Tropical Storm PHANFONE Advisory 12月27日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 30W (PHANFONE) WARNING NR 021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 30W (TY) (PHANFONE), LOCATED APPROXIMATELY 530 NM EAST OF
DA NANG, VIETNAM, HAS TRACKED NORTHWESTWARD AT 06 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS
THAT DEEP CONVECTION HAS SLIGHTLY WEAKENED BUT REMAINS PERSISTENT
AROUND THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION
IS PLACED WITH GOOD CONFIDENCE AND IS BASED ON 261813Z AMSR2 36GHZ
IMAGE WHICH SHOWS A MICROWAVE EYE. THE INITIAL INTENSITY OF 75 KNOTS
IS BASED ON DVORAK CURRENT INTENSITY (CI) ESTIMATES OF T4.5 (77
KNOTS) FROM RJTD AND RCTP AND SUPPORTED BY THE ADT CI OF T4.3 (72
KNOTS) AND A SATCON ESTIMATE OF 82 KNOTS. TY 30W IS EXPERIENCING
MODERATE VERTICAL WIND SHEAR (20 KNOTS) WHICH IS OFFSET BY AN
EXCELLENT POLEWARD OUTFLOW CHANNEL. SEA SURFACE TEMPERATURES REMAIN
FAVORABLE BETWEEN 26 AND 27 DEGREES CELSIUS. TY 30W IS TRACKING
NORTHWESTWARD WHILE POSITIONED ON THE SOUTHWESTERN EDGE OF A
SUBTROPICAL RIDGE (STR) LOCATED TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. AS THE DEEP CONVECTION AROUND THE LLCC CONTINUES TO WEAKEN,
THE PRIMARY STEERING FEATURE WILL SHIFT FROM THE STR TO THE LOWER
LEVEL SURGE FLOW FROM THE NORTHEAST. INCREASING VERTICAL WIND SHEAR
AND COOLER SEA SURFACE TEMPERATURES WILL CAUSE TY 30W TO DISSIPATE
BY TAU 48. DYNAMIC MODEL GUIDANCE IS IN POOR AGREEMENT WITH NAVGEM
INDICATING A NORTHWESTWARD TRACK AND GALWEM INDICATING A WESTWARD
TRACK. THE JTWC TRACK IS PLACED WITH LOW CONFIDENCE AND IS
POSITIONED JUST TO THE NORTH OF THE MULTI-MODEL CONSENSUS.//
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