WPAC: PRAPIROON - Post-Tropical

[cycloneye]

[1900hurricane]

Looks like microwave has picked up a partial eyewall structure. Prapiroon is still dealing with a dry air wedge, and northwesterly shear has begun to pick up a little bit, but this is a system that continues to strengthen steadily.

[euro6208]

[NotoSans]

WTPQ30 RJTD 300000
RSMC TROPICAL CYCLONE PROGNOSTIC REASONING
REASONING NO. 7 FOR TS 1807 PRAPIROON (1807)
1.GENERAL COMMENTS
TS PRAPIROON IS LOCATED AT 20.4N, 129.8E. INFORMATION ON THE
CURRENT POSITION IS BASED ON ANIMATED MSI. POSITIONAL ACCURACY IS
POOR BECAUSE THE CSC IS OBSCURE. THE SYSTEM IS IN A FAVORABLE
ENVIRONMENT FOR DEVELOPMENT UNDER THE INFLUENCE OF HIGH SSTS AND
GOOD UPPER-LEVEL OUTFLOW. THIS HAS CAUSED THE SYSTEM TO DEVELOP
OVER THE LAST SIX HOURS. INFORMATION ON CURRENT INTENSITY IS BASED
ON DVORAK INTENSITY ANALYSES.
2.SYNOPTIC SITUATION
THE SYSTEM IS MOVING SLOWLY NORTHWESTWARD ALONG THE SOUTHWESTERN
PERIPHERY OF A MID-LEVEL SUB-TROPICAL HIGH. ANIMATED MSI SHOWS THE
FORMATION OF A BAND WITH A CURVATURE SUGGESTING THE CSC. ANIMATED
MSI SHOWS GOOD CLOUD CHARACTERISTICS OF ANTICYCLONIC OUTFLOW.
3.TRACK FORECAST
THE SYSTEM WILL GRADUALLY ACCELERATE AND MOVE NORTH-NORTHWESTWARD
ALONG THE PERIPHERY OF A MID-LEVEL SUB-TROPICAL HIGH UNTIL FT24.
THE SYSTEM WILL THEN MOVE NORTHWARD ALONG THE PERIPHERY OF A
MID-LEVEL SUB-TROPICAL HIGH UNTIL FT72. THE JMA TRACK FORECAST IS
BASED ON GSM PREDICTIONS. JMA TRACK FORECAST CONFIDENCE IS FAIR
BECAUSE ALL NUMERICAL MODELS ARE IN CLOSE AGREEMENT.
4.INTENSITY FORECAST
THE SYSTEM WILL DEVELOP UNTIL FT48 DUE TO THE INFLUENCE OF
INTERACTION WITH HIGH SSTS AND GOOD UPPER LEVEL OUTFLOW. THE
SYSTEM WILL THEN WEAKEN UNTIL FT72 IN A STATE OF EXTRATROPICAL
TRANSITION. THE SYSTEM WILL TRANSFORM INTO AN EXTRATROPICAL
CYCLONE BY FT72. THE JMA INTENSITY FORECAST IS BASED ON GUIDANCE
DATA.
=

[euro6208]

