WPAC: SAOLA - Post-Tropical

[doomhaMwx]

SMAP pass from 0948Z 126kts

WP, 09, 202308300948, 30, SMAP, IR, , 2070N, 11970E, , 1, 118, 1, , , , 34, NEQ, 0, 0, 79, 55, , , , , 1, 0, , W, NASA, RSS, , , , , , , , , , , , , , , , , , , , , , , , , , , , 1, max. wind is 10 minute sustained
WP, 09, 202308300948, 30, SMAP, IR, , 2070N, 11970E, , 1, 118, 1, , , , 50, NEQ, 0, 58, 45, 39, , , , , 1, 0, , W, NASA, RSS, , , , , , , , , , , , , , , , , , , , , , , , , , , , 1, max. wind is 10 minute sustained
WP, 09, 202308300948, 30, SMAP, IR, , 2070N, 11970E, , 1, 118, 1, , , , 64, NEQ, 43, 47, 31, 27, , , , , 1, 0, , W, NASA, RSS, , , , , , , , , , , , , , , , , , , , , , , , , , , , 1, max. wind is 10 minute sustained

That would support 1-minute winds of 140kts.

[Hayabusa]

SMAP pass from 0948Z 126kts

WP, 09, 202308300948, 30, SMAP, IR, , 2070N, 11970E, , 1, 118, 1, , , , 34, NEQ, 0, 0, 79, 55, , , , , 1, 0, , W, NASA, RSS, , , , , , , , , , , , , , , , , , , , , , , , , , , , 1, max. wind is 10 minute sustained
WP, 09, 202308300948, 30, SMAP, IR, , 2070N, 11970E, , 1, 118, 1, , , , 50, NEQ, 0, 58, 45, 39, , , , , 1, 0, , W, NASA, RSS, , , , , , , , , , , , , , , , , , , , , , , , , , , , 1, max. wind is 10 minute sustained
WP, 09, 202308300948, 30, SMAP, IR, , 2070N, 11970E, , 1, 118, 1, , , , 64, NEQ, 43, 47, 31, 27, , , , , 1, 0, , W, NASA, RSS, , , , , , , , , , , , , , , , , , , , , , , , , , , , 1, max. wind is 10 minute sustained

That would support 1-minute winds of 140kts.

The 126kts is already in 1 min, 118 kts /0.93 = 126.8

[Kingarabian]

Basically reached 7.0 yesterday and stuck there for a couple of hours.

Quite a number of agencies stuck with T7.0, including the JTWC themselves. Yet there was no upgrade.

TPPN11 PGTW 301203

A. SUPER TYPHOON 09W (SAOLA)

B. 30/1130Z

C. 20.66N

D. 119.75E

E. ONE/HMWRI9

F. T7.0/7.0/S0.0/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 01A/PBO EYE/ANMTN. WMG EYE SURROUNDED BY W YIELDS AN
E# OF 6.0. ADDED 1.0 EYE ADJUSTMENT FOR CMG, TO YIELD A DT OF 7.0.
MET YIELDS 7.5 AND PT YIELDS 7.0. DBO DT.

I. ADDITIONAL POSITIONS:
30/0716Z 20.45N 120.08E SSMS


GOYETTE

Yeah it makes no sense.

[mrbagyo]

[ElectricStorm]

Hopefully we'll see an upgrade in the final post season BT, clearly was a Cat 5

[cycloneye]

 https://twitter.com/zeb199818/status/1696895832862192027

[cycloneye]

