WPAC: MEGI - Post-Tropical - Discussion

[euro6208]

WDPN31 PGTW 260300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (MEGI) WARNING NR 13//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON 20W (MEGI), LOCATED APPROXIMATELY 343 NM SOUTH OF KADENA
AB, HAS TRACKED WEST-NORTHWESTWARD AT 09 KNOTS OVER THE PAST SIX
HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS TIGHT SPIRAL
BANDING WRAPPING TIGHTLY INTO THE LOW LEVEL CIRCULATION CENTER. A 10
NM RAGGED EYE FEATURE FORMED BRIEFLY OVER THE LAST SIX HOURS, WHICH
WAS ALSO OBSERVED IN A 252239Z SSMIS 91GHZ IMAGE GIVING HIGH
CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY IS
ASSESSED AT 90 KTS, AND IS BASED ON CURRENT INTENSITY DVORAK
ESTIMATES OF T5.0 (90 KNOTS) FROM ALL AGENCIES. UPPER-LEVEL ANALYSIS
SHOWS EXCELLENT RADIAL OUTFLOW OVER THE SYSTEM, TAPPING INTO THE
WESTERLY MID-LATITUDE JET TO THE NORTH AND A LARGE TUTT CELL TO THE
EAST. VERTICAL WIND SHEAR IS VERY LOW (5 TO 10 KNOTS) AND SSTS ARE
ALSO FAVORABLE, NEAR 30 CELSIUS. CURRENTLY TY MEGI IS TRACKING
NORTHWEST ALONG THE PERIPHERY OF A BUILDING DEEP-LAYERED SUBTROPICAL
RIDGE POSITIONED TO THE NORTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TY MEGI WILL CONTINUE ITS NORTHWESTERN TRACK ALONG THE
CURRENT STEERING RIDGE THAT WILL CONTINUE TO BUILD THROUGHOUT THE
FORECAST PERIOD. SLIGHT INTENSIFICATION IS EXPECTED THROUGH TAU 24
REACHING A PEAK INTENSITY OF 100 KNOTS UNDER FAVORABLE ENVIRONMENTAL
CONDITIONS. RAPID WEAKENING WILL ENSUE FOLLOWING LANDFALL OVER THE
MOUNTAINOUS REGION OF CENTRAL TAIWAN AROUND TAU 36. TY MEGI IS
EXPECTED TO EMERGE OVER WATER OFF THE WESTERN SHORE OF TAIWAN
REORGANIZING AS A TROPICAL STORM, THEN MAKE LANDFALL AGAIN OVER
CHINA NEAR TAU 54. RAPID DISSIPATION IS EXPECTED AS TY MEGI TRACKS
FURTHER INLAND FULLY DISSIPATING BY TAU 96. DYNAMIC MODEL GUIDANCE
IS IN VERY GOOD AGREEMENT WITH ONLY MINOR DIFFERENCES IN TRACK
LOCATION AND SPEED. THE FORECAST TRACK IS PLACED NEAR THE MULTI-
MODEL CONSENSUS WITH HIGH CONFIDENCE.//
NNNN

[euro6208]

WDPN31 PGTW 260900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (MEGI) WARNING NR 14//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 20W (MEGI), LOCATED APPROXIMATELY 341 NM SOUTHEAST OF
TAIPEI, TAIWAN, HAS TRACKED WEST-NORTHWESTWARD AT 11 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS
AN 18-NM RAGGED EYE WITH TIGHTLY-CURVED BANDING WRAPPING INTO THE
LOW-LEVEL CIRCULATION CENTER (LLCC). A 260554Z SSMI 85GHZ IMAGE
SHOWS CONCENTRIC EYEWALLS WITH MULTIPLE CONVECTIVE BANDS WRAPPING
INTO A SYMMETRIC LLCC. BASED ON THE PRESENCE OF AN EYE, THERE IS
GOOD CONFIDENCE IN THE CURRENT POSITION AND RECENT TRACK MOTION. THE
INITIAL INTENSITY IS ASSESSED AT 95 KTS, AND IS BASED ON DVORAK
CURRENT INTENSITY ESTIMATES OF T5.0 (90 KNOTS) FROM ALL AGENCIES AND
A RECENT SATCON ESTIMATE OF 95 KNOTS. UPPER-LEVEL ANALYSIS REVEALS
EXCELLENT RADIAL OUTFLOW WITH ENHANCED POLEWARD OUTFLOW INTO A
MIDLATITUDE SHORTWAVE TROUGH TO THE NORTH. TY MEGI IS TRACKING WEST-
NORTHWESTWARD ALONG THE PERIPHERY OF A DEEP-LAYERED SUBTROPICAL
RIDGE (STR) POSITIONED TO THE NORTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TY 20W WILL CONTINUE TO TRACK WEST-NORTHWESTWARD IN A
STRAIGHT-RUNNER PATTERN WHILE INTENSIFYING TO A PEAK OF 100 KNOTS
BEFORE MAKING LANDFALL NEAR TAU 24 ALONG THE EASTERN COAST OF
TAIWAN. NEAR TAU 36, TY MEGI WILL RE-EMERGE OVER THE TAIWAN STRAIT
AFTER WEAKENING SIGNIFICANTLY DUE TO LAND INTERACTION, AND WILL
CROSS THE SOUTHEAST COAST OF CHINA BY TAU 48. THE STR IS EXPECTED TO
REMAIN STRONG AND EAST-WEST ORIENTED THROUGH THE FORECAST PERIOD. AS
A RESULT, THE DYNAMIC GUIDANCE REMAINS IN TIGHT AGREEMENT.
C. IN THE EXTENDED FORECAST PERIOD, THE SYSTEM WILL DISSIPATE
WHILE TURNING WEST-SOUTHWESTWARD OVER CHINA. OVERALL, THERE IS HIGH
CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH IS POSITIONED CLOSE TO
THE MULTI-MODEL CONSENSUS AND IS HIGHLY CONSISTENT WITH PREVIOUS
JTWC FORECASTS.//
NNNN

