WPAC: KHANUN - Post-Tropical

[ElectricStorm]

06W KHANUN 230731 1800 24.1N 130.3E WPAC 115 935

[Hayabusa]

Euro keeps this hanging for the next 10 days, it's gonna be an ACE maker if true

[cycloneye]

Oh boy.

[Sciencerocks]

[ElectricStorm]

Navy site isn't loading for me right now but best track is up to 120kts on TT

[1900hurricane]

Given the abundant SAR and SMAP data now combined with radar velocities, I think Khanun's intensity is at least a category overestimated.

[NotoSans]

 https://twitter.com/squirtleinhk/status/1686186407545511936

[Sciencerocks]

 https://twitter.com/VortixWx/status/1686191139487916032

[cycloneye]

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (KHANUN) WARNING NR 021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 25.0N 128.7E
INITIAL INTENSITY: 120 KTS
GEOGRAPHIC REFERENCE: 102 NM SOUTH-SOUTHEAST OF KADENA AB
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 08 KTS
SIGNIFICANT WAVE HEIGHT: 50 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A HIGHLY
SYMMETRIC TYPHOON WITH A ROUGHLY 20NM CRYSTAL CLEAR EYE AND TIGHTLY
WRAPPING BANDING FEATURES IN ALL QUADRANTS. A 010409Z AMSR2 89GHZ
COLOR COMPOSITE MICROWAVE IMAGE INDICATES A GENERALLY INTACT AND
THICK INNER EYEWALL WITH A MOAT-LIKE FEATURE POSSIBLY FORMING
AROUND IT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON A 20NM EYE VISIBLE IN MSI AND AMSR2 IMAGERY. THE INITIAL
INTENSITY OF 120 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A
RARE AGREEMENT AMONGST ALL AVAILABLE INTENSITY GUIDANCE. AGENCY
DVORAK INTENSITY ESTIMATES, CIMSS SATCON, ADT, D-MINT AND D-PRINT
ALL INDICATE 120 KTS WITH LITTLE VARIABILITY.

INITIAL WIND RADII BASIS: PERSISTENCE

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER STR
CENTERED OVER THE YELLOW SEA.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T6.5 - 127 KTS
RJTD: T6.0 - 115 KTS
RCTP: T6.0 - 115 KTS
KNES: T6.0 - 115 KTS
CIMSS SATCON: 126 KTS AT 010451Z
CIMSS ADT: 122 KTS AT 010530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 10-15 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE RADIAL
OTHER FACTORS: UPPER-LEVEL DRY AIR INTRUSION

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON 06W (KHANUN) IS FORECAST TO CONTINUE
TRACKING WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR
TO THE NORTH. THE SYSTEM IS FORECAST TO GRADUALLY WEAKEN OVER THE
NEXT 24 HOURS DUE TO PERSISTENT VERTICAL WIND SHEAR AND UPPER LEVEL
DRY AIR ENTRAINMENT. AFTER TAU 24, THE UPPER LEVEL STEERING PATTERN
WILL BEGIN TO SHIFT. THE STR TO THE NORTH WILL GRADUALLY SHIFT
WESTWARD AND A NEAR EQUATORIAL RIDGE (NER) TO THE SOUTH WILL
CONTINUE TO BUILD. BY TAU 48, THIS WILL SET UP A WEAK AND COMPETING
STEERING ENVIRONMENT THAT WILL LIKELY RESULT IN QUASI-STATIONARY OR
ERRATIC TRACK MOTION. DURING THIS TIME, SLOW TRACK SPEEDS COMBINED
WITH A TYPHOON STRENGTH LOW PRESSURE CENTER WILL UPWELL COPIOUS
AMOUNTS OF COOLER WATER BENEATH 06W. BY TAU 72, THIS COOLER WATER
COMBINED WITH ONGOING DRY AIR ENTRAINMENT WILL MORE RAPIDLY WEAKEN
THE SYSTEM. BY TAU 96, NOW TROPICAL STORM STRENGTH, THE RIDGES TO
THE NORTH AND SOUTH OF THE SYSTEM BOTH REORIENT TO THE WEST AND
FORCE 06W NORTHEASTWARD THROUGH THE REMAINING FORECAST PERIOD.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT THROUGH
TAU 48, WITH ALL MEMBERS FOLLOWING THE JTWC TRACK FORECAST CLOSELY.
AFTER TAU 48 HOWEVER, TWO GROUPS BEGIN TO FORM, HWRF, EGRI AND
UKMET DRIVE THE SYSTEM INTO MAINLAND CHINA WHILE THE REMAINING
MEMBERS TAKE A SHARP TURN NORTHEASTWARD THROUGH THE FORECAST
PERIOD. FOR THIS REASON THE JTWC TRACK FORECAST IS PLACED INITIALLY
WITH MEDIUM CONFIDENCE AND WITH LOW CONFIDENCE THEREAFTER. SIMILAR
TO NUMERICAL MODEL OUTPUT, RELIABLE MODEL INTENSITY GUIDANCE IS IN
GOOD AGREEMENT INITIALLY, WITH ALL MEMBERS SLOWLY WEAKENING THE
SYSTEM THROUGH TAU 36. THE SPREAD IN MEMBER GUIDANCE GROWS AFTER
TAU 48 AS VARIOUS MEMBERS RESOLVE THE COMPLEX ENVIRONMENT AND
IMPACTS OF THE AFOREMENTIONED UPWELLING. JTWC REMAINS ON THE UPPER
END OF THE GUIDANCE ENVELOPE THROUGHOUT THE FORECAST PERIOD. FOR
THESE REASON THE JTWC INTENSITY FORECAST IS PLACED INITIALLY WITH
MEDIUM CONFIDENCE AND WITH LOW CONFIDENCE THEREAFTER.

