Tropical Storm DUJUAN Advisory 2月20日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (DUJUAN) WARNING
NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 01W (DUJUAN), LOCATED APPROXIMATELY 134NM WEST-
NORTHWEST OF SONSOROL, PHILIPPINES HAS TRACKED WEST-SOUTHWESTWARD AT
02 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
DEPICTS A LARGE CONVECTIVE MASS TO THE NORTHWEST OF THE LOW LEVEL
CIRCULATION CENTER (LLCC) MOVING AWAY FROM THE LLCC DUE TO THE
STRONG EAST-SOUTHEASTERLY VWS. THE INITIAL INTENSITY REMAINS
SET AT 45 KNOTS WITH FAIR CONFIDENCE, IN LINE WITH AGENCY DVORAK
CURRENT INTENSITY ESTIMATES OF T3.0 (45 KTS) FROM PGTW, AN ADVANCED
DVORAK TECHNIQUE (ADT) ESTIMATE OF T2.9 (43 KTS), A SATELLITE
CONSENSUS (SATCON) OF 46KTS, AND SLIGHTLY HIGHER THAN A T2.5 FROM
KNES. ENVIRONMENTAL AND SATELLITE ANALYSIS SHOWS THE STRONG (25-30
KT) EASTERLY VERTICAL WIND SHEAR (VWS) HAS ERODED THE SYSTEM
STRUCTURE AND DECOUPLED THE UPPER AND LOWER-LEVEL PORTIONS OF THE
SYSTEM. WHILE THE ROBUST POLEWARD OUTFLOW AND WARM 29-30C SSTS
ARE HELPING MAINTAIN THE SYSTEM, THE VWS IS TOO STRONG, OFFSETING
ANY FURTHER DEVELOPMENT. TS 01W IS TRACKING ALONG THE SOUTHWEST
PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) POSITIONED
TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE IN THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 01W IS CONTINUING TO MOVE SLOWLY NORTHWESTWARD, AS THE STR
CENTERED TO THE EAST BEGINS TO MOVE WESTWARD. TS DUJUAN WILL MOVE
ALONG THE WEST SIDE OF THE STR WITH A NORTHWEST-SOUTHEAST
ORIENTATION. THE SYSTEM IS FORECAST TO MAKE LANDFALL ALONG THE
NORTHEAST COAST OF MINDANAO BETWEEN TAU 24 AND TAU 36, THEN TRACK
OVER THE CENTRAL PHILIPPINE ISLANDS, REACHING THE SOUTH COAST OF
MINDORO BY TAU 48. THE SYSTEM WILL CONTINUE TO BE BESET BY STRONG
VWS AND FRICTIONAL EFFECTS OF THE TERRAIN INTERACTION. NUMERICAL
MODEL GUIDANCE IS DECREASING IN OVERALL AGREEMENT WITH 145NM SPREAD
AT TAU 36, INCREASING TO 350NM AT TAU 72. OVERALL, THERE IS POOR
CONFIDENCE IN THE JTWC FORECAST TRACK THROUGH TAU 72.
   C. AFTER TAU 72, THE SYSTEM WILL CONTINUE TO WEAKEN, AFTER IT
COMES UNDER THE STEERING INFLUENCE OF THE LOWER LEVEL NORTHEASTERLY
FLOW. BETWEEN TAU 72 AND 96 THE SYSTEM WILL MOVE INTO THE SOUTH
CHINA SEA, ENCOUNTERING A MUCH COOLER, DRIER AIR MASS AND
CONVERGENT, UPPER-LEVEL FLOW, CAUSING TS DUJUAN TO BEGIN
DISSIPATING. NUMERICAL MODEL GUIDANCE HAS INCREASED IN DISPARITY IN
THE EXTENDED TAUS, WITH THE CONSENSUS MEMBERS. MODEL SPREAD
INCREASES TO 510NM BY TAU 96 DUE TO THE WESTERN OUTLIER OF GFS AND
EASTERN OUTLIER OF UKMET. THE JTWC FORECAST TRACK IS POSITIONED
CLOSE TO THE MULTI-MODEL CONSENSUS AND CLOSELY TRACKS THE ECMWF
SOLUTION WITH FAIR CONFIDENCE.//
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