WDPN32 PGTW 040900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (THIRTEEN) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.5N 147.0E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 268 NM EAST-NORTHEAST OF CHICHI JIMA
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS LOW-LEVEL
CLOUDS WRAPPING IN TO A LOW-LEVEL CIRCULATION CENTER (LLCC)
PARTIALLY OBSCURED BY CIRRUS CLOUDS. THE UPPER-LEVEL STRUCTURE IS
DISORGANIZED DUE TO LOW TO MODERATE SOUTHEASTERLY WIND SHEAR. WATER
VAPOR IMAGERY REVEALS WEAK RADIAL OUTFLOW CUT OFF BY AN UPPER-LEVEL
CYCLONE NEARBY TO THE SOUTHWEST. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED LLCC DEPICTED ON
ANIMATED MSI.

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

CURRENT STEERING MECHANISM: A LOBE OF A SUBTROPICAL RIDGE (STR) TO
THE EAST-NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 36 KTS AT 040333Z
   CIMSS ADT: 31 KTS AT 040530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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) 13W WILL TRACK
NORTH-NORTHWESTWARD FOR THE NEXT 24 HOURS BEFORE ROUNDING THE RIDGE
AXIS BETWEEN TAU 24-36. THE SYSTEM WILL TRACK NORTHWESTWARD BETWEEN
TAU 48-72 WHILE UNDERGOING EXTRATROPICAL TRANSITION AS THE SYSTEM
BECOMES EMBEDDED UNDER A DEEP-LAYER TROUGH OFF OF THE EAST COAST OF
JAPAN. DURING THE INITIAL 24-HOUR PERIOD, TD 13W WILL SLIGHTLY
INTENSIFY TO 35KTS WHILE IN A FAVORABLE ENVIRONMENT OF LOW SHEAR,
UPPER-LEVEL DIVERGENCE, AND WARM SEA SURFACE TEMPERATURES. AS THE
SYSTEM APPROACHES THE UPPER-LEVEL TROUGH, VERTICAL WIND SHEAR WILL
INCREASE. ADDITIONALLY, THE SYSTEM WILL PASS INTO COOL SEA SURFACE
TEMPERATURES BELOW 26C BETWEEN TAU 48-72, FURTHER SUPPORTING THE
COMPLETION OF EXTRATROPICAL TRANSITION.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN TIGHT
AGREEMENT IN THE NEAR-TERM TRACK GUIDANCE, WITH A MAXIMUM
ALONG-TRACK SPREAD OF 170NM BY TAU 72 DUE TO VARYING
INTERPRETATIONS OF HOW QUICKLY THE SYSTEM WILL SPEED UP AFTER
ROUNDING THE STR. SEVERAL MODELS LOSE TRACK OF THE VORTEX PRIOR TO
TAU 72, SUCH AS NAVGEM AND ECMWF. THE INTENSITY GUIDANCE IS ALSO IN
GOOD AGREEMENT HOVERING BETWEEN 30-35KTS THROUGHOUT THE FORECAST
PERIOD.

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