WDPN31 PGTW 110300 AMD
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 14W (BEBINCA) 
WARNING NR 005A AMENDED//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.7N 142.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 147 NM WEST OF NAVSTA GUAM
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 18 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
DEPRESSION (TD) 14W AS REMAINING STEADY IN SLOW INTENSIFICATION,
WITH PERSISTENT CONVECTION LOCATED JUST TO THE SOUTHEAST OF THE
LOW-LEVEL CIRCULATION CENTER (LLCC). MODERATE VERTICAL WIND SHEAR
(VWS) OF 20 KTS HAS BECOME EVIDENT AS TD 14W HAS STRUGGLED TO
CONSOLIDATE OVER THE LAST FEW HOURS WITH A SLIGHTLY TILTED VERTICAL
STRUCTURE TO THE SOUTHEAST. PARTIALLY EXPOSED LOW-LEVEL CONVECTIVE
BANDING CONTINUES TO NEATLY WRAP AROUND THE WESTERN PERIPHERY OF
THE SYSTEM, WHILE MUCH OF THE EASTERN FLANK REMAINS OBSCURED BY
SCATTERED CONVECTIVE CELLS AND CIRRUS BLOWOFF. DESPITE THE WEAK
RADIAL AND POLEWARD OUTFLOW, TD 14W HAS STRUGGLED TO INTENSIFY AS
EXPECTED OVER THE LAST FEW HOURS. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON A 110016Z ASCAT-B PASS SHOWING SWATHS
OF 30 KTS WITHIN THE NORTHEASTERN QUADRANT. THE INITIAL INTENSITY
IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED
ASCAT-B PASS AND AGENCY INTENSITY ESTIMATES LISTED BELOW.

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

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 40 KTS AT 0000Z
   CIMSS ADT: 57 KTS AT 0100Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: WEAK RADIAL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: INITIAL INTENSITY DECREASED FROM 6
HOURS AGO DUE TO A RECENT 110016Z ASCAT-B PASS. 

FORECAST DISCUSSION: TD 14W HAS REMAINED STEADY IN INTENSITY OVER
THE LAST FEW HOURS, HOWEVER, IS FORECASTED TO INTENSIFY AND TRACK
NORTH-NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF THE STR UNTIL
TAU 48. AFTER TAU 48, TD 14W WILL BEGIN TO TRACK NORTHWESTWARD
THROUGHOUT THE REMAINDER OF THE FORECAST PERIOD UNTIL TAU 120 AS
THE SYSTEM APPROACHES COASTAL CHINA. IN REGARD TO INTENSITY, TD 14W
WILL STEADILY INTENSIFY THROUGH TAU 48 AS ENVIRONMENTAL CONDITIONS
REMAIN LARGELY CONDUCIVE WITH LOW VERTICAL WIND SHEAR, WARM SEA
SURFACE TEMPERATURES OF ABOVE 29 C, AND SUPPORTIVE OCEAN HEAT
CONTENT VALUES. AFTER TAU 48, AMPLIFIED UPPER-LEVEL DIVERGENCE WILL
ALLOW FOR INCREASED INTENSIFICATION AS THE SYSTEM BEGINS TO MOVE
NORTHWESTWARD TO A MAXIMUM OF 100 KTS AFTER THE RYUKU ISLANDS. NEAR
THE END OF THE FORECAST PERIOD, TD 14W IS EXPECTED TO SLIGHTLY
WEAKEN AS DRY AIR ENTRAINS FROM THE WESTERN SEMICIRCLE, INTO THE
SOUTHERN QUADRANT. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
WITH A 45 NM CROSS TRACK SPREAD BY TAU 12. AFTER TAU 12,
CROSS-TRACK SPREAD BEGINS TO GRADUALLY INCREASE TO 120 NM BY TAU 72
LENDING MEDIUM CONFIDENCE TO THE JTWC FORECAST TRACK. FOLLOWING TAU
72, THE NUMERICAL MODEL GUIDANCE TRACK SPREAD BEGINS TO INCREASE
SIGNIFICANTLY, LENDING LOW CONFIDENCE TO THE FORECAST TRACK BETWEEN
TAU 72 AND TAU 120. INTENSITY GUIDANCE IS ASSESSED WITH MEDIUM
CONFIDENCE THROUGH TAU 72, AS STEADY TO MODERATE INTENSIFICATION IS
FORECASTED. AFTER TAU 72, THE INTENSITY GUIDANCE CONTINUES TO
REMAIN LESS RELIABLE AS MESOSCALE MODEL GUIDANCE INDICATES RAPID
INTENSIFICATION AFTER TAU 66, WHILE DETERMINISTIC MODEL GUIDANCE
(GFS AND ECMWF) ILLUSTRATE A GRADUAL INCREASE IN INTENSITY UNTIL
TAU 108, THEN DECREASE INTO THE END OF THE FORECAST PERIOD. THE
JTWC INTENSITY FORECAST ALIGNS CLOSELY WITH THE DETERMINISTIC
NUMERICAL MODEL GUIDANCE THROUGH TAU 72, WHILE INDICATING A PERIOD
OF AMPLIFIED INTENSIFICATION TO 100 KTS BY TAU 96. 

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

4. JUSTIFICATION FOR AMENDMENT: UPDATED MOVEMENT PAST SIX HOUR 
SPEED.//
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