WPAC: HAISHEN - Post-Tropical

[euro6208]

Huge bust if that eye doesn't want to go away. Limiting intensification.

[aspen]

And the inner eyewall is firing more convection...what the hell is wrong with this storm? I’ve never seen an inner eyewall refuse to die like this.

[mrbagyo]

And the inner eyewall is firing more convection...what the hell is wrong with this storm? I’ve never seen an inner eyewall refuse to die like this.

I think Haishen just needs another outflow channel to get rid of that inner eyewall. Interaction with a trough near the Ryukyu could do just that.

[euro6208]

WDPN32 PGTW 031500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (HAISHEN) WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 11W (HAISHEN), LOCATED APPROXIMATELY 580 NM EAST-
SOUTHEAST OF KADENA AB, OKINAWA, HAS TRACKED WEST-NORTHWESTWARD AT 12
KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS A 10 NM EYE SURROUNDED BY DEEP CONVECTION
WITH BANDING WRAPPING INTO THE SYSTEM. A BULLSEYE 031145Z ASCAT-A
IMAGE PAIRED WITH THE PINHOLE EYE LENDS GOOD CONFIDENCE IN THE INITIAL
POSITION. FURTHERMORE, THE ASCAT DATA WAS USED TO UPDATE THE CURRENT
WIND RADII. BASED ON MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES
OF T5.0-5.5 (90-102 KTS), THE INITIAL INTENSITY IS SET AT 100 KTS WITH
GOOD CONFIDENCE. THE UPPER LEVEL ENVIRONMENT IS CHARACTERIZED BY NEAR-
RADIAL OUTFLOW AND LOW (<10KT) VERTICAL WIND SHEAR (VWS). ACCOMPANIED
BY WARM SEA SURFACE TEMPERATURES AND CONDUCIVE OCEAN HEAT CONTENT
VALUES, TY 11W IS TRANSITING THROUGH A HIGHLY FAVORABLE ENVIRONMENT
FOR CONTINUED DEVELOPMENT. THE 03/0000Z 500 MB ANALYSIS SHOWS A DEEP
MIDLATITUDE SHORTWAVE TROUGH LOCATED OVER THE EAST CHINA SEA AND
WESTERN JAPAN WITH A SUBTROPICAL RIDGE (STR) ENTRENCHED NORTH OF THE
SYSTEM. A COL REGION IS POSITIONED NORTHWEST OF THE SYSTEM AND
NORTHEAST OF OKINAWA WITH MID-LEVEL WESTERLY FLOW OVER OKINAWA
REFLECTING THE POSITION OF THE AFOREMENTIONED TROUGH. TY 11W IS
TRACKING WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE DEEP-
LAYERED STR AND IS TRACKING TOWARDS THE COL REGION.
3. FORECAST REASONING.
A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE LAST PROGNOSTIC REASONING MESSAGE.
B. IN THE NEAR TERM, THE STR OVER JAPAN IS EXPECTED TO BUILD,
STEERING TY 11W WEST-NORTHWESTWARD. THE SHORTWAVE TROUGH WILL
GRADUALLY FILL OVER THE KOREAN PENINSULA, CAUSING THE SYSTEM TO ENTER
THE COL AND SLOWLY TURN POLEWARD THROUGH TAU 72. NUMERICAL MODEL
GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 48. AFTERWARDS, THE MODEL
SOLUTIONS BEGIN TO SLOWLY DIVERGE TO A SPREAD OF 175 NM BY TAU 72 AS
THE SYSTEM TURNS POLEWARD. ALL MODEL SOLUTIONS CURRENTLY SHOW TY 11W
PASSING EAST AND NORTHEAST OF THE SYSTEM. OF NOTE, THE ECMWF AND ECMWF
ENSEMBLE SOLUTION HAVE BEGUN TO DIVERGE FROM THE MAJORITY OF THE MODEL
SOLUTIONS, SHOWING A SHARPER POLEWARD TURN BEGINNING AT TAU 36. IN THE
NEAR TERM, TY 11W IS EXPECTED TO RAPIDLY INTENSIFY DUE TO A CONTINUED
FAVORABLE ENVIRONMENT WITH INTENSITY PEAKING AT 130 KTS BY TAU 24.
C. AFTER TAU 72, THE NUMERICAL MODEL GUIDANCE CONTINUED TO DIVERGE
WHICH WILL INCREASE THE UNCERTAINTY IN THE EXACT TRACK FORECAST. THE
ECMWF AND ECMWF ENSEMBLE SOLUTIONS ARE THE FURTHEST TRACKS TO THE EAST
OF THE MODEL SOLUTIONS AS THE SYSTEM PASSES SASEBO; THUS, THE TRACK
COULD SHIFT EASTWARD TOWARD KYUSHU. AFTER TAU 72, INCREASING VWS AND
COOLING SST WILL WEAKEN THE SYSTEM. AS THE SYSTEM INTERACTS WITH THE
SHORTWAVE TROUGH, EXTRATROPICAL TRANSITION IS EXPECTED TO COMMENCE. TY
11W WILL ACCELERATE POLEWARD, GAIN FRONTAL CHARACTERISTICS, AND
COMPLETE EXTRATROPICAL TRANSITION BY TAU 120. DUE TO THE MODEL SPREAD,
THERE IS MODERATE CONFIDENCE IN THE EXTENDED RANGE JTWC FORECAST TRACK
WHICH LIES NEAR THE MULTI-MODEL CONSENSUS.//
NNNN

