Tropical Storm MAN-YI Advisory 11月23日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 34W (MAN-YI) WARNING NR
13//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 34W (MAN-YI), LOCATED APPROXIMATELY 698 NM SOUTH-
SOUTHWEST OF IWO TO, HAS TRACKED NORTHWESTWARD AT 13 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY DEPICTS A ROBUST CENTRAL DENSE OVERCAST OBSCURING THE
LOW LEVEL CIRCULATION CENTER (LLCC). A 221801Z SSMI 37GHZ IMAGE
REVEALS DEEP CONVECTION CONCENTRATED ON THE WESTERN SIDE OF THE
LLCC DUE TO EASTERLY VERTICAL WIND SHEAR (VWS), AND A MICROWAVE
EYE, UPON WHICH THE INITIAL POSITION IS BASED WITH HIGH
CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 85 KNOTS,
BETWEEN DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW AND KNES OF
T5.0 (90 KTS), AND THE 221647Z SATCON ESTIMATE OF 81 KTS. STRONG
DIVERGENCE ALOFT AND WARM (26-28 DEGREES CELSIUS) SEA SURFACE
TEMPERATURES (SSTS) ARE FUELING THE PERSISTENT CONVECTION
DESPITE THE HIGH (20-25 KTS) VWS. TY 34W IS TRACKING ALONG THE
SOUTHWESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 34W IS FORECAST TO TRACK NORTH-NORTHWESTWARD TO
NORTHWARD THROUGH TAU 48 AS IT TRACKS ALONG THE WESTERN
PERIPHERY OF THE DEEP-LAYERED STR POSITIONED TO THE EAST. A
STRONG, BROAD HIGH PRESSURE SYSTEM WILL BUILD INTO JAPAN AFTER
TAU 24. LOW-LEVEL NORTHEASTERLY FLOW ASSOCIATED WITH THIS HIGH
IS FORECAST TO SLOW THE SYSTEM'S FORWARD MOTION AND TURN THE
SYSTEM NORTHWESTWARD TO WESTWARD BY TAU 36. TY 34W IS FORECAST
TO INTENSIFY SLIGHTLY TO 90 KTS BY TAU 12 DUE TO THE ROBUST
DIVERGENCE ALOFT AND WARM SSTS. HOWEVER, WEAKENING UPPER AIR
DIVERGENCE, ALONG WITH COLD AIR ADVECTION AND SUSTAINED
HIGH VWS, WILL RAPIDLY WEAKEN TY 34W AFTER TAU 12. THERE IS
SIGNIFICANT 220 NM SPREAD IN THE MODEL GUIDANCE AT TAU 72, WITH
ECMWF TO THE EAST OF THE MULTI-MODEL CONSENSUS SHOWING A MORE
PRONOUNCED KINK IN THE FORECAST TRACK, AND GFS TO THE WEST OF
THE MULTI-MODEL CONSENSUS.
C. AFTER TAU 72, NUMERICAL MODEL GUIDANCE CONTINUES TO DIVERGE
WITH A 425NM SPREAD IN SOLUTIONS AT TAU 120. THE BULK OF THE
MODELS INDICATE RAPID WEAKENING EXCEPT NAVGEM, WHICH MAINTAINS
TYPHOON STRENGTH THROUGH TAU 120. THE JTWC TRACK AND INTENSITY
FORECAST FAVORS A RAPID WEAKENING SCENARIO AND EVENTUAL
DISSIPATION SCENARIO ASSOCIATED WITH THE NORTHEASTERLY SURGE,
WHICH WILL ADVECT COOLER, MORE STABLE AIR INTO THE SYSTEM. THE
JTWC INTENSITY FORECAST IS BELOW THE INTENSITY CONSENSUS,
BETWEEN THE CONSENSUS AND HWRF AND STATISTICAL-DYNAMICAL MODEL
GUIDANCE FROM SHIPS-NAVGEM AND SHIPS-GFS. OVERALL, THERE IS A
LARGE DEGREE OF UNCERTAINTY IN THE TRACK FORECAST AT LATER TAUS.
HOWEVER, THE WEAKENED SYSTEM IS EXPECTED TO BE SUBJECT TO LOWER-
LEVEL EASTERLY STEERING FLOW AND TRACK SLOWLY NORTHWESTWARD TO
WESTWARD. THE JTWC TRACK FORECAST IS HEDGED BETWEEN THE ECMWF
SOLUTION AND THE MULTI-MODEL CONSENSUS WITH LOW CONFIDENCE.//
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