAINS IN A HIGHLY FAVORABLE ENVIRONMENT WITH LOW
VERTICAL WIND SHEAR AND STRONG DUAL OUTFLOW. THE POLEWARD OUTFLOW
SURGED OVER THE LAST SIX HOURS, AS EVIDENT ON ANIMATED WATER VAPOR
IMAGERY. ADDITIONALLY, SEA SURFACE TEMPERATURES (SSTS) AT OVER 31
DEGREES CELSIUS IN THE PHILIPPINE SEA ARE HIGHLY CONDUCIVE FOR
FURTHER DEVELOPMENT. THE CYCLONE IS TRACKING ALONG THE SOUTHERN
PERIPHERY OF AN EXTENSION OF THE DEEP-LAYERED SUBTROPICAL RIDGE
(STR) TO THE NORTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TY 24W WILL CONTINUE TO TRACK WESTWARD THROUGH TAU 24 ALONG
THE SOUTHERN PERIPHERY OF THE STEERING STR EXTENSION. UPPER-LEVEL
DYNAMICS AND SSTS WILL REMAIN FAVORABLE LEADING TO A PEAK INTENSITY
OF 120 KNOTS AT TAU 12. THE CYCLONE WILL MAKE LANDFALL AROUND TAU 24
NEAR CASIGURAN THEN RAPIDLY DECAY AS IT DRAGS THROUGH THE RUGGED
MOUNTAIN RANGES OF NORTHERN LUZON. AFTER TAU 24, TY 24W WILL TURN
POLEWARD AS THE STR EXTENSION RETREATS AND AN INDUCED RIDGE FORMS
BETWEEN TY 25W AND TY 24W AND ACTS AS THE WEAK PRIMARY STEERING
MECHANISM FOR THE REMAINDER OF THE FORECAST.
C. IN THE EXTENDED FORECAST, TY KOPPU WILL EXIT INTO THE LUZON
STRAIT AT TROPICAL STORM STRENGTH AND CONTINUE TO TRACK NORTHWARD.
MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT THROUGH TAU 24, BUT
SIGNIFICANTLY SPREADS AFTERWARDS. IN VIEW OF THIS, THE JTWC TRACK
FORECAST CONFIDENCE LEVEL IS LOW.//
NNNN

[1900hurricane]

JTWC's analysis for 0230Z was a 6.0. Wouldn't be surprised to see them go with 115 kt operationally at 06Z. Koppu is also running just about perfectly with the forecast points right now. Landfall should come within 24 hours.

[Yellow Evan]

6.5 DT with 5.5 FT based on constraints.

TXPQ26 KNES 170334
TCSWNP

A. 24W (KOPPU)

B. 17/0301Z

C. 15.9N

D. 124.1E

E. ONE/MTSAT

F. T5.5/5.5/D2.0/24HRS

G. IR/EIR/VIS

H. REMARKS...DG EYE IS EMBEDDED IN, AND SURROUNDED BY, W RESULTING IN
A DT OF 6.5 AFTER 0.5 IS ADDED AS AN EYE ADJUSTMENT. PT IS 5.5 AND MET
IS 5.0 BASED ON RAPID DEVELOPMENT OVER THE LAST 24 HOURS. THE AVERAGE
SUBJECTIVE DT CALCULATED HOURLY OVER THE LAST 6 HOURS IS 5.3 AND SERVES
AS THE BASIS FOR THE FT.

I. ADDL POSITIONS

NIL


...TURK

[mrbagyo]

Now a minimal CATEGORY 4 Typhoon
24W KOPPU 151017 0600 15.7N 123.8E WPAC 115 937

[euro6208]

