WPAC: LAN - Post-Tropical

[aspen]

Knowing the JTWC, they’ll probably go with a mere 115 kt.

07W LAN 230811 0000 26.8N 142.9E WPAC 115 936

How do they get 115 kt from a T6.5 manual Dvorak fix? Maybe leaning towards the super low satellite estimates? Some don’t even show this as a major.

[cycloneye]

WDPN31 PGTW 110300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (LAN) WARNING NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 26.8N 142.9E
INITIAL INTENSITY: 115 KTS
GEOGRAPHIC REFERENCE: 536 NM SOUTH-SOUTHEAST OF YOKOSUKA, JA
MOVEMENT PAST 6 HOURS: NORTHWARD AT 05 KTS
SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS TYPHOON LAN
FIGHTING OFF A FIERCE INCURSION OF DRY AIR AND SUBSIDENCE OVER THE
PAST EIGHT HOURS AND EMERGING STRONGER THAN EVER. THE EYEWALL HAS
THICKENED AND RE-DEVELOPED NEAR PERFECT SYMMETRY OVER THE PAST FOUR
HOURS AND IS NOW STRONGER THAN EVER. THE EYE HAS CONTRACTED TO 18NM
AND CONVECTION IN THE EYEWALL HAS INTENSIFIED. THE CURRENT
INTENSITY IS ALL THE WAY UP TO 115KTS BASED ON DVORAK ESTIMATES
FROM BOTH JTWC AND THE JMA. ADT AIDT DMINT AND DPRINT FROM CIMSS
ARE UNAMIONOUS IN THEIR SUPPORT OF THE 115KT INTENSITY. THE
POLEWARD OUTFLOW CHANNEL TO THE NORTHEAST MAY HAVE BEEN THE CAUSE
OF THE SURGE AND THE BOOSTED EXHAUST IS VISIBLE IN WATER VAPOR
ANIMATION. THE TUTT CELL INITIATING THAT CHANNEL IS PASSING THROUGH
THE SWEET SPOT TO THE DISTANT NORTH-NORTHEAST OF THE SYSTEM AND
THAT LINKAGE SHOULD LAST ANOTHER 12 HOURS OR SO UNTIL THE TUTT CELL
DRIFTS TOO FAR AWAY. AT THIS POINT THE BENEFITS OF THE ENHANCED
OUTFLOW IS EXCEEDING THE IMPEDIMENTS OF THE DRY AIR ENTRAINMENT IN
THE LOW AND MID LEVELS. THE SAME DRY ENVIRONMENT EXISTS BETWEEN THE
STORM AND HONSHU, BUT THANKS TO THE BOOSTED OUTFLOW AND VIGOROUS
CONVECTION, TY LAN HAS MANAGED TO COCOON ITSELF FROM THE WORST OF THE
EFFECTS OF THE UPSTREAM ENVIRONMENT. TY 07W IS TRACKING THROUGH THE
LAST MILES OF 30C SEA WATERS AND TOWARDS A LONG TRACK COVERED BY 28-
29 DEGREE SEA SURFACE TEMPERATURES. OCEAN HEAT CONTENT, HOWEVER, IS
ALREADY LOW AND TRENDING LOWER. THE SYSTEM HAS SLOWED MOVEMENT AND
TURNED POLEWARD DURING THE PAST SIX HOURS, BUT IS APPROACHING A
STRONGER PORTION OF THE SUBTROPICAL RIDGE.

INITIAL WIND RADII BASIS: THE RADII WERE SET WITH THE 101201Z ASCAT
PASS AND THEN ADJUSTED IN THREE QUADRANTS USING A RECENT 102356Z
ASCAT UHR PARTIAL IMAGE.

CURRENT STEERING MECHANISM: THE SOUTHWESTERN FLANK OF THE
SUBTROPICAL RIDGE.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T6.0 - 115 KTS
RJTD: T6.0 - 115 KTS
KNES: T6.5 - 127 KTS
CIMSS SATCON: 99 KTS AT 102330Z
CIMSS ADT: 115 KTS AT 102330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 0-5 KTS
SST: 29-30 CELSIUS
OUTFLOW: STRONG POLEWARD
OTHER FACTORS: FALLING OCEAN HEAT CONTENT, DRY AIR
ENTRAINMENT, AND SUBSIDENCE BETWEEN THE CURRENT POSITION AND THE
SOUTHERN COAST OF HONSHU WILL BE MAJOR FACTORS IN CAPPING
INTENSIFICATION, AND BRINGING ABOUT THE GRADUAL DECLINE OF THE STORM.

