Tropical Storm FENGSHEN Advisory sáb, 16-11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (FENGSHEN)
WARNING NR 016//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 26W (FENGSHEN), LOCATED APPROXIMATELY 404 NM NORTH-
NORTHWEST OF ANDERSEN AFB, HAS TRACKED NORTHWESTWARD AT 14 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS A 10NM EYE WITH WARMING IN THE CENTER. THE EYE IN THE
MSI LOOP SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. THE
INITIAL INTENSITY IS ASSESSED AT 95 KNOTS, WITHIN RANGE OF DVORAK
ESTIMATES OF T5.0-5.5 (90-102 KNOTS). TY 26W IS LOCATED IN AN AREA
OF LOW (10-15 KNOTS) VERTICAL WIND SHEAR, WARM SEA SURFACE
TEMPERATURES (28-29 DEGREES CELSIUS) AND GOOD POLEWARD UPPER LEVEL
OUTFLOW. TY 26W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A
DEEP-LAYERED SUBTROPICAL STEERING RIDGE SITUATED TO THE NORTH.
3. FORECAST REASONING.
   A.  THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 26W IS FORECAST TO GRADUALLY RECURVE AROUND THE WESTERN
PERIPHERY OF THE BROAD STR AFTER TAU 12. LOW VERTICAL WIND SHEAR,
PASSAGE OVER WARM WATER AND IMPROVING POLEWARD OUTFLOW FROM THE
PASSING MIDLATITUDE TROUGH TO THE NORTH WILL LIKELY FUEL FURTHER
INTENSIFICATION THROUGH TAU 12 WITH A PEAK INTENSITY OF 105 KNOTS
EXPECTED AT TAU 12. AFTER TAU 12, A WEAKENING TREND WILL BEGIN AS
THE SYSTEM TRANSITS UNDER UPPER-LEVEL WESTERLY WINDS AND ENCOUNTERS
INCREASING VERTICAL WIND SHEAR AND DRY AIR. THE PRIMARY STEERING
INFLUENCE WILL SHIFT TO A LOW-LEVEL HIGH THAT IS FORECAST TO BUILD
TO THE NORTH AFTER TAU 48, STEERING THE REMNANT LOW LEVEL
CIRCULATION OF TY 26W TO THE SOUTHWEST. NUMERICAL MODEL GUIDANCE IS
IN GOOD AGREEMENT WITH THIS OVERALL SCENARIO THROUGH TAU 36 WITH A
LOW CROSS-TRACK SPREAD (70NM), BUT THERE IS STILL SIGNIFICANT
UNCERTAINTY IN THE SECONDARY STEERING MECHANISM, LENDING POOR
CONFIDENCE TO THE INITIAL PORTION OF THE TRACK FORECAST.
   C. IN THE EXTENDED FORECAST PERIOD, TY 26W IS EXPECTED TO
CONTINUE WEAKENING QUICKLY UNDER STRONG (40 TO 50 KNOTS) WESTERLY
VERTICAL WIND SHEAR. NUMERICAL MODELS AGREE WITH THE WESTERLY TRACK
WITH THE SECONDARY STEERING MECHANISM, BUT VARY IN THEIR WEAKENING
TRENDS AND THE EXACT TRACK DURING THE EXTENDED PERIOD. THE JTWC
FORECAST TRACK IS PLACED NEAR CONSENSUS. THERE IS LOW CONFIDENCE IN
THIS PORTION OF THE JTWC FORECAST TRACK DUE TO THE COMPLEX STEERING
ENVIRONMENT AND DIFFERENCES IN TIMING OF THE SOUTHWARD TURN AND
ALONG-TRACK SPEED IN LATER TAUS.//
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