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JTWC/05W/#04/07-04 18Z Prognostic Reasoning
WDPN32 PGTW 042100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (FIVE) WARNING NR
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 20.1N 117.4E
INITIAL INTENSITY: 40 KTS
GEOGRAPHIC REFERENCE: 222 NM SOUTHEAST OF HONG KONG
MOVEMENT PAST 6 HOURS: WESTWARD AT 04 KTS
SIGNIFICANT WAVE HEIGHT: 14 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM (TS) 05W WITH WIDESPREAD BUILDING CONVECTION OVER THE CENTER
AND SOUTHERN PERIPHERY OF A PARTIALLY EXPOSED LOW-LEVEL CIRCULATION
CENTER (LLCC). THE LOW-LEVEL STRUCTURE APPEARS TO BE FURTHER
CONSOLIDATING COMPARED TO 6 HOURS AGO, BUT NORTHERLY SHEAR IS
PREVENTING THE SYSTEM FROM BECOMING MORE VERTICALLY STACKED.
ENVIRONMENTAL ANALYSIS INDICATES THAT 05W IS IN A FAVORABLE
ENVIRONMENT CHARACTERIZED BY STRONG EQUATORWARD OUTFLOW ALOFT, LOW
(10-15 KTS) NORTHERLY VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA
SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON THE PARTIALLY EXPOSED LLCC IN ANIMATED EIR
IMAGERY. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON THE HIGH END OF AGENCY DVORAK AND OBJECTIVE
INTENSITY ESTIMATES LISTED BELOW.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT WITH A
SUBTROPICAL RIDGE POSITIONED TO THE NORTH AND A NEAR-EQUATORIAL
RIDGE BUILDING TO THE SOUTHEAST.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.5 - 35 KTS
RJTD: T2.0 - 30 KTS
KNES: T2.5 - 35 KTS
CIMSS SATCON: 37 KTS AT 041713Z
CIMSS ADT: 37 KTS AT 041800Z
CIMSS AIDT: 37 KTS AT 041800Z
CIMSS DPRINT: 30 KTS AT 041800Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 10-15 KTS
SST: 29-30 CELSIUS
OUTFLOW: STRONG EQUATORWARD
ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
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: TS 05W IS FORECAST TO BEGIN TRACKING SLOWLY
NORTHWARD THROUGH TAU 24 AS THE SUBTROPICAL RIDGE TO THE SOUTHEAST
CONTINUES TO BUILD. ACTUAL TRACK MOTION IS UNCERTAIN THROUGH TAU 24
THOUGH, AS THE STEERING PATTERN REMAINS COMPETING. AFTER TAU 24,
THE STEERING PATTERN WILL BE MORE DEFINED AND THE SYSTEM WILL PICK
UP SPEED IN THE NORTH-NORTHEASTWARD DIRECTION, ALONG THE
NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE. THIS TRAJECTORY
WILL CONTINUE THROUGH TAU 72, WHEN RIDGING TO THE NORTH WILL STOP
THE VORTEX AND DRIVE IT WESTWARD INTO MAINLAND CHINA. IN TERMS OF
INTENSITY, 05W IS FORECAST TO QUICKLY INTENSIFY OVER THE NEXT 24
HOURS AS THE NORTHERLY SHEAR BEGINS TO BACK OFF. A PEAK INTENSITY
OF 75 KTS IS FORECAST TO OCCUR AROUND TAU 36-48. NEAR TAU 72, 05W
WILL BEGIN INCHING TOWARD THE COAST OF CHINA AND LAND INTERACTION
WILL BEGIN TO WEAK THE SYSTEM. ADDITIONALLY, DRY AIR WILL LIKELY
ADVECT OFF THE MOUNTAINS AND INTO THE VORTEX. AFTER TAU 72,
SIGNIFICANT TERRAIN INTERACTION WILL CAUSE 05W TO RAPIDLY WEAKEN AS
THE REMNANT VORTEX MOVES OFF TO THE WEST.
MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN MODERATE AGREEMENT
THROUGH TAU 72 WITH A 143 NM CROSS-TRACK SPREAD AT TAU 72. HOWEVER,
MODELS DRASTICALLY DIFFER AFTER TAU 72, WITH MODELS DEPICTING LARGE
VARIATIONS IN TRACK POSSIBILITIES. GFS DETERMINISTIC, ECMWF
DETERMINISTIC, AND ECMWF ENSEMBLE MEAN ALL TAKE THE VORTEX WESTWARD
INTO MAINLAND CHINA WHILE THE JGSM, UKMET, AND GFS ENSEMBLE MEAN
HAVE THE VORTEX MAKING A SHARP TURN BACK TO THE SOUTHWEST. THE JTWC
TRACK IS PLACED MORE IN LINE WITH THE FIRST SCENARIO WITH MEDIUM
CONFIDENCE THROUGH TAU 72 AND LOW CONFIDENCE THEREAFTER. INTENSITY
GUIDANCE IS IN RELATIVELY GOOD AGREEMENT, HOWEVER, WITH THE TRACK
BEING SO CLOSE TO LAND ON EITHER SIDE, A SMALL VARIATION IN THE
TRACK COULD CAUSE LARGE CHANGES TO THE INTENSITY OF THE STORM.
MODELS GENERALLY HAVE THE SYSTEM INTENSIFYING THROUGH TAU 48 AND
THEN WEAKENING THEREAFTER THOUGH. MULTIPLE RAPID INTENSIFICATION
AIDS CONTINUE TO TRIGGER, SO THE INITIAL INTENSIFICATION TREND MAY
BE A BIT HIGHER THAN FORECASTED. OVERALL, THE JTWC INTENSITY
FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH LOW
CONFIDENCE.
FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
TRACK 72-120 HR: LOW
INTENSITY 0 - 72 HR: LOW
INTENSITY 72-120 HR: LOW//
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楼主: 理可的呆萌呆毛
发表于 2025-7-5 05:15
发表于 2025-7-5 06:13