WDPN31 PGTW 300300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (PRAPIROON)
WARNING NR 07//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 09W (PRAPIROON), LOCATED APPROXIMATELY 349 NM
SOUTH-SOUTHEAST OF KADENA AB, HAS TRACKED NORTH-NORTHWESTWARD AT
06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A PARTIALLY-EXPOSED, WELL-DEFINED LOW-LEVEL
CIRCULATION CENTER (LLCC) DECOUPLED FROM THE DEEP CONVECTIVE BANDING
DUE TO MODERATE (15 TO 20 KNOTS) NORTHWESTERLY VERTICAL WIND SHEAR
(VWS). A 300115Z METOP-B 89GHZ IMAGE SHOWS SHALLOW BANDING WRAPPING
INTO A WELL-DEFINED LLCC WITH A CURVED DEEP CONVECTIVE BAND OVER THE
SOUTHERN SEMICIRCLE. OVERALL, THERE IS GOOD CONFIDENCE IN THE
CURRENT POSITION. THE INITIAL INTENSITY OF 45 KNOTS IS BASED ON
DVORAK ESTIMATES OF T3.0 (45 KNOTS) FROM ALL AGENCIES. ANIMATED
WATER VAPOR IMAGERY INDICATES DEGRADED POLEWARD OUTFLOW DUE TO THE
NORTHWESTERLY VWS, HOWEVER, EQUATORWARD OUTFLOW REMAINS ROBUST. TS
09W IS TRACKING NORTH-NORTHWESTWARD ALONG THE SOUTHWEST PERIPHERY OF
A DEEP LAYERED SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE EAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 09W WILL CONTINUE TO TRACK POLEWARD ALONG THE WESTERN
PERIPHERY OF THE STR THROUGH TAU 72. DYNAMIC GUIDANCE REMAINS IN
TIGHT AGREEMENT THROUGH TAU 48 LENDING HIGH CONFIDENCE TO THIS
PORTION OF THE FORECAST TRACK. AFTER TAU 48, DYNAMIC MODEL GUIDANCE
DIVERGES WITH INCREASING UNCERTAINTY AS THE SYSTEM BEGINS TO
INTERACT WITH THE MIDLATITUDE WESTERLIES. THE SYSTEM IS FORECAST TO
INTENSIFY SLOWLY THROUGH TAU 24 DUE TO THE MODERATE VWS. AFTER TAU
24, POLEWARD OUTFLOW IS FORECAST TO IMPROVE SIGNIFICANTLY ALLOWING
THE SYSTEM TO INTENSIFY AT A FASTER RATE TO A PEAK OF 75 KNOTS BY
TAU 48. DUE TO THE EXPOSED NATURE OF THE LLCC, THERE IS INCREASING
UNCERTAINTY IN THE INTENSITY FORECAST AND PEAK INTENSITY. HOWEVER,
THE CURRENT INTENSITY FORECAST REMAINS UNCHANGED FOR THE TIME BEING
AND WILL BE RE-ASSESSED DURING THE NEXT 12 HOURS IF THE SYSTEM
CONTINUES TO STRUGGLE.
C. BEYOND TAU 72, TS 09W WILL RE-CURVE WHILE UNDERGOING EXTRA-
TROPICAL TRANSITION AS IT CROSSES THE MOUNTAINOUS KOREAN PENINSULA
AND WEAKENS RAPIDLY. THE SYSTEM MAY DISSIPATE PRIOR TO COMPLETING
EXTRA-TROPICAL TRANSITION. OVERALL, THERE IS LOW CONFIDENCE IN THE
THE JTWC FORECAST TRACK DUE TO THE LARGE SPREAD IN SOLUTIONS AFTER
TAU 48.//
NNNN

[euro6208]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 30 JUN 2018 Time : 041000 UTC
Lat : 21:27:02 N Lon : 129:05:58 E


CI# /Pressure/ Vmax
3.2 / 991.5mb/ 49.0kt


Final T# Adj T# Raw T#
2.8 2.5 2.4

Center Temp : -17.3C Cloud Region Temp : -35.5C

Scene Type : CURVED BAND with 0.50 ARC in DK GRAY

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : WEST PACIFIC
Dvorak CI > MSLP Conversion Used : CKZ Method

Tno/CI Rules : Constraint Limits : 0.7T/6hr
Weakening Flag : ON
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 78km
- Environmental MSLP : 1007mb

Satellite Name : HIM-8
Satellite Viewing Angle : 28.3 degrees

****************************************************

[doomhaMwx]

Has been feelin' some northwesterly shear.

[euro6208]

Slightly weaker peak intensity as it passes by Okinawa.

