Tropical Storm TWENTYNINE Advisory vie, 17-12

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 29W (TWENTYNINE)
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 4.2N 104.0E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 176 NM NORTH OF SINGAPORE
   MOVEMENT PAST 6 HOURS: WESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
PARTIALLY EXPOSED BUT WELL DEFINED LOW LEVEL CIRCULATION CENTER,
WITH FLARING CONVECTION BEING SHEARED OFF TO THE WEST. A 161730Z
GPM COLORIZED 37GHZ MICROWAVE IMAGE DEPICTED A CYCLONICALLY CURVED
BAND OF DEEP CONVECTION EXTENDING FROM THE MALAYSIAN COAST TO THE
SOUTH OF THE ASSESSED CENTER, WITH LOW LEVEL SPIRAL BANDING
FEATURES EVIDENT IN THE OTHER QUADRANTS, WRAPPING INTO THE LLCC.
ANIMATED RADAR DATA FROM MALAYSIA IS SHOWING THE FIRST HINTS OF A
ROTATION JUST OFFSHORE NORTHEAST OF KUANTAN. THE INITIAL POSITION
IS PLACED WITH HIGH CONFIDENCE BASED ON THE GPM MICROWAVE IMAGE AND
RADAR DATA. THE INITIAL INTENSITY OF 25 KNOTS IS ASSESSED WITH HIGH
CONFIDENCE BASED ON A PGTW DVORAK FIX INTENSITY OF T1.5, AS WELL AS
A 161500Z SHIP OBSERVATION, LOCATED TO THE SOUTHEAST OF THE CENTER,
OF 23 KNOTS. ENVIRONMENTAL CONDITIONS ARE MARGINALLY FAVORABLE WITH
LOW TO MODERATE VWS, WARM SSTS (27-28C) AND GOOD POLEWARD OUTFLOW.
HOWEVER, PROXIMITY TO LAND WILL PROVE A HINDRANCE TO SIGNIFICANT
DEVELOPMENT.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF LOW TO MID-LEVEL
SUBTROPICAL RIDGE (STR) TO THE NORTH.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T1.5 - 25 KTS
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: PROXIMITY TO LAND.
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.
FORECAST DISCUSSION: TD 29W WILL CONTINUE TO TRACK SLOWLY WESTWARD
THROUGH THE FORECAST PERIOD, AND WILL MAKE LANDFALL JUST NORTH OF
KUANTAN, MALAYSIA WITHIN THE NEXT SIX HOURS. THE ENVIRONMENT IS
OVERALL FAVORABLE HOWEVER, THE PROXIMITY TO LAND SHOULD PROVE A
HINDRANCE TO SIGNIFICANT DEVELOPMENT. RECENT ANIMATED INFRARED
IMAGERY SUGGESTS THAT THE LLCC IS BEGINNING TO TUCK UNDER THE AREA
OF FLARING CONVECTION TO THE WEST, AND THUS IT IS POSSIBLE THAT THE
SYSTEM COULD BRIEFLY INTENSIFY TO 30 KNOTS PRIOR TO LANDFALL. ONCE
ASHORE, EXPECT STEADY DECAY OF THE CIRCULATION CENTER, WEAKENING
AND DISSIPATION NO LATER THAN TAU 24, THOUGH THE SYSTEM COULD
DISSIPATE WELL PRIOR TO THAT AS IT INTERACTS WITH THE COMPLEX
TERRAIN OF THE REGION.
MODEL DISCUSSION: NOT SURPRISINGLY FOR A WEAK SYSTEM SUCH AS THIS,
TRACK GUIDANCE IS IN POOR AGREEMENT, WITH A WIDE SPREAD IN
SOLUTIONS, SOME TACKING THE SYSTEM NORTHWESTWARD INTO THE FAR
NORTHERN MALACCA STRAIT, WHILE THE NAVGEM TURNS THE SYSTEM SOUTH
AND EAST. THE JTWC FORECAST REMAINS CONSISTENT WITH THE PREVIOUSLY
OBSERVED MOTION VECTOR AND ANALYSIS OF THE STEERING PATTERN. DUE TO
THE SHORT DURATION OF THE FORECAST, EVEN IN VIEW OF THE LARGE
SPREAD, THERE IS HIGH CONFIDENCE IN THE FORECAST TRACK. INTENSITY
GUIDANCE SOMEWHAT ODDLY ALL INDICATES INTENSIFICATION, EVEN OVER
LAND, THOUGH THIS IS HIGHLY UNLIKELY GIVEN THE TERRAIN FEATURES.
THUS THE INTENSITY GUIDANCE IS DISCOUNTED AND THE FORECAST RELIES
UPON TRENDS, WITH MEDIUM CONFIDENCE.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
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