WESTERN PACIFIC: TY 12W(DOLPHIN) CAT 1 US landfall south of TAIZHOU/CHINA/TS 14W(CHAN-HOM)/TS 13W(PEILOU)/TCFA for Invest 98W//09@1030 UTC

JTWC PH
JTWC FACEBOOK
Joint Typhoon Warning Center
National Hurricane Center

WDPN31 PGTW 090900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 054//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.1N 121.9E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 181 NM NORTH OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPANSIVE
SYSTEM WITH OUTER RAINBANDS EXTENDING FROM TAIWAN TO SHANGHAI AND A
VERY COMPACT, CLOUD-FILLED EYE EMBEDDED WITHIN A MUCH SMALLER INNER
CORE OF DEEP CONVECTION. ANIMATED RADAR DATA SHOWS THE EYE BECOMING
MORE RAGGED AND LESS-DEFINED AS IT APPROACHES THE COAST OF ZHEJIANG
PROVINCE, CHINA BUT THE WESTERN EYEWALL IN PARTICULAR IS
WELL-DEFINED AND NOW BRUSHING THE COAST NEAR SHITANGZHEN, CHINA.
SURFACE OBSERVATIONS FROM DACHEN DAO TO THE NORTH REPORTED
EAST-NORTHEAST WINDS OF 45 KNOTS AND AN MSLP READING OF 965 MB AT
0600Z. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED
ON THE RADAR DATA AND THE EYE FEATURE IN THE MSI. THE INITIAL
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE. SUBJECTIVE DVORAK
CURRENT INTENSITY ESTIMATES CONTINUE TO VASTLY OUTPERFORM THE
MAJORITY OF THE OBJECTIVE INTENSITY ESTIMATES (EXCEPT THE SATCON),
WHICH ARE STRUGGLING WITH THE COMPLEX STRUCTURE OF THE SYSTEM. THE
ENVIRONMENT REMAINS FAVORABLE, BUT THE IMMINENT LANDFALL MEANS THE
SYSTEM WILL NOT HAVE TIME TO TAKE ADVANTAGE OF THE FAVORABLE
CONDITIONS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF AN EXTENSION OF
THE SUBTROPICAL RIDGE (STR) CENTERED OVER SOUTHERN JAPAN AND
EXTENDING NORTHWEST TO THE SHANDONG PENINSULA. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 80 KTS AT 090600Z
   CIMSS ADT: 51 KTS AT 090600Z
   CIMSS AIDT: 66 KTS AT 090600Z
   CIMSS D-MINT: 60 KTS AT 090427Z
   CIMSS D-PRINT: 63 KTS AT 090530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: PROXIMITY TO LAND. 

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 (TY) 12W WILL MAKE LANDFALL ALONG THE
SOUTHEASTERN CHINESE COAST, SOUTH OF THE CITY OF TAIZHOU WITHIN THE
NEXT FEW HOURS. THE WESTERN EYEWALL IS ALREADY BRUSHING THE
COASTLINE AND THE LATEST RADAR ANIMATIONS SUGGEST THE SYSTEM MAY
ATTEMPT ONE MORE TROCHOIDAL WOBBLE SOUTHWESTWARD BEFORE CROSSING
THE COAST. OVERALL, THE SYSTEM WILL TRACK WESTWARD ALONG THE SOUTHERN
FLANK OF THE STR BUILDING TO THE NORTH FOR THE NEXT 12 HOURS, THEN
TURN NORTHWESTWARD AS THE RIDGE RECEDES SLIGHTLY EASTWARD. NO
CHANGE IN INTENSITY IS EXPECTED IN THE SHORT TIME PRIOR TO
LANDFALL. AFTER LANDFALL, THE SYSTEM WILL RAPIDLY WEAKEN AND
DISSIPATE OVER EAST-CENTRAL CHINA WITHIN 48 HOURS. 

