Tropical Storm HAISHEN Advisory 9月6日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (HAISHEN)
WARNING NR 022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 11W (HAISHEN), 156 NM EAST OF KADENA AB, OKINAWA,
JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT 09 KNOTS OVER THE PAST SIX
HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS
MAINTAINED A RAGGED BUT WELL-DEFINED 21-NM EYE; HOWEVER, FEEDER BANDS
HAVE LOOSENED AND CONVECTIVE TOPS HAVE WARMED. ADDITIONALLY, THE
NORTHWEST QUADRANT CONTINUED TO SHEAR AND ERODE. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE EYE FEATURE, ADJUSTED FOR A
SLIGHT SLANT AND LINED UP WITH A MICROWAVE EYE FEATURE  IN THE A 051742Z
ATMS IMAGE. THE INITIAL INTENSITY OF 105 KTS IS BASED ON THE LOW END OF
CONSTRAINED DVORAK ESTIMATES FROM PGTW AND RJTD AND REFLECTS THE
WEAKENING TREND. THE SYSTEM HAS TAPPED INTO INCREASED POLEWARD OUTFLOW
AHEAD OF A MAJOR SHORTWAVE TROUGH APPROACHING FROM THE WEST IN ADDITION
TO THE STRONG EQUATORWARD OUTFLOW. ALONG-TRACK SEA SURFACE TEMPERATURES
(SST) ALSO REMAIN WARM AT 29-30C. HOWEVER, RELATIVE VERTICAL WIND SHEAR
(VWS) HAS INCREASED TO 20-25 KTS AND OFFSET THE WARM SSTS AND ROBUST
OUTFLOW CHANNELS. THE CYCLONE CONTINUES TO TRACK UNDER THE STEERING
INFLUENCE OF THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST EAST-SOUTHEAST
OF HOKKAIDO, JAPAN.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
FROM THE LAST PROGNOSTIC REASONING MESSAGE.
   B. TY HAISHEN WILL CONTINUE TO TRACK POLEWARD THROUGH THE REMAINDER
OF THE FORECAST, PASSING TO THE WEST OF KYUSHU, CROSS THE KOREA STRAIT,
MAKE LANDFALL AROUND TAU 36 WEST OF BUSAN, SOUTH KOREA, THEN DRAG
NORTHWARD ALONG THE RUGGED MOUNTAIN RANGES OF THE KOREAN PENINSULA.
INCREASING VWS, COOLING SSTS, THEN LAND INTERACTION WILL GRADUALLY ERODE
THE SYSTEM DOWN TO 55 KTS PRIOR TO LANDFALL THEN RAPIDLY DOWND TO 30KTS
BY TAU 48 AFTER IT CROSSES INTO NORTH KOREA. CONCURRENTLY, TY HAISHEN
WILL COMMENCE EXTRATROPICAL TRANSITION BY TAU 36 AS IT ENTERS THE
BAROCLINIC ZONE, TRANSFORMING TO A COLD-CORE LOW BY TAU 48. NUMERICAL
MODELS REMAIN IN TIGHT AGREEMENT WITH THE EXCEPTION OF AFUM AS A
CONTINUED RIGHT OF TRACK OUTLIER. THE TIGHT AGREEMENT OVERALL IN
NUMERICAL MODEL SOLUTIONS YIELDS OVERALL HIGH CONFIDENCE IN THE JTWC
FORECAST TRACK.//
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