WPAC: LEEPI - Post-Tropical

[euro6208]

WDPN31 PGTW 110900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 19W (NINETEEN)
WARNING NR 02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 19W (NINETEEN), LOCATED APPROXIMATELY
349 NM NORTH OF ANDERSEN AFB, GUAM, HAS TRACKED NORTH-NORTHWESTWARD
AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS A COMPACT SYSTEM, APPROXIMATELY 120NM
DIAMETER, WITH A SYMMETRIC AREA OF DEEP CONVECTION OBSCURING THE LOW-
LEVEL CIRCULATION CENTER (LLCC). A 110739Z SSMIS 91GHZ COMPOSITE
IMAGE SHOWS SHALLOW BANDING OVER THE SOUTHWEST QUADRANT WITH DEEP
CONVECTIVE BANDING WRAPPING INTO A DEFINED LLCC, WHICH SUPPORTS THE
INITIAL POSITION WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS
ASSESSED AT 30 KNOTS BASED ON A PGTW DVORAK ESTIMATE OF T2.0 (30
KNOTS), HOWEVER, THE SYSTEM IS CONSOLIDATING QUICKLY AND WILL BE
UPGRADED TO A TROPICAL STORM AT THE NEXT WARNING CYCLE. UPPER-LEVEL
ANALYSIS INDICATES A ROBUST POLEWARD OUTFLOW CHANNEL INTO A TUTT
CELL POSITIONED TO THE NORTHEAST WITH OUTFLOW HINDERED TO THE
NORTHWEST BY NORTHERLY, CONVERGENT UPPER-LEVEL FLOW ASSOCIATED WITH
THE BROAD ANTICYCLONE ENTRENCHED SOUTH OF JAPAN. TD 19W IS TRACKING
ALONG THE SOUTHWESTERN PERIPHERY OF A LOW- TO MID-LEVEL SUBTROPICAL
RIDGE (STR) POSITIONED TO THE NORTH AND NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TD 19W IS FORECAST TO TRACK NORTHWESTWARD ALONG THE
SOUTHWESTERN PERIPHERY OF THE STR THROUGH THE FORECAST PERIOD. TD
19W WILL INTENSIFY TO A PEAK OF 40 KNOTS BY TAU 12 UNDER FAVORABLE
UPPER-LEVEL CONDITIONS. AFTER TAU 12, TD 19W SHOULD ENCOUNTER
INCREASING NORTHEASTERLY VERTICAL WIND SHEAR (VWS), WHICH WILL SERVE
TO WEAKEN THE SYSTEM. AS THE SYSTEM TRACKS FURTHER NORTHWEST, THE
VWS IS FORECAST TO INCREASE TO MODERATE TO STRONG LEVELS, WHICH WILL
LEAD TO DISSIPATION BY TAU 48. THERE IS A LARGE DEGREE OF
UNCERTAINTY IN THE INTENSITY FORECAST DUE TO THE COMPACT NATURE OF
THE SYSTEM AND THE ENHANCED OUTFLOW ASSOCIATED WITH THE TUTT CELL,
WHICH IS EXPECTED TO PERSIST FOR 12-24 HOURS. NUMERICAL MODEL
GUIDANCE IS IN TIGHT AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE
IN THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

TPPN13 PGTW 110913

A. TROPICAL DEPRESSION 19W (NW OF GUAM)

B. 11/0900Z

C. 19.89N

D. 143.15E

E. FIVE/HMWRI8

F. T2.5/2.5/D1.5/24HRS STT: D0.5/03HRS

G. IR/EIR

H. REMARKS: 47A/PBO PTLY XPSD LLCC/ANMTN. CNVCTN WRAPS .40 ON
LOG10 SPIRAL YIELDING A DT OF 2.5. PT AGREES WITH DT WHILE MET
YIELDS A 2.0. DBO DT.

I. ADDITIONAL POSITIONS:
11/0542Z 19.30N 143.68E SSMS
11/0739Z 19.35N 143.72E SSMS


LEMBKE

[euro6208]

[euro6208]

19W NINETEEN 180811 1200 19.8N 143.7E WPAC 35 996

Upgraded to the 15th TS of the season.

