WPAC: KOPPU - Post-Tropical

[dexterlabio]

Sky's the limit unless as stated by Evan core problems come into play or lengthy eye-wall
replacement cycle's.

This is the only difference this year has with 1997. Far western Pacific (including South China Sea) sure is boiling hot. It almost seems like the whole Pacific from west to east is on fire due to this El Nino.

[euro6208]

Up to 45 knots!

24W KOPPU 151014 0000 15.6N 136.1E WPAC 45 989

[Alyono]

horribly sheared. Won't get much beyond its 45 kts in the short term

[dexterlabio]

Interestingly the JTWC lowered its intensity forecast, down to 100kts. Graphics not updated yet.

[cycloneye]

WDPN31 PGTW 140300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (KOPPU) WARNING
NR 05//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 24W (KOPPU), LOCATED APPROXIMATELY 877 NM EAST
OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 16 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS
THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS BECOME PARTIALLY EXPOSED
FROM A DEEPENING CENTRAL DENSE OVERCAST FEATURE. THE INITIAL POSITION
LINES UP WELL WITH THE LLCC FEATURE IN THE 132212Z SSMI-S MICROWAVE
PASS. THE INITIAL INTENSITY OF 45 KNOTS IS HELD SLIGHTLY HIGHER THAN
AGENCY DVORAK ESTIMATES TO REFLECT THE DEEPENED STATE OF THE CYCLONE.
UPPER LEVEL ANALYSIS INDICATES A MARGINALLY-FAVORABLE ENVIRONMENT
WITH AN ANTICYCLONE JUST NORTH OF THE SYSTEM, PROVIDING STRONG
DIVERGENT OUTFLOW. HOWEVER, MODERATE (15-20 KNOT) NORTHEASTERLY
VERTICAL WIND SHEAR (VWS) IS PREVENTING FASTER INTENSIFICATION. SEA
SURFACE TEMPERATURES (SSTS) ARE NEAR 30 CELSIUS. TS 24W IS TRACKING
ALONG THE SOUTHERN PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE
(STR) TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC
REASONING MESSAGE.
B. TS 24W WILL CONTINUE TO TRACK WESTWARD THROUGH THE REMAINDER
OF THE FORECAST PERIOD UNDER THE STEERING INFLUENCE OF THE STR.
EXPECT SLOW INTENSIFICATION OVER THE NEXT 48 HOURS AS VWS CONTINUES
TO HINDER DEVELOPMENT. BEYOND TAU 48, VWS WILL RELAX AS THE UPPER
LEVEL WIND FLOW BECOMES MORE IN-PHASE WITH THE STORM MOTION.
ADDITIONALLY, SSTS WILL INCREASE ABOVE 30 CELSIUS. THESE WILL SUPPORT
AN INCREASED RATE OF INTENSIFICATION AS THE SYSTEM APPROACHES LUZON.
C. IN THE EXTENDED FORECAST, TS KOPPU WILL CONTINUE ON A WESTWARD
TRACK AS THE STR REMAINS THE DOMINANT STEERING MECHANISM. THE STORM
WILL SLOW AS IT REACHES THE WESTERN EXTENT OF THE STR AND UNDERGO A
RAPID INTENSIFICATION (RI) DUE TO THE FAVORABLE ENVIRONMENTAL
CONDITIONS, IN ADDITION TO INCREASED POLEWARD OUTFLOW AT THE EDGE OF
THE STR. THE RI WILL PEAK THE SYSTEM TO 120 KNOTS - POSSIBLY STRONGER
- RIGHT BEFORE LANDFALL INTO LUZON AT TAU 90. DYNAMIC MODEL GUIDANCE
IS IN GOOD AGREEMENT ON THE OVERALL TRACK; HOWEVER, A BIFURCATION
REMAINS AT THE END OF THE FORECAST PERIOD WHEN THE CYCLONE NEARS
LUZON. DUE TO THIS, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK
FORECAST ONLY UP TO TAU 72.//
NNNN

[euro6208]

Good ol shear that's affecting Champi also affecting Koppu.

[euro6208]

During the next 24 hours, it's going to pass over a hotspot and OHC above 75 until Luzon. Wonder if this will help in intensifying faster if shear lessens.