MODEL DISCUSSION: TRACK GUIDANCE IS IN STRONG AGREEMENT, WITH
MINIMAL CROSS-TRACK SPREAD THROUGH THE FORECAST PERIOD, LENDING
HIGH CONFIDENCE TO THE JTWC FORECAST TRACK, WHICH IS PLACED NEAR
THE AI CONSENSUS MEAN THROUGH THE FORECAST PERIOD. INTENSITY
GUIDANCE IS ALSO IN STRONG AGREEMENT DEPICTING RAPID WEAKENING
THROUGH THE FORECAST PERIOD, LENDING HIGH CONFIDENCE TO THE JTWC
INTENSITY FORECAST. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
NNNN

 

TPPN11 PGTW 090855

A. TYPHOON 12W (DOLPHIN)

B. 09/0830Z

C. 28.08N

D. 121.41E

E. THREE/GK2A

F. T4.0/4.5/S0.0/24HRS  STT: W0.5/03HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 15A/PBO TIGHTLY CURVED BNDG/ANMTN. EYE WITH A BAND
WIDTH OF 45NM YIELDS AN E# OF 4.0. SUBTRACTED 0.5 FOR A RAGGED EYE
AND ADDED 0.5 FOR BF TO YIELD A DT OF 4.0. MET AND PT AGREE. DBO
DT. INTENSITY ESTIMATE MAY NOT BE REPRESENTATIVE DUE TO PROXIMITY
TO LAND.

I. ADDITIONAL POSITIONS: NONE


   BALMER

Platform: RCM-2
Acquisition Date: 2026-08-08 21:37:05 UTC
Storm Name: WP122026 / DOLPHIN
Storm ID: WP12
Storm Center Longitude: 123.640
Storm Center Latitude: 27.510
Incidence Angle (Degrees): 52.208
Quadrant 1 NE VMax (kts): 76.02
Quadrant 2 SE VMax (kts): 77.46
Quadrant 3 SW VMax (kts): N/A
Quadrant 4 NW VMax (kts): N/A
RMax (nmi): 11.00 - 80.00

 

WDPN33 PGTW 090900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (CHAN-HOM) WARNING 
NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 32.3N 150.7E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 668 NM SOUTHEAST OF MISAWA, JAPAN
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY 
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC), DEVOID OF SIGNIFICANT 
DEEP CONVECTION. TRACK MOTION HAS BECOME INCREASINGLY ERRATIC OVER 
THE PAST SIX HOURS DUE TO THE SYSTEM BEING CURRENTLY POSITIONED IN A 
WEAK AND COMPETING STEERING PATTERN DEFINED BY STRONG SUBTROPICAL 
RIDGING TO THE NORTHEAST AND SOUTHWEST, AND A COL WEAKNESS IN THE 
RIDGE TO THE NORTHWEST OVER HOKKAIDO. OVER THE LAST 1-2 HOURS, THE 
LLCC HAS BEGUN A COUNTERCLOCKWISE LOOP WHILE REMAINING QUASI-
STATIONARY. ANIMATED WATER VAPOR IMAGERY, ATMOSPHERIC MOTION VECTORS 
(AMV), AND MODEL ANALYSIS FIELDS DEPICT A COMPLEX UPPER-LEVEL LOW 
(ULL) CENTERED JUST NORTH OF THE LLCC WITH A TROUGH EXTENDING TO THE 
SOUTHEAST. THE PROXIMITY OF THE ULL TO THE NORTH CREATES AN 
UNFAVORABLE ENVIRONMENT FOR TS 14W, INDUCING CONVERGENT NORTHWESTERLY 
SUBSIDENT FLOW AND SIGNIFICANT DRY AIR ENTRAINMENT OVER THE CORE. 
PHASE CLASSIFICATION WORKSHEETS INDICATE THE SYSTEM IS A HYBRID OR 
BORDERLINE SUBTROPICAL CYCLONE AT THIS TIME, EXHIBITING 
CHARACTERISTICS OF BOTH A TROPICAL AND SUBTROPICAL CYCLONE. UPSTREAM, 
JUST EAST OF JAPAN, WATER VAPOR IMAGERY DEPICTS A LARGE UPPER-LEVEL 
DEFORMATION ZONE AND A DEEP TROUGH MOVING RAPIDLY INTO THE NORTHERN 
SEA OF JAPAN (SOJ), BOTH OF WHICH WILL HAVE A SIGNIFICANT IMPACT ON 
THE FUTURE EVOLUTION OF TS 14W. THE INITIAL POSITION IS ASSESSED WITH 
HIGH CONFIDENCE BASED ON THE EXPOSED LLCC IN THE MSI. THE INITIAL 
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, BASED PRIMARILY ON THE 
CIMSS SATCON ESTIMATE AND PERSISTENCE WITH EARLIER SCATTEROMETER 
DATA. THE ENVIRONMENT IS MARGINALLY UNFAVORABLE WITH UNFAVORABLE 
UPPER-LEVEL CONDITIONS OFFSETTING OTHERWISE FAVORABLE PARAMETERS 
(WARM SEA SURFACE TEMPERATURES AND LOW VERTICAL WIND SHEAR).