[NotoSans]

Inner eye has almost collapsed and surrounding convection has significantly cooled. This ERC has likely ended and the new eye would contract and start to clear out within the next 6 to 12 hours.

[Highteeld]

New eyewall convection looks much more dominant now than a few hours ago

[gatorcane]

Looks well organized:
http://rammb.cira.colostate.edu/ramsdis ... display=24

[aspen]

That outer eyewall now seems to finally be dominant. Eye temps are rising a bit.

[1900hurricane]

Made a new forecast. I was pressed for time, so it's a little more brief this time.

 https://twitter.com/1900hurricane/status/1301567563248345089

[Highteeld]

Huge eye coming in

[Highteeld]

Huge eye coming in

https://i.imgur.com/EVvNJf0.png

Would go with 105-110 knots for the next update.

[NotoSans]

Personal Dvorak fix for 18Z would be T6.0/6.0, although a high-end T5.5/5.5 is also justifiable.

But AMSU pass at 12Z is already at 940mb/113kt, so I’d go conformably with 115kt at 18Z.

[aspen]

Huge eye coming in

https://i.imgur.com/EVvNJf0.png

Some positive eye temps are starting to show up from that opening. Dvorak numbers just shot up, and raws are up to T#6.5.

[Highteeld]

Current Intensity Analysis



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

----- Current Analysis -----
Date : 03 SEP 2020 Time : 170000 UTC
Lat : 21:13:47 N Lon : 135:44:24 E


CI# /Pressure/ Vmax
5.8 / 946.6mb/109.8kt


Final T# Adj T# Raw T#
5.8 6.5 6.5

Estimated radius of max. wind based on IR : 14 km

Center Temp : +4.6C Cloud Region Temp : -74.2C

Scene Type : EYE

[1900hurricane]

ATMS pass:

[Highteeld]

12z Euro forecast for 18z today (now) is at 949 mb, probably very close to reality

[Highteeld]

12z Euro forecast for 18z today (now) is at 949 mb, probably very close to reality

really bombs out from there, down to 900 mb in 18 hours

[1900hurricane]

My 110 kt 00Z forecast might be a little low if it really starts kicking here the next six hours.

[Highteeld]

My 110 kt 00Z forecast might be a little low if it really starts kicking here the next six hours.

The convection over the western eyewall has intensified a lot over the last hour, so it might be ready to RI

[1900hurricane]

Probably going to be some really spectacular visible imagery once the sun comes up today.