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: TYPHOON 07W LAN IS PEAKING AND IS EXPECTED TO
BEGIN A STEADY BUT SLOW DECLINE AS IT APPROACHES THE COAST OF
JAPAN. THE SUBTROPICAL RIDGE WILL BUILD SOUTHWESTWARD AND FORCE THE
SYSTEM AWAY FROM ITS CURRENT NORTHERLY TRACK AND MORE TO THE
NORTHWEST BEGINNING NEAR TAU 24. DECLINING OCEAN HEAT CONTENT AND SEA
SURFACE TEMPERATURES WILL INITIATE THE WEAKENING, AND EVENTUALLY THE
ABUNDANT DRY AIR UPSTREAM AND DECREASING UPPER LEVEL DIVERGENCE WILL
FURTHER AFFECT THE GRADUAL DECLINE. STILL, THE SYSTEM IS EXPECTED TO
HIT THE COAST ABOVE TYPHOON STRENGTH. AS THE KUROSHIO IS VERY NEAR THE
COAST THIS TIME OF YEAR, THERE ARE ONLY A FEW MILES OF COLD WATER ON
THE POLEWARD SIDE OF THE CURRENT TO WEAKEN THE STORM. 700-300MB
MOISTURE PROGS DO SHOW THE SYSTEM CARRYING ITS MOISTURE CORE ALL
THE WAY TO THE COAST BUT NOT BY MUCH. SOME DRY AIR WILL UNDOUBTEDLY
MAKE ITS WAY INTO THE CORE. GIVEN THE VERY WARM WATERS ALONG THE
WEST COAST OF HONSHU IT IS LIKELY THAT THE SYSTEM WILL EMERGE INTO
THE SEA OF JAPAN AND REORGANIZE BEFORE GRADUALLY ROLLING OVER
TOWARDS HOKKAIDO.

MODEL DISCUSSION: TRACK GUIDANCE HAS BEEN REASSURING IN ITS
CONSISTENCY IN POINTING AT A LANDFALL WEST OF NAGOYA IN THE
HAMMAMATSU-IZU HONTO REGION. THE CLOSEST DOD INSTALLATION TO THE
STRIKE WILL BE THE USMC CAMP FUJI COMBAT ARMS TRAINING CENTER. GALE
FORCE WINDFIELDS ARE EXPECTED TO COME VERY CLOSE TO THE MIURA
PENINSULA, HOWEVER, AND GIVEN THE TIME AND DISTANCE TO IMPACT, THE
CERTAINTY OF THAT COVERAGE IS LOW. THANKS TO THE RELATIVELY TIGHT
PACKING OF THE TRACK GUIDANCE THE TRACK FORECAST STAYS JUST A
LITTLE RIGHT OF THE MULTI-MODEL CONSENSUS, FAVORING THE EUROPEAN AND
AMERICAN ENSEMBLES AS WELL AS THE BETA EFFECT. THE INTENSITY
GUIDANCE IS UNANIMOUS IN SHOWING THE PEAK OF THE STORM DURING THE
NEXT 12 TO 18 HOURS AND A GRADUAL LINEAR DECLINE THEREAFTER. THE
JTWC INTENSITY FORECAST IS PREDICATED ON THE STATISTICAL DYNAMICAL
GUIDANCE WHICH IS DOING WELL TO BALANCE THE FAVORABLE AND
UNFAVORABLE FACTORS OF OCEAN HEAT CONTENT VERTICAL WINDSHEAR
MOISTURE AND DECREASING UPPER LEVEL DIVERGENCE.

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

[cycloneye]

 https://twitter.com/VortixWx/status/1689825391505027073

[Sciencerocks]

[Sciencerocks]

[cycloneye]

07W LAN 230811 1200 27.9N 142.6E WPAC 105 943

[aspen]

Upwelling looks to be taking a toll on Lan. I think its peak last night was around 120-125 kt. IMO, it didn’t get quite good enough to be worthy of STY status.

[cycloneye]

