WDPS31 PGTW 010300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 23P (URMIL) WARNING NR 
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.0S 177.5E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 358 NM SOUTH OF SUVA, FIJI
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 23 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 23P (URMIL) IS QUICKLY TRACKING SOUTHEASTWARD
UNDER THE INFLUENCE OF THE WESTERN PERIPHERY OF THE DEEP LAYER STR,
WHILE BECOMING INCREASINGLY EMBEDDED BENEATH AN UPPER-LEVEL MAJOR
SHORTWAVE TROUGH ASSOCIATED WITH THE SUBTROPICAL WESTERLIES. OVER
THE PAST SIX HOURS, THE LLCC HAS BECOME PARTIALLY EXPOSED, AS
DEPICTED BY ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI).
ENVIRONMENTAL CONDITIONS HAVE BECOME INCREASINGLY UNFAVORABLE, WITH
HIGH VERTICAL WIND SHEAR (25-30 KTS), MARGINAL SEA SURFACE
TEMPERATURES BETWEEN 26 C AND 27 C, AND INCREASED DRY-AIR
ENTRAINMENT WRAPPING INTO THE CORE FROM THE WESTERN SEMICIRCLE. THE
INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON ANIMATED
MSI, CONSISTENT WITH A 282134Z GMI 89 GHZ IMAGE. THE INITIAL
INTENSITY OF 55 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON
SUBJECTIVE AGENCY DVORAK ESTIMATES AND CIMSS OBJECTIVE INTENSITY
ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: 281757Z SAR DATA AND 281828Z SMOS DATA

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) POSITIONED
DIRECTLY TO THE EAST-NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   KNES: T4.5 - 77 KTS
   PHFO: T4.5 - 77 KTS
   CIMSS ADT: 55 KTS AT 010100Z
   CIMSS AIDT: 52 KTS AT 010100Z
   CIMSS D-MINT: 52 KTS AT 282207Z
   CIMSS D-PRINT: 53 KTS AT 010100Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 25-30 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 23P (URMIL) WILL
CONTINUE ITS SOUTHEASTWARD TRAJECTORY FOR THE REMAINDER OF THE
FORECAST PERIOD, DRIVEN BY THE STR POSITIONED TO THE
EAST-NORTHEAST. TC 23P IS FORECASTED TO CONTINUE UNDERGOING
SUBTROPICAL TRANSITION INTO TAU 12, INTERACTING WITH A MAJOR
SHORTWAVE TROUGH ASSOCIATED WITH THE SUBTROPICAL WESTERLIES. DURING
THIS PERIOD, INCREASING DRY-AIR ENTRAINMENT IS FORECASTED TO
CONTINUE WRAPPING INTO THE VORTEX FROM THE WEST, RESULTING IN AN
ELONGATED LLCC, TILTED VERTICAL STRUCTURE, AND A LOSS OF
SIGNIFICANT DEEP CONVECTION. TC 23P IS FORECASTED TO COMPLETE
SUBTROPICAL TRANSITION BY TAU 24 WITH A MAXIMUM SURFACE INTENSITY
NEAR 40 KTS. 

MODEL DISCUSSION: CROSS-TRACK SPREAD AMONG JTWC CONSENSUS SOLUTIONS
REMAIN UNDER 80 NM THROUGHOUT THE FORECAST PERIOD. THE JTWC
FORECASTED TRACK IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH
HIGH CONFIDENCE. INTENSITY SPREAD HAS DECREASED AND IMPROVED INTO
TAU 24, THEREFORE, THE JTWC FORECASTED INTENSITY LIES CLOSELY TO
THE MULTI MODEL CONSENSUS WITH HIGH CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
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