Tropical Storm YUTU Advisory Thu Nov 01

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 31W (YUTU) WARNING NR
44//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 31W (YUTU), LOCATED APPROXIMATELY 180 NM SOUTHEAST
OF HONG KONG, HAS TRACKED NORTH-NORTHWESTWARD AT 07 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
SHOWS DEEP CONVECTION BECOMING MORE RAGGED AND DISORGANIZED AROUND AN
ILL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION
IS PLACED WITH FAIR CONFIDENCE, FOLLOWING THE REGION OF MAXIMUM
CONVECTIVE CURVATURE IN THE 010552Z ATMS 88.2GHZ MICROWAVE IMAGE. THE
INITIAL INTENSITY IS ASSESSED AT 45 KNOTS, BASED ON DVORAK ESTIMATES
OF T3.0 FROM PGTW, RJTD, AND RCTP. THE SYSTEM IS CURRENTLY
EXPERIENCING MODERATE VERTICAL WIND SHEAR (15 TO 25 KNOTS), WITH GOOD
POLEWARD OUTFLOW BUT RESTRICTED ELSEWHERE. SEA SURFACE TEMPERATURES
ARE ONLY MARGINAL FOR DEVELOPMENT (26 DEGREES CELSIUS). TS 31W
CONTINUES TO TRACK TOWARD THE NORTH-NORTHWEST AROUND A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 31W IS FORECAST TO CONTINUE ON A NORTH-NORTHWESTWARD TRACK.
AS IT INTERACTS WITH STRONG MID-LATITUDE WESTERLIES, VERTICAL WIND
SHEAR IS EXPECTED TO DRAMATICALLY INCREASE. TOGETHER WITH COOLER SEA
SURFACE TEMPERATURES, TS 31W IS EXPECTED TO DISSIPATE OVER WATER
AROUND TAU 36. DYNAMIC MODEL GUIDANCE GREATLY DIVERGES IN A CLASSIC
SQUASHED SPIDER PATTERN, GIVEN THAT THE LLCC OF TS 31W IS EXPECTED TO
DECOUPLE UNDER THE INFLUENCE OF STRONG MID-LATITUDE DYNAMICS. THE
OFFICIAL FORECAST TRACK CALLS FOR A SLOWING IN FORWARD MOTION THROUGH
DISSIPATION. THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK.//
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