WDPN31 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (LAN) WARNING NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 27.9N 142.6E
INITIAL INTENSITY: 105 KTS
GEOGRAPHIC REFERENCE: 468 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 05 KTS
SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS WARMING
CONVECTIVE CLOUD TOPS SURROUNDING A STILL WELL-DEFINED 29 NM
DIAMETER EYE, REFLECTING THE FIRST STAGE OF A WEAKENING TREND. A
PREVIOUSLY ROBUST POLEWARD OUTFLOW CHANNEL HAS CONTINUED TO WANE
AS THE DRIVING MECHANISM, AN UPPER-LEVEL LOW TO THE NORTH, MOVES
AWAY FROM THE SYSTEM. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON BASED ON THE CLEAR EYE FEATURE EVIDENT IN THE
EIR AND 111137Z METOP-B MHS 89 GHZ MICROWAVE IMAGERY. THE CURRENT
POSITION CONFIRMS THAT TY 07W IS BEGINNING AN ANTICIPATED TURN
TOWARD THE NORTHWEST AS RIDGING BUILDS TO THE NORTH AND EAST OF THE
SYSTEM. THE INITIAL INTENSITY OF 105 KTS IS ASSESSED WITH HIGH
CONFIDENCE BASED ON MULTI-AGENCY ON SUPPORTIVE, MULTI-AGENCY
SUBJECTIVE DVORAK AND UW-CIMSS OBJECTIVE SATELLITE INTENSITY
ESTIMATES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T6.0 - 115 KTS
RJTD: T6.0 - 115 KTS
RCTP: T5.5 - 102 KTS
KNES: T6.0 - 115 KTS
CIMSS SATCON: 108 KTS AT 111200Z
CIMSS ADT: 112 KTS AT 111130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 5-10 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE POLEWARD

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: TY 07W WILL CONTINUE ITS TURN TOWARD THE
NORTHWEST OVER THE NEXT SIX HOURS AS SUBTROPICAL RIDGING BUILDS TO
THE NORTH AND EAST, UNINHIBITED BY FEATURES ASSOCIATED WITH THE
MID-LATITUDE BAROCLINIC ZONE WELL TO THE NORTH. THE SYSTEM WILL
FOLLOW THE FLOW ASSOCIATED WITH THE CURRENT STEERING RIDGE
THROUGHOUT THE FORECAST PERIOD, FIRST NORTHWESTWARD THROUGH TAU 36
AND INCREASINGLY POLEWARD THEREAFTER. A DEEP-LAYER TROUGH WILL DIG
EQUATORWARD TO THE NORTHWEST OF THE SYSTEM IN THE EXTENDED PERIOD,
SETTING A LIMIT TO THE WESTERN EXTENT OF THE STEERING RIDGE AND THE
DEPENDENT STORM TRACK. TY 07W IS STILL EXPECTED TO MAKE LANDFALL AT
TYPHOON INTENSITY SOUTHEAST OF KYOTO AND OSAKA JUST AFTER TAU 72,
ALTHOUGH DECLINING OCEAN HEAT CONTENT, CONTENTION WITH DRIER AIR
UPSTREAM, AND REDUCED DIVERGENCE ALOFT WILL CONTINUE TO SLOWLY
WEAKEN THE SYSTEM. IN THE EXTENDED RANGE PASSAGE OVER LAND AND
INTERACTION WITH A DEVELOPING TROUGH TO THE NORTHWEST WILL
ACCELERATE THE WEAKENING TREND AND INDUCE THE BEGINNING OF
EXTRATROPICAL TRANSITION.

MODEL DISCUSSION: THE ENVELOPE OF GLOBAL AND ENSEMBLE MODEL TRACK
FORECAST SOLUTIONS HAS NARROWED SINCE THE LAST CYCLE, WITH GREATER
UNCERTAINTY REMAINING IN THE EXTENDED PERIOD REGARDING THE TIMING OF
THE EXPECTED TURN TO THE NORTH AND POST-TURN TRACK SPEED. THEREFORE,
CONFIDENCE IN THE TRACK FORECAST IS MEDIUM EARLY ON AND LOW IN THE
EXTENDED PERIOD. INTENSITY FORECASTS ARE IN GOOD AGREEMENT THROUGH
MOST OF THE FORECAST PERIOD, AND THE ENVIRONMENTAL FACTORS AT PLAY
ARE
FAIRLY STRAIGHTFORWARD. HOWEVER, THERE IS SOME UNCERTAINTY REGARDING
HOW THE CURRENTLY OBSERVED CHANGES IN STORM STRUCTURE WILL PROCEED,
LENDING OVERALL MEDIUM CONFIDENCE TO THE PREDICTED INTENSITY.