[cycloneye]

WDPN31 PGTW 140900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (KOPPU) WARNING NR
06//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 24W (KOPPU), LOCATED APPROXIMATELY 757 NM
SOUTH-SOUTHEAST OF KADENA AB, OKINAWA, JAPAN HAS TRACKED WESTWARD AT
11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) CONTINUES TO DEPICT AN EXPOSED LOW LEVEL CIRCULATION
CENTER (LLCC), DISPLACED 49NM NORTHEAST FROM THE ASSOCIATED
CONVECTION. A 140554Z SSMI 85GHZ MICROWAVE IMAGE SHOWS WELL DEFINED
SHALLOW BANDING WRAPPING INTO THE LLCC, WHICH, IN CONJUNCTION WITH
THE MSI LOOP, SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE.
THE CURRENT INTENSITY IS BASED ON A PREVIOUS ASCAT BULLSEYE FROM
140007Z SHOWING 45 KNOT WINDS AND IS SUPPORTED BY A SATCON INTENSITY
ESTIMATE FROM 140512Z OF 44 KNOTS. THE CURRENT AND FORECASTED WIND
RADII HAVE ALSO BEEN ADJUSTED BASED ON THE AFOREMENTIONED ASCAT
IMAGE. UPPER LEVEL ANALYSIS INDICATES A MARGINALLY-FAVORABLE
ENVIRONMENT WITH AN ANTICYCLONE JUST NORTH OF THE SYSTEM, PROVIDING
STRONG DIVERGENT OUTFLOW. HOWEVER, MODERATE (15-20 KNOT)
NORTHEASTERLY VERTICAL WIND SHEAR (VWS) IS PREVENTING VERTICAL
ALIGNMENT AND FASTER INTENSIFICATION. SEA SURFACE TEMPERATURES
(SSTS) ARE NEAR 30 CELSIUS. TS 24W IS TRACKING ALONG THE SOUTHERN
PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC
REASONING MESSAGE.
B. TS KOPPU WILL CONTINUE TO TRACK WESTWARD THROUGH TAU 72 UNDER
THE STEERING INFLUENCE OF THE STR. EXPECT SLOW INTENSIFICATION OVER
THE NEXT 48 HOURS AS VWS REMAINS MODERATE AND CONTINUES TO HINDER
DEVELOPMENT. BEYOND TAU 48, VWS WILL RELAX AS THE UPPER LEVEL WIND
FLOW BECOMES MORE IN-PHASE WITH THE STORM MOTION. ADDITIONALLY, SSTS
WILL INCREASE ABOVE 30 CELSIUS. THESE ENVIRONMENTAL CONDITIONS WILL
SUPPORT A PERIOD OF RAPID INTENSIFICATION AS THE STORM APPROACHES
LUZON.
C. IN THE EXTENDED FORECAST, TS 24W WILL SLOW AND TURN MORE
NORTHWESTWARD AS THE SYSTEM REACHES THE WESTERN EXTENT OF THE
STEERING STR. TS KOPPU WILL CONTINUE TO INTENSIFY UNTIL IT BEGINS TO
INTERACT WITH THE MOUNTAINOUS TERRAIN IN LUZON. THE STORM WILL PASS
OVER THE NORTHEASTERN TIP OF LUZON AS IT CONTINUES TO TURN POLEWARD
AND ROUND THE WESTERN PERIPHERY OF THE STR. DYNAMIC MODEL GUIDANCE
IS IN GOOD OVERALL AGREEMENT AND NOW ALL FAVOR A RECURVE SCENARIO AT
THE END OF THE FORECAST PERIOD; REMOVING THE PREVIOUS BIFURCATION
SCENARIO. ALTHOUGH THE OVERALL TRACK IS BETTER DEFINED, THE DEGREE
AND TIMING OF THE RECURVE IS STILL WIDESPREAD, CAUSING LOW
CONFIDENCE IN THE JTWC FORECAST TRACK, SPECIFICALLY BEYOND TAU 48.//
NNNN

[Typhoon Hunter]

Interestingly the JTWC lowered its intensity forecast, down to 100kts. Graphics not updated yet.

If you note the prognostic reasoning they predict peak of 120kts if not higher between the 100kts position and landfall.

JMA also forecast a 25kts increase from 65kts to 90kts between 48-72 hours. Such a rapid intensification forecast is pretty rare from them.

