• Pacific-SW: TC 04P W4

    From Weather Alert@21:1/175 to All on Fri Dec 11 22:10:00 2020
    WTPS33 PGTW 112100
    MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
    SUBJ/TROPICAL CYCLONE 04P (FOUR) WARNING NR 004//
    RMKS/
    1. TROPICAL CYCLONE 04P (FOUR) WARNING NR 004
    01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
    MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    WIND RADII VALID OVER OPEN WATER ONLY
    ---
    WARNING POSITION:
    111800Z --- NEAR 14.3S 177.9E
    MOVEMENT PAST SIX HOURS - 215 DEGREES AT 14 KTS
    POSITION ACCURATE TO WITHIN 030 NM
    POSITION BASED ON CENTER LOCATED BY SATELLITE
    PRESENT WIND DISTRIBUTION:
    MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
    WIND RADII VALID OVER OPEN WATER ONLY
    RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT
    085 NM SOUTHEAST QUADRANT
    055 NM SOUTHWEST QUADRANT
    030 NM NORTHWEST QUADRANT
    REPEAT POSIT: 14.3S 177.9E
    ---
    FORECASTS:
    12 HRS, VALID AT:
    120600Z --- 15.2S 175.9E
    MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
    WIND RADII VALID OVER OPEN WATER ONLY
    RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT
    090 NM SOUTHEAST QUADRANT
    050 NM SOUTHWEST QUADRANT
    130 NM NORTHWEST QUADRANT
    VECTOR TO 24 HR POSIT: 265 DEG/ 07 KTS
    ---
    24 HRS, VALID AT:
    121800Z --- 15.3S 174.5E
    MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
    WIND RADII VALID OVER OPEN WATER ONLY
    RADIUS OF 034 KT WINDS - 200 NM NORTHEAST QUADRANT
    120 NM SOUTHEAST QUADRANT
    060 NM SOUTHWEST QUADRANT
    070 NM NORTHWEST QUADRANT
    VECTOR TO 36 HR POSIT: 265 DEG/ 04 KTS
    ---
    36 HRS, VALID AT:
    130600Z --- 15.4S 173.6E
    MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
    WIND RADII VALID OVER OPEN WATER ONLY
    RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT
    130 NM SOUTHEAST QUADRANT
    070 NM SOUTHWEST QUADRANT
    100 NM NORTHWEST QUADRANT
    VECTOR TO 48 HR POSIT: 290 DEG/ 02 KTS
    ---
    EXTENDED OUTLOOK:
    48 HRS, VALID AT:
    131800Z --- 15.3S 173.3E
    MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
    WIND RADII VALID OVER OPEN WATER ONLY
    RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT
    040 NM SOUTHEAST QUADRANT
    030 NM SOUTHWEST QUADRANT
    030 NM NORTHWEST QUADRANT
    RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT
    140 NM SOUTHEAST QUADRANT
    090 NM SOUTHWEST QUADRANT
    130 NM NORTHWEST QUADRANT
    VECTOR TO 72 HR POSIT: 245 DEG/ 01 KTS
    ---
    72 HRS, VALID AT:
    141800Z --- 15.5S 172.9E
    MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
    WIND RADII VALID OVER OPEN WATER ONLY
    RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT
    050 NM SOUTHEAST QUADRANT
    040 NM SOUTHWEST QUADRANT
    040 NM NORTHWEST QUADRANT
    RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT
    150 NM SOUTHEAST QUADRANT
    120 NM SOUTHWEST QUADRANT
    140 NM NORTHWEST QUADRANT
    VECTOR TO 96 HR POSIT: 180 DEG/ 01 KTS
    ---
    LONG RANGE OUTLOOK:
    ---
    96 HRS, VALID AT:
    151800Z --- 16.0S 172.9E
    MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
    WIND RADII VALID OVER OPEN WATER ONLY
    RADIUS OF 064 KT WINDS - 050 NM NORTHEAST QUADRANT
    050 NM SOUTHEAST QUADRANT
    050 NM SOUTHWEST QUADRANT
    000 NM NORTHWEST QUADRANT
    RADIUS OF 050 KT WINDS - 080 NM NORTHEAST QUADRANT
    060 NM SOUTHEAST QUADRANT
    060 NM SOUTHWEST QUADRANT
    040 NM NORTHWEST QUADRANT
    RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT
    160 NM SOUTHEAST QUADRANT
    160 NM SOUTHWEST QUADRANT
    150 NM NORTHWEST QUADRANT
    VECTOR TO 120 HR POSIT: 130 DEG/ 03 KTS
    ---
    120 HRS, VALID AT:
    161800Z --- 16.7S 173.8E
    MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT
    WIND RADII VALID OVER OPEN WATER ONLY
    RADIUS OF 064 KT WINDS - 060 NM NORTHEAST QUADRANT
    060 NM SOUTHEAST QUADRANT
    060 NM SOUTHWEST QUADRANT
    050 NM NORTHWEST QUADRANT
    RADIUS OF 050 KT WINDS - 110 NM NORTHEAST QUADRANT
    130 NM SOUTHEAST QUADRANT
    110 NM SOUTHWEST QUADRANT
    070 NM NORTHWEST QUADRANT
    RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT
    190 NM SOUTHEAST QUADRANT
    170 NM SOUTHWEST QUADRANT
    150 NM NORTHWEST QUADRANT
    ---
    REMARKS:
    112100Z POSITION NEAR 14.5S 177.4E.
