Tropical Storm FENGSHEN Advisory вт, 12.11.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 26W (TWENTYSIX)
WARNING NR 02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 26W (TWENTYSIX), LOCATED APPROXIMATELY
1038 NM EAST OF SAIPAN, CNMI, HAS TRACKED WEST-NORTHWESTWARD AT 12
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY SHOWS THE SYSTEM MAINTAINED OVERALL CONVECTIVE STRUCTURE AS
IT CONTINUES TO CONSOLIDATE. THE INITIAL POSITION IS PLACED WITH
GOOD CONFIDENCE BASED ON A RAGGED AND PARTLY OBSCURED LOW LEVEL
CIRCULATION FEATURE IN THE 111624Z SSMI 36GHZ COLORIZED IMAGE. THE
INITIAL INTENSITY OF 25 KNOTS IS BASED ON THE DVORAK ESTIMATES OF
T1.5/25KTS FROM PGTW AND RJTD. BASED ON ANALYSES, THE ENVIRONMENT IS
OVERALL FAVORABLE FOR DEVELOPMENT WITH LIGHT TO MODERATE (10-20KT)
VERTICAL WIND SHEAR (VWS), FAIR EQUATORWARD OUTFLOW, AND WARM (29C)
ALONG-TRACK SST VALUES. THE CYCLONE IS TRACKING ALONG THE SOUTHERN
PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TD 26W WILL CONTINUE IN ITS CURRENT TRACK UNDER THE STR UP TO
TAU 72. THE OVERALL FAVORABLE ENVIRONMENT WILL ENHANCE A GRADUAL
INTENSIFICATION, REACHING 75KTS BY TAU 72. NUMERICAL MODELS ARE IN
TIGHT AGREEMENT, LENDING HIGH CONFIDENCE TO THIS PORTION OF THE JTWC
TRACK FORECAST.
   C. AFTER TAU 72, TD 26W WILL TURN MORE NORTHWARD AS THE STR
WEAKENS IN RESPONSE TO A MID-LATITUDE TROUGH APPROACHING FROM THE
NORTHWEST, CREST THE STR AXIS, AND ACCELERATE NORTHEASTWARD ON THE
POLEWARD SIDE OF THE STR. STRONG JET WINDS AHEAD OF THE TROUGH WILL
INTRODUCE A VIGOROUS POLEWARD OUTFLOW AND BRING THE SYSTEM TO A PEAK
OF 85KTS BY TAU 96. AFTERWARD, INCREASING VWS AND COOLING SSTS WILL
BEGIN TO ERODE THE SYSTEM. CONCURRENTLY, TD 26W WILL BEGIN EXTRA-
TROPICAL TRANSITION AS IT APPROACHES THE COLD BAROCLINIC ZONE.
NUMERICAL MODELS ARE IN FAIR AGREEMENT WITH SPREADING TO 240NM BY
TAU 120; HOWEVER, THERE ARE DISTINCT DIFFERENCES IN THE ALONG-TRACK
SPEED ESPECIALLY DURING THE RECURVE NORTHEASTWARD. THEREFORE, THERE
IS LOW CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC TRACK
FORECAST.//
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