WDPN32 PGTW 301500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (SAOLA) WARNING NR
028//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 20.7N 119.7E
INITIAL INTENSITY: 130 KTS
GEOGRAPHIC REFERENCE: 282 NM SOUTH-SOUTHWEST OF TAIPEI, TAIWAN
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 06 KTS
SIGNIFICANT WAVE HEIGHT: 46 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
09W (SAOLA) REMAINS A SUPER TYPHOON (STY) BUT IS STARING TO SHOW
SIGNS OF WEAKENING ACROSS THE SPECTRUM OF AVAILABLE DATA. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A 20NM WIDE
STADIUM EYE WITH EYE TEMPERATURES MAINTAINING A VERY CONSISTENT 17C
OVER THE PAST SIX HOURS. ANIMATED RADAR DATA AND A 300906Z SSMIS
91GHZ IMAGE CONFIRM THREE IMPORTANT FACTS; THE EYE HAS BEGUN TO
SHRINK SINCE AROUND 1100Z, THE NORTHERN EYEWALL HAS ERODED
SIGNIFICANTLY OVER THE PAST SIX HOURS AND THE SECONDARY EYEWALL IS
BEGINNING TO DOMINATE THE OVERALL STRUCTURE. IN TERMS OF INTENSITY,
WE HAVE BEEN LUCKY TO RECEIVE TWO GOLD-STANDARD INTENSITY
MEASUREMENTS IN THE LAST THREE HOURS; A 300908Z SMAP PASS REVEALED
118 KNOT 10-MIN WINDS IN THE SOUTHEASTERN QUADRANT, WHICH CONVERT
TO 126 KNOT 1-MIN WINDS, AND A 301001Z RCM-3 PARTIAL SAR PASS.
WHILE THE SAR DID NOT COVER THE ENTIRETY OF THE STORM, IT DID COVER
THE EYE AND THE SOUTHEASTERN QUADRANT, WHERE THE HIGHEST WINDS HAVE
BEEN OVER THE PAST 24 HOURS, AND REVEALED A MAXIMUM WIND OF 129
KNOTS. THUS THE INTENSITY IS SET TO 130 KNOTS WITH HIGH CONFIDENCE,
REGARDLESS OF THE T7.0 DVORAK BASED ESTIMATES FROM ALL AGENCIES.
130 KNOTS IS ALSO SUPPORTED BY THE ADT, AIDT, DPRINT AND SATCON
ESTIMATES. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE, HOWEVER THE
ONSET OF THE EYEWALL REPLACEMENT CYCLE (EWRC) IS PROVING TO THE
PRIMARY FACTOR IN THE WEAKENING OF THE SYSTEM.

INITIAL WIND RADII BASIS: SAR AND SMAP DATA

CURRENT STEERING MECHANISM: SOUTHWESTERN EDGE OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T7.0 - 140 KTS
RJTD: T7.0 - 140 KTS
RCTP: T7.0 - 140 KTS
KNES: T7.0 - 140 KTS
CIMSS ADT: 132 KTS AT 301130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 5-10 KTS
SST: 30-31 CELSIUS
OUTFLOW: MODERATE RADIAL
OTHER FACTORS: EYEWALL REPLACEMENT CYCLE (EWRC)

ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: HIGH
INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: STY 09W WILL CONTINUE TO TRACK TOWARDS THE
WEST-NORTHWEST FOR THE NEXT 24 HOURS ALONG THE SOUTHWEST SIDE OF
THE STR FAR TO THE NORTHEAST. THE PRIMARY STEERING INFLUENCE
RAPIDLY SHIFTS TO A TRANSIENT ANTICYCLONE WHICH PASSES TO THE NORTH
IN THE WAKE OF A DEEP, MID-LATITUDE TROUGH THAT WILL SWING EAST
THROUGH CENTRAL CHINA OVER THE NEXT DAY. STY 09W WILL TURN WESTWARD
BETWEEN TAU 36 AND TAU 48 UNDER THE INFLUENCE OF THIS TRANSIENT
ANTICYCLONE. FROM AN INTENSITY PERSPECTIVE, THE SYSTEM WILL SLOWLY
BUT STEADILY WEAKEN THROUGH TAU 48 FIRST IN RESPONSE TO THE ONGOING
EWRC, FROM WHICH THE SYSTEM WILL NOT HAVE TIME TO RECOVER, AND
SECOND IN RESPONSE TO AN EXPECTED UPTICK IN SOUTHERLY WIND SHEAR
AFTER TAU 36. AFTER TAU 48, THE INFLUENCE OF A DRY AIR ENTRAINING
INTO THE CORE OF THE SYSTEM, INCREASED VERTICAL WIND SHEAR AND
DISRUPTION OF THE LOW-LEVEL FLOW DUE TO TERRAIN INTERACTION, WILL
LEAD TO A FASTER PACE OF WEAKENING. AS THE SYSTEM QUICKLY WEAKENS
AS IT PASSES SOUTH OF HONG KONG, THE STEERING LEVEL WILL STEADILY
PROGRESS TO LOWER LEVELS OF THE ATMOSPHERE, WHERE THE STEERING
GRADIENT WILL BE MUCH WEAKER AS A WEAKNESS IN THE STEERING PATTERN
DEVELOPS. AS THE SYSTEM WEAKENS BELOW TROPICAL STORM STRENGTH, IT
WILL COME UNDER THE STEERING INFLUENCE OF THE LOW TO MID-LEVEL
SOUTHWESTERLY MONSOONAL FLOW, AND TURN SHARPLY BACK TOWARDS THE
EAST-NORTHEAST BY THE END OF THE FORECAST PERIOD.

