Tropical Storm PEIPAH Advisory Mon Sep 16

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 17W (SEVENTEEN)
WARNING NR 03//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 17W (SEVENTEEN), LOCATED APPROXIMATELY
651 NM SOUTHEAST OF IWO TO, JAPAN, HAS TRACKED NORTHWESTWARD AT 13
KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL IMAGERY
SHOWS A FULLY-EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) TRACKING
NORTHWARD, PROVIDING HIGH CONFIDENCE IN THE INITIAL POSITION. A
142359Z METOP-C ASCAT IMAGE DISPLAYS AN AREA OF 30 KNOT WINDS NEAR
THE LLCC, WHICH LENDS HIGH CONFIDENCE TO THE INITIAL INTENSITY OF 30
KNOTS. DESPITE STRONG EQUATORWARD OUTFLOW AND HIGH (30-31 CELSIUS)
SEA SURFACE TEMPERTURE (SST), TD 17W REMAINS IN AN UNFAVORABLE
ENVIRONMENT CHARACTERIZED BY HIGH (25-40 KNOTS) VERTICAL WIND SHEAR
(VWS). TD 17W CONTINUES TO TRACK AROUND THE SOUTHWESTERN PERIPHERY
OF A SHALLOW, NORTH-TO-SOUTH ORIENTED SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. FOR THE DURATION OF THE FORECAST, TD 17W WILL TRACK
NORTHWESTWARD ALONG THE STR. THE ENVIRONMENT IS EXPECTED TO REMAIN
UNFAVORABLE FOR FURTHER INTENSIFICATION AS VWS VALUES PERSIST AT
40-50 KNOTS, SHEARING THE SYSTEM UNTIL DISSIPATION AROUND TAU 48.
WITH MINOR DIFFERENCES IN ALONG TRACK SPEED, NUMERICAL GUIDANCE IS IN
FAIR AGREEMENT, PLACING FAIR CONFIDENCE IN THE JTWC TRACK FORECAST
WHICH IS LAID CLOSE TO CONSENSUS.//
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