Tropical Storm FENGSHEN Advisory 11月13日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (FENGSHEN)
WARNING NR 006//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 26W (FENGSHEN), LOCATED APPROXIMATELY 771 NM
EAST-NORTHEAST OF ANDERSEN AFB, GUAM, HAS TRACKED WEST-NORTHWESTWARD
AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY INDICATES A MEDIUM-SIZED SYSTEM WITH FLARING DEEP
CONVECTION AND RAIN BANDS CONSTRAINED CLOSE TO THE LOW LEVEL
CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH GOOD
CONFIDENCE BASED ON THE SEMI-LLC FEATURE IN THE 1632Z SSMI 85GHZ
COLORIZED MICROWAVE IMAGE AND CLOSE TO A TIGHT CLUSTER OF AGENCY
FIXES. THE INITIAL INTENSITY OF 35KTS IS BASED ON THE DVORAK
INTENSITY ESTIMATES OF T2.5/35KTS FROM PGTW AND RJTD. THE SYSTEM IS
IN, OVERALL, A FAVORABLE AREA FOR FURTHER DEVELOPMENT WITH WARM (29-
30 CELSIUS) SEA SURFACE TEMPERATURES, LOW (10-15 KNOT) VERTICAL WIND
SHEAR (VWS) AND GOOD EQUATORWARD OUTFLOW. THE CYCLONE IS TRACKING
ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE
(STR).
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 26W WILL CONTINUE ON ITS CURRENT TRACK UNDER THE STR
THROUGH TAU 48 WHEN IT WILL BEGIN TO TURN POLEWARD AS IT ROUNDS THE
WESTERN EDGE OF THE STR AXIS. THE OVERALL FAVORABLE ENVIRONMENT WILL
PROMOTE GRADUAL INTENSIFICATION TO A PEAK 85KTS BY TAU 72. THERE IS
A LARGE SPREAD IN THE MODEL SOLUTIONS (270 NM AT TAU 72) WITH HIGH
UNCERTAINTY IN THE TIMING OF THE RECURVE.
   C. AFTER TAU 72, TS 26W WILL RECURVE SHARPLY NORTHEASTWARD TO
EAST-NORTHEASTWARD AND WILL GRADUALLY WEAKEN AS IT INTERACTS WITH AN
APPROACHING MIDLATITUDE TROUGH AND STRONG VWS. THE SYSTEM IS
EXPECTED TO BEGIN EXTRA-TROPICAL TRANSITION BY TAU 96, HOWEVER,
GLOBAL MODELS ARE BUILDING A LOW-LEVEL RIDGE TO THE NORTH THAT IS
EXPECTED TO IMPEDE THE FORWARD MOTION. DUE TO THIS COMPLEX, EVOLVING
SYNOPTIC PATTERN, THE NUMERICAL MODEL SOLUTIONS ARE IN VERY POOR
AGREEMENT, LENDING LOW CONFIDENCE IN THE EXTENDED PORTION OF THE
JTWC FORECAST TRACK./
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