Tropical Storm HALONG Advisory Fri Aug 08

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (HALONG) WARNING NR 40//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 11W (HALONG), LOCATED APPROXIMATELY 510 NM SOUTH OF
IWAKUNI, JAPAN, HAS TRACKED NORTHWARD AT 08 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A 30 NM
CLOUD-FILLED EYE, THEREFORE, THERE IS GOOD CONFIDENCE IN THE CURRENT
POSITION. A 070521Z NOAA-19 IMAGE REVEALS A SLIGHT BREAK IN THE
EYEWALL OVER THE NORTHWEST QUADRANT WITH THE PRIMARY FEEDER BAND
LOCATED OVER THE SOUTHEAST QUADRANT. TY 11W IS CURRENTLY PASSING
ABOUT 25 NM EAST OF MINAMIDAITO AND KITADAITO ISLANDS, WHICH
REPORTED MAXIMUM SUSTAINED SURFACE WINDS OF APPROXIMATELY 65 KNOTS
(32.1 M/S) AND MINIMUM SLP OF 954.3 MB. THE SURFACE OBSERVATIONS AS
WELL AS DVORAK INTENSITY ESTIMATES RANGING FROM T4.0 (65 KNOTS) TO
T4.5 (77 KNOTS) SUPPORT THE CURRENT INTENSITY ASSESSMENT OF 75
KNOTS, WHICH REFLECTS THE RECENT WEAKENING TREND. ANIMATED WATER
VAPOR IMAGERY INDICATES NEAR-RADIAL OUTFLOW AIDED BY AN UPPER-LOW
POSITIONED NEAR TOKYO. TY 11W IS TRACKING POLEWARD ALONG THE WESTERN
PERIPHERY OF THE POLEWARD-ORIENTED SUBTROPICAL RIDGE (STR)
POSITIONED SOUTH OF CENTRAL JAPAN.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING.
   B. TY 11 IS FORECAST TO TRACK GENERALLY NORTHWARD THROUGH TAU 36
ALONG THE WESTERN PERIPHERY OF THE STR. AFTER TAU 36, THE STR IS
FORECAST TO BUILD OVER THE EAST SEA AND RE-ORIENT AS A MIDLATITUDE
SHORTWAVE TROUGH DIGS OVER THE KOREAN PENINSULA AND WESTERN JAPAN,
WHICH SHOULD ALLOW THE SYSTEM TO ACCELERATE NORTH-NORTHEASTWARD AND
BEGIN EXTRA-TROPICAL TRANSITION (ETT). TY 11W IS FORECAST TO
MAINTAIN INTENSITY AT 75 KNOTS UNTIL TAU 24 AFTERWHICH THE SYSTEM
SHOULD RE-INTENSIFY AS POLEWARD OUTFLOW IMPROVES. TY 11W WILL MAKE
LANDFALL AFTER TAU 48 AND IS FORECAST TO WEAKEN SIGNIFICANTLY DUE TO
THE ROUGH TERRAIN OVER WESTERN JAPAN. AS THE SYSTEM EMERGES OVER THE
EAST SEA, IT WILL CONTINUE TO WEAKEN DUE TO COOLER SST AND
INCREASING VERTICAL WIND SHEAR. DYNAMIC MODEL GUIDANCE IS IN GOOD
AGREEMENT, THEREFORE, THE JTWC FORECAST IS POSITIONED CLOSE TO THE
MULTI-MODEL CONSENSUS.
   C. IN THE EXTENDED TAUS, TY 11W WILL ACCELERATE NORTH-
NORTHEASTWARD AND IS FORECAST TO COMPLETE ETT BY TAU 96. BASED ON
THE TIGHT MODEL AGREEMENT, THERE IS OVERALL HIGH CONFIDENCE IN THE
JTWC FORECAST TRACK.//
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