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

[Sciencerocks]

 https://twitter.com/zeb199818/status/1690011289970438144

[cycloneye]

WDPN31 PGTW 112100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (LAN) WARNING NR 017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 28.2N 142.4E
INITIAL INTENSITY: 95 KTS
GEOGRAPHIC REFERENCE: 448 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 03 KTS
SIGNIFICANT WAVE HEIGHT: 34 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A RAPIDLY
DECAYING INNER CORE OF TYPHOON 07W (LAN) OVER THE PAST 12 HOURS.
THE STORM IS STRUGGLING TO CLOSE OFF EVEN A -60 DEGREE CELSIUS COLD
RING AROUND THE EYE. THIS IS LIKELY DUE TO OCEANIC UPWELLING, AS
NCODA OCEAN ANALYSIS SHOWS THAT LAN IS MOVING OVER A LOCAL MINIMUM
IN OCEANIC HEAT CONTENT OF LESS THAN 20 KJ PER SQUARE CENTIMETER,
AND PROCEEDING VERY SLOWLY AT A CURRENT SPEED OF 3 KT AS IT DOES
SO. THE INITIAL INTENSITY IS SET AT 95 KT BASED ON A BLEND OF
FALLING AGENCY DVORAK ESTIMATES AND OBJECTIVE SATELLITE-DERIVED
ESTIMATES, BUT CONFIDENCE IN THIS ASSESSMENT IS LOW DUE TO THE
ONGOING RAPID EVOLUTION OF THE STORM. UPPER-LEVEL OUTFLOW IS
PREDOMINANTLY EQUATORWARD, AND A DEEPLY DRY AIRMASS REMAINS
NORTHWEST OF 07W BETWEEN THE STORM AND MAINLAND JAPAN.

INITIAL WIND RADII BASIS: PERSISTENCE

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T6.0 - 115 KTS
RJTD: T6.0 - 115 KTS
RCTP: T5.5 - 102 KTS
KNES: T5.5 - 102 KTS
CIMSS ADT: 97 KTS AT 111730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 0-5 KTS
SST: 27-28 CELSIUS
OUTFLOW: MODERATE EQUATORWARD
OTHER FACTORS: DRY AIR MASS TO THE NORTHWEST

ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: LOW
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 07W (LAN) IS MOVING AT ITS SLOWEST
FORWARD SPEED SO FAR AS THE SUBTROPICAL RIDGE TO ITS NORTHEAST IS
TEMPORARILY WEAKENED BY AN UPPER-LEVEL LOW CURRENTLY EAST OF JAPAN.
THE RIDGE IS EXPECTED TO BUILD WESTWARD OVER THE NEXT 48 HOURS,
CAUSING A TURN NORTHWESTWARD OR WEST-NORTHWESTWARD AND SLIGHT
ACCELERATION. THIS RIDGE EAST OF JAPAN WILL CONTINUE TO GUIDE THE
TYPHOON AROUND ITS WESTERN PERIPHERY, WITH LAN TURNING NORTHWESTWARD
AND THEN NORTHWARD AS IT CROSSES HONSHU BETWEEN 72 AND 96 HOURS. A
WEAK UPPER-LEVEL TROUGH OVER NORTHEASTERN CHINA IS THEN EXPECTED TO
TURN 07W NORTH-NORTHEASTWARD OVER THE SEA OF JAPAN. THE JTWC TRACK
FORECAST IS SIMILAR TO THE PREVIOUS FORECAST AND SHOWS LAN PASSING
OVER ISE BAY, JAPAN AND NAGOYA, JAPAN BETWEEN 72 AND 96 HOURS.
SIGNIFICANT CROSS-TRACK MODEL SPREAD OF ABOUT 200 NM DOES REMAIN
AROUND THE LANDFALL POINT, MAKING THE EXACT LANDFALL LOCATION
UNCERTAIN. THIS IS PRIMARILY DUE TO FUZZINESS IN THE STRENGTH AND
SHAPE OF THE SUBTROPICAL RIDGE TO LAN'S NORTHEAST OVER THE NEXT FEW
DAYS. DYNAMICAL ENSEMBLES CONTINUE TO SHOW THAT A RELATIVELY WIDE
RANGE OF LANDFALL LOCATIONS IN JAPAN ARE POSSIBLE, WITH IMPACTS AS
FAR WEST AS IWAKUNI OR AS FAR EAST AS YOKOSUKA STILL WITHIN THE
ENVELOPE OF POSSIBILITIES. TURNING TO THE INTENSITY FORECAST, IT IS
CURRENTLY CHALLENGING, AS TYPHOON LAN IS PASSING OVER A PATCH OF
SHALLOW WARM WATER WHICH HAS COOLED BENEATH THE CIRCULATION,
CAUSING ABRUPT WEAKENING. SOME STABILIZATION OR RECOVERY OF THE
TYPHOON IS LIKELY DURING THE 24-48 HOUR PERIOD AS THE STORM MOVES
NEAR AN EDDY OF HIGHER OCEANIC HEAT CONTENT, BUT OVERALL HEAT
CONTENT VALUES WILL REMAIN LOW. THERE IS THUS A HARD CEILING ON
LAN'S INTENSITY PRIOR TO LANDFALL IN JAPAN, BUT THE EXTENT OF
SHORT-TERM WEAKENING IS DIFFICULT TO PREDICT WITH CONFIDENCE. THE
JTWC FORECAST SHOWS WEAKENING TO 85 KT BY 24 HOURS, THEN FLATLINING
THROUGH 48 HOURS DUE TO PRESUMED IMPROVEMENT IN OCEANIC CONDITIONS.
SLIGHT WEAKENING TO 80 KT JUST BEFORE LANDFALL IN JAPAN IS FORECAST
DUE TO THE ONSET OF SOME MID-LEVEL VERTICAL SHEAR AS LAN GETS
CLOSER TO A WEAK UPPER-LEVEL TROUGH OVER THE YELLOW SEA, ALONG WITH
COOLER JAPANESE COASTAL WATERS. UPON CROSSING HONSHU, LAN WILL
ENTER THE SEA OF JAPAN IN ABOUT 96 HOURS, WHERE ITS INTENSITY COULD
REMAIN AROUND 50 KT FOR A TIME, AS WATERS THERE ARE WARM. HOWEVER,
CONTINUED NORTH-NORTHEASTWARD MOTION IS EXPECTED TO BRING LAN INTO
A ZONE OF ELEVATED WIND SHEAR ASSOCIATED WITH THE UPPER-LEVEL
TROUGH OVER NORTHEASTERN CHINA, AND THE ASSOCIATED BAROCLINIC
INTERACTION SHOULD INITIATE EXTRATROPICAL TRANSITION COINCIDENT
WITH STEADY WEAKENING BY 120 HOURS.