[euro6208]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 9.0
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 11 AUG 2018 Time : 112000 UTC
Lat : 20:15:28 N Lon : 143:09:21 E


CI# /Pressure/ Vmax
2.4 /1000.1mb/ 34.0kt


Final T# Adj T# Raw T#
2.4 2.7 3.3

Center Temp : -71.6C Cloud Region Temp : -60.1C

Scene Type : IRREGULAR CDO

Subtropical Adjustment : OFF

Extratropical Adjustment : OFF

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 : OFF
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : N/A
- Environmental MSLP : 1006mb

Satellite Name : HIM-8
Satellite Viewing Angle : 23.9 degrees

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

[NotoSans]

With a bullseye ASCAT pass the agencies cannot simply turn a blind eye to it now. This is at least a 55-knot system.

[1900hurricane]

If JTWC said it was "consolidating quickly" in the 06Z advisory, why didn't they upgrage to a tropical storm then instead of putting it off to 12Z?

[euro6208]

Looks like JTWC finally agreeing with ASCAT for a change. Thank god.

19W NINETEEN 180811 1200 20.1N 143.6E WPAC 55 989

[euro6208]

[mrbagyo]

Here's that bullseye ASCAT pass.


Is JMA still sleeping?

[euro6208]

Forecast to peak at 70 knots now. Incredible.

[euro6208]

WDPN31 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (NINETEEN)
WARNING NR 03//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 19W (NINETEEN), LOCATED APPROXIMATELY 391 NM
NORTH OF ANDERSEN AFB, HAS TRACKED NORTH-NORTHWESTWARD AT 11 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS A MIDGET SYSTEM WITH A 140-160NM DIAMETER CENTRAL
DENSE OVERCAST FEATURE OBSCURING THE LOW-LEVEL CIRCULATION CENTER
(LLCC). A 111155Z MHS 89GHZ IMAGE SHOWS TIGHTLY-CURVED BANDING
WRAPPING INTO THE LLCC, WHICH, ALONG WITH A 111156Z ASCAT AMBIGUITY
ANALYSIS, SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. THE
INITIAL INTENSITY IS ASSESSED AT 55 KNOTS BASED ON A 111156Z ASCAT
IMAGE SHOWING NUMEROUS 45 KNOT WINDS WITH 50-55 KNOT WINDS IN THE
CORE. DUE TO THE RAPID INTENSIFICATION (RI) OF THE SYSTEM (FROM 20
KNOTS TO 55 KNOTS) OVER THE PAST 18 HOURS, DVORAK ESTIMATES FROM
PGTW AND KNES ARE TOO LOW AT T2.5 (35 KNOTS). UPPER-LEVEL ANALYSIS
INDICATES A ROBUST POLEWARD OUTFLOW CHANNEL INTO A TUTT CELL
POSITIONED TO THE NORTHEAST WITH OUTFLOW HINDERED TO THE NORTHWEST
BY NORTHERLY, CONVERGENT UPPER-LEVEL FLOW ASSOCIATED WITH THE BROAD
ANTICYCLONE ENTRENCHED SOUTH OF JAPAN. TS 19W IS TRACKING ALONG THE
SOUTHWESTERN PERIPHERY OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE
(STR) POSITIONED TO THE NORTH AND NORTHEAST.
3. FORECAST REASONING.
A. DUE TO THE ONGOING RI PHASE AND MIDGET CHARACTERISTICS OF THE
SYSTEM, THERE IS A MAJOR CHANGE TO THE FORECAST PHILOSOPHY, WHICH
NOW INCLUDES A SIGNIFICANT INCREASE IN INITIAL INTENSITY AND PEAK
INTENSITY (70 KNOTS). ADDITIONALLY, THE 34 KNOT WIND RADII HAVE BEEN
ADJUSTED BASED ON A DETAILED ANALYSIS OF THE ASCAT IMAGE.
B. TS 19W IS FORECAST TO TRACK NORTHWESTWARD ALONG THE
SOUTHWESTERN PERIPHERY OF THE STR THROUGH THE FORECAST PERIOD. TD
19W WILL INTENSIFY TO A PEAK OF 70 KNOTS BY TAU 12 UNDER FAVORABLE
UPPER-LEVEL CONDITIONS. AFTER TAU 24, TS 19W SHOULD ENCOUNTER
INCREASING NORTHEASTERLY VERTICAL WIND SHEAR (VWS), WHICH WILL SERVE
TO WEAKEN THE SYSTEM. AS THE SYSTEM TRACKS FURTHER NORTHWEST, THE
VWS IS FORECAST TO INCREASE TO MODERATE TO STRONG LEVELS, WHICH WILL
LEAD TO DISSIPATION BY TAU 72. THERE IS A LARGE DEGREE OF
UNCERTAINTY IN THE INTENSITY FORECAST DUE TO THE COMPACT NATURE OF
THE SYSTEM AND THE ENHANCED OUTFLOW ASSOCIATED WITH THE TUTT CELL,
WHICH IS EXPECTED TO PERSIST FOR 12-24 HOURS. NUMERICAL MODEL
GUIDANCE IS IN TIGHT AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE
IN THE JTWC FORECAST TRACK.//
NNNN

