WPAC: CHAN-HOM - Post-Tropical

[wxman57]

I'm not sure how the forecasters at JTWC are measuring Chan-hom's wind radii, but I used a spliced ASCAT image from 0030Z and MB Ruler to measure them as follows (NE, SE, SW, NE):

39 mph: 275, 240, 190, 210
58 mph: 140, 150, 75, 90
74 mph: 75, 75, 0, 0

That's well over twice the size in the latest JTWC advisory. Note that there were no 74 mph winds indicated on the ASCAT image so I allowed for a bit of a low bias in the heavier convection and estimated where they might be. With convection now lacking from the SW through north, Chan-hom's intensity is probably in the 70-85 kt range.

[euro6208]

Our storm2k friend and local typhoon chaser TyphoonHunter will be chasing this monster typhoon...

[cycloneye]

[img]WDPN31 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (CHAN-HOM) WARNING NR 29//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 09W (CHAN-HOM), LOCATED APPROXIMATELY 506 NM
SOUTHWEST OF IWO TO, HAS TRACKED WESTWARD AT 10 KNOTS OVER THE PAST
SIX HOURS. ANIMATED ENHANCED IR IMAGERY SHOWS A NEAR CLOUD FILLED
LLCC AS THE APPARENT EYE HAS SEEMINGLY COLLAPSE ALONG WITH THE DEEP
CONVECTION IN THE NORTHWESTERN QUADRANT. A 071205Z AMSU-B IMAGE
CONTINUES TO SHOW A MICROWAVE EYE AND THE LACK OF DEEP CONVECTION ON
THE NORTHERN SIDE OF THE LLCC. THE POSITION IS BASED ON THE
AFOREMENTIONED IMAGERY WITH GOOD CONFIDENCE. THE INTENSITY IS HELD
AT 80 KNOTS IN KEEPING WITH DVORAK CURRENT INTENSITY ESTIMATES FROM
ALL AGENCIES. UPPER-LEVEL ANALYSIS DEPICTS A FAVORABLE ENVIRONMENT
WITH MODERATE (15 TO 20 KNOTS) VWS AND NEAR-RADIAL OUTFLOW. TY 09W
IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A STR EXTENSION.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TY 09W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD UNDER
THE STEERING INFLUENCE OF THE STR THROUGH TAU 72. IT IS EXPECTED TO
INTENSIFY STEADILY PEAKING AT 125 KNOTS BY TAU 48 DUE TO CONTINUED
FAVORABLE ENVIRONMENTAL CONDITIONS. DYNAMIC GUIDANCE IS IN TIGHT
AGREEMENT THROUGH TAU 72, LENDING HIGH CONFIDENCE TO THIS PORTION OF
THE TRACK FORECAST.
C. AFTER TAU 72, TY CHAN-HOM WILL BEGIN TO TRACK MORE TO THE
NORTH AS THE STR EXTENSION RETREATS TO THE EAST AND BREAKS DOWN DUE
TO AN INBOUND MID-LATITUDE TROUGH. EXPECT SOME DECREASE IN INTENSITY
DUE TO LIMITED OHC AND LAND INTERACTION SOUTH OF SHANGHAI, DESPITE
GOOD POLEWARD OUTFLOW. NUMERICAL GUIDANCE HAS BEGUN TO SPREAD FROM
THE 00Z RUN DUE TO SOME UNCERTAINTY IN THE TIMING AND POSITION OF
THE MID-LATITUDE TROUGHS EFFECTS ON THE STEERING STR. AS SUCH, THERE
IS A LOW CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH IS LAID CLOSE
TO THE MULTI-MODEL CONSENSUS.//
NNNN[/img]

[wxman57]

Our storm2k friend and local typhoon chaser TyphoonHunter will be chasing this monster typhoon...

http://i.imgur.com/zu4GWH6.png

Is he planning on heading down to Taipei? He may not see much in Okinawa. JTWC's track is right of the model guidance. Both the Euro & GFS take the center not far north of Taipei on Friday.

