Tropical Storm WUTIP Advisory 2月24日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 02W (WUTIP) WARNING NR
19//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON 02W (WUTIP), LOCATED APPROXIMATELY 142 NM WEST-
SOUTHWEST OF NAVSTA GUAM, HAS TRACKED NORTHWESTWARD AT 06 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY DEPICTS A WELL-DEFINED BUT ERODING EYEWALL, PARTICULARLY ON
THE WESTERN SIDE, AS WELL AS WARMING CLOUD TOPS AND A COOLING EYE. A
231431Z GMI 89GHZ IMAGE REVEALS WHAT APPEARS TO BE DOUBLE EYEWALLS,
AND IT IS SUSPECTED THAT STY 02W IS UNDERGOING AN EYEWALL
REPLACEMENT CYCLE (ERC). THE INITIAL POSITION IS BASED ON RADAR
IMAGERY AND THE EYE IN EIR IMAGERY WITH HIGH CONFIDENCE. AFTER
RAPIDLY INTENSIFYING FOR A 24-HOUR PERIOD, STY 02W HAS MAINTAINED
THE 135-KT INTENSITY WHILE IT UNDERGOES THE ERC. THE CURRENT
INTENSITY IS BETWEEN THE RANGE OF MULTIAGENCY DVORAK CURRENT
INTENSITY ESTIMATES FROM T6.5 (127 KTS) TO T7.0 (140 KTS), AND
AGREES WITH A 241604Z SATCON ESTIMATE OF 136 KTS. OBSERVATIONS FROM
ANDERSEN AFB ON GUAM SHOW WINDS HAVE SLACKENED, WITH GUSTS BETWEEN
30-40 KTS AS CONVECTIVE RAINBANDS MOVE OVER THE AREA, AND SUSTAINED
WINDS WEAKENING FROM 28 KTS TO 22 KTS OVER THE PAST 6 HOURS. UPPER-
LEVEL CONDITIONS REMAIN FAVORABLE WITH LOW TO MODERATE (10 TO 20
KNOTS) SOUTHEASTERLY VERTICAL WIND SHEAR (VWS) OFFSET BY A ROBUST
POLEWARD OUTFLOW CHANNEL AND GOOD EQUATORWARD OUTFLOW. SST VALUES
HAVE DECREASED TO 27C BUT REMAIN FAVORABLE. STY 02W IS TRACKING
NORTHWESTWARD UNDER THE STEERING INFLUENCE OF A DEEP-LAYERED
SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. STY 02W SHOULD CONTINUE TO TRACK NORTHWESTWARD TO NORTHWARD
UNDER THE STEERING INFLUENCE OF THE AFOREMENTIONED STR TO THE
NORTHEAST THROUGH TAU 72. AFTER TAU 24, THE STR WILL ERODE SOMEWHAT,
ALLOWING FOR A MORE NORTHWARD TRACK. NUMERICAL MODEL GUIDANCE IS IN
FAIR AGREEMENT IN THE NEAR-TERM, WITH A 168NM SPREAD IN THE MODEL
SOLUTIONS AT TAU 72. THE GALWEM AND UKMET MODEL SOLUTION ARE FURTHER
EAST AND SHOW A MORE NORTH-NORTHWESTWARD TRACK THAN DO THE OTHER
MODELS, WHILE ECMWF, HWRF, NAVGEM, AND GFS ARE IN LINE WITH OR
SLIGHTLY WEST OF THE MULTI-MODEL CONSENSUS. IN GENERAL, THERE IS
SOME UNCERTAINTY IN THE INTENSITY FORECAST DUE TO MODEL DIFFICULTY
IN RESOLVING INTERNAL PROCESSES IN TROPICAL CYCLONES. HOWEVER, THE
SYSTEM IS EXPECTED TO MAINTAIN AT STY STRENGTH THROUGH TAU 24 DUE TO
THE STRONG POLEWARD OUTFLOW. SLIGHT ADDITIONAL INTENSIFICATION TO
140 KTS IS POSSIBLE BY TAU 12 AFTER STY 02W COMPLETES THE ONGOING
ERC AND THE NEW PRIMARY EYEWALL CONTRACTS. AFTER TAU 24, STY 02W
WILL WEAKEN STEADILY AS OUTFLOW DIMINISHES.
   C. AFTER TAU 72, INCREASING VWS (20 TO 40 KNOTS) AND CONVERGENCE
ASSOCIATED WITH A SHORTWAVE TROUGH WILL RAPIDLY WEAKEN THE SYSTEM.
THE WEAKENED SYSTEM WILL ACCELERATE WEST-NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF A STRONG LOW-LEVEL RIDGE AND NORTHEASTERLY
SURGE FORECAST TO BUILD SOUTH AND SOUTHEAST OF JAPAN. DUE TO THE
COMPLEX AND RAPIDLY EVOLVING SYNOPTIC PATTERN, THERE IS INCREASING
UNCERTAINTY IN THE EXACT TRACK WITH A 485NM SPREAD IN SOLUTIONS AT
TAU 120. NAVGEM AND THE GFS ENSEMBLE ARE THE NORTHEASTERN OUTLIERS
AND SHOW A MORE PRONOUNCED KINK TO THE NORTH BEFORE TURNING THE
TRACK WESTWARD THAN DO THE OTHER MODELS AND THE MULTI-MODEL
CONSENSUS. NAVGEM MAINTAINS AN UNREALISTICALLY HIGH INTENSITY
THROUGHOUT THE FORECAST PERIOD DESPITE THE ENVIRONMENT BECOMING
UNFAVORABLE, THUS SUBJECTING ITS MODEL TRACKER TO STEERING
INFLUENCES DEEPER IN THE ATMOSPHERE AND ALLOWING THE MORE NORTHWARD
TRACK AT LATER TAUS. ECMWF, GFS, AND HWRF DIVERGE TO THE SOUTHWEST
OF THE MULTI-MODEL CONSENSUS, MORE REALISTICALLY REPRESENTING THE
INFLUENCE OF LOW-LEVEL NORTHEASTERLY SURGE ON A WEAKENED SYSTEM. STY
02W IS FORECAST TO WEAKEN MORE RAPIDLY IN LATER TAUS THAN PREVIOUSLY
DUE TO DRY, COLD AIR ASSOCIATED WITH THE NORTHEASTERLY COLD SURGE,
COOLER SSTS, AND THE LOSS OF FAVORABLE POLEWARD OUTFLOW. THE JTWC
FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH LOW
CONFIDENCE.//
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