WDPN31 PGTW 230300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 28W (TWENTYEIGHT) 
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.9N 112.7E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 354 NM EAST OF HO CHI MINH CITY, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A BROAD,
MOSTLY EXPOSED LOW-LEVEL CIRCULATION WITH A SECONDARY VORTEX,
POSSIBLY ASSOCIATED WITH THE REMNANTS OF PREVIOUS INVEST AREA 98W, 
ROTATING CYCLONICALLY AROUND THE CENTER TO THE NORTH AND EAST. THE 
INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON MULTI-
AGENCY FIXES AND A 222236Z SSMIS PASS. THE INITIAL INTENSITY OF 30 KTS 
IS ASSESSED WITH HIGH CONFIDENCE BASED ON A CONSENSUS OF AVAILABLE 
SUBJECTIVE DVORAK AND AUTOMATED INTENSITY ESTIMATES AS WELL AS A 
RECENTLY RECEIVED 230122Z METOP-B ASCAT PASS.

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

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGING (STR) TO THE
NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 40 KTS AT 222237Z
   CIMSS ADT: 30 KTS AT 222320Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL DEPRESSION (TD) 28W WILL CONTINUE
TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE STR FOR THE NEXT
12 HOURS. THEREAFTER, THE STEERING RIDGE IS EXPECTED TO BUILD INTO
A MORE CONTINUOUS WEST TO EAST ORIENTATION AS A SHORTWAVE TROUGH
CURRENTLY ANALYZED OVER THE NORTHWESTERN PORTION OF THE SOUTH CHINA
SEA TRANSLATES EASTWARD. THE REORIENTED RIDGE WILL STEER THE SYSTEM
WESTWARD TO WEST-SOUTHWESTWARD THROUGH THE REMAINDER OF THE
FORECAST PERIOD. THE SYSTEM IS EXPECTED TO SLOWLY INTENSIFY OVER
THE NEXT 24 HOURS AS IT CONTINUES TO INTERACT WITH A NORTHEASTERLY
COLD SURGE ANALYZED OVER THE WESTERN PORTION OF THE SOUTH CHINA
SEA, WHICH WILL DRIVE BOTH CONVECTIVE DEVELOPMENT OVER THE WESTERN
PERIPHERY OF THE CIRCULATION AND WRAPPING OF STRONGER SURGE
ASSOCIATED WINDS AROUND THE CIRCULATION. ENTRAINMENT OF DRIER AIR
ASSOCIATED WITH THE SURGE, PASSAGE OVER COOLER WATER, AND
INCREASING VERTICAL WIND SHEAR WILL RESULT IN INEVITABLE
DISSIPATION BY TAU 72. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS AGAIN IN GOOD
AGREEMENT REGARDING THE OVERALL FORECAST SCENARIO. TRACK FORECAST
SPREAD, DRIVEN BY DIFFERING PREDICTIONS OF THE STORM STRUCTURE,
COLD SURGE EVOLUTION, AND ADJUSTMENTS IN THE STEERING FLOW PATTERN,
HAVE DECREASED SLIGHTLY SINCE THE PREVIOUS CYCLE. HOWEVER, THE
GEFS ENSEMBLE CONTINUES TO TRACK THE SYSTEM AND ITS REMNANTS A BIT TO 
THE SOUTH OF THE PRIMARY MODEL GROUPING. THE CURRENT TRACK FORECAST IS
PLACED NEAR BOTH THE MULTI-MODEL CONSENSUS AND PREVIOUS JTWC
FORECAST WITH MEDIUM CONFIDENCE. AVAILABLE INTENSITY FORECAST GUIDANCE 
DEPICTS A STEADY STATE TO SLIGHT INTENSIFICATION IN THE NEAR-TERM 
FOLLOWED BY DISSIPATION WITHIN 48 TO 72 HOURS.

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