[euro6208]

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

----- Current Analysis -----
Date : 26 SEP 2016 Time : 083000 UTC
Lat : 21:36:53 N Lon : 125:50:25 E


CI# /Pressure/ Vmax
5.6 / 941.4mb/104.6kt


Final T# Adj T# Raw T#
5.3 5.2 5.2

Estimated radius of max. wind based on IR : 12 km

Center Temp : -16.2C Cloud Region Temp : -63.5C

Scene Type : EYE

Positioning Method : SPIRAL ANALYSIS

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

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : ON
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 221km
- Environmental MSLP : 1004mb

Satellite Name : HIM-8
Satellite Viewing Angle : 30.6 degrees

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

[euro6208]

Typhoons making landfall in the Asia Pacific region seems so common, it seems natural. Less excitement but bigger and stronger than there counterparts.

[1900hurricane]

An eyewall that size will definitely slow down strengthening for now.

[Dave C]

Josh should get daytime landfall with this, Radar shows it's completed the ERC nicely!

[cycloneye]

 https://twitter.com/JMGarciaRivera/status/780499375596400640

[euro6208]

100 knots Category 3.

WDPN31 PGTW 262100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (MEGI) WARNING NR 16//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 20W (MEGI), LOCATED APPROXIMATELY 228 NM SOUTHEAST OF
TAIPEI, TAIWAN, HAS TRACKED WEST-NORTHWESTWARD AT 11 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS A
30-NM RAGGED EYE WITH TIGHTLY-CURVED BANDING WRAPPING INTO THE
LOW-LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS BASED ON
THE EYE IN THE EIR LOOP WHICH LINES UP WELL WITH A LOW REFLECTIVITY
MICROWAVE EYE FEATURE IN THE 261654Z ATMS PASS. THE INITIAL INTENSITY
IS ASSESSED AT 100 KNOTS AND IS BASED ON DVORAK CURRENT INTENSITY
ESTIMATES OF T5.5 FROM ALL AGENCIES. UPPER-LEVEL ANALYSIS INDICATES
EXCELLENT RADIAL OUTFLOW WITH ENHANCED POLEWARD OUTFLOW INTO A
MIDLATITUDE SHORTWAVE TROUGH TO THE NORTH. TY MEGI IS TRACKING WEST-
NORTHWESTWARD ALONG THE PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE
(STR) POSITIONED TO THE NORTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TY 20W IS FORECAST TO CONTINUE TRACKING WEST-NORTHWESTWARD,
DRAG THROUGH CENTRAL TAIWAN SHORTLY AFTER TAU 12, THEN CROSS THE
TAIWAN STRAIT BEFORE MAKING A FINAL LANDFALL IN EASTERN CHINA JUST
BEFORE TAU 36. AFTERWARDS, A SECONDARY STR OVER NORTHEASTERN CHINA
WILL ASSUME STEERING AND CAUSE THE CYCLONE TO TRACK ON A FLATTER
WESTWARD TRAJECTORY. A GRADUAL WEAKENING IS EXPECTED OVER THE NEXT 12
HOURS AS INCREASED VERTICAL WIND SHEAR (VWS) ASSOCIATED WITH THE
LEADING EDGE OF THE SECONDARY STR IMPACTS THE SYSTEM. AFTER LANDFALL
INTO TAIWAN, RAPID WEAKENING IS EXPECTED AS LAND INTERACTION,
COMBINED WITH INCREASING VWS, ERODES THE SYSTEM. TY MEGI WILL
EVENTUALLY DISSIPATE INLAND NORTH OF HONG-KONG BY TAU 72. THE DYNAMIC
GUIDANCE REMAINS IN TIGHT AGREEMENT WITH SOME SPREADING AFTER
LANDFALL IN CHINA. OVERALL, THERE IS HIGH CONFIDENCE IN THE JTWC
TRACK FORECAST.//
NNNN

[euro6208]

TPPN10 PGTW 262125

A. TYPHOON 20W (MEGI)

B. 26/2100Z

C. 22.70N

D. 123.60E

E. THREE/HMWRI8

F. T5.5/5.5/D1.0/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 09A/PBO RAGGED EYE/ANMTN. WMG EYE SURROUNDED BY LG
YIELDS AN E# OF 5.0. ADDED 1.0 FOR EYE ADJUSTMENT TO YIELD A DT
OF 6.0. MET AND PT YIELD A 5.5. DBO PT.