[cycloneye]

WDPN31 PGTW 072100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (CHAN-HOM) WARNING NR 30//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 09W (CHAN-HOM), LOCATED APPROXIMATELY 571 NM
SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTHWESTWARD AT
13 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED IR IMAGERY SHOWS
THE SYSTEM HAS MAINTAINED OVERALL CONVECTIVE SIGNATURE AND A 35-NM
EYE. THE INITIAL POSITION IS BASED ON THE MICROWAVE EYE FEATURE IN
THE 1638Z NPP IMAGE WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 80
KNOTS IS BASED ON CONGRUENT DVORAK ESTIMATES FROM PGTW, KNES, AND
RJTD. UPPER-LEVEL ANALYSIS DEPICTS A FAVORABLE ENVIRONMENT WITH
MODERATE (15-20 KNOT) VWS EASILY OFFSET BY RADIAL OUTFLOW. THE
CYCLONE IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-
LAYERED EXTENSION OF THE STR TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TY 09W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD UNDER
THE STEERING INFLUENCE OF THE STR THROUGH TAU 72. IT IS EXPECTED TO
INTENSIFY STEADILY PEAKING AT 120 KNOTS BY TAU 48 AS FAVORABLE
ENVIRONMENTAL CONDITIONS PERSIST. DYNAMIC GUIDANCE IS IN TIGHT
AGREEMENT THROUGH THIS PERIOD, LENDING HIGH CONFIDENCE TO THIS
PORTION OF THE TRACK FORECAST.
C. AFTER TAU 72, TY CHAN-HOM WILL BEGIN TO TRACK MORE TO THE
NORTH AS THE STR EXTENSION RETREATS TO THE EAST AND BREAKS DOWN DUE
TO AN INBOUND MID-LATITUDE TROUGH. EXPECT SOME DECREASE IN INTENSITY
DUE TO INCREASING VWS AND LAND INTERACTION SOUTH OF SHANGHAI, CHINA.
NUMERICAL GUIDANCE SPREAD OUT SIGNIFICANTLY LENDING LOW CONFIDENCE
IN THIS PORTION OF THE JTWC FORECAST TRACK, WHICH IS LAID CLOSE TO
THE MULTI-MODEL CONSENSUS.//
NNNN

[TropicalAnalystwx13]

Chan-hom has an absolutely massive circulation. As a result, dry air from the surrounding environment has been able to more effectively be entrained into the inner core of the cyclone. This can be mixed out over time--and Chan-hom has 72 more hours to strengthen--but it's definitely a slow process.

[Yellow Evan]

http://www.tropicaltidbits.com/analysis/models/?model=gem&region=wpac&pkg=z500_mslp&runtime=2015070712&fh=18&xpos=206.5&ypos=973
cmc
Interesting model run ‎ north Taipei takes a hit, then a 3 way fujiwara comes into effect LINFA is pushed south, NANGKA is flung into japan and CHAN-HOM runs chasos over the Japanese islands and then coast hugs japan.

CMC is Fujiwara happy in general

[dhoeze]

ot:

Guys do you have any updated link of the Euro Models? the one that i have been using for years is no longer working:

http://old.ecmwf.int/products/forecasts ... %21%21step


Super thanks,

http://www.tropicaltidbits.com/analysis ... ypos=586.4

Thanks Spiral!!! This is a big help indeed. They didnt retain the feature they had before which is a moving presentation of the forecast?

[xtyphooncyclonex]

Starting...


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

----- Current Analysis -----
Date : 08 JUL 2015 Time : 080000 UTC
Lat : 20:38:44 N Lon : 131:59:24 E


CI# /Pressure/ Vmax
5.2 / 953.1mb/ 94.8kt


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

Estimated radius of max. wind based on IR : 21 km

Center Temp : -21.0C Cloud Region Temp : -66.0C

Scene Type : EYE

Positioning Method : RING/SPIRAL COMBINATION

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

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

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 135km
- Environmental MSLP : 1002mb

Satellite Name : MTSAT2
Satellite Viewing Angle : 28.3 degrees

[euro6208]

