WDPN32 PGTW 300900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 26W (TWENTYSIX) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.8N 150.9E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 297 NM EAST OF SAIPAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL DEPRESSION (TD) 26W HAS BECOME MORE ORGANIZED AND
INTENSIFIED OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY (MSI) DEPICTS PATCHY BUT PERSISTENT DEEP
CONVECTION OVER THE WESTERN PERIPHERY OF A PARTIALLY EXPOSED
LOW-LEVEL CIRCULATION. THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON MSI AND A 300530Z PGTW POSITION FIX. THE
INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED
ON A CONSENSUS OF SUBJECTIVE AND AUTOMATED INTENSITY ESTIMATES
LISTED BELOW, FURTHER SUPPORTED BY WIND SPEED DATA FROM A 300212Z
OCEANSAT-3 PASS.

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

CURRENT STEERING MECHANISM: LOW TO MID-LEVEL FLOW ASSOCIATED WITH A
DEEP-LAYER SUBTROPICAL RIDGE (STR) TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   CIMSS ADT: 31 KTS AT 300540Z
   CIMSS AIDT: 33 KTS AT 300540Z
   CIMSS D-MINT: 31 KTS AT 300307Z
   CIMSS D-PRINT: 29 KTS AT 300640Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

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: TD 26W IS EXPECTED TO TRACK SLIGHTLY NORTH OF
WESTWARD THROUGH TAU 36 UNDER THE CONTINUED INFLUENCE OF THE STR TO
THE NORTHEAST. THEREAFTER, THE SYSTEM WILL SLOWLY TURN POLEWARD AS
A DEVELOPING SHORTWAVE TROUGH TO THE NORTHWEST ERODES THE WESTERN
PORTION OF THE STEERING RIDGE. THE REORIENTED RIDGE WILL DRIVE THE
SYSTEM GENERALLY POLEWARD THROUGH THE REMAINDER OF THE FORECAST
PERIOD, WITH A WESTWARD NUDGE EXPECTED IN THE EXTENDED RANGE AS THE
AFOREMENTIONED TROUGH MOVES EASTWARD THE STEERING RIDGING REBUILDS
WESTWARD A BIT IN ITS WAKE. FAVORABLE ENVIRONMENTAL CONDITIONS
INCLUDING DECREASING VERTICAL WIND SHEAR, NEAR-TERM RADIAL OUTFLOW
ALOFT FOLLOWED BY ENHANCEMENT ON THE POLEWARD SIDE AS THE SYSTEM
REACHES THE WESTERN EDGE OF THE STEERING RIDGE, AND PASSAGE OVER
VERY WARM WATER WILL SUPPORT INTENSIFICATION THROUGH TAU 96.
EASTERLY VERTICAL WIND SHEAR AND THE INTRODUCTION OF DRIER AIR FROM
THE SURROUNDING ENVIRONMENT IS EXPECTED TO LIMIT THE RATE OF
INTENSIFICATION FOR THE FIRST 24 TO 36 HOURS OF THE FORECAST. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN BROAD OVERALL
AGREEMENT WITH THE OVERALL FORECAST SCENARIO, DEPICTING NEAR-TERM
WESTWARD TO WEST-NORTHWESTWARD MOTION FOLLOWED BY A POLEWARD TURN.
HOWEVER, DEPICTIONS OF THE INTERACTION BETWEEN A DEVELOPING
SHORTWAVE TROUGH TO THE NORTHWEST AND THE STEERING RIDGE VARY
WIDELY BETWEEN SOLUTIONS, YIELDING SIGNIFICANT DIFFERENCES IN
DEPICTIONS OF THE STEERING FLOW AND TIMING AND LOCATION OF THE
POLEWARD TURN. CONSENSUS MODEL GUIDANCE HAS CONSISTENTLY WALKED
WESTWARD OVER THE PAST SEVERAL CYCLES, ALIGNING CLOSER TO THE AI
MODEL CONSENSUS, WHICH HAS BEGUN TO STABILIZE AFTER SIMILARLY
WALKING WESTWARD ON PREVIOUS CYCLES. THE CURRENT JTWC TRACK
FORECAST FAVORS AI MODEL SOLUTIONS AND LIES SLIGHTLY WEST OF THE
PREVIOUS FORECAST. THE FORECAST IS PLACED WITH LOW CONFIDENCE AS THE 
GUIDANCE PACKAGE IS STILL SPREAD, ALBEIT LESS THAN THE PREVIOUS 
CYCLE, AND HAS NOT YET SETTLED ON A FINAL LOCATION OF THE POLEWARD 
TURN. ASIDE FROM HAFS-A, WHICH DEPICTS A LOWER RATE OF 
INTENSIFICATION ON THE CURRENT RUN, INTENSITY FORECAST GUIDANCE HAS 
COME INTO BETTER AGREEMENT REGARDING SLOW TO STEADY INTENSIFICATION 
IN THE NEAR- TO MEDIUM-TERM. THE CURRENT INTENSITY FORECAST IS 
CONSISTENT WITH THE PREVIOUS FORECAST GIVE THE TREND IN GUIDANCE 
TOWARD ADDITIONAL SUPPORT.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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