INITIAL WIND RADII BASIS: PERSISTENCE. 

CURRENT STEERING MECHANISM: COMPETING AND WEAK STEERING PATTERN,
INCREASINGLY DOMINATED BY THE LOW- TO MID-LEVEL SUBTROPICAL RIDGE
(STR) CENTERED SOUTHWEST OF THE WESTERN ALEUTIANS. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   CIMSS SATCON: 40 KTS AT 090440Z
   CIMSS ADT: 25 KTS AT 090600Z
   CIMSS AIDT: 27 KTS AT 090600Z
   CIMSS D-MINT: 33 KTS AT 090603Z
   CIMSS D-PRINT: 31 KTS AT 090640Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: WEAK EASTWARD

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: GLOBAL MODELS AGREE THAT TS 14W WILL REMAIN
TRAPPED IN A COMPETING STEERING PATTERN FOR ANOTHER FEW HOURS AND 
REMAIN QUASI-STATIONARY. BY TAU 12, HOWEVER, ALL MAJOR GLOBAL MODELS
DEPICT A RAPID CHANGE IN THE UPPER-LEVEL PATTERN, WITH THE STR TO
THE NORTHEAST BUILDING QUICKLY AND EXTENDING NORTHWESTWARD,
SUPPLANTING THE RIDGE WEAKNESS CURRENTLY POSITIONED OVER HOKKAIDO. 
ONCE THIS OCCURS, TS 14W WILL EJECT FROM ITS QUASI-STATIONARY 
POSITION AND ACCELERATE NORTHWESTWARD. BY TAU 36, RIDGING OVER KOREA 
IS FORECAST TO RAPIDLY BUILD AND EXTEND NORTHEASTWARD, ULTIMATELY 
BRIDGING WITH THE RIDGE SOUTHEAST OF KAMCHATKA. THIS WILL DRIVE TS 
14W WESTWARD AFTER TAU 48. LANDFALL ON THE EASTERN COAST OF HONSHU IS 
EXPECTED SHORTLY AFTER TAU 48, AS THE SYSTEM TRACKS QUICKLY WESTWARD 
ALONG THE SOUTHERN FLANK OF THE MID-LEVEL STR TO THE NORTH. THE 
SYSTEM EMERGES INTO THE SOJ BY TAU 60, BUT BEGINS TO DECELERATE AFTER 
TAU 72 AS IT SHALLOWS AND MOVES INTO A WEAKER STEERING PATTERN. IN 
TERMS OF INTENSITY, THE KEY FACTOR WILL BE THE PROXIMITY AND 
ORIENTATION TO A SERIES OF UPPER-LEVEL LOWS (ULL). THE CURRENT ULL IS 
POSITIONED IN AN UNFAVORABLE SUBSIDENT QUADRANT NORTH OF TS 14W. OVER 
THE NEXT 18-24 HOURS, THE ULL IS EXPECTED TO FILL AND MOVE SLIGHTLY 
NORTHWARD, WHICH WILL INHIBIT SIGNIFICANT INTENSIFICATION. AROUND TAU 
24, THE DEEP TROUGH CURRENTLY CUTTING ACROSS THE NORTHERN SOJ WILL 
CUT OFF INTO AN ISOLATED ULL, WHICH WILL DIVE SOUTHWARD ALONG THE 
EASTERN COAST OF HONSHU TO A POSITION WEST OF TS 14W. THIS WILL OPEN 
UP A ROBUST POLEWARD OUTFLOW CHANNEL COINCIDENT WITH TS 14W CROSSING 
THE AXIS OF THE WARM KUROSHIO CURRENT. THESE TWO FACTORS COMBINE TO 
ALLOW FOR A PERIOD OF MARKED INTENSIFICATION, UP TO A PEAK OF 50-55 
KNOTS BY TAU 36. HOWEVER, BY TAU 48, THE ULL WILL TRANSLATE SOUTH OF 
TS 14W, WHILE THE SYSTEM MOVES OVER THE COOLER WATERS OF THE OYASHIO 
CURRENT ALONG THE COAST. THESE NEGATIVE INFLUENCES WILL LEAD TO A 
GENERAL WEAKENING TREND AS THE SYSTEM APPROACHES LANDFALL. THE SYSTEM 
WILL RAPIDLY WEAKEN OVER LAND BEFORE EMERGING INTO THE SOJ AS A 
MINIMAL TROPICAL STORM, WHICH WILL BE IN THE EARLY PHASES OF 
SUBTROPICAL TRANSITION (STT). THE SYSTEM WILL COMPLETE STT BY TAU 72 
WHILE SIMULTANEOUSLY WEAKENING DUE TO INCREASED VWS AND DRY AIR 
ENTRAINMENT THROUGH THE REMAINDER OF THE FORECAST PERIOD. 