I. ADDITIONAL POSITIONS:
26/1654Z 22.15N 124.28E ATMS


BERMEA

[euro6208]

[1900hurricane]

[euro6208]

Josh should get daytime landfall with this, Radar shows it's completed the ERC nicely!

It's going to be a very interesting day.

https://twitter.com/earthuncuttv
https://twitter.com/iCyclone

[euro6208]

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

----- Current Analysis -----
Date : 26 SEP 2016 Time : 230000 UTC
Lat : 22:47:46 N Lon : 123:17:45 E


CI# /Pressure/ Vmax
6.3 / 925.4mb/122.2kt


Final T# Adj T# Raw T#
6.3 6.0 6.0

Estimated radius of max. wind based on IR :N/A km

Center Temp : -10.9C Cloud Region Temp : -73.2C

Scene Type : EYE

Positioning Method : FORECAST INTERPOLATION

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

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : ON
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 221km
- Environmental MSLP : 1004mb

Satellite Name : HIM-8
Satellite Viewing Angle : 33.3 degrees

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

[euro6208]

Poor Taiwan...

[euro6208]

WDPN31 PGTW 270300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (MEGI) WARNING NR 17//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 20W (MEGI), LOCATED APPROXIMATELY 152 NM SOUTHEAST OF
TAIPEI, TAIWAN, HAS TRACKED NORTHWESTWARD AT 13 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A
35-NM RAGGED EYE WITH TIGHTLY-CURVED BANDING WRAPPING INTO THE
LOW-LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS BASED ON
THE EYE IN THE MSI LOOP WHICH LINES UP WELL WITH A LOW REFLECTIVITY
MICROWAVE EYE FEATURE IN THE 262231Z 36GHZ GPM PASS. THE INITIAL
INTENSITY IS ASSESSED AT 100 KNOTS AND IS BASED ON DVORAK CURRENT
INTENSITY ESTIMATES OF T5.5 FROM ALL AGENCIES. UPPER-LEVEL ANALYSIS
INDICATES EXCELLENT RADIAL OUTFLOW WITH ENHANCED POLEWARD OUTFLOW
INTO A MIDLATITUDE SHORTWAVE TROUGH TO THE NORTH. HOWEVER, MOST
RECENT WATER VAPOR SATELLITE IMAGERY INDICATES SUBSIDENCE ALONG THE
NORTHWEST QUADRANT, INDICATING THE SYSTEM IS APPROACHING AN AREA OF
INCREASING VERTICAL WIND SHEAR (VWS). TY MEGI IS TRACKING
WEST-NORTHWESTWARD ALONG THE PERIPHERY OF A DEEP-LAYERED SUBTROPICAL
RIDGE (STR) POSITIONED TO THE NORTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TY 20W IS FORECAST TO CONTINUE TRACKING WEST-NORTHWESTWARD,
DRAG THROUGH CENTRAL TAIWAN SHORTLY AFTER TAU 06, THEN CROSS THE
TAIWAN STRAIT BEFORE MAKING A FINAL LANDFALL IN EASTERN CHINA JUST
BEFORE TAU 24. AFTERWARDS, A SECONDARY STR OVER NORTHEASTERN CHINA
WILL ASSUME STEERING AND CAUSE THE CYCLONE TO TRACK ON A FLATTER
WESTWARD TRAJECTORY. A GRADUAL WEAKENING IS EXPECTED OVER THE NEXT FEW
HOURS AS INCREASED VERTICAL WIND SHEAR (VWS) ASSOCIATED WITH THE
LEADING EDGE OF THE SECONDARY STR IMPACTS THE SYSTEM. AFTER LANDFALL
INTO TAIWAN, RAPID WEAKENING IS EXPECTED AS LAND INTERACTION,
COMBINED WITH INCREASING VWS, ERODES THE SYSTEM. TY MEGI WILL
EVENTUALLY DISSIPATE INLAND NORTH OF HONG-KONG BY TAU 48. THE DYNAMIC
GUIDANCE REMAINS IN TIGHT AGREEMENT WITH SOME SPREADING AFTER
LANDFALL IN CHINA. OVERALL, THERE IS HIGH CONFIDENCE IN THE JTWC
TRACK FORECAST.//
NNNN

[euro6208]

Great webcam from Hualien where Megi is expected to make landfall...

http://ndhu-landis.click2stream.com/

[euro6208]

[1900hurricane]

I'm interested to see what Josh's and James's pressure traces look like for a storm with such a large size.

[euro6208]

Trying to strengthen more before landfall...

[euro6208]