WDPN31 PGTW 180900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 24W (TWENTYFOUR) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 29.6N 158.8E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 413 NM NORTHEAST OF MINAMI TORI SHIMA
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 11 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY-
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) ON THE WESTERN EDGE OF A 
CURVED CONVECTIVE BAND. AN 180548Z SSMIS 91GHZ COLOR COMPOSITE 
MICROWAVE IMAGE INDICATES A DEFINED LLCC DISPLACED ABOUT 45NM 
NORTHWEST OF A DEFINED UPPER-LEVEL CIRCULATION CENTER. THE INITIAL 
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE SSMIS IMAGE. THE 
INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON 
THE PGTW DVORAK FIX. ENVIRONMENTAL CONDITIONS ARE MARGINALLY 
FAVORABLE WITH LOW VERTICAL WIND SHEAR AND EASTWARD OUTFLOW OFFSET BY 
THE DRY AIR ENTRAINMENT AND BORDERLINE SST VALUES (26C).

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

CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A DEEP-
LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST AND
SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   KNES: T1.5 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE EASTWARD
   OTHER FACTORS: EXTENSIVE MID- TO UPPER-LEVEL DRY AIR
ENTRAINMENT.

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: TD 24W IS FORECAST TO RECURVE NORTH-
NORTHEASTWARD TO NORTHEASTWARD THROUGH THE FORECAST PERIOD
ALONG THE NORTHWESTERN TO NORTHERN PERIPHERY OF THE STR. THE SYSTEM
WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) NEAR TAU 12 AS IT BEGINS
TO INTERACT WITH THE MIDLATITUDE WESTERLIES. TD 24W WILL COMPLETE
ETT BY TAU 36 AS IT MERGES WITH A STRONG FRONTAL ZONE AND TRACKS
OVER COOLER SST VALUES (24-25C).

MODEL DISCUSSION: WITH THE EXCEPTION OF AN ERRONEOUS, LOOPING AFUM
TRACKER, NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT LENDING
HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. RELIABLE INTENSITY
GUIDANCE SUPPORTS A BRIEF INTENSIFICATION TO 35 KNOTS THEN A STEADY
WEAKENING TREND THROUGH TAU 36. THERE IS A POSSIBILITY THAT THE
SYSTEM MAY DISSIPATE PRIOR TO COMPLETING ETT.   

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