Tropical Depression JELAWAT Advisory Bulletin (JTWC)
WTPN31 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL DEPRESSION 18W (JELAWAT) WARNING NR 007//
RMKS/
1. TROPICAL DEPRESSION 18W (JELAWAT) WARNING NR 007
01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
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WARNING POSITION:
181200Z --- NEAR 7.3N 125.2E
MOVEMENT PAST SIX HOURS - 280 DEGREES AT 07 KTS
POSITION ACCURATE TO WITHIN 025 NM
POSITION BASED ON CENTER LOCATED BY A COMBINATION OF
SATELLITE, SYNOPTIC DATA AND EXTRAPOLATION
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
REPEAT POSIT: 7.3N 125.2E
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FORECASTS:
12 HRS, VALID AT:
190000Z --- 7.6N 122.1E
MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
VECTOR TO 24 HR POSIT: 280 DEG/ 13 KTS
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24 HRS, VALID AT:
191200Z --- 8.1N 119.6E
MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
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REMARKS:
181500Z POSITION NEAR 7.4N 124.4E.
18DEC23. TROPICAL DEPRESSION 18W (JELAWAT), LOCATED APPROXIMATELY
18 NM EAST-NORTHEAST OF DAVAO, PHILIPPINES, HAS TRACKED WESTWARD AT
07 KNOTS OVER THE PAST SIX HOURS. TD 18W CONTINUES TO DECAY RAPIDLY
AS THE ASSOCIATED CONVECTIVE ACTIVITY PROGRESSIVELY BECOMES MORE
FRAGMENTED AND DISPERSED TO THE NORTH AND SOUTH OF THE ILL-DEFINED
LOW LEVEL CIRCULATION. THE INITIAL POSITION IS PLACED WITH LOW
CONFIDENCE BASED ON CURRENT TRAJECTORY AND STORM MOTION, SLOWED
DOWN TO ACCOUNT FOR FRICTIONAL EFFECTS. THE INITIAL INTENSITY IS HELD
AT 25 KNOTS, AT BEST. TD JELAWAT WILL CONTINUE TO TRACK WESTWARD UNDER
THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE TO THE NORTH AND
DISSIPATE BY TAU 12, LIKELY SOONER, DUE TO CONTINUED INTERACTION WITH
THE RUGGED AND INCREASED VERTICAL WIND SHEAR. THIS IS THE FINAL WARNING
ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM
WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION. MINIMUM CENTRAL
PRESSURE AT 181200Z IS 1007 MB.//
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Tropical Depression JELAWAT Forecast Advisory (JTWC)
WDPN31 PGTW 180900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 18W (JELAWAT)
WARNING NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 7.2N 125.9E
INITIAL INTENSITY: 25 KTS
GEOGRAPHIC REFERENCE: 393 NM WEST-NORTHWEST OF SONSOROL
MOVEMENT PAST 6 HOURS: WESTWARD AT 07 KTS
SIGNIFICANT WAVE HEIGHT: 0 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS CONTINUED
DEEP, ALBEIT FRAGMENTED, CONVECTION AS TD JELAWAT MADE LANDFALL
INTO THE RUGGED MOUNTAINOUS TERRAIN OF MINDANAO, OBSCURING THE
LOW-LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE USING EXTRAPOLATED AND SLOWED DOWN STORM MOTION
AND REFERENCED FROM THE WIND OBSERVATION FROM DAVAO, 17NM TO THE
WEST. THE INITIAL INTENSITY OF 25 KTS IS ALSO ASSESSED WITH MEDIUM
CONFIDENCE BASED ON RATE OF DECAY DUE TO THE INTERACTION OF JELAWAT
WITH SURROUNDING RUGGED TERRAIN, AND REFLECTS THE 6-HR DEGRADED
CONVECTIVE STRUCTURE. ANALYSIS INDICATES A HIGHLY UNFAVORABLE
ENVIRONMENT MOSTLY DUE TO THE FRICTIONAL EFFECTS OF THE RUGGED
TERRAIN AND THE LACK OF MOISTURE.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTH
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: NO CURRENT ESTIMATE
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
VWS: 5-10 KTS
SST: OVER LAND
OUTFLOW: MODERATE WESTWARD
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 18W WILL CONTINUE TO PROGRESS
WEST-NORTHWESTWARD THROUGHOUT THE REMAINDER OF THE FORECAST PERIOD
UNDER THE CONTINUED INFLUENCE OF THE WELL-ESTABLISHED STEERING
RIDGE TO THE NORTH. THE SYSTEM IS FORECAST TO MAINTAIN ITS CURRENT
INTENSITY, AT BEST, UP TO TAU 12 THEN DISSIPATE BY TAU 24, VERY
LIKELY SOONER, DUE TO PERSISTENT FRICTIONAL EFFECT OF THE TERRAIN
AND THE INCREASE OF VERTICAL WIND SHEAR.
MODEL DISCUSSION: TRACK FORECAST GUIDANCE DERIVED FROM THE
NUMERICAL MODEL SUITE IS IN TIGHT AGREEMENT OVER THE NEXT 24 HOURS
BUT GIVEN THE UNCERTAINTY AND THE WEAKENED STATE OF THE LLC, THERE
IS ONLY MEDIUM CONFIDENCE IN THE JTWC TRACK AND INTENSITY
FORECASTS.
FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
INTENSITY 0 - 72 HR: MEDIUM//
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