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS BEGINNING TO SHOW
INCREASED UNCERTAINTY, AS THE MODELS DEPICT DIFFERENCES IN THE
PATTERN EVOLUTION. THROUGH TAU 48, THE BULK OF THE GUIDANCE IS
CONSISTENT WITH THE EARLIER RUN, WITH THE ECMWF CONTINUING TO MARK
THE NORTHERN EDGE OF THE ENVELOPE, TAKING THE SYSTEM INLAND EAST OF
HONG KONG AROUND TAU 48 AND THEN SKIRTING THE COASTLINE THROUGH THE
REMAINDER OF THE FORECAST PERIOD. THE GFS MEANWHILE REMAINS THE
SOUTHERN EDGE MARKER, BUT WITH THIS RUN INTRODUCES THE SHARP TURN
BACK TO THE EAST AFTER TAU 72, AS DOES THE NAVGEM AND TO A LESSER
DEGREE, THE GEFS ENSEMBLE MEAN. THE GFS IS PARTICULARLY FAST IN
TURNING THE SYSTEM AND RACING IT OFF TO THE NORTHEAST, NEARING THE
SOUTHERN TAIWAN STRAIT BY TAU 120. THE JTWC FORECAST LIES CLOSE TO
THE CONSENSUS MEAN THROUGH THE FORECAST. CONFIDENCE IS HIGH TO
ABOUT TAU 48, BUT LOW THEREAFTER DUE TO THE LARGE SPREAD DEPICTED
IN THE GUIDANCE AFTER TAU 72. INTENSITY GUIDANCE IS IN VERY GOOD
AGREEMENT, WITH ALL MODELS INDICATING STEADY WEAKENING THROUGH THE
FORECAST PERIOD. THE JTWC FORECAST LIES ON THE HIGHER END OF THE
ENVELOPE WITH MEDIUM CONFIDENCE.

FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
TRACK 72-120 HR: LOW
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
NNNN

[Hayabusa]

...A 301001Z RCM-3 PARTIAL SAR PASS.
WHILE THE SAR DID NOT COVER THE ENTIRETY OF THE STORM, IT DID COVER
THE EYE AND THE SOUTHEASTERN QUADRANT, WHERE THE HIGHEST WINDS HAVE
BEEN OVER THE PAST 24 HOURS, AND REVEALED A MAXIMUM WIND OF 129
KNOTS.

Profile plots updated, 132 kts max winds

[doomhaMwx]

Taiwan's Pratas/Dongsha buoy recorded a min pressure of 961.9mb at 17Z, 23-24km from Saola's eye. Max windspeed and gust so far is 33.3m/s (65kt) and 47m/s (91kt) respectively. Inputting the pressure obs in Schloemer Equation (10nmi RMW, 1005mb POCI) gives a central pressure estimate of 925-930mb.

