WDPN31 PGTW 160300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (NOKAEN) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.2N 128.9E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 505 NM EAST-SOUTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM (TS) 01W (NOKAEN) AS A PARTIALLY EXPOSED LOW LEVEL
CIRCULATION CENTER (LLCC) WITH A RECENT BURST OF DEEP CONVECTION
SHEARED SLIGHTLY WESTWARD. THE VORTEX REMAINS SHALLOW, DESPITE THE
HALF-HEARTED ATTEMPT AT INTENSIFYING. THE ENVIRONMENT IS MARGINALLY
FAVORABLE, CHARACTERIZED BY STRONG UPPER-LEVEL DIFFLUENCE, WARM
(28-29 C) SEA SURFACE TEMPERATURES, AND OFFSET BY HIGH (20-25 KTS)
EASTERLY VERTICAL WIND SHEAR AND DRY AIR WRAPPING CYCLONICALLY INTO
THE CORE FROM THE WEST. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE PARTIALLY EXPOSED LLCC PRESENT IN ANIMATED
MSI. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND OBJECTIVE INTENSITY
ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE (STR) CENTERED TO
THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RCTP: T2.5 - 35 KTS
   CIMSS ADT: 33 KTS AT 160140Z
   CIMSS AIDT: 33 KTS AT 160140Z
   CIMSS D-PRINT: 27 KTS AT 160140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: NORTHEASTERLY COLD SURGE TO THE NORTH OF THE
STORM AND DRY AIR ENTRAINMENT

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 01W WILL TRACK NORTHWESTWARD FOR THE NEXT
36 HOURS AS IT TRACKS ALONG THE WESTERN PERIPHERY OF THE STEERING
RIDGE CURRENTLY CENTERED TO THE NORTHEAST. AS IT TRACKS
NORTHWESTWARD, NOKAEN WILL ENCOUNTER THE NORTHEASTERLY COLD SURGE
AROUND TAU 48, INTRODUCING COPIOUS AMOUNTS OF COOLER AND DRIER AIR
THAT WILL AGGRESSIVELY SMOTHER THE VORTEX, ALLOWING IT TO BE MORE
SUSCEPTIBLE TO LOWER-LEVEL STEERING INFLUENCES AND OPENING THE
POSSIBILITY FOR ERRATIC MOVEMENT. ADDITIONALLY, THE ENHANCED
GRADIENT FLOW OF THE COLD SURGE MAY TEMPORARILY INTENSIFY THE STORM
OR INCREASE THE SIZE OF THE WIND RADII. BY TAU 72, 01W WILL BE MET
WITH THE ADVANCING FRONTAL BOUNDARY ASSOCIATED WITH THE COLD SURGE
AND PUSHED SOUTHWARD. THE NOKAEN IS EXPECTED TO TEETER AROUND
TROPICAL STORM STRENGTH BETWEEN TAUS 12-72, WITH THE DRY AIR AND
WIND SHEAR OFFSET BY A ROBUST POLEWARD OUTFLOW CHANNEL. BY TAU 48,
HOWEVER, THE OUTFLOW CHANNEL IS LOST AND THE DRY AIR WILL SMOTHER
THE SYSTEM, ULTIMATELY LEADING TO NOKAEN'S TERMINAL WEAKENING AND 
DISSIPATION BEYOND THE TAU 120.

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT IN A NORTHWESTWARD TRACK FOR THE NEXT 48 HOURS, BUT
UNCERTAINTY INCREASES REGARDING THE TRACK MOTION WHEN 01W
ENCOUNTERS THE COLD SURGE AND THE UNPREDICTABLE NATURE OF THE
STEERING ENVIRONMENT. THE JTWC TRACK FORECAST IS PLACED CLOSE TO
THE MULTI-MODEL CONSENSUS WITH MEDIUM CONFIDENCE FROM TAU 0-72 AND
LOW CONFIDENCE FROM TAU 72-120. RELIABLE INTENSITY AIDS ARE IN
MODERATE AGREEMENT IN A STAGNANT INTENSITY FOR THE MAJORITY OF THE
FORECAST PERIOD, HOWEVER, MESOSCALE MODELS ARE INDICATING THE
POSSIBILITY FOR A PEAK INTENSITY BEYOND 40 KTS. AS A RESULT, THE
JTWC INTENSITY FORECAST IS ASSESSED WITH OVERALL MEDIUM CONFIDENCE.

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