MODEL DISCUSSION: TRACK GUIDANCE IS IN FAIRLY GOOD AGREEMENT
THROUGH THE FORECAST PERIOD. ALL CONSENSUS MEMBERS DEPICT A SLOW,
QUASI-STATIONARY MOTION FOR THE FIRST FEW HOURS, FOLLOWED BY A
SHARP TURN NORTHWESTWARD BEFORE TAU 12, THEN A WESTWARD TURN BY TAU
48. THE JGSM AND GFS DETERMINISTIC TRACKERS ARE POSITIONED ON THE
NORTHERN EDGE OF THE GUIDANCE ENVELOPE, WHILE THE ECMWF AND
EXPERIMENTAL GOOGLE DEEPMIND ARE POSITIONED ON THE SOUTHERN EDGE.
CROSS-TRACK SPREAD INCREASES TO 100NM AT TAU 48, AND GRADUALLY
INCREASES TO 150NM AT TAU 96. ENSEMBLE GUIDANCE IS CONTINUING TO
TREND TOWARDS INCREASING UNCERTAINTY AND MEMBER DISPERSION. THE
ENSEMBLE MEMBER ENVELOPE OF THE EXPERIMENTAL JTWC SUPER ENSEMBLE
NOW STRETCHES FROM YOKOSUKA TO MISAWA AT LANDFALL, INCREASING TO A
RANGE FROM SASEBO TO THE DPRK-ROK BORDER BY THE END OF THE FORECAST
PERIOD. THE JTWC FORECAST IS POSITIONED CLOSE TO THE AI CONSENSUS
MEAN, WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD
AGREEMENT, WITH ALL CONSENSUS MEMBERS CONFINED TO A TIGHT ENVELOPE
WHICH PEAKS BETWEEN 45-50 KNOTS AT TAU 36 FOLLOWED BY SHARP
WEAKENING THROUGH THE REMAINDER OF THE FORECAST. THE JTWC FORECAST
IS PLACED NEAR THE CONSENSUS MEAN WITH MEDIUM CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
NNNN

 

 

