WDPS31 PGTW 280300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 23P (URMIL) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.4S 170.7E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 212 NM SOUTHEAST OF PORT VILA, VANUATU
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 23P (URMIL) WITH A COMPLETELY OBSCURED LOW LEVEL
CIRCULATION CENTER (LLCC). DEEP CONVECTION HAS PERSISTED SINCE THE
PREVIOUS WARNING, OFFSET TO THE NORTHEASTERN QUADRANT OF THE SURFACE
CIRCULATION, WHILE CLOUD TOP TEMPERATURES HAVE WARMED OVER THE LAST
FEW HOURS, DEPICTED ON ANIMATED EIR SATELLITE IMAGERY.
ENVIRONMENTAL CONDITIONS HAVE REMAINED MARGINALLY FAVORABLE, WITH
MODERATE VERTICAL WIND SHEAR (15-20 KTS), 27 C TO 28 C SEA SURFACE
TEMPERATURES, AND MODERATE POLEWARD AND EQUATORWARD OUTFLOW. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON AN EARLIER
272153Z METOP-B ASCAT PASS. THE INITIAL INTENSITY OF 65 KTS IS
ASSESSED WITH HIGH CONFIDENCE, BASED ON AN EARLIER 271819Z SAR
PASS, CIMSS OBJECTIVE INTENSITY ESTIMATES, AND SUBJECTIVE AGENCY
DVORAK ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: 271819Z SAR DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE CENTERED TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   KNES: T4.0 - 65 KTS
   PHFO: T4.0 - 65 KTS
   NFFN: T3.5 - 55 KTS
   CIMSS SATCON: 53 KTS AT 272100Z
   CIMSS ADT: 63 KTS AT 280100Z
   CIMSS AIDT: 56 KTS AT 280100Z
   CIMSS D-MINT: 52 KTS AT 272217Z
   CIMSS D-PRINT: 56 KTS AT 280100Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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) IS
FORECASTED TO CONTINUE SOUTHEASTWARD FOR THE REMAINDER OF THE
FORECAST PERIOD UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE TO THE
EAST. WITH REGARDS TO INTENSITY, THE SYSTEM IS FORECASTED TO
GRADUALLY INTENSIFY TO A MAXIMUM OF 75 KTS OVER THE NEXT 24 HOURS.
AFTERWARDS, ENVIRONMENTAL CONDITIONS WILL INITIATE A TERMINAL
WEAKENING TREND FOR TC 23P, WITH THE VORTEX ENCOUNTERING 30+ KTS OF
MID-LEVEL VERTICAL WIND SHEAR, COOLER SEA SURFACE TEMPERATURES (26
C TO 27 C), AND DRY AIR ENTRAINMENT WRAPPING INTO THE WESTERN AND
NORTHERN QUADRANTS. THE AFOREMENTIONED ENVIRONMENTAL CONDITIONS
WILL QUICKEN SUBTROPICAL TRANSITION AFTER TAU 24, WITH TC 23P
COMPLETING SUBTROPICAL TRANSITION BY TAU 36 DUE TO ENHANCED VWS
GREATER THAN 30 KTS AND DRY-AIR ENTRAINMENT. TC 23P WILL RETAIN
ELEVATED SURFACE INTENSITIES NEAR 65 KTS AT TAU 36, THROUGH ITS
TRANSITION INTO AN ASYMMETRIC WARM-CORE CYCLONE AND CONTINUE TO
WEAKEN THEREAFTER AS THE SYSTEM BECOMES COMPLETELY EMBEDDED WITHIN
AN EQUATORWARD EXTENSION OF A MID-LATITUDE LONGWAVE TROUGH.

MODEL DISCUSSION: MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON A
CONTINUED SOUTHEASTWARD TRACK OF 23P AS IT IS DRIVEN POLEWARD BY
THE STR TO THE EAST. CROSS TRACK SPREAD IS 50 NM BY TAU 36. THE
JTWC FORECASTED TRACK IS PLACED CLOSE TO THE MULTI MODEL CONSENSUS
WITH HIGH CONFIDENCE. INTENSITY GUIDANCE CONTINUES TO AGREE ON A
SHORT TERM WINDOW FOR INTENSIFICATION UNTIL TAU 24, AND A TERMINAL
WEAKENING TREND THEREAFTER. THE JTWC FORECASTED INTENSITY IS PLACED
CLOSE TO THE MULTI MODEL CONSENSUS WITH MEDIUM CONFIDENCE,
ACCOUNTING FOR UNCERTAINTIES IN THE FORECASTED POLEWARD OUTFLOW AND
QUICKENED SUBTROPICAL TRANSITION PHASE.

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