WPAC: MEGI - Post-Tropical - Discussion

[euro6208]

EURO at landfall. Much weaker than past runs.

[1900hurricane]

Maybe one day we'll get a clean ASCAT pass...

[Alyono]

EURO at landfall. Much weaker than past runs.

that's post landfall

[mrbagyo]

96W INVEST 160922 1200 9.0N 138.5E WPAC 20 1010


Looks a little farther north of 9N to me.


Light Showers Rain and 79 F at Yap Island - Yap Int. Airport
Winds are Calm. The pressure is 1008.1 mb and the humidity is 94%.
Last Updated on Sep 22 2016, 11:50 pm LST.

000
SAKA31 PTYA 221600
METAR PTYA 221550Z 00000KT 9SM -RA FEW016 SCT030 OVC120 25/24 A2975
RMK SHRAE35RAB35 SLP074 T02500244=

[euro6208]

WTPN21 PGTW 221930
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT REISSUED//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/220552Z SEP 16//
AMPN/REF A IS TROPICAL CYCLONE FORMATION ALERT (WTPN21 PGTW 220600)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
180 NM EITHER SIDE OF A LINE FROM 12.5N 140.7E TO 17.2N 135.7E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 17 TO 22 KNOTS. METSAT
IMAGERY AT 221800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 14.1N 140.1E. THE SYSTEM IS MOVING NORTH-NORTHWESTWARD AT 14
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 96W) PREVIOUSLY LOCATED
NEAR 8.9N 140.1E IS NOW LOCATED NEAR 14.1N 140.1E, APPROXIMATELY 270
NM WEST OF GUAM. ANIMATED INFRARED AND RECENT MICROWAVE SATELLITE
IMAGERY DEPICT A BROAD LOW-LEVEL CIRCULATION WITH FORMATIVE
CONVECTIVE BANDING OVER THE NORTHEASTERN QUADRANT. A 220859Z SSMIS
91GHZ MICROWAVE IMAGE SHOWS FRAGMENTED, DISORGANIZED SHALLOW
CONVECTION IN THESE SAME AREAS. UPPER-LEVEL ANALYSIS REVEALS A
FAVORABLE ENVIRONMENT WITH GOOD OUTFLOW AND LOW VERTICAL WIND SHEAR.
ADDITIONALLY, ALONG-TRACK SEA SURFACE TEMPERATURES ARE FAVORABLE
(GREATER THAN 28C). DYNAMIC MODEL GUIDANCE INDICATES GRADUAL
INTENSIFICATION OVER THE NEXT 24-36 HOURS AS THE SYSTEM TRACKS
NORTHWESTWARD. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 17
TO 22 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005
MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS REMAINS HIGH. THIS SUPERSEDES REF A.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
231930Z.//
NNNN

[euro6208]

TPPN10 PGTW 221815

A. TROPICAL DISTURBANCE 96W (W OF GUAM)

B. 22/1750Z

C. 15.18N

D. 140.71E

E. FIVE/HMWRI8

F. T1.5/1.5/S0.0/24HRS STT: S0.0/06HRS

G. IR/EIR

H. REMARKS: 38A/PBO SBC/ANMTN. .25 WRAP ON LOG10 SPIRAL YIELDS
A 1.5 DT. MET AND PT AGREE WITH DT. DBO DT.

I. ADDITIONAL POSITIONS: NONE


BERMEA

[euro6208]

PEAK WINDS

Some wind totals from the overnight hours (airport obs)

Saipan: Max Sustained: 26 mph Max Gust: 38 mph
Peak wind gust over the last couple days: 40 mph on Thu

Guam: Max Sustained: 23 mph Max Gust: 33 mph
Peak wind gust over the last couple days: 39 mph on Wed
just before midnight.

[euro6208]

GFS is weaker and weaker with this.

Has a struggling system but still forecasting a typhoon.

What a cold upwelling could do.

[Dave C]

It may be just taking longer to develop which is affecting it's strength down the road. Is it me or did this thing seem to redevelop a new center further north?

[euro6208]

Looks like 20W is here

96W TWENTY 160922 1800 14.1N 140.1E WPAC 20 1005

[euro6208]

TPPN10 PGTW 230020

A. TROPICAL DISTURBANCE 96W (W OF GUAM)

B. 23/0000Z

C. 16.52N

D. 140.04E

E. FIVE/HMWRI8

F. T2.0/2.0/D1.0/24HRS STT: D0.5/03HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 40A/PBO SBC/ANMTN. .30 WRAP ON LOG10 SPIRAL YIELDS
A 2.0. MET NAD PT AGREE WITH DT. DBO DT.