WDPN31 PGTW 170900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (KOPPU) WARNING NR 18//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 24W (KOPPU), LOCATED APPROXIMATELY 175 NM EAST-
NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 05 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS A MORE DEFINED 10-NM EYE FEATURE WITH A DEEPENING
CONVECTIVE STRUCTURE. A 170256Z GPM 36GHZ MICROWAVE IMAGE SHOWED A
COMPACT MICROWAVE EYE FEATURE WHILE THE 89GHZ IMAGE SHOWS DEEP
CONVECTION SURROUNDING MOST OF THE EYE WITH SPIRAL BANDING WRAPPING
INTO THE FEATURE. THE TYPHOON HAS CONTINUED TO UNDERGO RAPID
INTENSIFICATION (RI), WITH ITS INTENSITY ASSESSED AT 115 KNOTS BASED
ON DVORAK INTENSITY ESTIMATES OF T6.0 (115 KNOTS) FROM ALL AGENCIES.
THE INITIAL POSITION IS BASED ON THE EYE FEATURE IN THE MSI
ANIMATION WITH HIGH CONFIDENCE. EXCELLENT ENVIRONMENT CONDITIONS ARE
SUPPORTING THE RI WITH LOW VERTICAL WIND SHEAR (VWS), EXCELLENT DUAL
CHANNEL OUTFLOW, AND SEA SURFACE TEMPERATURES (SSTS) ABOVE 31
CELSIUS. TY KOPPU IS TRACKING ALONG THE SOUTHERN PERIPHERY OF AN
EXTENSION OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TY 24W WILL CONTINUE TO TRACK WESTWARD THROUGH TAU 24 ALONG
THE SOUTHERN PERIPHERY OF THE STEERING STR. ENVIRONMENTAL CONDITIONS
WILL SUPPORT CONTINUED INTENSIFICATION PRIOR TO LANDFALL OVER
CENTRAL LUZON NEAR TAU 24. AFTERWARDS THE TYPHOON WILL RAPIDLY DECAY
DUE TO LAND INTERACTION OVER THE MOUNTAINOUS TERRAIN IN LUZON. NEAR
TAU 36, THE SYSTEM WILL TURN POLEWARD AS IT ROUNDS THE STR AXIS. THE
TYPHOON WILL TRACK NORTHWARD, ALBEIT SLOWLY, DUE TO A COMPETING
STEERING ENVIRONMENT WITH A SECOND STR TO THE WEST.
C. IN THE EXTENDED TAUS, TY KOPPU WILL REEMERGE OVER WATER IN THE
LUZON STRAIT AT TROPICAL STORM STRENGTH AND CONTINUE TO TRACK SLOWLY
NORTHWARD. THE CYCLONE WILL BEGIN TO INTENSIFY ONCE AGAIN DUE TO LOW
VWS AND WARM SSTS. DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT
THROUGH TAU 24, BUT SIGNIFICANTLY SPREADS AFTER LANDFALL. DUE TO THE
LARGE SPREAD IN MODEL SOLUTIONS, THERE IS LOW OVERALL CONFIDENCE IN
THE JTWC FORECAST TRACK.//
NNNN

[cycloneye]

Do you have the link to the radar?

[1900hurricane]

Really slowing to a crawl now. JMA now has landfall coming after 21Z, at which point they are expecting a violent typhoon (>= 105 kt, their T7.0 or category 5 equivalent).

Running a little north and east of the forecast point right now. Also starting to get some warm medium grey showing up in the eye.

[dexterlabio]

Are we sure this will hit before noon tomorrow? Coz the latest movement seems like it will make landfall sooner than that...

[supercane]

JMA forecast largely unchanged between 6Z and 12Z:
WTPQ50 RJTD 170600
RSMC TROPICAL CYCLONE ADVISORY
NAME TY 1524 KOPPU (1524)
ANALYSIS
PSTN 170600UTC 15.8N 123.8E GOOD
MOVE W 07KT
PRES 930HPA
MXWD 095KT
GUST 135KT
50KT 80NM
30KT 210NM SOUTHWEST 180NM NORTHEAST
FORECAST
24HF 180600UTC 16.2N 121.7E 70NM 70%
MOVE W SLOWLY
PRES 955HPA
MXWD 080KT
GUST 115KT
48HF 190600UTC 17.0N 121.5E 110NM 70%
MOVE ALMOST STATIONARY
PRES 985HPA
MXWD 050KT
GUST 070KT
72HF 200600UTC 17.7N 121.5E 220NM 70%
MOVE ALMOST STATIONARY
PRES 985HPA
MXWD 050KT
GUST 070KT
96HF 210600UTC 18.8N 121.7E 240NM 70%
MOVE N SLOWLY
120HF 220600UTC 20.1N 122.0E 260NM 70%
MOVE N SLOWLY =

WTPQ50 RJTD 171200
RSMC TROPICAL CYCLONE ADVISORY
NAME TY 1524 KOPPU (1524)
ANALYSIS
PSTN 171200UTC 15.9N 123.1E GOOD
MOVE W 07KT
PRES 930HPA
MXWD 095KT
GUST 135KT
50KT 80NM
30KT 210NM SOUTHWEST 180NM NORTHEAST
FORECAST
24HF 181200UTC 16.6N 121.6E 70NM 70%
MOVE NW SLOWLY
PRES 955HPA
MXWD 080KT
GUST 115KT
48HF 191200UTC 17.3N 121.6E 160NM 70%
MOVE ALMOST STATIONARY
PRES 985HPA
MXWD 050KT
GUST 070KT
72HF 201200UTC 18.0N 121.6E 220NM 70%
MOVE ALMOST STATIONARY
PRES 985HPA
MXWD 050KT
GUST 070KT
96HF 211200UTC 19.2N 121.8E 240NM 70%
MOVE N SLOWLY
120HF 221200UTC 20.5N 122.1E 260NM 70%
MOVE N SLOWLY =