WDPN31 PGTW 300900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (PRAPIROON)
WARNING NR 08//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 09W (PRAPIROON), LOCATED APPROXIMATELY 327 NM
SOUTH-SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED
NORTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED MSI SHOWS
A PARTIALLY-EXPOSED AND WOBBLY LLC WITH THE MAIN BULK OF CONVECTION
SHEARED SOUTHWARD. THE INITIAL POSITION IS PLACED WITH TENTATIVE
CONFIDENCE ON THE CENTROID OF MULTI AGENCY FIXES TO OFFSET THE WOBBLY
STORM MOTION. THE INITIAL INTENSITY OF 45 KNOTS IS SUPPORTED BY
AGENCY DVORAK ESTIMATES AND REFLECTS THE UNCHANGED CONVECTIVE
SIGNATURE. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF
MODERATE (15-20 KNOT) NORTHWESTERLY VWS. HOWEVER, A STRONG
EQUATORWARD OUTFLOW IS PROVIDING AMPLE VENTILATION TO THE DISPLACED
CONVECTION. ADDITIONALLY, ALONG-TRACK SSTS ARE VERY CONDUCIVE AT
29-30 CELSIUS. THE CYCLONE IS TRACKING ALONG THE SOUTHWEST PERIPHERY
OF A LARGE-AMPLITUDE STR TO THE EAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 09W WILL CONTINUE TO TRACK POLEWARD ALONG THE WESTERN
PERIPHERY OF THE STR. IT IS FORECAST TO INTENSIFY SLOWLY AS THE
OVERALL ENVIRONMENT, ENHANCED BY INCREASING POLEWARD OUTFLOW, REMAINS
FAVORABLE UP TO TAU 48 WHERE IT WILL PEAK AT 65 KNOTS. AFTERWARD,
INCREASING VWS, LANDFALL INTO SOUTH KOREA AND THE TAEBEK MOUNTAIN
RANGE WILL RAPIDLY ERODE THE SYSTEM. WITH COAMPS AS THE SOLE
RIGHT-OF-TRACK OUTLIER, DYNAMIC GUIDANCE REMAINS IN TIGHT AGREEMENT
THROUGH TAU 48 WITH INCREASING SPREAD AFTERWARD.
C. BEYOND TAU 72, TS PRAPIROON WILL RE-CURVE NORTHEASTWARD WHILE
UNDERGOING EXTRA-TROPICAL TRANSITION (ETT) AS IT CROSSES THE RUGGED
KOREAN PENINSULA AND WEAKENS RAPIDLY. THERE IS A DISTINCT POSSIBILITY
THE SYSTEM WILL DISSIPATE PRIOR TO COMPLETING ETT. OVERALL, THERE IS
LOW CONFIDENCE IN THE THE JTWC FORECAST TRACK DUE TO THE INITIAL
WOBBLY STORM MOTION AND THE LARGE SPREAD IN SOLUTIONS AFTER TAU 48.//
NNNN

[euro6208]

TPPN10 PGTW 300925

A. TROPICAL STORM 09W (PRAPIROON)

B. 30/0900Z

C. 21.21N

D. 129.00E

E. FIVE/HMWRI8

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 .70 ON LOG10 SPIRAL
YIELDING A DT OF 3.0. MET AND PT AGREE. DBO DT.

I. ADDITIONAL POSITIONS: NONE


VEERKAMP

TXPQ29 KNES 300907
TCSWNP

A. 09W (PRAPIROON)

B. 30/0830Z

C. 21.2N

D. 128.7E

E. THREE/HIMAWARI-8

F. T3.0/3.0/D1.5/24HRS

G. IR/EIR/VIS/AMSR2

H. REMARKS...THIS INTENSITY ESTIMATE WAS DERIVED USING 4 KM IR DATA. LOW
LEVEL CIRCULATION LOCATED 1/3 DEG INTO OVERCAST RESULTS IN DT=3.5. MET=3.0
AND PT=3.0. FT IS BASED ON MET DUE TO UNCERTAINTY IN THE PRECISE CENTER
LOCATION.

I. ADDL POSITIONS

30/0421Z 20.8N 129.1E AMSR2


...BOLL

[1900hurricane]

Prapiroon has been having issues maintaining convection over the circulation center. It's covered for now, but the Mei-yu induced northwesterly shear may expose the center again at any time.

[cycloneye]

[euro6208]