WDPN31 PGTW 080900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (CHAN-HOM) WARNING NR 32//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 09W (CHAN-HOM), LOCATED APPROXIMATELY 450 NM
SOUTHEAST OF KADENA AB, HAS TRACKED NORTHWESTWARD AT 11 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MSI SHOWS THE SYSTEM HAS MAINTAINED
GOOD OVERALL CONVECTIVE SIGNATURE WITH A RAGGED 32 NM EYE. THE
CONVECTION CONTINUES TO BE STRAINED ON THE NORTHERN SIDE OF THE LLCC
DUE TO UPPER LEVEL SUBSIDENCE. THE EYE POSITION IS RE-ENFORCED BY A
080511Z AMSU-B IMAGE ALSO SHOWING THE DEEP CONVECTION FAVORING THE
SOUTHERN PORTION OF THE SYSTEM. THE INITIAL POSITION IS BASED ON THE
ABOVE IMAGERY WITH GOOD CONFIDENCE. THE INTENSITY HAS BEEN RAISED TO
85 KNOTS AS THE EYE FEATURE AND TOTAL STRUCTURE OF THE SYSTEM HAS
IMPROVED OVER THE PAST 6 HOURS. UPPER LEVEL ANALYSIS INDICATES A
CONTINUED FAVORABLE ENVIRONMENT WITH MODERATE (15-20 KNOT) VWS WHICH
IS OFFSET BY GOOD RADIAL OUTFLOW. THE CYCLONE IS TRACKING ALONG THE
SOUTHWESTERN PERIPHERY OF AN EXTENSION OF THE STR TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TY 09W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD UNDER
THE STEERING INFLUENCE OF THE STR THROUGH TAU 72. IT IS EXPECTED TO
INTENSIFY STEADILY PEAKING AT 120 KNOTS BY TAU 48 AS FAVORABLE
ENVIRONMENTAL CONDITIONS PERSIST. BY TAU 72, TY 09 CHAN-HOM WILL
MAKE LAND FALL NEAR WENZHOU, ZHEJIANG AND BEGIN DECAYING DUE TO LAND
INTERACTION. DYNAMIC GUIDANCE IS IN TIGHT AGREEMENT THROUGH THIS
PERIOD, LENDING HIGH CONFIDENCE TO THIS PORTION OF THE TRACK
FORECAST.
C. IN THE EXTENDED FORECAST, TY 09W WILL CONTINUE TO TRACK THOUGH
ZHEJIANG AND BEGIN TO TRACK POLEWARD AS THE STR EXTENSION RETREATS
TO THE EAST AND BREAKS DOWN DUE TO AN INBOUND MID-LATITUDE TROUGH.
EXPECT CONTINUED DECAY AS THE SYSTEM TRACKS THROUGH THE NORTHERN END
OF THE WAYISHAN RANGE. TY CHAN-HOM IS EXPECTED TO CROSS INTO THE
YELLOW SEA AT THE END OF THE FORECAST PERIOD, ALTHOUGH THE SYSTEM
WILL BE SIGNIFICANTLY WEAKER. NUMERICAL GUIDANCE IS SPREAD OUT
SIGNIFICANTLY BEYOND TAU 72 LENDING LOW CONFIDENCE IN THE EXTENDED
FORECAST OF THE JTWC TRACK.//
NNNN

[euro6208]

000
WTPQ31 PGUM 080841
TCPPQ1

BULLETIN
TYPHOON CHAN-HOM (09W) ADVISORY NUMBER 32
NATIONAL WEATHER SERVICE TIYAN GU WP092015
800 PM CHST WED JUL 8 2015

...TYPHOON CHAN-HOM MAINTAINING INTENSITY...

CHANGES WITH THIS ADVISORY
--------------------------
NONE.

WATCHES AND WARNINGS
--------------------
NONE.

SUMMARY OF 700 PM CHST...0900 UTC...INFORMATION
-----------------------------------------------
LOCATION...20.8N 132.2E

ABOUT 475 MILES SOUTHEAST OF OKINAWA
ABOUT 970 MILES NORTHWEST OF GUAM
ABOUT 970 MILES WEST-NORTHWEST OF SAIPAN

MAXIMUM SUSTAINED WINDS...100 MPH
PRESENT MOVEMENT...NORTHWEST...325 DEGREES AT 13 MPH.

