Cat 2 Typhoon Phanfone tracking across the Visayan Sea



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TY 30W( PHANFONE) WESTERN NORTH PACIFIC
As of 12:00 UTC Dec 24, 2019:

Location: 11.4°N 124.8°E
Maximum Winds: 90 kt ( 170km/h)
Gusts: 110 kt ( 205km/h)

Minimum Central Pressure:  mb
CATEGORY US: 2

WDPN31 PGTW 241500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 30W (PHANFONE)
WARNING NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 30W (PHANFONE), LOCATED APPROXIMATELY 294 NM SOUTHEAST
OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 17 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED IMAGERY REVEALS A
PERSISTENT 17 NM WIDE EYE SURROUNDED BY A COLD, CONVECTIVE
EYEWALL. THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION, WHICH
IS BASED ON THE EYE. THE INITIAL INTENSITY IS ASSESSED AT 90 KTS,
BETWEEN THE RJTD DVORAK CURRENT INTENSITY ESTIMATE OF T4.5 (77
KTS) AND THE PGTW AND KNES DVORAK CURRENT INTENSITY ESTIMATES OF
T5.5 (102 KTS) GIVEN BEFORE THE SYSTEM TRACKED OVER LAND, BASED ON
THE MAINTAINED STRUCTURE AS THE SYSTEM TRACKS ACROSS THE WATERS
WITHIN THE PHILIPPINES ARCHIPELAGO. THE ENVIRONMENT IS FAVORABLE
FOR CONTINUED DEVELOPMENT WITH LOW (10-15 KT) VERTICAL WIND SHEAR
(VWS), GOOD POLEWARD AND EQUATORWARD OUTFLOW AND WARM (28-29
CELSIUS) SEA SURFACE TEMPERATURES (SSTS). TY 30W HAS ACCELERATED
WESTWARD ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL RIDGE (STR)
TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 30W WILL TRACK GENERALLY WEST-NORTHWESTWARD THROUGHOUT
THE FORECAST. BETWEEN TAUS 12 AND 36, THE FAVORABLE ENVIRONMENT IS
EXPECTED TO PARTIALLY OFFSET THE LAND INTERACTION, ALLOWING THE
SYSTEM TO MAINTAIN INTENSITY AT 90 KTS. SMALL TRACK VARIATIONS
TAKING THE SYSTEM MORE OR LESS OVER LAND WILL IMPACT THE INTENSITY
THROUGH TAU 24. ONCE TY 30W EMERGES IN THE SOUTH CHINA SEA, IT
WILL INTENSIFY TO A MAXIMUM OF 95 KTS AT TAU 48. DUE TO THE
COMPLICATED NATURE OF THE LAND INTERACTION, THERE IS HIGH
UNCERTAINTY IN THIS PORTION OF THE INTENSITY FORECAST. HWRF,
COAMPS-GFS, AND ECMWF INTENSITY GUIDANCE IS SIGNIFICANTLY ABOVE
THE MULTI-MODEL CONSENSUS AND AT THE TOP OF OR ABOVE THE 70%
PROBABILITY CURVE; HOWEVER, THE GFS INTENSITY SOLUTION IS
SIGNIFICANTLY BELOW THE CONSENSUS. THE JTWC INTENSITY FORECAST IS
HEDGED SLIGHTLY ABOVE THE MULTI-MODEL CONSENSUS, TOWARDS HWRF AND
ECMWF IN RECOGNITION OF THE FAVORABLE ENVIRONMENT. THERE IS STRONG
AGREEMENT IN THE MODEL TRACK GUIDANCE THROUGH TAU 72, LENDING HIGH
CONFIDENCE TO THIS PORTION OF THE JTWC TRACK FORECAST. THE JTWC
FORECAST TRACK IS HEDGED SLIGHTLY SOUTH OF THE MULTI-MODEL TRACK
CONSENSUS TOWARDS THE ECMWF SOLUTION.
   C. AFTER TAU 72, TY 30W WILL BEGIN TO ENCOUNTER DECREASING SSTS
(26-27 DEGREES CELSIUS), INCREASING VWS AND RELATIVELY COOL, DRY
AIR FROM A BUILDING SURFACE HIGH PRESSURE SYSTEM TO THE NORTH. AS
A RESULT, TY 30W WILL BEGIN A RAPID WEAKENING TREND. FURTHERMORE,
THE SYSTEM WILL SLOW AS IT APPROACHES A COL BETWEEN THE STEERING
STR AND A LESS PRONOUNCED STR TO THE WEST. MODEL GUIDANCE SPREADS
SIGNIFICANTLY IN BOTH NORTH-SOUTH PLACEMENT AND ALONG TRACK SPEED
AFTER TAU 72. ECMWF AND NAVGEM, WHICH MAINTAIN A MUCH HIGHER
INTENSITY THROUGHOUT THE FORECAST PERIOD, AS WELL THE UKMET
ENSEMBLE MEAN, CURVE THE SYSTEM SHARPLY TO THE NORTHWEST INTO THE
AREA OF WEAK STEERING. HOWEVER, GFS AND THE GFS ENSEMBLE CONTINUE
NORTHWESTWARD WITHOUT A SHARP TURN, AND GALWEM AND UKMET CURVE THE
SYSTEM WEST-SOUTHWESTWARD. THE JTWC FORECAST TRACK NOW CURVES
NORTHWESTWARD AT TAU 120. AS TY 30W WEAKENS, IT WILL BECOME
SUBJECT TO THE STEERING INFLUENCE OF THE LOWER LEVEL NORTHEASTERLY
SURGE THROUGH TAU 96, WHICH IS THE CAUSE OF THE BRIEF DUE WESTWARD
MOTION. HOWEVER, AFTERWARDS, DEEP-LAYERED SUBTROPICAL RIDGING WILL
BUILD BACK INTO THE AREA, STEERING THE WEAKENING TY 30W
NORTHWESTWARD AT TAU 120.//
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TRACK AND INTENSITY GUIDANCE

Rédigé par PATRICK HOAREAU le Mardi 24 Décembre 2019 à 19:12