[supercane]

JTWC upgraded to super typhoon at 130kt.
WTPN51 PGTW 171500
WARNING ATCG MIL 24W NWP 151017133044
2015101712 24W KOPPU 019 02 290 06 SATL 020
T000 159N 1232E 130 R064 045 NE QD 050 SE QD 025 SW QD 035 NW QD R050 060 NE QD 070 SE QD 040 SW QD 060 NW QD R034 110 NE QD 155 SE QD 105 SW QD 115 NW QD
T012 161N 1222E 140 R064 045 NE QD 045 SE QD 030 SW QD 035 NW QD R050 065 NE QD 070 SE QD 050 SW QD 065 NW QD R034 115 NE QD 145 SE QD 110 SW QD 120 NW QD
T024 165N 1215E 110
T036 171N 1211E 080
T048 177N 1211E 065
T072 188N 1213E 050 R034 070 NE QD 075 SE QD 065 SW QD 065 NW QD
T096 200N 1218E 055
T120 214N 1224E 065
AMP
SUBJ: SUPER TYPHOON 24W (KOPPU) WARNING NR 019
1. SUPER TYPHOON 24W (KOPPU) WARNING NR 019
UPGRADED FROM TYPHOON 24W
<rest omitted>

WDPN31 PGTW 171500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 24W (KOPPU) WARNING NR
19//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUPER TYPHOON (STY) 24W (KOPPU), LOCATED APPROXIMATELY 149 NM
EAST-NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-
NORTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY SHOWS A CONTINUED DEEPENING OF THE
SYSTEM, WITH DEEP CONVECTION SURROUNDING A 20NM SHARP EYE THAT
SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. A 171029Z SSMIS
91GHZ MICROWAVE IMAGE SHOWED A DEEP CONVECTIVE STRUCTURE SURROUNDING
THE MICROWAVE EYE FEATURE WITH THE STRONGEST CONVECTION ALONG THE
WESTERN SEMI-CIRCLE. THE CYCLONE HAS BEEN INCREASED TO SUPER TYPHOON
INTENSITY BASED ON CONTINUED RAPID INTENSIFICATION AND AN ASSESSMENT
OF DVORAK INTENSITY ESTIMATES FROM ALL AGENCIES. STY 24W CONTINUES
TO ENCOUNTER EXCELLENT ENVIRONMENTAL CONDITIONS WITH LOW VERTICAL
WIND SHEAR (VWS), EXCELLENT DUAL CHANNEL OUTFLOW, AND SEA SURFACE
TEMPERATURES (SSTS) ABOVE 31 CELSIUS. STY KOPPU IS TRACKING ALONG
THE SOUTHERN PERIPHERY OF AN EXTENSION OF THE DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. STY 24W WILL CONTINUE TO TRACK WESTWARD THROUGH TAU 24 ALONG
THE SOUTHERN PERIPHERY OF THE STEERING STR. ENVIRONMENTAL CONDITIONS
WILL SUPPORT CONTINUED INTENSIFICATION PRIOR TO LANDFALL OVER
CENTRAL LUZON IN ABOUT 12 HOURS. AFTERWARDS, STY KOPPU WILL RAPIDLY
DECAY DUE TO LAND INTERACTION OVER THE MOUNTAINOUS TERRAIN IN LUZON.
BEYOND TAU 24, THE SYSTEM WILL TURN POLEWARD AS IT ROUNDS THE STR
AXIS. THE CYCLONE WILL TRACK NORTHWARD, ALBEIT SLOWLY, DUE TO A
COMPETING STEERING ENVIRONMENT WITH A SECOND STR TO THE WEST.
C. IN THE EXTENDED TAUS, STY KOPPU WILL RE-EMERGE OVER WATER IN
THE LUZON STRAIT AT TROPICAL STORM STRENGTH AND CONTINUE TO TRACK
SLOWLY NORTHWARD. THE SYSTEM WILL BEGIN TO INTENSIFY ONCE AGAIN DUE
TO LOW VWS AND WARM SSTS, REACHING TYPHOON INTENSITY BY THE END OF
THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT
AGREEMENT THROUGH TAU 12, BUT SIGNIFICANTLY SPREADS AFTER LANDFALL.
DUE TO THE LARGE SPREAD IN MODEL SOLUTIONS, THERE IS LOW OVERALL
CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN

[cycloneye]

Mercy with them.

[NotoSans]

Forecast from JTWC and JMA are probably a bit slow in short-term. I expect a landfall before 00Z.