DISCUSSION AND OUTLOOK
----------------------
AT 700 PM CHST...0900 UTC...THE CENTER OF TYPHOON CHAN-HOM WAS
LOCATED NEAR LATITUDE 20.8 DEGREES NORTH AND LONGITUDE 132.2
DEGREES EAST. MOVEMENT IS TO THE NORTHWEST AT 13 MPH.
CHAN-HOM IS EXPECTED TO MAINTAIN THIS GENERAL TRACK THE NEXT
FEW DAYS WITH LITTLE CHANGE IN FORWARD SPEED.

MAXIMUM SUSTAINED WINDS ARE NOW 100 MPH. TYPHOON FORCE WINDS EXTEND
OUTWARD UP TO 40 MILES FROM THE CENTER...AND TROPICAL STORM FORCE
WINDS EXTEND OUT TO 170 MILES. SLOW INTENSIFICATION IS EXPECTED
OVER THE NEXT COUPLE OF DAYS.

NEXT ADVISORY
-------------
THE NEXT SCHEDULED ADVISORY WILL BE ISSUED BY THE NATIONAL WEATHER
SERVICE AT 200 AM EARLY WEDNESDAY MORNING.

$$

EDSON

[euro6208]

It's trying to become a monster...

[euro6208]

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

----- Current Analysis -----
Date : 08 JUL 2015 Time : 090000 UTC
Lat : 20:39:06 N Lon : 131:55:47 E


CI# /Pressure/ Vmax
5.3 / 951.2mb/ 97.2kt


Final T# Adj T# Raw T#
5.2 4.9 4.9

Estimated radius of max. wind based on IR : 23 km

Center Temp : -10.2C Cloud Region Temp : -59.7C

Scene Type : EYE

Positioning Method : RING/SPIRAL COMBINATION

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

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

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 135km
- Environmental MSLP : 1002mb

Satellite Name : MTSAT2
Satellite Viewing Angle : 28.4 degrees

[cycloneye]

The intensity forecast has little by little at every warning is going down.

[wxman57]

I used the 1239Z ASCAT pass and MB Ruler to measure the wind field. Unfortunately, the ASCAT pass only caught the eastern half of Chan-hom, but here's what I got:

39 mph: 350nm NE, 260nm SE
58 mph: 170nm NE, 170nm SE
74 mph: 90nm NE, 85nm SE (Rough estimate as ASCAT didn't have any 64+kt winds)

JTWC's latest advisory had TS winds extending out to only 145nm at most. I'd still like to know what they use to estimate the wind field. Chan-hom is a much larger than average typhoon:

WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT
035 NM SOUTHEAST QUADRANT
035 NM SOUTHWEST QUADRANT
035 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT
140 NM SOUTHEAST QUADRANT
145 NM SOUTHWEST QUADRANT
120 NM NORTHWEST QUADRANT

[cycloneye]

[xtyphooncyclonex]

Disappointing typhoon. Remained mostly a TS throughout its life.

[euro6208]

Still open...

[euro6208]

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

----- Current Analysis -----
Date : 08 JUL 2015 Time : 223000 UTC
Lat : 22:26:36 N Lon : 129:40:22 E


CI# /Pressure/ Vmax
5.4 / 946.8mb/ 99.6kt


Final T# Adj T# Raw T#
4.9 4.6 2.8

Center Temp : +12.3C Cloud Region Temp : -48.3C

Scene Type : CURVED BAND with 0.67 ARC in LT GRAY
Maximum CURVED BAND with 0.68 ARC in LT GRAY
at Lat: 22:26:24 N Lon: 129:52:11 E

Positioning Method : SPIRAL ANALYSIS

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

Tno/CI Rules : Constraint Limits : 0.5T/hour
Weakening Flag : ON
Rapid Dissipation Flag : FLAG

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 131km
- Environmental MSLP : 1000mb

Satellite Name : MTSAT2
Satellite Viewing Angle : 31.4 degrees

[euro6208]

Disappointing typhoon. Remained mostly a TS throughout its life.

Still a very dangerous typhoon regardless. It's large size will cause hugeeeee waves for the coast and winds will be widespread...