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

[NotoSans]

 https://twitter.com/squirtleinhk/status/1686337922541264896

[cycloneye]

 https://twitter.com/iCyclone/status/1686310954361872385

[Sciencerocks]

[cycloneye]

 https://twitter.com/EarthUncutTV/status/1686365729464205312

[Hayabusa]

Naha automatic synoptic station located 26 12N , 127 41E, 28m asl reporting 50 kts winds, mslp 974.5mb @ 1500z

202308011500 AAXX 01154 47936 46/// /0750 10266 20259 39690 49745 58032=

[Mob1]

For now, looks like Naha will only get a glancing blow. Although, some models have it moving over them (in a weakened state) in a few days as steering currents collapse and it just meanders around the same general area.

With that said, the highest gust I can find of the island is still a very respectable 112 mph.

[Sciencerocks]

 https://twitter.com/VortixWx/status/1686446451092504582

[1900hurricane]

Wind observations thus far seem to be matching up well spatially and by magnitude to what SAR had this morning if extrapolated with the storm motion and evolution since then. There is a very large radius of near maximum winds in the northern semicircle. Naha recently saw a 52.5 m/s (102 kt) wind gust.

[xtyphooncyclonex]

Both the GFS and ECMWF seem to agree on Khanun holding onto typhoon strength for over a week. GFS goes even more bonkers... maintains intensity well into TAU 240!

Interesting to note that while the JMA largely concurs with the models (matter of fact, they have revised it up to 75 kts for day 5), the JTWC is much much more aggressive with weakening from upwelling.

[Sciencerocks]

[cycloneye]

WDPN32 PGTW 020300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (KHANUN) WARNING NR 024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 25.8N 127.0E
INITIAL INTENSITY: 100 KTS
GEOGRAPHIC REFERENCE: 60 NM SOUTHWEST OF KADENA AB
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 04 KTS
SIGNIFICANT WAVE HEIGHT: 36 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
AFTER PASSING WITHIN 53NM TO THE SOUTH OF KADENA AB, TYPHOON (TY)
06W (KHANUN) HAS CONTINUED TO TRACK GENERALLY TOWARDS THE
WEST-NORTHWEST. HOWEVER, THE STORM TOOK A BRIEF PIT-STOP BETWEEN
ROUGHLY 2100Z AND 0000Z, WITH RADAR DATA SHOWING THE SYSTEM
BECOMING NEARLY QUASI-STATIONARY DURING THIS PERIOD, BEFORE ONCE
AGAIN HEADING OFF TO THE NORTHWEST. RECENT 89GHZ SSMIS MICROWAVE
IMAGERY FROM 012117Z SHOWED A VERY LARGE SECONDARY EYEWALL
APPROXIMATELY 75-90NM OUT FROM THE CENTER AND A CLEAR MOAT
SURROUNDING THE INNER CORE. THE MOST RECENT ANIMATED RADAR DATA
SHOWS THE EYE OF THE SYSTEM PASSING SOUTH OF KUMEJIMA ISLAND BY
0200Z. WINDS AT KUMEJIMA ARE NOT ALL THAT IMPRESSIVE CONSIDERING
THE STATION IS ON THE OUTER EDGE OF THE INNER EYEWALL, BUT
PRESSURES HAVE DROPPED PRECIPITOUSLY, DOWN TO 954MB BY 0200Z. NAHA
CONTINUES TO REPORT SUSTAINED WINDS OVER 50 KNOTS WITH GUSTS AS
HIGH AS 78 KNOTS IN THE OUTER EYEWALL. THE INITIAL INTENSITY HAS
BEEN LOWERED SLIGHTLY, TO 100 KNOTS, WITH MEDIUM CONFIDENCE. THE
INITIAL INTENSITY IS IN LINE WITH THE MAJORITY OF THE AGENCY DVORAK
CURRENT INTENSITY ESTIMATES BUT WELL BELOW THE PREPONDERANCE OF THE
AUTOMATED ESTIMATES WHICH ARE CLUSTERED BETWEEN 112 KNOTS TO 127
KNOTS. CONDITIONS REMAIN GENERALLY FAVORABLE WITH WARMS SSTS, GOOD
POLEWARD OUTFLOW EXTENDING EAST INTO A TUTT-CELL SOUTH OF TOKYO AND
LOW SHEAR.