MODEL DISCUSSION: THE JTWC TRACK FORECAST IS CLOSE TO THE
MULTI-MODEL CONSENSUS AND IS SIMILAR TO THE PREVIOUS FORECAST. THE
JTWC INTENSITY FORECAST IS HIGHER THAN THE DYNAMICAL GLOBAL MODELS
IN THE SHORT-TERM, BUT LOWER THAN THE HAFS MESOSCALE MODEL THROUGH
48 HOURS DUE TO THE MODEL'S UNREALISTICALLY HIGH DEPICTION OF
TYPHOON LAN'S CURRENT INTENSITY.

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

[Sciencerocks]

[cycloneye]

WP, 07, 2023081200, , BEST, 0, 285N, 1418E, 85, 960, TY

[ScottNAtlanta]

Looks like it has just gone through an eyewall replacement cycle and that eye is going to be HUGE!

[cycloneye]

[cycloneye]

WDPN31 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (LAN) WARNING NR 018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 28.5N 141.8E
INITIAL INTENSITY: 85 KTS
GEOGRAPHIC REFERENCE: 422 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 06 KTS
SIGNIFICANT WAVE HEIGHT: 33 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THAT THE
TYPHOON'S CORE HAS CONTINUED TO DEGRADE OVER THE PAST SIX HOURS,
WITH THE INNER RING OF CLOUD TOPS WARMING SO MUCH THAT A
WELL-DEFINED EYEWALL IS NO LONGER PRESENT. THE COLDEST CLOUD TOPS
ARE NOW OCCURRING IN A CONCENTRIC BAND AT ABOUT 70 NM RADIUS FROM
THE LOW-LEVEL CIRCULATION CENTER (LLCC). AN 112051Z SSMIS MICROWAVE
PASS CONFIRMED THE DEGRADATION OF THE EYEWALL, WITH ONLY ABOUT 40
PERCENT COVERAGE AROUND THE LLCC. OCEANIC UPWELLING IS ALMOST
CERTAINLY TO BLAME FOR THE RECENT WEAKENING TREND, AND LAN
CONTINUES TO MOVE SLOWLY AT 6 KT, ALBEIT A LITTLE FASTER THAN SIX
HOURS AGO. THE INITIAL INTENSITY IS SET AT 85 KT, FOLLOWING FALLING
AGENCY DVORAK ESTIMATES AND OBJECTIVE SATELLITE-DERIVED ESTIMATES,
BUT CONFIDENCE IN THIS ASSESSMENT IS LOWER THAN AVERAGE DUE TO THE
RAPID EVOLUTION OF THE STORM.