[euro6208]

WDPN31 PGTW 140900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (KOPPU) WARNING NR
06//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 24W (KOPPU), LOCATED APPROXIMATELY 757 NM
SOUTH-SOUTHEAST OF KADENA AB, OKINAWA, JAPAN HAS TRACKED WESTWARD AT
11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) CONTINUES TO DEPICT AN EXPOSED LOW LEVEL CIRCULATION
CENTER (LLCC), DISPLACED 49NM NORTHEAST FROM THE ASSOCIATED
CONVECTION. A 140554Z SSMI 85GHZ MICROWAVE IMAGE SHOWS WELL DEFINED
SHALLOW BANDING WRAPPING INTO THE LLCC, WHICH, IN CONJUNCTION WITH
THE MSI LOOP, SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE.
THE CURRENT INTENSITY IS BASED ON A PREVIOUS ASCAT BULLSEYE FROM
140007Z SHOWING 45 KNOT WINDS AND IS SUPPORTED BY A SATCON INTENSITY
ESTIMATE FROM 140512Z OF 44 KNOTS. THE CURRENT AND FORECASTED WIND
RADII HAVE ALSO BEEN ADJUSTED BASED ON THE AFOREMENTIONED ASCAT
IMAGE. UPPER LEVEL ANALYSIS INDICATES A MARGINALLY-FAVORABLE
ENVIRONMENT WITH AN ANTICYCLONE JUST NORTH OF THE SYSTEM, PROVIDING
STRONG DIVERGENT OUTFLOW. HOWEVER, MODERATE (15-20 KNOT)
NORTHEASTERLY VERTICAL WIND SHEAR (VWS) IS PREVENTING VERTICAL
ALIGNMENT AND FASTER INTENSIFICATION. SEA SURFACE TEMPERATURES
(SSTS) ARE NEAR 30 CELSIUS. TS 24W IS TRACKING ALONG THE SOUTHERN
PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC
REASONING MESSAGE.
B. TS KOPPU WILL CONTINUE TO TRACK WESTWARD THROUGH TAU 72 UNDER
THE STEERING INFLUENCE OF THE STR. EXPECT SLOW INTENSIFICATION OVER
THE NEXT 48 HOURS AS VWS REMAINS MODERATE AND CONTINUES TO HINDER
DEVELOPMENT. BEYOND TAU 48, VWS WILL RELAX AS THE UPPER LEVEL WIND
FLOW BECOMES MORE IN-PHASE WITH THE STORM MOTION. ADDITIONALLY, SSTS
WILL INCREASE ABOVE 30 CELSIUS. THESE ENVIRONMENTAL CONDITIONS WILL
SUPPORT A PERIOD OF RAPID INTENSIFICATION AS THE STORM APPROACHES
LUZON.
C. IN THE EXTENDED FORECAST, TS 24W WILL SLOW AND TURN MORE
NORTHWESTWARD AS THE SYSTEM REACHES THE WESTERN EXTENT OF THE
STEERING STR. TS KOPPU WILL CONTINUE TO INTENSIFY UNTIL IT BEGINS TO
INTERACT WITH THE MOUNTAINOUS TERRAIN IN LUZON. THE STORM WILL PASS
OVER THE NORTHEASTERN TIP OF LUZON AS IT CONTINUES TO TURN POLEWARD
AND ROUND THE WESTERN PERIPHERY OF THE STR. DYNAMIC MODEL GUIDANCE
IS IN GOOD OVERALL AGREEMENT AND NOW ALL FAVOR A RECURVE SCENARIO AT
THE END OF THE FORECAST PERIOD; REMOVING THE PREVIOUS BIFURCATION
SCENARIO. ALTHOUGH THE OVERALL TRACK IS BETTER DEFINED, THE DEGREE
AND TIMING OF THE RECURVE IS STILL WIDESPREAD, CAUSING LOW
CONFIDENCE IN THE JTWC FORECAST TRACK, SPECIFICALLY BEYOND TAU 48.//
NNNN

[Yellow Evan]

Keep in mind if the shear backs away like forecast, the storm will develop excellent outflow.

[1900hurricane]

The center is still exposed, but not as badly as it was earlier. Looks like it might have sunk back to the SW a little bit towards the convection. The convection is also scooting a little bit back up to the north.

[NotoSans]

ECMWF continues to trend westward at 12Z, indicating a landfall near the southern coast of China. Meanwhile GFS is still indicating a sharp recurve scenario.

[cycloneye]

Track more south. JTWC 21:00 UTC warning at 45kts.Landfall at Luzon probability is increasing but the question is how strong and how fast it moves as that factor will determine how much of the effects will Luzon have.The main thing for those living in NorthCentral Luzon at this point is to be preparing for a hit of a fairly strong Typhoon.