INITIAL WIND RADII BASIS: PERSISTENCE

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED OVER THE YELLOW SEA.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T6.0 - 115 KTS
RJTD: T5.5 - 102 KTS
RCTP: T6.0 - 115 KTS
KNES: T5.5 - 102 KTS
CIMSS ADT: 119 KTS AT 012330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 0-5 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: OUTSIDE OF THE BRIEF PIT-STOP SOUTHWEST OF
OKINAWA, TY 06W HAS IN GENERAL CONTINUED TRACKING TOWARDS THE
WEST-NORTHWEST ALONG THE SOUTHERN SIDE OF THE STEERING RIDGE TO THE
NORTH. THE SYSTEM CONTINUES TO SLOW DOWN WHILE CONTINUING TO TREK
FURTHER INTO THE EAST CHINA SEA OVER THE NEXT 24 TO 36 HOURS AS THE
CENTER OF THE STEERING RIDGE SHIFTS TO THE SOUTHWEST AND BLOCKS
FURTHER WESTWARD PROGRESSION. THE SYSTEM IS EXPECTED TO BECOME
QUASI-STATIONARY IN THE VICINITY OF THE 124E LONGITUDE LINE BETWEEN
TAU 36 AND 48 UNDER THE COMPETING STEERING INFLUENCES OF THE
BLOCKING RIDGE TO THE NORTHWEST AND THE NEAR EQUATORIAL RIDGE (NER)
TO THE WEST OF GUAM. AFTER BOUNCING AROUND LIKE A BEACH BALL IN THE
GENERAL ADMISSION SECTION OF DODGER STADIUM FOR 24 HOURS OR SO, THE
NER TO THE SOUTH BUILDS IN AND KICKS THE SYSTEM OUT TO THE
NORTHEAST AFTER TAU 72. AFTER TAU 72, TY 06W WILL PICK UP SPEED
AS IT CONTINUES TO TREK TOWARDS THE EAST-SOUTHEAST, PASSING CLOSE
TO ASAMI OSHIMA BY TAU 120. AS THE SYSTEM CONTINUES TO SLOW DOWN AS
IT TRACKS WESTWARD, IT WILL BEGIN TO UPWELL SIGNIFICANTLY COOLER
WATERS TO THE SURFACE, SOME MODELS SUGGESTING AS MUCH AS -4C OF SST
COOLING. THE UPWELLING WILL LIKELY INHIBIT COMPLETION OF THE
ONGOING EYEWALL REPLACEMENT CYCLE (EWRC). THUS, THE SYSTEM IS
EXPECTED TO SLOWLY WEAKEN FOR THE FIRST 24 HOURS FOLLOWED BY A MORE
PRECIPITOUS DROP-OFF THROUGH TAU 72. IT SHOULD BE NOTED HOWEVER THAT
WHILE THE SYSTEM WILL BE WEAKENING THROUGH THE MAJORITY OF THE
FORECAST, THE WIND FIELD WILL AT THE SAME TIME CONTINUE TO EXPAND.

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE REMAINS CONSISTENT
WITH THE PREVIOUS MODEL RUN, WITH ALL THE CONSENSUS MEMBERS
INDICATING A SLOWING TRACK TO THE WEST TO TAU 48, THEN A SHARP TURN
TO THE EAST-NORTHEAST BY TAU 72. SOME NEAR-TERM WOBBLES SHOULD BE
ANTICIPATED AS THE EWRC CONTINUES, AND ERRATIC UNPREDICTABLE
MOTION IS EXPECTED ONCE THE SYSTEM BECOMES QUASI-STATIONARY AROUND
TAU 36. AFTER TAU 72, THE GUIDANCE ENVELOPE EXPANDS BOTH IN THE CROSS
AND ALONG-TRACK SENSE. THE HAFS-A TRACKER NOW SHOWS THE SYSTEM PASSING
OVER SOUTHERN OKINAWA AFTER TAU 72, WHILE THE GFS AND GEFS ENSEMBLE
MEAN SHOW A PASSAGE ALONG THE NORTHERN TIP OF THE ISLAND. THE
REMAINDER OF THE GUIDANCE IS SPREAD ACROSS A 100NM ENVELOPE EXTENDING
TO THE NORTH. IN THE ALONG-TRACK SENSE, THE ECMWF AND NAVGEM ARE IN A
HURRY TO GET TO THE JAPANESE MAIN ISLANDS, FAR OUTPACING THE GFS AND
THE OTHER CONSENSUS MEMBERS, GENERATING A LARGE ALONG-TRACK SPREAD.
TRACK CONFIDENCE MEDIUM TO LOW IN THE LATER TAUS. INTENSITY GUIDANCE
IS IN FAIRLY GOOD AGREEMENT, THOUGH HWRF IS AGGRESSIVELY CALLING FOR
INTENSIFICATION UP TO 115 KNOTS AND REMAINS ABOUT 15 KNOTS ABOVE THE
CONSENSUS MEAN THROUGH THE REMAINDER OF THE FORECAST, WHILE THE HAFS-A
TAKES THE OPPOSITE TACK, AND IS ABOUT 15 KNOTS BELOW THE MEAN THROUGH
TAU 120. THE JTWC FORECAST TRACKS THE MEAN, AS WELL AS THE SHIPS AND
COAMPS-TC GUIDANCE 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//