INITIAL WIND RADII BASIS: PERSISTENCE

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T5.5 - 102 KTS
RJTD: T5.5 - 102 KTS
KNES: T5.0 - 90 KTS
CIMSS ADT: 84 KTS AT 112340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 0-5 KTS
SST: 27-28 CELSIUS
OUTFLOW: MODERATE EQUATORWARD
OTHER FACTORS: DRY AIR MASS TO THE NORTHWEST

ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: LOW
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 07W (LAN) APPEARS TO HAVE MADE A TURN
WEST-NORTHWESTWARD DURING THE PAST SIX HOURS WHILE SLIGHTLY
ACCELERATING, INDICATING THAT THE SUBTROPICAL RIDGE TO THE
NORTHEAST IS BEGINNING TO BUILD WESTWARD. THIS RIDGE WILL CONTINUE
TO GUIDE THE TYPHOON AROUND ITS WESTERN PERIPHERY, WITH LAN TURNING
NORTHWESTWARD AND THEN NORTHWARD AS IT CROSSES HONSHU BETWEEN 72
AND 96 HOURS. A WEAK UPPER-LEVEL TROUGH OVER NORTHEASTERN CHINA IS
THEN EXPECTED TO TURN 07W NORTH-NORTHEASTWARD OVER THE SEA OF
JAPAN. THE JTWC TRACK FORECAST IS SIMILAR TO THE PREVIOUS FORECAST
AND SHOWS LAN PASSING ALONG THE WEST SIDE OF ISE BAY, JAPAN JUST
AFTER 72 HOURS. MODEL SPREAD HAS TIGHTENED AROUND THE LANDFALL POINT
SOMEWHAT SINCE THE PREVIOUS FORECAST, BUT THE ECMWF AND GFS
ENSEMBLE ENVELOPES REMAIN ABOUT 200 NM WIDE AT THE LANDFALL POINT.
THIS IS PRIMARILY DUE TO SOME UNCERTAINTY IN THE STRENGTH AND SHAPE
OF THE SUBTROPICAL RIDGE TO LAN'S NORTHEAST OVER THE NEXT FEW DAYS.
REGARDING THE INTENSITY FORECAST, LAN CONTINUES TO DEGRADE DUE TO
COLD UPWELLING, BUT IS NOW ACCELERATING SLIGHTLY AND WILL MOVE OVER
A WARMER EDDY DURING THE NEXT 24-48 HOURS. SOME STABILIZATION OR
RECOVERY OF THE TYPHOON IS THUS EXPECTED, AND THE JTWC FORECAST
SHOWS A CONSTANT INTENSITY OF 85 KT THROUGH 48 HOURS, THOUGH
SHORT-TERM FLUCTUATIONS MAY OCCUR. SLIGHT WEAKENING TO 75 KT BY 72
HOURS JUST BEFORE LANDFALL IN JAPAN IS FORECAST DUE TO THE ONSET OF
SOME MID-LEVEL VERTICAL SHEAR AS LAN GETS CLOSER TO A WEAK
UPPER-LEVEL TROUGH OVER THE YELLOW SEA, ALONG WITH COOLER JAPANESE
COASTAL WATERS. UPON CROSSING HONSHU, LAN WILL ENTER THE SEA OF
JAPAN IN ABOUT 96 HOURS, WHERE IT COULD REMAIN A TROPICAL STORM FOR
A TIME, AS WATERS THERE ARE WARM. HOWEVER, CONTINUED
NORTH-NORTHEASTWARD MOTION IS EXPECTED TO BRING LAN INTO A ZONE OF
ELEVATED WIND SHEAR ASSOCIATED WITH THE UPPER-LEVEL TROUGH OVER
NORTHEASTERN CHINA, AND THE ASSOCIATED BAROCLINIC INTERACTION
SHOULD INITIATE EXTRATROPICAL TRANSITION COINCIDENT WITH STEADY
WEAKENING BY 120 HOURS.

MODEL DISCUSSION: THE JTWC TRACK AND INTENSITY FORECASTS ARE BOTH
CLOSE TO THE MULTI-MODEL CONSENSUS. BOTH TRACK AND INTENSITY MODEL
SPREAD HAVE NARROWED SOMEWHAT SINCE THE PREVIOUS FORECAST.

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

[cycloneye]

WDPN31 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (LAN) WARNING NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 28.9N 141.4E
INITIAL INTENSITY: 85 KTS
GEOGRAPHIC REFERENCE: 394 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 05 KTS
SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A MEDIUM-SIZED
SYMMETRICAL CYCLONE THAT HAS MAINTAINED ITS OVERALL CONVECTIVE AND
WRAP STRUCTURE AND A LARGE 40-NM BANDING EYE. THE INITIAL POSITION
IS PLACED WITH HIGH CONFIDENCE BASED ON THE BANDING EYE THAT WAS
CONCENTRIC WITH THE MICROWAVE EYE FEATURE IN THE 120611Z SSMIS
IMAGE. THE INITIAL INTENSITY OF 85KTS IS BASED ON AN OVERALL
ASSESSMENT OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS
THE SUSTAINED 6-HR CONVECTIVE AND WRAP STRUCTURE. ANALYSIS
INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH LOW VWS AND
MODERATE OUTFLOW OFFSET BY LOCALIZED LOW SST AND OHC VALUES DUE TO
OCEANIC UPWELLING.