[1900hurricane]

00Z and 06Z intensities in best track have been bumped up to 35 kt and 45 kt, respectively.

[NotoSans]

I would actually upgrade this system to TS at 18Z yesterday.

[Cunxi Huang]

Seems like JMA will issue a GW or upgrade 19W w/o a GW at 15z analysis. The chance is high because 12z ASCAT overpass already indicates a broad area of 40-45 kt winds.

[mrbagyo]

[NotoSans]

finally

WTPQ21 RJTD 111500

RSMC TROPICAL CYCLONE ADVISORY

NAME TS 1815 LEEPI (1815) UPGRADED FROM TD

ANALYSIS

PSTN 111500UTC 20.6N 143.5E FAIR

MOVE N 07KT

PRES 998HPA

MXWD 040KT

GUST 060KT

30KT 120NM EAST 60NM WEST

FORECAST

24HF 121500UTC 25.3N 140.6E 60NM 70%

MOVE NNW 14KT

PRES 1000HPA

MXWD 040KT

GUST 060KT =

[Cunxi Huang]

TS 1815 (Leepi)
Issued at 18:55 UTC, 11 August 2018

<Analysis at 18 UTC, 11 August>
Scale -
Intensity -
Center position N20°55' (20.9°)
E143°35' (143.6°)
Direction and speed of movement N 15 km/h (7 kt)
Central pressure 998 hPa
Maximum wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
≥ 30 kt wind area E 220 km (120 NM)
W 110 km (60 NM)

<Forecast for 06 UTC, 12 August>
Intensity -
Center position of probability circle N23°05' (23.1°)
E141°55' (141.9°)
Direction and speed of movement NW 25 km/h (14 kt)
Central pressure 996 hPa
Maximum wind speed near center 23 m/s (45 kt)
Maximum wind gust speed 35 m/s (65 kt)
Radius of probability circle 70 km (40 NM)

<Forecast for 18 UTC, 12 August>
Intensity -
Center position of probability circle N25°35' (25.6°)
E140°10' (140.2°)
Direction and speed of movement NNW 30 km/h (15 kt)
Central pressure 1000 hPa
Maximum wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 110 km (60 NM)

<Forecast for 18 UTC, 13 August>
Intensity -
TD
Center position of probability circle N29°00' (29.0°)
E134°40' (134.7°)
Direction and speed of movement NW 30 km/h (15 kt)
Central pressure 1008 hPa
Radius of probability circle 200 km (110 NM)

[euro6208]

No longer expected to intensify into a typhoon.

