WDPN32 PGTW 172100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (PULASAN) WARNING NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.3N 133.4E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 396 NM SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A FULLY
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC), WITH MULTIPLE ISOLATED
AREAS OF ROTATION CIRCULATING AROUND A CENTRAL VORTEX. ASSOCIATED
CONVECTION HAS REMAINED SEPARATED FROM THE LOW-LEVEL CIRCULATION
WITHIN THE NORTHERN AND WESTERN QUADRANTS, ALTHOUGH AN OBSERVED
INCREASE IN FLARING CONVECTION HAS BEEN OBSERVED WITHIN THE
SOUTHEAST QUADRANT OVER THE LAST FEW HOURS. A TROPICAL UPPER
TROPOSPHERIC TROUGH (TUTT) HAS CONTINUED TO FEED DRY AIR INTO THE
WESTERN PERIPHERY OF THE SYSTEM, LEAVING MUCH OF THE WESTERN HALF
OF 15W VOID OF ANY SUPPORTIVE CONVECTION. IN REGARD TO THE
UPPER-LEVELS, OUTFLOW ALOFT HAS IMPROVED OVER THE LAST SIX HOURS,
WITH A SOUTHWARD EXTENDING EQUATORWARD CHANNEL AND WEAK RADIAL
OUTFLOW ASSOCIATED WITH THE AFOREMENTIONED CONVECTION. THE INITIAL
POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE FULLY
EXPOSED LOW-LEVEL CIRCULATION CENTER OBSERVED ON ANIMATED EIR, AS
MULTIPLE AREAS OF CYCLONIC TURNING ARE PRESENT. THE INITIAL
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON AN EARLIER
170857Z RCM-2 SAR PASS. ALTHOUGH 65 KTS WERE OBSERVED IN EARLIER
AVAILABLE WIND DATA, THE AREA OF ENHANCED WINDS REMAIN ISOLATED AND
150 NM TO THE NORTHWEST.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TY 15W CONTINUES TO MAINTAIN THE
CHARACTERISTICS OF A MONSOON DEPRESSION, WITH ASSOCIATED BROAD
TURNING AND A BAND OF INTENSE WINDS LOCATED 140 NM TO 300 NM NORTH
AND EAST OF THE ASSESSED CENTER. THE SYSTEM'S NORTHWEST TRACK IS
EXPECTED TO CONTINUE THROUGH THE 72 HOUR FORECAST PERIOD, AS
SUBTROPICAL RIDGING TO THE NORTH WILL DRIVE 15W WESTWARD ALONG THE
SOUTHERN PERIPHERY. ALTHOUGH THE FORECASTED TRACK IS EXPECTED TO
REMAIN BETWEEN 35 NM AND 45 NM SOUTHWEST OF OKINAWA, THE NATURE AND
CHARACTERISTICS OF THE ASSOCIATED BROAD WIND FIELD COULD IMPACT
OKINAWA SOONER, WHILE THE SOUTHEASTWARD EXTENSION OF THE MONSOON
DEPRESSION MAY ALLOW FOR A SECOND ENHANCED WIND EVENT AS THE SYSTEM
PROGRESSES TO THE NORTHWEST AND TOWARD MAINLAND CHINA. AFTER TAU
36, A WEAKENING IN THE SURFACE PRESSURE GRADIENT WILL ALLOW FOR THE
FORECASTED WEAKENING OF 15W BEFORE LANDFALL. AFTER LANDFALL, THE
SYSTEM WILL RAPIDLY WEAKEN DUE TO TOPOGRAPHIC INTERACTION, A
DECREASING PRESSURE GRADIENT, AND INCREASED DRY-AIR ENTRAINMENT
FROM THE TUTT CELL ALOFT.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN TIGHT
AGREEMENT AS THE SYSTEM TRACKS NORTHWESTWARD, WITH A MAXIMUM
CROSS-TRACK SPREAD OF 115 NM JUST BEFORE LANDFALL. AFTER LANDFALL,
THE MEMBERS OF THE JTWC CONSENSUS DIVERGE SIGNIFICANTLY NEAR TAU 72
DURING THE SYSTEM'S RAPID WEAKENING PHASE. THE JTWC FORECAST IS
ALIGNED WITH THE MULTI-MODEL CONSENSUS, LENDING HIGH CONFIDENCE TO
THE 0-72 HR TRACK. THE MODEL INTENSITY GUIDANCE HAS IMPROVED SINCE
THE LAST FORECAST, WITH GFS BEING THE ONLY OUTLIER THROUGH THE 72
HOUR FORECAST PERIOD, SHOWING INITIAL AND SUSTAINED WEAKENING. THE
JTWC INTENSITY FORECAST REMAINS CLOSELY ALIGNED WITH MULTI-MODEL
INTENSITY CONSENSUS.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
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