[Sciencerocks]

[cycloneye]

WDPN32 PGTW 302100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (SAOLA) WARNING NR
029//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 20.9N 118.8E
INITIAL INTENSITY: 130 KTS
GEOGRAPHIC REFERENCE: 270 NM EAST-SOUTHEAST OF HONG KONG
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
SIGNIFICANT WAVE HEIGHT: 44 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS SUPER
TYPHOON (STY) SAOLA (09W) HAS LIKELY REACHED PEAK INTENSITIES OVER
THE LAST SIX HOURS, AS THE VERY TIGHT SYMMETRY OBSERVED 12 HOURS
PRIOR HAS SINCE SLIGHTLY EXPANDED, SHOWING LARGE CONVECTIVE SPIRAL
BANDING BEGINNING TO PROTRUDE AWAY FROM THE SYSTEMS LLCC.
ADDITIONALLY, THE VERY SYMMETRIC EYE OF 16NM PERSISTS, YET HAS
CONTINUED TO DECREASE IN SIZE SINCE THE PREVIOUS WARNING. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A 301800Z
HM9 ENHANCED INFRARED IMAGE. THE INITIAL INTENSITY OF 130 KTS IS
ASSESSED WITH HIGH CONFIDENCE BASED ON MULTI-AGENCY DVORAK INTENSITY
ESTIMATES OF T7.0 AND SUBJECTIVE INTENSITY ESTIMATES OF: CIMSS ADT
134KT, CIMSS AIDT 130KTS, AND CIMSS DPRINT 124KTS AT 302050Z.

INITIAL WIND RADII BASIS: PERSISTENCE

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T7.0 - 140 KTS
RJTD: T7.0 - 140 KTS
RCTP: T7.0 - 140 KTS
KNES: T7.0 - 140 KTS
CIMSS ADT: 134 KTS AT 301730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 5-10 KTS
SST: 30-31 CELSIUS
OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: HIGH
INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: STY SOALA IS FORECAST TO CONTINUE ON A
WEST-NORTHWESTWARD TRACK THROUGH TAU 72, SKIRTING THE COAST OF
SOUTHERN CHINA. A SIGNIFICANT DROP IN OCEAN HEAT CONTENT FROM TAU
12 FORWARD, ALONG WITH THE FRONT RIGHT QUADRANT EXPERIENCE THE
EFFECTS OF LAND INTERACTION, ARE EXPECTED TO WEAKEN THE SYSTEM
RATHER QUICKLY AND DROP TO AN INTENSITY OF NEAR 45 KTS BY TAU 120.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE ALIGNS WELL THROUGH TAU
72, SHOWING SOLUTIONS NEARING THE SOUTHERN COAST OF CHINA WITH A
CROSS-TRACK SPREAD OF 122NM. POST TAU 72, MOST MEMBERS OF THE JTWC
CONSENSUS TRACK THE SYSTEM SOUTH THROUGH TAU 96, AND THEN
CHECK-MARKING BACK ON A RECIPROCAL HEADING TO THE EAST-NORTHEAST.
THE ECMWF ENSEMBLE, HOWEVER, CONTINUES ON A WEST-SOUTHWESTWARD
TRACK POST TAU 72 THROUGH TAU 120.

FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
TRACK 72-120 HR: LOW
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: LOW//
NNNN

[Sciencerocks]

 https://twitter.com/zoom_earth/status/1697022627590570238

[Ed_2001]

18z HAFS takes Saola directly into Hong Kong as a weakening but still powerful typhoon

[cycloneye]

09W SAOLA 230831 0000 21.0N 118.1E WPAC 135 922

[cycloneye]

Will Hong Kong get it?

[TyphoonNara]

09W SAOLA 230831 0600 21.2N 117.8E WPAC 135 921

Apparently JTWC thinks Saola, which is undergoing EWRC right now, has the same strength as its peak... JTWC has done a very poor and baffling job on Saola so far.

[StormTracker89]

JTWC too high on last two analyses based on coincident SAR passes from 2155z. RS2 showed 124kt while RCM3 showed 128kt. EWRC is ongoing and having an effect even if the Dvorak estimates have held steady. Interesting that agency fix Data-T numbers are all around T6.0 as well.