INITIAL WIND RADII BASIS: AMSR2 WINDSPEED DATA.

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO
THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T5.0 - 90 KTS
RJTD: T5.5 - 102 KTS
RCTP: T4.5 - 77 KTS
KNES: T4.5 - 77 KTS
CIMSS SATCON: 76 KTS AT 120056Z
CIMSS ADT: 82 KTS AT 120530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 5-10 KTS
SST: 28-29 CELSIUS
OUTFLOW: MODERATE EQUATORWARD
OTHER FACTORS: DRY AIR INTRUSION FROM THE NORTHWEST.

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON LAN WILL CONTINUE ON ITS CURRENT TRACK
TOWARD CENTRAL HONSHU, JAPAN. AFTER TAU 48, IT WILL TRACK MORE
NORTHWARD AS THE STR RECEDES IN RESPONSE TO A MID-LATITUDE TROUGH
APPROACHING FROM THE NORTHWEST, MAKE LANDFALL NEAR MINAMISE, CREST
THE STR AXIS AROUND TAU 72 AS IT PASSES JUST TO THE EAST OF KYOTO,
EXIT INTO THE SEA OF JAPAN (SOJ), THEN ACCELERATE NORTHEASTWARD ON
THE POLEWARD SIDE OF THE STR. THE MARGINAL ENVIRONMENT WILL SUSTAIN
THE CURRENT INTENSITY OF 85KTS UP TO TAU 48; AFTERWARD, LAND
INTERACTION AND INCREASING VWS WILL REDUCE IT TO 65KTS BY TAU 72.
DESPITE THE RELATIVELY WARM SST IN THE SOJ, INCREASING VWS, THEN
INTERACTION WITH THE BAROCLINIC ZONE AS TY 07W BEGINS
EXTRA-TROPICAL TRANSITION AROUND TAU 96 WILL GRADUALLY ERODE IT TO
A 40-KT COLD CORE LOW BY TAU 120.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY GOOD AGREEMENT WITH
A GRADUAL AND EVEN SPREAD TO JUST 138NM BY TAU 72, THEN TO 213NM BY
TAU 120, LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST UP TO
TAU 72 THEN MEDIUM CONFIDENCE AFTERWARD. THERE IS MEDIUM CONFIDENCE
IN THE JTWC INTENSITY FORECAST UP TO TAU 72 THEN LOW AFTERWARD DUE
TO VARIABILITY INHERENT WITH EXTRA-TROPICAL TRANSITION.

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

[Sciencerocks]

[cycloneye]

WDPN31 PGTW 121500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (LAN) WARNING NR 020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 29.1N 140.8E
INITIAL INTENSITY: 80 KTS
GEOGRAPHIC REFERENCE: 376 NM SOUTH OF YOKOSUKA, JAPAN
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 06 KTS
SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A
MEDIUM-SIZED SYMMETRICAL CYCLONE THAT HAS MOSTLY MAINTAINED ITS
OVERALL CONVECTIVE AND WRAP STRUCTURE, ALBEIT WITH AN ENLARGED 60-NM
BANDING EYE, EXPOSING A DEFINED LOW LEVEL CIRCULATION CENTER
(LLCC). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON
THE EXPOSED LLCC FEATURE. THE INITIAL INTENSITY OF 80KTS IS BASED ON
AN OVERALL ASSESSMENT OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND
REFLECTS THE SLIGHT 6-HR DETERIORATION. ANALYSIS INDICATES A
MARGINALLY FAVORABLE ENVIRONMENT WITH LOW VWS AND MODERATE OUTFLOW
OFFSET BY LOCALIZED LOW SST AND OHC VALUES DUE TO OCEANIC UPWELLING
AND DRY AIR INTRUSION.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO
THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T4.0 - 65 KTS
KNES: T4.5 - 77 KTS
CIMSS ADT: 82 KTS AT 121130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
VWS: 0-5 KTS
SST: 28-29 CELSIUS
OUTFLOW: MODERATE EQUATORWARD
OTHER FACTORS: DRY AIR INTRUSION WRAPPING IN FROM THE NORTHWEST.


