Tropical Storm THIRTYFIVE Advisory 12月29日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 35W (THIRTYFIVE)
WARNING NR 18//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 35W (THIRTYFIVE), LOCATED APPROXIMATELY
345 NM EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED
NORTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY DEPICTS A WEAKLY DEFINED LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH FLARING DEEP CONVECTION OVER THE
NORTHWEST QUADRANT. HOWEVER, A 281835Z SSMI 85GHZ COMPOSITE IMAGE
SHOWS IMPROVED LOW-LEVEL BANDING WRAPPING INTO A DEFINED LLCC, WHICH
SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. THE IMPROVED
STRUCTURE IS LIKELY DUE TO THE SLIGHTLY IMPROVED UPPER-LEVEL
ENVIRONMENT CHARACTERIZED BY LOW TO MODERATE SOUTHEASTERLY VERTICAL
WIND SHEAR (VWS) AND STRONG DIFFLUENCE ALOFT. A 281212Z ASCAT IMAGE
DEPICTS A DEFINED, ELONGATED CIRCULATION POSITIONED ALONG THE
SOUTHEAST EDGE OF AN EXPANSIVE AREA OF NORTHEASTERLY GALE-FORCE
WINDS. DESPITE THE SLIGHT IMPROVEMENT IN STRUCTURE, PROXIMITY TO
LAND IS HINDERING SIGNIFICANT DEVELOPMENT, THEREFORE, THE INITIAL
INTENSITY REMAINS ASSESSED AT 30 KNOTS BASED ON DVORAK CURRENT
INTENSITY ESTIMATES OF 2.0 (30 KNOTS) FROM PGTW AND RJTD. TD 35W IS
TRACKING NORTHWESTWARD UNDER THE STEERING INFLUENCE OF A LOW- TO MID-
LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THROUGH TAU 48, TD 35W WILL TRACK WESTWARD TO WEST-
SOUTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF THE AFOREMENTIONED
STR. TD 35W IS EXPECTED TO INTENSIFY SLOWLY DUE TO INTERACTION WITH
LAND. AFTER TAU 48, TD 35W WILL TURN SOUTHWESTWARD IN RESPONSE TO A
NORTHEAST SURGE EVENT. WITH THE EXCEPTION OF NVGI, DYNAMIC MODEL
GUIDANCE IS IN TIGHT AGREEMENT WITH A SPREAD OF 60NM AT TAU 72. THE
28/12Z RUN OF ECMWF INITIALIZES A WEAK LOW PRESSURE AREA AT TAU 0
AND FURTHER WEAKENS THE SYSTEM AS IT CROSSES THE PHILIPPINES,
THEREFORE, THERE IS NO VORTEX TRACKER (ECMI) CURRENTLY AVAILABLE.
   C. AFTER TAU 72, TD 35W WILL TURN WESTWARD WITH SLIGHT
INTENSIFICATION EXPECTED TO A PEAK OF 45 KNOTS BY TAU 120. DESPITE
EARLY PROBLEMS INITIALIZING AND TRACKING THE VORTEX, ECMWF SLP
FIELDS INDICATE TD 35W WILL REINTENSIFY AND TURN WESTWARD AS
INDICATED IN THE BULK OF THE GUIDANCE. OVERALL, NUMERICAL MODEL
GUIDANCE REMAINS IN POOR AGREEMENT WITH A SPREAD OF 260NM AT TAU
120, THEREFORE, THERE IS LOW OVERALL CONFIDENCE (HIGH UNCERTAINTY)
IN THE JTWC FORECAST TRACK.//
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