Tropical Storm FUNG-WONG Advisory Fri Sep 19

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (FUNG-WONG) WARNING
NR 04//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 16W (FUNG-WONG), LOCATED APPROXIMATELY 356 NM
EAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT 15 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS INTENSE DEEP CONVECTIVE BANDING ACROSS THE SOUTHERN
SEMI-CIRCLE WHILE THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS BECOME
EXPOSED AND FRAGMENTED BANDING IS BUILDING ALONG THE NORTHERN
FLANKS. A PREVIOUS 180053Z ASCAT PASS REVEALED A SLIGHTLY ASYMMETRIC
LOW LEVEL CIRCULATION WITH WEAK CENTRAL WINDS WHILE THE STRONGEST
WINDS WHERE LOCATED ALONG THE OUTER DEEP CONVECTION. THE CURRENT
POSITION IS BASED ON THE MSI LOOP WITH GOOD CONFIDENCE DUE TO THE
EXPOSED NATURE OF THE LLCC. THE INITIAL INTENSITY REMAINS ASSESSED
AT 35 KNOTS BASED ON THE AFOREMENTIONED ASCAT PASS AS DVORAK
INTENSITY ESTIMATES RANGE FROM 30 TO 35 KNOTS. UPPER-LEVEL ANALYSIS
INDICATES A MARGINALLY CONDUCIVE ENVIRONMENT AS VERTICAL WIND SHEAR
(VWS) HAS INCREASED TO MODERATE LEVELS (10 TO 20 KNOTS) AND
EQUATORWARD OUTFLOW REMAINS STRONG. TS FUNG-WONG IS CURRENTLY
TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE
(STR) THAT IS POSITIONED TO THE NORTHEAST OF THE SYSTEM.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING.
   B. OVER THE NEXT 36 HOURS, TS 16W WILL TRACK TO THE NORTHWEST
UNDER THE INFLUENCE OF THE STR THAT IS EXPECTED TO WEAKEN AND BREAK
AS A SUBTROPICAL TROUGH MOVES IN. AS THE STR BREAKS DOWN, THE SYSTEM
WILL SLOW DOWN UNDER THE SIGNIFICANTLY WEAKER RIDGE. WHILE THERE IS
THE POSSIBILITY OF RAPID INTENSIFICATION AS THE SYSTEM TRACKS INTO A
MORE FAVORABLE UPPER-LEVEL ENVIRONMENT, THE PROXIMITY OF TS 16W TO
THE NORTHEAST COAST OF LUZON COULD POTENTIALLY LIMIT
INTENSIFICATION. MODELS ARE IN GOOD AGREEMENT ON THE TRACK THROUGH
TAU 48 WITH ALL SHOWING THE SYSTEM ENTERING THE BREAK IN THE RIDGE
AND PROCEEDING POLEWARD.
   C. IN THE EXTENDED FORECAST, A DEEP SUBTROPICAL TROUGH, REACHING
AS FAR SOUTH AS TAIWAN, BEGINS TO PRESS THE STR, ACCELERATING FUNG-
WONG NORTHEASTWARD AS IT CONTINUES TO BECOME EMBEDDED IN THE
BAROCLINIC BOUNDARY AND COMPLETE EXTRA-TROPICAL TRANSITION BY THE
END OF THE FORECAST PERIOD. MODEL GUIDANCE HAS BECOME BETTER ALIGNED
WITH MOST AGREEING WITH THE GENERAL RECURVE SCENARIO ALTHOUGH THERE
REMAINS A LARGE VARIANCE IN TRANSLATIONAL SPEED AFTER TAU 72. NAVGEM
CONTINUES TO REMAIN AN OUTLIER AS IT DOES NOT WEAKEN THE RIDGE AND
SHOWS THE SYSTEM PROCEEDING MORE POLEWARD ALONG THE MORE BUILT
RIDGE. THE OFFICIAL FORECAST IS MORE ALIGNED WITH THE GFS TRACK AND
GFS ENSEMBLE SOLUTIONS IN THE EXTENDED FORECAST DUE TO THE MORE
LIKELY SCENARIO OF THE STR TO THE EAST OF THE SYSTEM BUILDING IN
MORE SLOWLY AND NOT AS STRONG. DUE TO THE SIGNIFICANT DIFFERENCES IN
THE EXTENT AND SPEED OF THE TRACK IN THE EXTENDED TAUS, THERE IS
OVERALL LOW CONFIDENCE IN THE FORECAST.//
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