WDPN31 PGTW 152100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 16W (SIXTEEN) 
WARNING NR 022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.9N 152.9E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 470 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:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
WEAKLY-DEFINED LOW-LEVEL CIRCULATION (LLC) WITH FLARING DEEP
CONVECTION SHEARED OVER THE NORTHWEST QUADRANT OF THE LLC. A
151826Z SSMIS 91GHZ COMPOSITE IMAGE REVEALS FRAGMENTED BANDING OVER
THE NORTHERN SEMICIRCLE BUT WEAK CONVECTIVE STRUCTURE ELSEWHERE.
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 ADT: 32 KTS AT 151750Z

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 BETWEEN TAU 36
TO 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: WITH THE EXCEPTION OF THE ECMWF ENSEMBLE MEAN
(EEMN), NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH THE
FORECAST PERIOD WITH A SPREAD OF 31NM AT TAU 36. 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 30 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 85 KNOTS.

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