Tropical Storm WUTIP Advisory 2月23日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (WUTIP) WARNING NR 15//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
  TYPHOON (TY) 02W (WUTIP), LOCATED APPROXIMATELY 211 NM SOUTH-
SOUTHWEST OF ANDERSEN AFB, HAS TRACKED WEST-NORTHWESTWARD AT 12
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
SHOWS A VERY COMPACT SYSTEM, WITH DEEP CORE CONVECTION AND A 10NM
EYE THAT POPS IN AND OUT OF VIEW. A 221712Z SSMI 89GHZ MICROWAVE
IMAGE SHOWED STRONG CONVECTIVE BANDING THE VERY DISTINCT PINHOLE
EYE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A
COMBINATION OF THE INFRARED EYE, MICROWAVE EYE FEATURE AND RADAR FIX
DATA FROM THE ANDERSEN AFB NEXRAD. THE INITIAL INTENSITY IS BEING
HELD AT 105 KNOTS WITH HIGH CONFIDENCE BASED ON THE DVORAK CURRENT
INTENSITY ESTIMATES OF T5.5 (102 KNOTS) FROM BOTH KNES AND PGTW AND
A SATELLITE CONSENSUS ESTIMATE OF 109 KNOTS. THE ENVIRONMENT REMAINS
FAVORABLE WITH STRONG, PRIMARILY WESTWARD OUTFLOW, LOW TO MODERATE
(15-20 KNOTS) VWS AND WARM (29 CELSIUS) SSTS. OVER THE PAST SIX
HOURS, TY 02W HAS TAKEN A SLIGHTLY MORE WESTWARD COURSE BUT THIS IS
LIKELY JUST A WOBBLE ALONG THE GENERAL NORTHWESTWARD TRACK UNDER THE
STEERING INFLUENCE OF A SUBTROPICAL RIDGE (STR) POSITIONED TO THE
NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS FORECAST.
   B. THE PREVIOUSLY FORECASTED BREAK IN THE STEERING RIDGE IS
BEGINNING TO BE REFLECTED IN THE MODEL ANALYSES, PARTICULARLY IN THE
MID- TO UPPER-LEVELS. OVER THE NEXT 24 HOURS, EXPECT TY 02W TO TURN
STEADILY MORE NORTHWEST THEN NORTH AFTER TAU 48 INTO THE BREAK IN
THE RIDGE. AS THE STEERING RIDGE ERODES AND MOVES EAST, TY 02W WILL
ENTER A COL REGION, AND SLOW SIGNIFICANTLY, BECOMING NEARLY QUASI-
STATIONARY AFTER TAU 72 DUE TO THE WEAK STEERING FLOW ASSOCIATED
WITH THE COL. TY 02W HAS LIKELY PEAKED IN INTENSITY AT 105 KNOTS AND
FROM THIS POINT ON IS FORECAST TO SLOWLY WEAKEN AS THE ENVIRONMENT
BECOMES INCREASINGLY UNFAVORABLE WITH DECREASING MID-LEVEL HUMIDITY,
INCREASING VWS AND COOLER SSTS. THERE WILL BE A SHORT PERIOD OF
STEADY INTENSITY BETWEEN TAUS 48 AND 72, AS THE SYSTEM TAPS INTO A
MORE ROBUST POLEWARD OUTFLOW CHANNEL, OFFSETTING THE OTHERWISE
NEGATIVE ENVIRONMENTAL CONDITIONS. MODEL GUIDANCE IS IN GOOD
AGREEMENT THROUGH TAU 36 WITH A SPREAD OF 70NM BUT WITH INCREASING
UNCERTAINTY BEYOND THIS POINT. BY TAU 72, THE SPREAD BETWEEN
OUTLIERS (NAVGEM AND GALWEM) INCREASES TO 140NM, WITH BOTH MODELS
AGREEING ON THE OVERALL TRACK TOWARDS THE NORTH. THE MAJORITY OF THE
MODEL GUIDANCE HAS SHIFTED TO THE WEST WITH THIS RUN AND THE JTWC
TRACK THROUGH TAU 72 LIES VERY NEAR THE MULTI-MODEL CONSENSUS TRACK
WITH HIGH CONFIDENCE.
   C. BEYOND TAU 72, TY 02W IS FORECAST TO DRIFT SLOWLY NORTHWARD IN
THE PREVIOUSLY DISCUSSED WEAK STEERING FLOW. BEING CAUGHT IN THE
WEAK STEERING FLOW, THE SYSTEM WILL NOT BE CAPTURED BY THE WESTERLY
FLOW AND THEREFORE WILL SLOWLY DRIFT NORTH. ENVIRONMENTAL CONDITIONS
FURTHER DETERIORATE DURING THIS TIMEFRAME, WITH INCREASING VWS,
COOLER SSTS AND LOWER MID-LEVEL MOISTURE COMBINING TO WEAKEN THE
SYSTEM TO ONLY 40 KNOTS BY TAU 120. AT THIS POINT, THE PRIMARY
STEERING MECHANISM BECOMES THE LOWER-LEVEL FLOW ASSOCIATED WITH A
TRANSIENT MID-LATITUDE HIGH PRESSURE SYSTEM EAST OF JAPAN WHICH WILL
PUSH THE SYSTEM ONTO A MORE WESTERLY TRACK. ALL MODEL GUIDANCE
AGREES WITH THIS GENERAL SCENARIO WITH THE EXCEPTION OF THE JGSM AND
GFS ENSEMBLE WHICH ARE STILL TRYING TO RECURVE THE SYSTEM TO THE
NORTHEAST BUT THIS SOLUTION IS NOT CURRENTLY FAVORED. THE GALWEM,
ECMWF AND EGRR TRACKERS ARE INDICATING A SHARPER TURN WESTWARD AS
THEY DISSIPATE THE SYSTEM AT A FASTER RATE AND SHIFT THE STEERING
MECHANISM A BIT EARLIER RESULTING IN A SPREAD OF 500M BETWEEN THE
GALWEM AND THE GFS ENSEMBLE AT TAU 120. THE JTWC FORECAST TRACK LIES
JUST WEST OF THE CONSENSUS WITH MODERATE CONFIDENCE.//
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