[euro6208]

WDPN31 PGTW 142100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (KOPPU) WARNING NR
08//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 24W (KOPPU), LOCATED APPROXIMATELY 685 NM
EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-SOUTHWESTWARD AT 10
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY DEPICTS PERSISTENT DEEP CONVECTION DISPLACED
SLIGHTLY WEST OF A LOW LEVEL CIRCULATION CENTER (LLCC). A 141750Z
AMSU-B MICROWAVE IMAGE REVEALS DEFINED SHALLOW SPIRAL BANDING
WRAPPING INTO THE LLCC WITH THE BULK OF THE DEEP CONVECTION OVER THE
SOUTHWESTERN QUADRANT. THE CURRENT POSITION IS BASED ON THE EIR LOOP
AND SATELLITE FIXES FROM PGTW AND RJTD WITH GOOD CONFIDENCE. THE
CURRENT INTENSITY HAS BEEN HELD AT 45 KNOTS BASED ON AN OVERALL
ASSESSMENT OF DVORAK INTENSITY ESTIMATES FROM ALL REPORTING
AGENCIES. UPPER LEVEL ANALYSIS INDICATES A MARGINALLY-FAVORABLE
ENVIRONMENT WITH AN ANTICYCLONE JUST NORTH OF THE SYSTEM, PROVIDING
STRONG DIVERGENT OUTFLOW. HOWEVER, MODERATE (20-25 KNOT)
NORTHEASTERLY VERTICAL WIND SHEAR (VWS) IS PREVENTING VERTICAL
ALIGNMENT AND SUBSEQUENT INTENSIFICATION. SEA SURFACE TEMPERATURES
(SSTS) ARE NEAR 30 CELSIUS. TS 24W IS TRACKING ALONG THE SOUTHERN
PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC
REASONING MESSAGE.
B. TS KOPPU WILL CONTINUE TO TRACK WESTWARD THROUGH TAU 72 ALONG
THE SOUTHERN PERIPHERY OF THE STEERING STR. EXPECT SLOW
INTENSIFICATION OVER THE NEXT 48 HOURS AS VWS REMAINS MODERATE;
HINDERING DEVELOPMENT AND PREVENTING VERTICAL ALIGNMENT. BEYOND TAU
48, VWS WILL RELAX AS THE UPPER LEVEL WIND FLOW BECOMES MORE IN-
PHASE WITH THE STORM MOTION. ADDITIONALLY, SSTS WILL INCREASE ABOVE
30 CELSIUS. THESE ENVIRONMENTAL CONDITIONS WILL SUPPORT A PERIOD OF
RAPID INTENSIFICATION AS THE STORM APPROACHES LUZON.
C. IN THE EXTENDED FORECAST, TS 24W WILL SLOW AND TURN MORE
NORTHWESTWARD AS THE CYCLONE REACHES THE WESTERN EXTENT OF THE
STEERING STR. TS KOPPU WILL CONTINUE TO INTENSIFY UNTIL IT BEGINS TO
INTERACT WITH THE MOUNTAINOUS TERRAIN IN LUZON. THE STORM WILL PASS
OVER THE NORTHERN LUZON AS IT CONTINUES TO TURN POLEWARD AND ROUND
THE WESTERN PERIPHERY OF THE STR. DYNAMIC MODEL GUIDANCE IS OVERALL
IN GOOD AGREEMENT TROUGH TAU 72. HOWEVER, DUE TO SIGNIFICANT
DIFFERENCE AMONG AVAILABLE TRACKERS IN THE EXTENDED TAUS, THERE IS
LOW CONFIDENCE IN THE JTWC TRACK.//
NNNN

[euro6208]

EURO literally stalls this over Luzon for almost 3 days.

[euro6208]

18Z GFS 898 mb and strengthening...

[euro6208]

Super favorable environment if shear relaxes then rapid intensification is likely...

[cycloneye]

TPPN10 PGTW 150033

A. TROPICAL STORM 24W (KOPPU)

B. 14/2332Z

C. 15.12N

D. 131.76E

E. FIVE/MTSAT

F. T3.0/3.0/D0.5/24HRS STT: S0.0/03HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 40A/PBO SBC/ANMTN. CNVCTN WRAPS .65 ON LOG10
SPIRAL, YIELDING A DT OF 3.0. MET AND PT AGREE WITH DT. DBO DT.

I. ADDITIONAL POSITIONS: NONE


CHAPPOTIN

[Alyono]

could cause horrific flooding as this may linger over northern Luzon for several days