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JTWC/01W/#17/01-18 18Z Prognostic Reasoning
WDPN31 PGTW 182100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (NOKAEN) WARNING
NR 017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 16.1N 125.7E
INITIAL INTENSITY: 30 KTS
GEOGRAPHIC REFERENCE: 286 NM EAST-NORTHEAST OF MANILA,
PHILIPPINES
MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 07 KTS
SIGNIFICANT WAVE HEIGHT: 12 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A MAINLY
OBSCURED LOW-LEVEL CIRCULATION CENTER ASSOCIATED WITH TROPICAL
DEPRESSION (TD) 01W (NOKAEN). THE SYSTEM HAS BEEN STRUGGLING TO
MAINTAIN ITS STRUCTURE DUE TO SIGNIFICANT AMOUNT OF DRY AIR
SURROUNDING IT, AS WELL AS LOW TO MODERATE (15-20 KTS) VERTICAL
WIND SHEAR (VWS). OVER THE LAST FEW HOURS SOME CENTRAL CONVECTION
HAS DEVELOPED, ALONG WITH A PERIPHERAL DEEP CONVECTION PRIMARILY
THROUGHOUT THE NORTHERN SEMICIRCLE. THIS WAS ELEVATED BY A ROBUST
POLEWARD OUTFLOW CHANNEL. OTHER ENVIRONMENTAL PARAMETER RESULTING
IN MARGINALLY FAVORABLE OVERALL CONDITIONS IS WARM (26-27 C) SEA
SURFACE TEMPERATURE (SST). THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON LOW-LEVEL CLOUD TRACING CONSISTENT WITH
THE EXTRAPOLATION FROM A 181557Z OCEANSAT-3 IMAGE DEPICTING AN
IDENTIFIABLE AREA OF CALMER WINDS. THE INITIAL INTENSITY OF 30 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE RECENTLY DEVELOPING
CENTRAL CONVECTION IN CONJUNCTION WITH THE SUBJECTIVE DVORAK AND
OBJECTIVE ESTIMATES LISTED BELOW.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) CENTERED TO THE
EAST
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T1.5 - 25 KTS
RJTD: T2.0 - 30 KTS
RCTP: T1.5 - 25 KTS
KNES: T2.0 - 30 KTS
CIMSS ADT: 33 KTS AT 181730Z
CIMSS AIDT: 31 KTS AT 181900Z
CIMSS D-MINT: 22 KTS AT 181701Z
CIMSS D-PRINT: 25 KTS AT 181830Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 10-15 KTS
SST: 26-27 CELSIUS
OUTFLOW: STRONG POLEWARD
ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: NOT APPLICABLE
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TD 01W IS PROJECTED TO TRANSIT THE
NORTHWESTERN PERIPHERY OF THE EASTERN STR THROUGH TAU 36. A
SYNOPTIC PATTERN EVOLUTION IS ANTICIPATED SUBSEQUENT TO THAT TIME,
CHARACTERIZED BY THE EASTWARD RETREAT AND ATTENUATION OF THIS
STEERING RIDGE, OCCURRING IN CONCERT WITH THE ZONAL EXPANSION OF A
SEPARATE STR DEVELOPING TO THE WEST OF THE SYSTEM. THIS FUNDAMENTAL
SHIFT IN THE DEEP-LAYER STEERING REGIME IS EXPECTED TO INDUCE AN
EQUATORWARD DEFLECTION IN THE TRAJECTORY OF TD 01W AFTER TAU 36,
FORCING IT ONTO THE EASTERN FLANK OF THE NOW-ASCENDANT WESTERN STR.
ON THE INTENSITY FORECAST, SLIGHT DECREASE IN VWS COMBINED WITH
GOOD POLEWARD OUTFLOW WILL RESULT IN MINOR INTENSIFICATION TO 40
KTS BETWEEN TAUS 36 AND 48. SHORTLY AFTER, THE PRESENCE OF A
DEEP-LAYER, DRY AIR MASS SURROUNDING THE VORTEX, COMBINED WITH
DRAMATICALLY INCREASING VWS AND PERSISTENT NORTHEASTERLY SURGE
EVENT IMMEDIATELY TO THE NORTHWEST WILL RESULT IN STEADY WEAKENING,
WITH FULL DISSIPATION EXPECTED AROUND OR SOON AFTER TAU 72.
MODEL DISCUSSION: THE NUMERICAL MODEL INTENSITY GUIDANCE SUITE
DEMONSTRATES A FAIR DEGREE OF AGREEMENT THROUGHOUT THE FORECAST
PERIOD, WITH ALL AVAILABLE GUIDANCE INICATING INITIAL INTENSIFICATION
TO 35-40 KTS, FOLLOWED BY STEADY WEAKENING AFTERWARDS. THE INTENSITY
SPREAD DURING THE LATTER STAGE IS APPROXIMATELY 20 KTS, RESULTING IN
SOME UNCERTAINTY ASSOCIATED WITH THE TIMELINE OF THE DISSIPATION. AS A
RESULT, INTENSITY FORECAST IS ASSESSED WITH MEDIUM CONFIDENCE. IN
REGARD TO THE TRACK, THE INITIAL 24-HOUR CROSS-TRACK SPREAD IS 38 NM
INDICATING GOOD AGREEMENT. HOWEVER SHORTLY AFTER, MODEL GUIDANCE
ENVELOPE OPENS UP SIGNIFICANTLY, REACHING 300 NM AT TAU 72, RESULTING
IN LOW LONG-TERM TRACK CONFIDENCE. THE FASTEST AND TIGHTEST TURN IS
PROJECTED BY NAVGEM, WHILE ECMWF MODELS ARE THE SLOWEST AND WIDEST IN
REGARD TO THE TURN ANGLE. JTWC OFFICIAL TRACK FORECAST IS LAID IN
RELATIVELY CLOSE PROXIMITY TO THE MULTI-MODEL CONSENSUS, SLIGHTLY ON
THE OUTSIDE OF THE PROJECTED TURN.
FORECAST CONFIDENCE:
TRACK 00-72 HR: MEDIUM
TRACK 72-120 HR: LOW
INTENSITY 00-72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
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楼主: 红豆棒冰冰
发表于 2026-1-19 04:10
发表于 2026-1-19 05:30