WDPN32 PGTW 090900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W (PEILOU) WARNING NR 
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.2N 142.7E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 229 NM SOUTH-SOUTHEAST OF IWO TO
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM (TS) 13W (PEILOU) AS A WELL-DEFINED, ALBEIT SHEARED,
PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC), WITH THE
DEEP CONVECTION CONFINED TO THE SOUTHEASTERN SEMICIRCLE. THE
090602Z SSMIS 91GHZ IMAGE REVEALS THE SYSTEM IS VERY COMPACT, WITH
DEFINED LOW-LEVEL CLOUD BANDING AND A DISCONTINUOUS AND DISORGANIZED 
BAND OF DEEP CONVECTION EXTENDING FROM THE EASTERN QUADRANT AND 
WRAPPING TO THE SOUTH. ENVIRONMENTAL ANALYSIS REVEALS A MARGINALLY 
FAVORABLE ENVIRONMENT, CHARACTERIZED BY LOW TO MODERATE (15-20 KTS) 
VERTICAL WIND SHEAR (VWS). WARM (29-30 C) SEA SURFACE TEMPERATURES 
(SST) AND STRONG EQUATORWARD OUTFLOW, OFFSET BY A RELATIVELY DRY 
ENVIRONMENT ALONG THE NORTHERN PERIPHERY OF THE SYSTEM. THE INITIAL 
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PARTIALLY EXPOSED 
LLCC IN ANIMATED MSI, SUPPLEMENTED BY THE 090602Z SSMIS MICROWAVE 
DATA. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH HIGH CONFIDENCE 
BASED ON THE 090044Z ASCAT DATA, CIMSS AUTOMATED INTENSITY ESTIMATES, 
AND THE AGENCY DVORAK FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: ESTABLISHED WIND RADII USING THE 090044Z
SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: THE NORTHERN PERIPHERY OF AN ELONGATED
NEAR-EQUATORIAL RIDGE (NER) AND A BELT OF STRONG LOW-LEVEL
WESTERLIES TO THE SOUTH OF THE SYSTEM.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS SATCON: 42 KTS AT 090640Z
   CIMSS ADT: 31 KTS AT 090710Z
   CIMSS AIDT: 30 KTS AT 090640Z
   CIMSS D-MINT: 33 KTS AT 090602Z
   CIMSS D-PRINT: 35 KTS AT 090640Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG EASTWARD

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: TS 13W IS FORECAST TO CONTINUE TRACKING
EAST-SOUTHEASTWARD FOR THE NEXT 12 HOURS, WHILE IT REMAINS ON THE
NORTHERN PERIPHERY OF THE STEERING NER. BY AROUND TAU 12, 13W WILL
CURVE NORTHEASTWARD AS IT GETS TRAPPED BY THE ENHANCED
WEST-NORTHWESTERLY GRADIENT FLOW ASSOCIATED WITH TS 14W (CHAN-HOM),
WHICH WILL ALSO CAUSE AN ACCELERATION IN FORWARD MOTION.
SIMULTANEOUSLY, 13W WILL BE PROPELLED INTO THE STEERING INFLUENCE
OF A BUILDING SUBTROPICAL RIDGE CURRENTLY CENTERED TO ITS
NORTHEAST, WHICH WILL REINFORCE THE NORTHEASTWARD TRACK THROUGH TAU
72. REGARDING INTENSITY, PEILOU IS FORECAST TO STEADILY INTENSIFY
THROUGH TAU 36, AS THE SYSTEM IS ABLE TO FEND OFF DRY AIR
ENTRAINMENT AND MAINTAIN A GOOD EASTWARD OUTFLOW CHANNEL DUE TO AN
UPPER-LEVEL TROUGH POSITIONED TO THE NORTH. AFTER ABOUT TAU 36, THE
UPPER-LEVEL TROUGH IS EXPECTED TO PASS OVER THE SYSTEM, INDUCING
HIGHER SHEAR AND DRY AIR. PEILOU IS FORECAST TO QUICKLY WEAKEN IN
THE INCREASINGLY UNFAVORABLE ENVIRONMENT AND DISSIPATE BY TAU 72.
HOWEVER, SINCE 13W IS A COMPACT AND SHALLOW SYSTEM, IT IS MORE
SUSCEPTIBLE TO ENVIRONMENTAL CHANGES. THEREFORE, IT MAY DISSIPATE
SOONER THAN ANTICIPATED IF THE UPPER-LEVEL TROUGH EXTENDS FURTHER
EQUATORWARD THAN CURRENTLY ANTICIPATED. ALTERNATIVELY, PEILOU MAY
SUSTAIN TROPICAL DEPRESSION INTENSITY BEYOND 72 HOURS IF THE
ENVIRONMENT REMAINS MARGINALLY FAVORABLE PAST TAU 36.