I. ADDITIONAL POSITIONS:
22/1830Z 15.68N 140.30E SSMS


BERMEA

[euro6208]

TXPQ21 KNES 222152
TCSWNP

A. TROPICAL DISTURBANCE (96W)

B. 22/2100Z

C. 15.1N

D. 140.5E

E. FIVE/HIMAWARI-8

F. T2.0/2.0/D0.5/12HRS

G. IR/EIR/VIS

H. REMARKS...THE CENTER IS RE-POSITIONED DUE TO REFORMATION OF THE LLCC
FARTHER NORTH. IRREGULAR CDO OF 2.25 DEGREES RESULT IN A DT OF 3.0. MET=
3.0 AND PT= 3.0. FT IS BASED ON TRADITIONAL DVORAK CONSTRAINTS LIMITING
CHANGES IN FT TO HALF OVER SIX HRS.

I. ADDL POSITIONS

NIL


...SZATANEK

[xtyphooncyclonex]

TS 1617 (Megi)
Issued at 01:15 UTC, 23 September 2016

<Analysis at 00 UTC, 23 September>
Scale -
Intensity -
Center position N15°40' (15.7°)
E140°05' (140.1°)
Direction and speed of movement WNW 25 km/h (14 kt)
Central pressure 1000 hPa
Maximum wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
≥ 30 kt wind area ALL 220 km (120 NM)

<Forecast for 12 UTC, 23 September>
Intensity -
Center position of probability circle N16°20' (16.3°)
E137°35' (137.6°)
Direction and speed of movement W 20 km/h (12 kt)
Central pressure 996 hPa
Maximum wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 70 km (40 NM)

<Forecast for 00 UTC, 24 September>
Intensity -
Center position of probability circle N17°00' (17.0°)
E135°25' (135.4°)
Direction and speed of movement WNW 20 km/h (11 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 110 km (60 NM)

<Forecast for 00 UTC, 25 September>
Intensity Strong
Center position of probability circle N18°50' (18.8°)
E130°20' (130.3°)
Direction and speed of movement WNW 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 200 km (110 NM)
Storm warning area ALL 280 km (150 NM)

<Forecast for 00 UTC, 26 September>
Intensity Strong
Center position of probability circle N20°05' (20.1°)
E125°35' (125.6°)
Direction and speed of movement WNW 20 km/h (12 kt)
Central pressure 955 hPa
Maximum wind speed near center 40 m/s (80 kt)
Maximum wind gust speed 60 m/s (115 kt)
Radius of probability circle 260 km (140 NM)
Storm warning area ALL 370 km (200 NM)

[1900hurricane]

Looks like JTWC is in the process of renumbering Megi to 20W as well.

[euro6208]

Peaks at 100 knots Cat 3.

WDPN31 PGTW 230300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 20W (MEGI)
WARNING NR 01//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION 20W (MEGI), LOCATED APPROXIMATELY 1170 NM
EAST-SOUTHEAST OF TAIPEI, TAIWAN, HAS TRACKED NORTH-NORTHWESTWARD
AT 13 KNOTS OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED
ON ANIMATED MULTISPECTRAL SATELLITE IMAGERY, SATELLITE FIXES FROM
RJTD AND PGTW, AND A 222136Z SSMIS PASS. THERE IS LOW CONFIDENCE IN
THE INITIAL POSITION GIVEN A DISPARITY IN FIXES AND LACK OF A CLEAR,
DEFINITIVE CENTER FEATURE IN RECENT SATELLITE IMAGERY. THE INTENSITY
OF 30 KNOTS IS CONSISTENT WITH SUBJECTIVE DVORAK INTENSITY ESTIMATES
FROM ALL REPORTING AGENCIES. TD 20W HAS CONSOLIDATED FROM A BROAD
MONSOONAL CIRCULATION INTO A TROPICAL DEPRESSION OVER THE PAST SIX
HOURS, WITH TIGHTLY-WRAPPED, DEEP CONVECTIVE BANDING NOW EVIDENT IN
MULTISPECTRAL SATELLITE IMAGERY. UPPER-LEVEL RIDGING NEAR THE
CIRCULATION AND TROPICAL UPPER-TROPOSPHERIC TROUGH (TUTT) CELLS TO
THE NORTH AND WEST ARE PROVIDING STRONG UPPER-LEVEL OUTFLOW,
SUPPORTING DEVELOPMENT.
3. FORECAST REASONING.
A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE FOR 20W AND
SETS THE FORECAST PHILOSOPHY
B. TD 20W IS EXPECTED TO TURN WEST-NORTHWESTWARD OVER THE NEXT
12 HOURS AND CONTINUE ALONG A GENERALLY WEST-NORTHWESTWARD
TRAJECTORY OVER THE NEXT 24 HOURS FOLLOWING THE FLOW ASSOCIATED WITH
A SUBTROPICAL STEERING RIDGE TO THE NORTH. STEADY INTENSIFICATION IS
ANTICIPATED AS THE SYSTEM CONTINUES TO CONSOLIDATE, SUPPORTED BY
STRONG UPPER-LEVEL OUTFLOW, LOW TO MODERATE VERTICAL WIND SHEAR AND
PASSAGE OVER WARM WATER. THE AVAILABLE NUMERICAL MODEL TRACK
FORECAST GUIDANCE IS IN GOOD AGREEMENT, WITH ALL SOLUTIONS
INDICATING A TRACK TOWARD OR NEAR TAIWAN OVER THE NEXT SEVERAL DAYS.
THE CURRENT FORECAST LIES CLOSE TO THE MULTI-MODEL CONSENSUS WITH
HIGH CONFIDENCE, EXCEPT IN THE VERY NEAR TERM DUE TO NOTED
UNCERTAINTY IN THE CURRENT POSITION.
C. IN THE EXTENDED PERIOD, TD 20W SHOULD CONTINUE TO TRACK WEST-
NORTHWESTWARD UNDER THE CONTINUED STEERING INFLUENCE OF THE
SUBTROPICAL RIDGE. PEAK INTENSITY IS EXPECTED TO OCCUR AROUND TAU 96
AS ENVIRONMENTAL CONDITIONS REMAIN GENERALLY FAVORABLE. THE EXACT
INTENSITY TREND AFTER TAU 96 WILL DEPEND ON IF AND HOW THE
CIRCULATION INTERACTS WITH TAIWAN. MODEL GUIDANCE REMAINS IN
GENERALLY GOOD AGREEMENT DURING THE EXTENDED PERIOD, LENDING HIGH
CONFIDENCE TO THAT PORTION OF THE TRACK FORECAST AS WELL.//
NNNN

