Tropical Storm TEMBIN Advisory 12月21日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 33W (THIRTY-THREE)
WARNING NR 01//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 33W (THIRTY-THREE), LOCATED APPROXIMATELY
211 NM WEST-NORTHWEST OF KOROR, PALAU, HAS TRACKED WEST-NORTHWESTWARD
AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY SHOWS A RAPIDLY CONSOLIDATING SYSTEM WITH FORMATIVE
BANDS WRAPPING INTO AND DEEPENING CENTRAL CONVECTION OBSCURING THE
LOW LEVEL CIRCULATION. THE INITIAL POSITION IS BASED ON THE EIR LOOP
WITH LOW CONFIDENCE. THE INITIAL INTENSITY OF 25 KNOTS IS BASED ON AN
OVERALL ASSESSMENT OF MULTI-AGENCY DVORAK ESTIMATES. UPPER-LEVEL
ANALYSIS INDICATES A FAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG
POLEWARD OUTFLOW AND LOW TO MODERATE (10-15 KNOT) VERTICAL WIND
SHEAR (VWS). ADDITIONALLY, SEA SURFACE TEMPERATURES IN THE PHILIPPINE
SEA AT 29 CELSIUS ARE CONDUCIVE FOR DEVELOPMENT. THE CYCLONE IS
CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL
RIDGE (STR)
TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE. AND SETS THE
FORECAST PHILOSOPHY ON THIS SYSTEM.
   B. TD 33W IS FORECAST TO TRACK ON A MORE WESTWARD TRAJECTORY AS
THE STR TO THE NORTHWEST ASSUMES STEERING FROM THE CURRENT STR. THE
SYSTEM WILL MAKE LANDFALL OVER NORTHEASTERN MINDANAO AFTER TAU 24 AND
CROSS THE SOUTHERN PHILIPPINE ARCHIPELAGO. BY TAU 72, TD 33W WILL
MAKE LANDFALL OVER PALAWAN JUST SOUTH OF PUERTO PRINCESA. THE
AFOREMENTIONED FAVORABLE CONDITIONS ARE EXPECTED TO PERSIST, LIMITED
ONLY BY FRICTIONAL EFFECTS FROM THE ISLANDS. BY TAU 72, THE SYSTEM
WILL REACH 60 KNOTS.
   C. AFTER TAU 72, TD 33W WILL RESUME A WEST-NORTHWESTWARD TRACK AS
THE STEERING STR WEAKENS. THE SYSTEM WILL EXIT INTO THE SOUTH CHINA
SEA AND FURTHER INTENSIFY AS FAVORABLE CONDITIONS PERSIST, PEAKING AT
A TYPHOON INTENSITY OF 65 KNOTS BY TAU 96. AFTERWARD, VWS IS EXPECTED
TO INCREASE, GRADUALLY WEAKENING THE SYSTEM TO 45 KNOTS RIGHT BEFORE
LANDFALL INTO SOUTHERN VIETNAM BY TAU 120. THE INITIAL SET OF NUMERIC
MODEL GUIDANCE IS IN GOOD AGREEMENT WITH SOME SPREADING AT THE
EXTENDED TAUS. NAVGEM IS A NOTABLE NORTHERN OUTLIER. GIVEN THESE AND
THE FORMATIVE STAGE OF THE SYSTEM, THERE IS LOW CONFIDENCE IN THE
INITIAL JTWC TRACK FORECAST.//
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