WDPN31 PGTW 160300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 16W (SIXTEEN) 
WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.1N 151.3E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 375 NM EAST OF ANDERSEN AFB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 10 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TD 16W HAS CONTINUED TO WEAKEN AS INDICATED IN ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI), WHICH REVEALS A BROAD,
WEAKLY-DEFINED LOW-LEVEL CIRCULATION (LLC) AND RAPIDLY-DECAYING
CONVECTION. ADDITIONALLY, MSI SHOWS NUMEROUS OUTFLOW BOUNDARIES
ALONG THE NORTHERN FLANK ASSOCIATED WITH THE RELATIVELY DRY
ENVIRONMENT. A 152039Z SSMIS 91GHZ IMAGE DEPICTS DISORGANIZED
CONVECTION ALONG THE NORTHERN FLANK WITH A BROAD LLC POSITIONED TO
THE SOUTH. A 152135Z ASCAT-A BULLSEYE IMAGE DEPICTS A BROAD
CIRCULATION WITH EXTENSIVE 0-10 KNOT CORE WINDS AND 20-25 KNOT
EASTERLIES DISPLACED OVER THE NORTH QUADRANT, WHICH SUPPORTS THE
INITIAL INTENSITY OF 25 KNOTS WITH MEDIUM CONFIDENCE. UPPER-LEVEL
ANALYSIS CONTINUES TO INDICATE A MARGINAL ENVIRONMENT WITH 20- TO 30-
KNOT UPPER-LEVEL NORTHEASTERLIES DIVERGING OVER THE SYSTEM INTO A 
BROAD TUTT CELL POSITIONED NEAR 23N 143E. SEA SURFACE TEMPERATURE 
AND OCEAN HEAT CONTENT VALUES REMAIN HIGHLY CONDUCIVE, HOWEVER, 
VERTICAL WIND SHEAR HAS INCREASED TO MODERATE LEVELS (15 TO 20 
KNOTS) WITH DRY AIR ENTRAINING INTO THE SYSTEM CORE.

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

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
ENTRENCHED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T1.5 - 25 KTS
   CIMSS SATCON: 43 KTS AT 152057Z
   CIMSS ADT: 37 KTS AT 152350Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: WEAK POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: MEDIUM
   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: TD 16W IS EXPECTED TO TRACK WESTWARD ALONG THE
SOUTHERN PERIPHERY OF THE STR THROUGH TAU 48 THEN TURN WEST-
NORTHWESTWARD THROUGH TAU 120 AS IT TRACKS ALONG THE SOUTHWEST
PERIPHERY OF THE STR. TD 16W SHOULD SLOWLY INTENSIFY BY TAU 48 AS
ENVIRONMENTAL CONDITIONS GRADUALLY IMPROVE. AFTER TAU 48, TD 16W
WILL STEADILY INTENSIFY THROUGH THE REMAINDER OF THE PERIOD TO A
PEAK INTENSITY OF 75 KNOTS BY TAU 120. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT
THROUGH THE FORECAST PERIOD WITH A SPREAD OF 50NM AT TAU 24. DUE TO 
THE WEAK NATURE OF THE LLC, THERE IS ADDITIONAL UNCERTAINTY IN THE 
INITIAL POSITION OF THIS BROAD LLC, WHICH COULD LEAD TO MINOR SHIFTS 
IN THE TRACK AND CPA TIMING AS THE SYSTEM TRACKS TOWARD GUAM. 
INTENSITY GUIDANCE IS IN FAIR AGREEMENT THROUGH TAU 36 WITH A RANGE 
OF 25 TO 35 KNOTS. AFTER TAU 36, INTENSITY GUIDANCE DIVERGES WITH 
INCREASED UNCERTAINTY IN THE JTWC INTENSITY FORECAST. THE JTWC 
INTENSITY FORECAST REMAINS CONSERVATIVE BUT IS SUPPORTED BY THE JTWC
INTENSITY CONSENSUS, WHICH PEAKS AT 80 KNOTS.

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