WDPN31 PGTW 010300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (PRAPIROON)
WARNING NR 11//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 09W (PRAPIROON), LOCATED APPROXIMATELY 176 NM
SOUTH OF KADENA AB, OKINAWA, HAS TRACKED NORTHWESTWARD AT 10 KNOTS
OVER THE PAST SIX HOURS. UPPER-LEVEL ANALYSIS INDICATES AN IMPROVING
ENVIRONMENT WITH DECREASING (10-15 KNOTS) NORTH-NORTHWESTERLY
VERTICAL WIND SHEAR (VWS). THIS IS CLEARLY EVIDENT IN ANIMATED WATER
VAPOR IMAGERY, WHICH SHOWS EXPANDING POLEWARD OUTFLOW IN ADDITION TO
THE ROBUST EQUATORWARD OUTFLOW. CONSEQUENTLY, ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY INDICATES A CONSOLIDATING SYSTEM WITH
DEEP CONVECTION BUILDING OVER THE LOW-LEVEL CIRCULATION CENTER
(LLCC) AND SPIRAL BANDING OVER THE SOUTHERN SEMICIRCLE. THE IMPROVED
CONVECTIVE STRUCTURE IS ALSO EVIDENT IN A 30/2219Z SSMIS 37GHZ IMAGE
SHOWING CONVECTIVE BANDING WRAPPING INTO A RAGGED LLCC, WHICH
SUPPORTS THE CURRENT POSITION WITH GOOD CONFIDENCE. BASED ON THE
IMPROVED ORGANIZATION, THE INITIAL INTENSITY IS ASSESSED AT 50
KNOTS, HEDGED ABOVE THE DVORAK ESTIMATES OF 3.0 (45 KNOTS) FROM ALL
AGENCIES. TS 09W IS TRACKING ALONG THE WESTERN PERIPHERY OF A DEEP-
LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 09W WILL CONTINUE TO TRACK POLEWARD ALONG THE WESTERN
PERIPHERY OF THE STR. WITH THE EXCEPTION OF THE LONE OUTLIER,
NAVGEM, THE BULK OF THE DYNAMIC MODEL GUIDANCE IS IN EXCEPTIONALLY
TIGHT AGREEMENT THROUGH TAU 48 WITH AN 83-NM SPREAD IN SOLUTIONS
NEAR BUSAN, KOREA. UPPER-LEVEL CONDITIONS ARE FORECAST TO BE
FAVORABLE FOR FURTHER INTENSIFICATION THROUGH TAU 24 WITH LOW VWS
AND IMPROVING POLEWARD OUTFLOW ASSOCIATED WITH AN APPROACHING
MIDLATITUDE SHORTWAVE TROUGH--A PEAK INTENSITY OF 65 KNOTS IS
FORECAST AT TAU 24. AFTER TAU 30, NORTH OF 30N LATITUDE, VWS IS
FORECAST TO INCREASE WITH COOLER SST (25C), WHICH WILL SERVE TO
WEAKEN TS 09W AS IT APPROACHES THE SOUTHERN COAST OF SOUTH KOREA. AS
TS PRAPIROON TRACKS OVER THE MOUNTAINOUS TERRAIN OF SOUTH KOREA, IT
IS EXPECTED TO WEAKEN RAPIDLY WHILE UNDERGOING EXTRA-TROPICAL
TRANSITION (ETT). THERE IS A DISTINCT POSSIBILITY THE SYSTEM WILL
DISSIPATE PRIOR TO COMPLETING ETT OVER THE COLD SST OF THE EAST SEA.
OVERALL, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN

[1900hurricane]

JMA is up to a Severe Tropical Storm.

STS 1807 (Prapiroon)
Issued at 04:45 UTC, 1 July 2018

<Analysis at 04 UTC, 1 July>
Scale -
Intensity -
Center position N23°50' (23.8°)
E127°25' (127.4°)
Direction and speed of movement NNW 20 km/h (10 kt)
Central pressure 990 hPa
Maximum wind speed near center 25 m/s (50 kt)
Maximum wind gust speed 35 m/s (70 kt)
≥ 30 kt wind area SE 430 km (230 NM)
NW 260 km (140 NM)

<Estimate for 05 UTC, 1 July>
Scale -
Intensity -
Center position N23°55' (23.9°)
E127°20' (127.3°)
Direction and speed of movement NNW 20 km/h (10 kt)
Central pressure 990 hPa
Maximum wind speed near center 25 m/s (50 kt)
Maximum wind gust speed 35 m/s (70 kt)
≥ 30 kt wind area SE 430 km (230 NM)
NW 260 km (140 NM)

<Forecast for 15 UTC, 1 July>
Intensity -
Center position of probability circle N25°35' (25.6°)
E126°40' (126.7°)
Direction and speed of movement NNW 20 km/h (11 kt)
Central pressure 980 hPa
Maximum wind speed near center 30 m/s (60 kt)
Maximum wind gust speed 45 m/s (85 kt)
Radius of probability circle 70 km (40 NM)
Storm warning area ALL 150 km (80 NM)

<Forecast for 03 UTC, 2 July>
Intensity Strong
Center position of probability circle N28°10' (28.2°)
E127°00' (127.0°)
Direction and speed of movement N 25 km/h (13 kt)
Central pressure 975 hPa
Maximum wind speed near center 35 m/s (65 kt)
Maximum wind gust speed 50 m/s (95 kt)
Radius of probability circle 150 km (80 NM)
Storm warning area ALL 220 km (120 NM)

<Forecast for 00 UTC, 3 July>
Intensity -
Center position of probability circle N33°50' (33.8°)
E127°40' (127.7°)
Direction and speed of movement N 30 km/h (15 kt)
Central pressure 990 hPa
Maximum wind speed near center 25 m/s (50 kt)
Maximum wind gust speed 35 m/s (70 kt)
Radius of probability circle 280 km (150 NM)

<Forecast for 00 UTC, 4 July>
Intensity -
LOW
Center position of probability circle N39°25' (39.4°)
E132°40' (132.7°)
Direction and speed of movement NNE 35 km/h (20 kt)
Central pressure 996 hPa
Maximum sustained wind speed 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 410 km (220 NM)

[euro6208]

Impressive radar.