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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON LAN WILL CONTINUE ON ITS CURRENT TRACK
TOWARD CENTRAL HONSHU, JAPAN. AFTER TAU 48, IT WILL TRACK MORE
NORTHWARD AS THE STR RECEDES IN RESPONSE TO A MID-LATITUDE TROUGH
APPROACHING FROM THE NORTHWEST, MAKE LANDFALL NEAR MINAMISE AROUND
TAU 60, CREST THE STR AXIS BY TAU 72, EXIT INTO THE SEA OF JAPAN
(SOJ), THEN ACCELERATE NORTHEASTWARD ON THE POLEWARD SIDE OF THE STR.
THE MARGINAL ENVIRONMENT WILL SUSTAIN THE CURRENT INTENSITY OF 80KTS
UP TO TAU 24; AFTERWARD, INCREASING VWS, DRY AIR INTRUSION, THEN LAND
INTERACTION WILL REDUCE IT TO 50KTS BY TAU 72. DESPITE THE RELATIVELY
WARM SST IN THE SOJ, INCREASING VWS, THEN INTERACTION WITH THE
BAROCLINIC ZONE AS TY 07W BEGINS EXTRA-TROPICAL TRANSITION AROUND TAU
96 WILL GRADUALLY ERODE IT TO A 40-KT COLD CORE LOW BY TAU 120.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY GOOD AGREEMENT WITH
A GRADUAL AND EVEN SPREAD TO JUST 176NM BY TAU 72, LENDING HIGH
CONFIDENCE TO THIS PORTION OF THE JTWC TRACK FORECAST. AFTERWARD,
THE MODELS SPREAD OUT TO 320NM ACROSS AND NOTICEABLE ALONG TRACK
DIFFERENCES BY TAU 120, LENDING MEDIUM CONFIDENCE TO THE EXTENDED
PORTION OF THE TRACK FORECAST. THERE IS MEDIUM CONFIDENCE IN THE
JTWC INTENSITY FORECAST UP TO TAU 72 THEN LOW AFTERWARD DUE TO
VARIABILITY INHERENT WITH EXTRA-TROPICAL TRANSITION.


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

[cycloneye]

Tropical Depression Seven-E Discussion Number 1
NWS National Hurricane Center Miami FL EP072023
300 PM MDT Sat Aug 12 2023

Satellite images indicate that the area of low pressure located
several hundred miles south-southwest of the southern tip of the
Baja California peninsula has attained sufficient organization to be
classified as a tropical depression. The last couple of microwave
satellite overpasses show a similar scenario, with cold
convective curved bands becoming better organized around a low-level
center, which appears to be located near the northern edge of the
convective cloud mass based on recent visible satellite images. The
latest TAFB subjective Dvorak estimate is T-2.0. Based on these
data, Invest 98E is upgraded to Tropical Depression Seven-E with an
initial intensity of 30 kt.

Weak mid-level ridging well to the north of the depression will
steer the cyclone toward the west-northwest at about 10 kt over the
next few days. Beyond 72 h, the ridge should strengthen enough to
cause a turn to the west with a slight increase in forward speed.
The NHC forecast track is in best agreement with the HCCA and TVCE
consensus models.

Environmental conditions are quite favorable for strengthening over
the next 48-60 h, with warm ocean temperatures, low vertical
wind shear and a relatively moist low to mid-level troposphere. The
NHC forecast peaks the system at 75 kt in 48-60 h, which is near
the middle of the intensity guidance. The ECMWF version of the
SHIPS RI index shows a 52 percent chance of a 65 kt increase in
winds over the next 72 h, so there is a chance the cyclone could
strengthen more than forecast. After that time, the cyclone is
forecast to move into a much drier environment along with slowly
decreasing sea-surface temperatures. There is high confidence on
significant weakening beyond 72 h due to the very dry airmass that
the cyclone will be moving into.

FORECAST POSITIONS AND MAX WINDS

INIT 12/2100Z 14.9N 113.2W 30 KT 35 MPH
12H 13/0600Z 15.2N 114.2W 40 KT 45 MPH
24H 13/1800Z 15.5N 115.9W 50 KT 60 MPH
36H 14/0600Z 15.7N 117.6W 60 KT 70 MPH
48H 14/1800Z 16.1N 119.2W 75 KT 85 MPH
60H 15/0600Z 16.6N 120.8W 75 KT 85 MPH
72H 15/1800Z 17.1N 122.8W 70 KT 80 MPH
96H 16/1800Z 17.6N 127.7W 50 KT 60 MPH
120H 17/1800Z 17.8N 133.1W 35 KT 40 MPH

$$
Forecaster Hagen/Berg

[Sciencerocks]