[cycloneye]

WDPN32 PGTW 310900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (SAOLA) WARNING NR
031//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 21.2N 117.8E
INITIAL INTENSITY: 135 KTS
GEOGRAPHIC REFERENCE: 211 NM EAST-SOUTHEAST OF HONG KONG
MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 03 KTS
SIGNIFICANT WAVE HEIGHT: 48 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM HAS
MAINTAINED A HIGHLY SYMMETRICAL AND DENSE CENTRAL CONVECTION WITH A
SHARPLY OUTLINED 20-NM EYE. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE EYE. THE INITIAL INTENSITY OF 135KTS
IS ALSO PLACED WITH HIGH CONFIDENCE BASED ON AN OVERALL ASSESSMENT
OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE SUSTAINED
INTENSE 6-HR CONVECTIVE AND WRAP MSI SIGNATURE. ANALYSIS INDICATES
A HIGHLY FAVORABLE ENVIRONMENT WITH VERY WARM SST IN THE SOUTH
CHINA SEA, LOW VWS, AND STRONG RADIAL OUTFLOW. ADDITIONALLY, STY
09W IS SLOWLY UNDERGOING AN EYEWALL REPLACEMENT CYCLE (ERC) BUT HAS
NOT WEAKENED THE SYSTEM AS OF YET.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: DEEP LAYER SUBTROPICAL RIDGE (STR) TO
THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T7.0 - 140 KTS
RJTD: T7.0 - 140 KTS
RCTP: T7.0 - 140 KTS
CIMSS ADT: 134 KTS AT 310530Z
CIMSS D-PRINT: 121 KTS AT 310630Z
CIMSS D-MINT: 131 KTS AT 302140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
VWS: 5-10 KTS
SST: 30-31 CELSIUS
OUTFLOW: STRONG RADIAL

ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: HIGH
INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: STY SAOLA WILL TRACK ON A FLATTER
WEST-NORTHWESTWARD TO WESTWARD TRAJECTORY AS THE STEERING STR
BUILDS. AFTER TAU 36, A SECONDARY STR TO THE WEST WILL ASSUME
STEERING AND DRIVE THE CYCLONE SOUTHWESTWARD. THE ERC IS EXPECTED
TO SLOWLY WEAKEN THE CORE OF THE STY 10W; THIS, IN ADDITION TO LAND
INTERACTION WITH EASTERN SEABOARD OF CHINA WILL LEAD TO A GRADUAL
WEAKENING TO 70KTS BY TAU 48 AFTER IT BRUSHES HONG KONG. AFTER TAU
48, A MORE RAPID EROSION IS EXPECTED AS COOL DRY AIR FROM THE
CHINESE INTERIOR INTRUDES INTO THE LOW LEVEL CIRCULATION, KNOCKING
DOWN THE INTENSITY TO 40KTS BY TAU 72. AFTERWARD, A SCALED DOWN AND
WEAKER 35-KT 09W WILL LOOP AND DRIFT NORTHEASTWARD WITH THE MONSOON
FLOW, ENHANCED BY A SHALLOW NEAR-EQUATORIAL RIDGE TO THE SOUTH.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL AGREEMENT WITH
THE LOOPING TRACK BUT DIVERGE SIGNIFICANTLY AFTER TAU 72, LENDING
MEDIUM CONFIDENCE TO THE JTWC TRACK FORECAST UP TO TAU 72, THEN LOW
CONFIDENCE AFTERWARD. A NOTABLE OUTLIER IS UKMET THAT CONTINUES THE
VORTEX SOUTHWESTWARD TOWARD VIETNAM AFTER TAU 72. ANOTHER NOTABLE
OUTLIER IS GFS WITH A MUCH WIDER LOOP AFTER TAU 72.

FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
TRACK 72-120 HR: LOW
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: LOW//

[Kingarabian]

JTWC too high on last two analyses based on coincident SAR passes from 2155z. RS2 showed 124kt while RCM3 showed 128kt. EWRC is ongoing and having an effect even if the Dvorak estimates have held steady. Interesting that agency fix Data-T numbers are all around T6.0 as well.

Well SAR isn't the most accurate estimate for TC intensity.

[doomhaMwx]

Radar and microwave show that EWRC is complete, but the eastern eyewall is now relatively weaker.