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN MODERATE
AGREEMENT THROUGH TAU 72, WITH MINIMAL ALONG-TRACK SPREAD BUT A
CROSS-TRACK SPREAD OF 22NM AT TAU 72. NAVGEM IS THE NOTABLE
OUTLIER, AND DEPICTS A SIGNIFICANT DEVIATION FROM THE REST OF MODEL
GUIDANCE. DISCOUNTING NAVGEM, THE JTWC TRACK FORECAST IS PLACED
WITH MEDIUM CONFIDENCE. RELIABLE INTENSITY GUIDANCE IS IN GOOD
AGREEMENT FOR THE DURATION OF THE FORECAST PERIOD, WITH ALL
RELIABLE MODELS DEPICTING A PEAK BETWEEN 40-50 KTS AT AROUND TAU
24-36. THE JTWC INTENSITY FORECAST IS IN LINE WITH THE HAFS-A, HWRF,
GFS, AND COAMPS-TC SOLUTIONS, AND THE MULTI-MODEL CONSENSUS, AND
IS ASSESSED WITH MEDIUM CONFIDENCE. UNCERTAINTY IN THE INTENSITY
FORECAST STEMS FROM THE PLACEMENT OF THE UPPER-LEVEL TROUGH NEAR
THE END OF THE FORECAST.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM//
NNNN

 

WTPN21 PGTW 090600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 98W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 22.4N 156.2E TO 25.6N 159.9E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 17 TO 22 KNOTS. METSAT
IMAGERY AT 080900Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 22.5N 156.4E. THE SYSTEM IS MOVING NORTHEASTWARD AT 18
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 98W) PREVIOUSLY LOCATED 
NEAR 19.6N 150.5E IS NOW LOCATED NEAR 22.5N 156.4E, APPROXIMATELY 608 
NM WEST-NORTHWEST OF WAKE ISLAND. ANIMATED MULTISPECTRAL IMAGERY (MSI) 
DEPICTS A DEVELOPED LOW-LEVEL CIRCULATION CENTER (LLCC), OBSCURED BY 
UPPER-LEVEL CONVECTION EMBEDDED WITHIN A LONGWAVE TROUGH. A PARTIAL 
082301Z ASCAT-C PASS REVEALED AN ELONGATED AND RELATIVELY WEAK 
CIRCULATION EMBEDDED WITHIN A BAND OF STRONG SOUTHWESTERLY MONSOONAL 
FLOW ON THE EASTERN FLANK OF A LARGE CYCLONIC GYRE. MAXIMUM WINDS IN 
THE ASCAT IMAGERY ARE 20-25 KNOTS IN THE EASTERN HEMISPHERE OF THE 
CIRCULATION. ENVIRONMENTAL ANALYSIS SHOWS FAVORABLE CONDITIONS FOR 
DEVELOPMENT WITH LOW VERTICAL WIND SHEAR (10 TO 15KTS), WARM SEA 
SURFACE TEMPERATURES (29 TO 30 C), AND GOOD POLEWARD OUTFLOW. 
DETERMINISTIC MODELS BRIEFLY DEVELOP 98W INTO A WEAK TROPICAL 
DEPRESSION THAT GENERALLY TRACKS NORTH-NORTHEASTWARD ALONG THE 
EASTERN PERIPHERY OF THE CYCLONIC GYRE PATTERN. FOR ENSEMBLE MODELS, 
ECENS INDICATES A HIGHER INTENSITY OF 98W AS OPPOSED TO GEFS 
MAINTAINING A LOWER CONFIDENCE AND INTENSITY. BOTH HOWEVER, AGREE 
UPON THE NORTH-NORTHEAST TRACK OF 98W OVER THE NEXT 24 HOURS.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 17 TO 22 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 
100600Z.//
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