Tropical Storm MALIKSI Advisory Pzt, 01.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 20W (TWENTY)
WARNING NR 03//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) TROPICAL DEPRESSION 20W, LOCATED
APPROXIMATELY 75 NM SOUTH-SOUTHEAST OF PAGAN, CNMI, HAS TRACKED
WEST-NORTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY SHOWS FORMATIVE BANDS FEEDING-IN
MOSTLY FROM THE SOUTH HAVE MAINTAINED DEEP CONVECTIVE CELLS ALTHOUGH
THE CELLS REMAIN FRAGMENTED AND POORLY ORGANIZED. ADDITIONALLY, AT
LEAST TWO OTHER VORTICES APPEAR TO BE OSCILLATING NORTHEAST OF THE
MAIN LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS
BASED ON THE ABOVE ANIMATION AND EXTRAPOLATED FROM A NOTCH FEATURE ON
A 302257Z SSMI-S MICROWAVE IMAGE. THE INITIAL INTENSITY IS AVERAGED
FROM OBJECTIVE AND SUBJECTIVE DVORAK ESTIMATES FROM CIMS, PGTW, KNES,
AND RJTD. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS UNDER A RIDGE
AXIS IN AN AREA OF LIGHT (05-10 KNOT) VERTICAL WIND SHEAR (VWS).
ANIMATED WATER VAPOR IMAGERY SHOWS ENHANCED POLEWARD OUTFLOW INTO A
TUTT CELL NORTH OF THE RIDGE AXIS. THERE IS ALSO AMPLE EQUATORWARD
OUTFLOW ENHANCED BY STRONG NORTHEASTERLY WIND FLOW AWAY FROM THE
RIDGE AXIS. THE CYCLONE IS CURRENTLY TRACKING ALONG THE SOUTHWESTERN
PERIPHERY OF A DEEP LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
A MID-LATITUDE TROUGH DIGGING EASTWARD INTO THE YELLOW SEA IS POISED
TO WEAKEN THE STR.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE LAST
PROGNOSTIC REASONING BULLETIN.
   B. TD 20W IS EXPECTED TO TRACK ALONG THE PERIMETER OF THE STR. THE
AFOREMENTIONED TROUGH WILL WEAKEN THE STEERING RIDGE AND CAUSE THE TD
TO RECURVE NORTHEASTWARD AFTER TAU 48. THE SYSTEM WILL GRADUALLY
INTENSIFY AS UPPER LEVEL CONDITIONS REMAIN FAVORABLE, PEAKING AT TAU
72 DUE TO INCREASED OUTFLOW DURING ITS INITIAL EXPOSURE TO THE STRONG
WESTERLIES AHEAD OF THE TROUGH. THE NUMERICAL GUIDANCE MODELS ARE
SPLIT WITH JGSM, NOGAPS, AND GFDN DEVIATING TOWARDS THE SOUTHWEST AT
THE RECURVATURE POINT. THERE IS LOW CONFIDENCE IN THE INITIAL 72
HOURS OF THE FORECAST GIVEN THE EXTREME TRACK SOLUTIONS AND THE
POSSIBILITY OF A LLCC REFORMATION.
   C. AFTER TAU 72, TD 20W IS EXPECTED TO ACCELERATE NORTHEASTWARD
AND BECOME EXTRA-TROPICAL BY END OF FORECAST. THE SYSTEM WILL RAPIDLY
WEAKEN AS VWS INCREASES AND SEA SURFACE TEMPERATURES DECREASE. THERE
IS ALSO LOW CONFIDENCE IN THE EXTENDED PORTION OF THE FORECAST MAINLY
DUE TO DIFFERENCES IN LATERAL SPEED IN THE MODEL GUIDANCE.    //
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