    11DEC20. TROPICAL CYCLONE (TC) 04P (FOUR), LOCATED APPROXIMATELY 230
    NM NORTH OF SUVA, FIJI, HAS TRACKED SOUTHWESTWARD AT 14 KNOTS OVER
    THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
    IMAGERY DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER
    (LLCC) WITH THE ASSOCIATED DEEP CONVECTION BEING SHEARED TO THE
    NORTHEAST. AN 111837Z 91 GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALS
    CONVECTIVE BANDING WRAPPING INTO A DEFINED LLCC. BETWEEN THE EIR AND
    THE MICROWAVE IMAGERY, THERE IS HIGH CONFIDENCE IN THE INITIAL
    POSITION. HEDGED SLIGHTLY HIGHER THAN MULTI-AGENCY DVORAK CURRENT
    INTENSITY ESTIMATES OF T2.5 (35 KTS, PGTW/KNES/NFFN) AND SUPPORTED BY
    A 111320Z SATCON ESTIMATE OF 40 KTS, THE INITIAL INTENSITY REMAINS
    ASSESSED AT 40 KTS WITH GOOD CONFIDENCE. ENVIRONMENTAL ANALYSIS
    REVEALS A MARGINAL ENVIRONMENT WITH HIGH (30-35 KTS) VERTICAL WIND
    SHEAR (VWS) BEING OFFSET BY DIFFLUENT FLOW ALOFT AND WARM (29-30
    CELSIUS) SEA SURFACE TEMPERATURES. IN THE NEAR TERM, TC 04P IS
    EXPECTED TO TRACK WEST-SOUTHWESTWARD TO WESTWARD ALONG A SUBTROPICAL
    RIDGE (STR) TO THE SOUTH. FURTHERMORE, THE SYSTEM CONTINUES TO TRACK
    ALONG THE SOUTHERN PERIPHERY OF A LARGE MONSOON DEPRESSION (INVEST
    91P) WHICH IS FORECAST TO INTENSIFY INTO A TROPICAL CYCLONE OVER THE
    NEXT 1-2 DAYS. DUE TO THE PROXIMITY OF INVEST 91P TO TC 04P, THERE
    WILL LIKELY BE SOME DIRECT CYCLONE INTERACTION (DCI) AND POSSIBLE
    FUJIWHARA EFFECTS NEAR TAU 60. DUE TO THE COMPLEX SCENARIO, THERE IS
    HIGH UNCERTAINTY IN THE TRACK FORECAST AND INTENSITY FORECAST AS
    MODELS HAVE BEEN INCONSISTENT FROM RUN TO RUN. THE 11/12Z GFS RUN
    INDICATES INVEST 91P WILL BE THE DOMINANT SYSTEM WITH TC 04P SKIRTING
    WESTWARD TOWARDS VANUATU. CONVERSELY, NAVGEM DEPICTS TC 04P AS THE
    DOMINANT SYSTEM AND TURNS THE SYSTEM SHARPLY POLEWARD BY TAU 36 THEN
    TRACKS SOUTHEASTWARD PASSING TO THE WEST OF FIJI. BASED ON THIS
    UNCERTAINTY IN TIMING, INTENSITY, AND TRACK, THE JTWC FORECAST TRACK
    SHOWS A SLOW/QUASI-STATIONARY MOTION FROM TAU 48 TO TAU 96. FOLLOWING
    THIS, AN APPROACHING SHORTWAVE TROUGH SHOULD CAUSE THE STR TO BUILD
    TO THE EAST AND NORTHEAST AND THUS CAUSE TC 04P TO BEGIN TO TRANSIT
    POLEWARD UNDER ITS STEERING INFLUENCE. THROUGH TAU 36, THE SYSTEM IS
    EXPECTED TO STRUGGLE DUE TO PERSISTENT HIGH VWS AND DCI. AFTERWARDS,
    THE MERGED SYSTEM IS FORECAST TO GRADUALLY INTENSIFY TO A PEAK OF 80
    KTS BY TAU 120 AS THE SURROUNDING ENVIRONMENT IMPROVES. OF NOTE, THE
    COMPLEXITY OF THIS SCENARIO ALSO PRESENTS AN ALTERNATE SCENARIO WHERE
    INVEST 91P BECOMES THE DOMINANT SYSTEM AND TC 04P DISSIPATES. DUE TO
    THIS UNCERTAINTY AND POOR AGREEMENT BETWEEN THE NUMERICAL MODEL
    GUIDANCE, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC FORECAST TRACK.
    MAXIMUM SIGNIFICANT WAVE HEIGHT AT 111800Z IS 14 FEET. NEXT WARNINGS
    AT 120300Z, 120900Z, 121500Z AND 122100Z.//
    NNNN
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