WDPN31 PGTW 112100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (NINETEEN)
WARNING NR 04//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 19W (NINETEEN), LOCATED APPROXIMATELY 249 NM
SOUTH-SOUTHEAST OF IWO TO, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT
10 KNOTS OVER THE PAST SIX HOURS. ANIMATED EIR SATELLITE IMAGERY
SHOWS A COMPACT SYSTEM THAT HAS VIRTUALLY MAINTAINED ITS CONVECTIVE
SIGNATURE OVER THE PAST SIX HOURS AS IT TRACKED MORE POLEWARD INTO A
WESTWARD PROPAGATING TUTT. THE INITIAL POSITION IS EXTRAPOLATED FROM
AN 111628Z ATMS MICROWAVE PARTIAL PASS AND CONFORMED WITH THE BEST
TRACK. THE INITIAL INTENSITY OF 55 KNOTS IS HELD HIGHER THAN
CONGRUENT AGENCY AND OBJECTIVE DVORAK ESTIMATES OF T3.0 TO REFLECT
THE SUSTAINED CONVECTIVE SIGNATURE. UPPER-LEVEL ANALYSIS INDICATES
THE SYSTEM IS IN A NARROW ZONE OF LOW (10-KNOT) VWS AND HAS
MAINTAINED A ROBUST POLEWARD OUTFLOW CHANNEL INTO A TUTT CELL TO THE
NORTHEAST. HOWEVER, SUBSIDENCE IS BEGINNING TO TAKE ITS TOLL ALONG
THE NORTHERN FLANK AS TS 19W CLOSES IN ON THE AFOREMENTIONED TUTT.
THE CYCLONE IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A LOW- TO
MID-LEVEL STR TO THE NORTHEAST.
3. FORECAST REASONING.
A. THERE IS A MINOR CHANGE TO THE FORECAST PHILOSOPHY, WHICH IS
MAINLY TO SCALE DOWN THE FORECAST INTENSITIES.
B. TS 19W WILL TRACK NORTH-NORTHWESTWARD TO NORTHWESTWARD UNDER
THE STR THROUGH THE FORECAST PERIOD. THE MARGINALLY FAVORABLE
CONDITIONS WILL SUSTAIN ITS CURRENT INTENSITY UP TO TAU 12.
AFTERWARD, INCREASING VWS AND SUBSIDENCE ASSOCIATED WITH THE
APPROACHING TUTT WILL CAUSE A GRADUAL WEAKENING TO 35 KNOTS BY TAU
36. AFTER TAU 36, AS THE SYSTEM TRACKS FURTHER NORTHWEST, THE VWS
WILL INCREASE TO STRONG LEVELS, WHICH WILL LEAD TO DISSIPATION BY TAU
72. THERE IS A DEGREE OF UNCERTAINTY IN THE INTENSITY FORECAST DUE
TO THE COMPACT NATURE OF THE SYSTEM. HOWEVER, NUMERICAL MODEL TRACK
GUIDANCE REMAINS IN TIGHT AGREEMENT, LENDING HIGH CONFIDENCE IN THE
JTWC FORECAST TRACK.//
NNNN

[euro6208]

WDPN31 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (LEEPI) WARNING NR 05//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 19W (LEEPI), LOCATED APPROXIMATELY 205 NM
SOUTH-SOUTHEAST OF IWO TO, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT
10 KNOTS OVER THE PAST SIX HOURS. ANIMATED EIR SATELLITE IMAGERY
SHOWS THE COMPACT SYSTEM SLIGHTLY DEEPENED AS IT MAINTAINED A ROBUST
OUTFLOW CHANNEL INTO A TUTT CELL TO THE NORTHEAST. THE INITIAL
POSITION IS EXTRAPOLATED FROM A DEFINED LLC IN THE 112326Z GPM
MICROWAVE PASS WITH GOOD CONFIDENCE. THE INITIAL INTENSITY OF 60
KNOTS IS HELD HIGHER THAN
AGENCY AND OBJECTIVE DVORAK ESTIMATES OF T2.5-T3.0 TO REFLECT THE
SLIGHTLY IMPROVED CONVECTIVE SIGNATURE. UPPER-LEVEL ANALYSIS INDICATES
THE SYSTEM IS IN A NARROW ZONE OF LOW (10-KNOT) VWS AND TRACKING
CLOSER TO A TUTT TO THE NORTH. SUBSIDENCE IS NOW APPARENT ALONG THE
NORTHERN FLANK AS TS 19W CLOSES IN ON THE TUTT. THE CYCLONE IS
TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A LOW- TO MID-LEVEL STR
TO THE NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TS 19W WILL TRACK NORTH-NORTHWESTWARD TO NORTHWESTWARD UNDER
THE STR THROUGH THE FORECAST PERIOD. THE MARGINALLY FAVORABLE
CONDITIONS WILL SUSTAIN ITS CURRENT INTENSITY UP TO TAU 12.
AFTERWARD, INCREASING VWS AND SUBSIDENCE ASSOCIATED WITH THE TUTT
WILL CAUSE A GRADUAL WEAKENING TO 50 KNOTS BY TAU 36. AFTER TAU 36,
AS THE SYSTEM TRACKS ON A MORE NORTHWESTWARD TRAJECTORY, THE VWS
WILL INCREASE TO STRONGER LEVELS, WHICH WILL CAUSE RAPID WEAKENING
AND LEAD TO DISSIPATION BY TAU 72. THERE IS A DEGREE OF UNCERTAINTY
IN THE INTENSITY FORECAST DUE TO THE COMPACT NATURE OF THE SYSTEM.
HOWEVER, NUMERICAL MODEL TRACK GUIDANCE REMAINS IN TIGHT AGREEMENT,
LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN