WDPN31 PGTW 100300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 14W (FOURTEEN) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.8N 146.8E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 200 NM SOUTHEAST OF WFO GUAM 
   MOVEMENT PAST 6 HOURS: WESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 10 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS PERSISTENT
FLARING AND DEEP CONVECTION DIRECTLY OVER THE LOW-LEVEL CIRCULATION
CENTER (LLCC) OF TROPICAL DEPRESSION (TD) 14W. LOW-LEVEL CONVECTIVE
BANDS HAVE STARTED TO ORGANIZE ALONG THE WESTERN PERIPHERY OF THE
BROAD CYCLONIC FLOW OVER THE LAST FEW HOURS, WHILE OBSERVABLE
UPPER-LEVEL POLEWARD OUTFLOW HAS CONTINUED TO AID AND IMPROVE THE
OVERALL CONSOLIDATION TD 14W. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON THE 092313Z 89 GHZ GPM MICROWAVE IMAGE
SHOWING IMPROVED LOW-LEVEL CONVECTIVE CLOUD LINES CURVING INTO THE
ASSESSED POSITION. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON A PARTIAL 092257Z ASCAT-B IMAGE SHOWING A SWATH
OF 25 KTS INTENSITIES THROUGHOUT THE EASTERN SEMICIRCLE AND AGENCY
ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.0 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TD 14W WILL TRACK GENERALLY NORTHWESTWARD
THROUGHOUT THE FORECAST PERIOD ALONG THE WESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE. THE SYSTEM IS EXPECTED TO STEADILY INTENSIFY
THROUGH TAU 72 AS THE ENVIRONMENT REMAINS CONDUCIVE FOR FURTHER
DEVELOPMENT WITH VERTICAL WIND SHEAR (VWS) REMAINING LESS THAN 15
KTS, SEA SURFACE TEMPERATURES MAINTAIN AVERAGES ABOVE 30 C, AND
UPPER-LEVEL OUTFLOW AIDS IN SUSTAINED INTENSIFICATION. AS THE
SYSTEM CONTINUES TO TRACK TO THE NORTHWEST ALONG THE WESTERN EDGE
OF THE STEERING RIDGE, A CONTINUED CONDUCIVE ENVIRONMENT WILL ALLOW
TD 14W TO MAINTAIN STEADY TO MODERATE INTENSIFICATION WITH
ASSOCIATED SUPPORTIVE OCEAN HEAT CONTENT (OHC) VALUES THROUGH THE
CORRIDOR TO MINAMI DAITO JIMA. FOLLOWING TAU 72, MODERATE
INTENSIFICATION TO 100 KTS BY TAU 120 IS FORECASTED AS THE SYSTEM
ACCELERATES NORTHWESTWARD AS IT APPROACHES KADENA WITH IMPROVING
UPPER-LEVEL POLEWARD OUTFLOW.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE USED IN THE JTWC
CONSENSUS (CONW) REMAINS IN MODERATE AGREEMENT WITH A CROSS-TRACK
SPREAD OF 130 NM BY TAU 72, INCREASING TO 135 NM BY TAU 120.
PROBABILISTIC GUIDANCE FROM ECMWF (EPS) AND GFS (GEFS) ENSEMBLES
ARE IN GOOD AGREEMENT THAT A GENERALLY NORTHWEST TRACK WILL
CONTINUE THROUGHOUT THE 120 HOUR FORECAST PERIOD, LENDING MEDIUM
CONFIDENCE TO THE JTWC TRACK FORECAST. INTENSITY GUIDANCE REMAINS
IN MEDIUM CONFIDENCE THROUGH TAU 72, AS STEADY TO MODERATE
INTENSIFICATION IS EXPECTED, HOWEVER, DETERMINISTIC INTENSITY
GUIDANCE PAST 72 HOURS BECOMES LESS RELIABLE AS GFS HAS ILLUSTRATED
A MAX INTENSITY OF ONLY 55 KTS AT TAU 120. THE JTWC INTENSITY
FORECAST IS MORE ALIGNED WITH THE COAMPS-TC EPS INTENSITY GUIDANCE,
WITH STEADY TO MODERATE INTENSIFICATION FORECASTED INTO TAU 84,
WHILE A PERIOD OF RAPID INTENSIFICATION WITH PROBABILITIES OF
HIGHER 60 PERCENT IS EXPECTED AFTER TAU 84, LENDING LOW CONFIDENCE
BETWEEN TAU 72 AND TAU 120.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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