[euro6208]

Update from Okinawa.

Stars And Stripes

[cycloneye]

[doomhaMwx]

The center of STS Prapiroon is passing west of Okinawa island this Sunday night JST.




A station in Okinawa's Naha city recorded a wind gust of 106kph (29.6 m/s) @ around 7pm JST.
https://www.jma.go.jp/en/amedas_h/today ... oupCode=65

[mrbagyo]

[NotoSans]

Lowest SLP recorded in Kumejima so far is 974.9 mb while maximum sustained winds recorded in the Okinawa region are around 27 m/s.

[NotoSans]

JMA's latest reasoning

WTPQ30 RJTD 011800
SMC TROPICAL CYCLONE PROGNOSTIC REASONING
REASONING NO.14 FOR STS 1807 PRAPIROON (1807)
1.GENERAL COMMENTS
STS PRAPIROON IS LOCATED AT 26.1N, 126.8E. INFORMATION ON THE
CURRENT POSITION IS BASED ON ANIMATED MSI AND SURFACE
OBSERVATIONS. POSITIONAL ACCURACY IS GOOD. THE SYSTEM IS IN A
FAVORABLE ENVIRONMENT FOR DEVELOPMENT UNDER THE INFLUENCE OF HIGH
SSTS AND GOOD UPPER-LEVEL OUTFLOW. THIS HAS CAUSED THE SYSTEM TO
DEVELOP OVER THE LAST SIX HOURS. INFORMATION ON CURRENT INTENSITY
IS BASED ON DVORAK INTENSITY ANALYSES AND SURFACE OBSERVATIONS.
2.SYNOPTIC SITUATION
THE SYSTEM IS MOVING NORTHWARD ALONG THE WESTERN PERIPHERY OF A
MID-LEVEL SUB-TROPICAL HIGH. ANIMATED MSI SHOWS THE ELONGATION OF
A BAND WITH A CURVATURE SUGGESTING THE CSC. ANIMATED MSI SHOWS
GOOD CLOUD CHARACTERISTICS OF ANTICYCLONIC OUTFLOW. WATER VAPOR
IMAGERY SHOWS DRY AIR IN THE DIRECTION OF THE MOVEMENT. GPM/GMI 89
GHZ MICROWAVE IMAGERY SHOWS THE SYSTEM HAS A BAND WITH CURVATURE
INDICATING THE CSC.
3.TRACK FORECAST
THE SYSTEM WILL MOVE NORTHWARD ALONG THE PERIPHERY OF A MID-LEVEL
SUB-TROPICAL HIGH UNTIL FT24. THE SYSTEM WILL THEN MOVE
NORTH-NORTHEASTWARD ALONG THE PERIPHERY OF A MID-LEVEL
SUB-TROPICAL HIGH UNTIL FT48. THE SYSTEM WILL THEN MOVE
NORTHEASTWARD UNDER THE INFLUENCE OF MID-LATITUDE PREVAILING
WESTERLIES UNTIL FT72. THE JMA TRACK FORECAST IS BASED ON GSM
PREDICTIONS. JMA TRACK FORECAST CONFIDENCE IS FAIR BECAUSE ALL
NUMERICAL MODELS ARE IN CLOSE AGREEMENT.
4.INTENSITY FORECAST
THE SYSTEM WILL DEVELOP UNTIL FT12 DUE TO THE INFLUENCE OF
INTERACTION WITH HIGH SSTS AND GOOD UPPER LEVEL OUTFLOW. THE
SYSTEM WILL THEN GRADUALLY WEAKEN UNTIL FT24 DUE TO THE INFLUENCE
OF INTERACTION WITH LOWER SSTS AND LOW TCHP. THE SYSTEM WILL THEN
WEAKEN UNTIL FT72 IN A STATE OF EXTRATROPICAL TRANSITION. THE
SYSTEM WILL TRANSFORM INTO AN EXTRATROPICAL CYCLONE BY FT72. THE
JMA INTENSITY FORECAST IS BASED ON GUIDANCE DATA.
=