WDPN31 PGTW 182100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (MITAG) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.3N 116.5E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 141 NM EAST-SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM (TS) 23W WITH A LOW-LEVEL CIRCULATION (LLCC) THAT HAS
CONSOLIDATED OVER THE PAST 6 HOURS WITH INCREASED CONVECTIVE
ACTIVITY AND IMPROVED EQUATORWARD OUTFLOW. ENVIRONMENTAL ANALYSIS
INDICATES A MARGINALLY FAVORABLE ENVIRONMENT, CHARACTERIZED BY WARM 
SEA SURFACE TEMPERATURES (29-30 C) AND LOW VERTICAL WIND SHEAR (5-10 
KTS), OFFSET BY DRY AIR ENTRAINMENT FROM THE WEST. THE INITIAL 
POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE OBSCURED LLCC. 
LOW-LEVEL CLOUD WRAPPING IS STILL VISIBLE THROUGH THE EDGES OF MID-
LEVEL TURNING. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH 
MEDIUM CONFIDENCE BASED ON THE AGENCY AND OBJECTIVE INTENSITY 
ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: AN ELONGATED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 41 KTS AT 181737Z
   CIMSS ADT: 35 KTS AT 181730Z
   CIMSS AIDT: 37 KTS AT 181730Z
   CIMSS D-MINT: 32 KTS AT 181737Z
   CIMSS D-PRINT: 27 KTS AT 181830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

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: A TROUGH TRANSITING EAST TOWARDS THE EAST
CHINA SEA HAS CONTINUED TO ALLOW FOR TS 23W TO TRANSIT ALONG A
NORTHWESTWARD TRACK FOR THE NEXT 24HRS. THE INFLUENCE OF THE TROUGH
WILL BE SHORT LIVED AND THE REBUILDING OF THE STR WILL PUSH THE STORM 
WESTWARD FOR THE REMAINDER OF THE FORECAST PERIOD. LANDFALL IS 
EXPECTED TO OCCUR BETWEEN TAUS 24-36 NORTHEAST OF HONG KONG. THE 
SYSTEM WILL MAINTAIN A STRENGTH OF 40KTS THROUGH TAU 12. ALTHOUGH THE
ENVIRONMENT REMAINS MARGINALLY FAVORABLE, DRY AIR ENTRAINMENT FROM
THE WEST WILL INHIBIT FURTHER INTENSIFICATION. WINDS REMAIN
STRONGEST ON THE EASTERN SIDE OF THE CIRCULATION. AFTER LANDFALL,
23W WILL RAPIDLY WEAKEN, WITH DISSIPATION FORECAST TO OCCUR NO LATER 
THAN TAU 48 OVER SOUTHERN CHINA.

MODEL DISCUSSION: MODELS ARE IN BETTER AGREEMENT CONTINUING THE 
NORTHWESTWARD TRACK AND DEPICTING LANDFALL JUST NORTHWEST OF HONG 
KONG. NAVGEM REMAINS THE EXCEPTION WITH A SOUTHERN LANDFALL OVER HONG 
KONG. THE JTWC TRACK IS PLACED WITH MEDIUM CONFIDENCE HEDGED SLIGHTLY 
TO THE NORTH OF MOST CONSENSUS MEMBERS. A SIGNIFICANT AMOUNT OF DRY
AIR ENTERING THE WESTERN SIDE OF THE SYSTEM IS SHOWN ALTHOUGH SHEAR
REMAINS LOW. AS SUCH, THE JTWC INTENSITY FORECAST IS PLACED WITH
MEDIUM CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM//
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