[euro6208]

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

----- Current Analysis -----
Date : 23 SEP 2016 Time : 044000 UTC
Lat : 15:47:05 N Lon : 138:52:56 E


CI# /Pressure/ Vmax
1.8 /1006.5mb/ 28.0kt


Final T# Adj T# Raw T#
1.8 2.1 3.2

Center Temp : -18.8C Cloud Region Temp : -53.2C

Scene Type : IRREGULAR CDO*

Positioning Method : FORECAST INTERPOLATION

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

Tno/CI Rules : Constraint Limits : 0.2T/hour
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : N/A
- Environmental MSLP : 1008mb

Satellite Name : HIM-8
Satellite Viewing Angle : 18.6 degrees

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

[euro6208]

WDPN31 PGTW 230900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 20W (MEGI) WARNING
NR 02//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 20W (MEGI), LOCATED APPROXIMATELY 800 NM
SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTHWESTWARD AT
20 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) SHOWS THE SYSTEM IS SLOWLY CONSOLIDATING, ALBEIT
FORMATIVE BANDS REMAIN FRAGMENTED. THE INITIAL POSITION IS BASED ON A
PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER EVIDENT IN THE MSI
LOOP AND LINES UP WITH A LOW REFLECTIVITY CIRCULATION FEATURE IN THE
222139Z SSMIS MICROWAVE IMAGE. THE INITIAL INTENSITY OF 35 KNOTS IS
BASED ON AN OVERALL ASSESSMENT OF AGENCY AND OBJECTIVE DVORAK
ESTIMATES AND REFLECTS THE SLIGHT INTENSIFICATION. THERE IS LOW
CONFIDENCE IN THE INITIAL POSITION GIVEN THE FORMATIVE NATURE OF THE
CYCLONE. UPPER LEVEL ANALYSIS INDICATES THE STORM IS IN THE VICINITY
OF AN ANTICYCLONIC POINT SOURCE WITH LOW VERTICAL WIND SHEAR AND
EXCELLENT DUAL OUTFLOW. ADDITIONALLY, SEA SURFACE TEMPERATURES AT 30C
ARE EXCEPTIONALLY WARM AND CONDUCIVE FOR FURTHER DEVELOPMENT. THE
CYCLONE IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF A MID-LEVEL
REFLECTION OF THE SUBTROPICAL RIDGE (STR) TO THE NORTH-NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO FORECAST PHILOSOPHY FROM THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TS 20W IS EXPECTED TO CONTINUE ON A NORTHWESTWARD TRAJECTORY
THROUGHOUT ITS LIFESPAN, STEERED BY THE STR THAT IS FORECAST TO
BUILD. ENVIRONMENTAL CONDITIONS WILL REMAIN FAVORABLE FOR STEADY
INTENSIFICATION, REACHING A PEAK OF 100 KNOTS BY TAU 72 AS THE SYSTEM
DRIFTS ACROSS THE WARM PHILIPPINE SEA.
C. IN THE EXTENDED PERIOD, TS MEGI WILL CROSS SOUTHERN TAIWAN AND
THE TAIWAN STRAIT PRIOR TO MAKING LANDFALL IN EASTERN CHINA BEFORE
TAU 120. LAND INTERACTION WILL BE THE PRIMARY CAUSE OF ITS RAPID
WEAKENING DURING THIS STAGE. MODEL GUIDANCE REMAINS IN GENERALLY GOOD
AGREEMENT, LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST.//
NNNN

[euro6208]

[Dave C]

Seems to be organizing quickly now, well formed cdo developing with curved banding features.

[1900hurricane]

Well hello there Megi.