WDPN31 PGTW 050300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15E (NOLO) WARNING NR 058//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.8N 179.3E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 794 NM NORTHWEST OF JOHNSTON ISLAND
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 46 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON (TY)
15E (NOLO) WITH A RAGGED, PARTIALLY CLOUD-FILLED EYE WITH A
TEMPERATURE OF 16 C SURROUNDED BY A THICK, NEARLY SYMMETRICAL
CONVECTIVE RING WHICH HAS MAINTAINED CLOUD TOP TEMPERATURES OF -60
C OVER THE PAST SIX HOURS. 15E HAS ALSO CONTINUED DEVELOPING OUTER
RAINBANDS THAT ARE WRAPPING IN ON THE EASTERN AND SOUTHERN FLANKS,
ALTHOUGH THE DEEPEST CONVECTION REMAINS CONFINED TO THE PRIMARY
RING. ENVIRONMENTAL CONDITIONS ARE ASSESSED AS FAVORABLE, WITH WARM
(28-29 C) SEA SURFACE TEMPERATURES (SSTS), LOW (5-10 KTS) VERTICAL
WIND SHEAR (VWS), AND MODERATE RADIAL OUTFLOW ALOFT. THE INITIAL
POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE EYE IN MSI.
THE INITIAL INTENSTY IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A
BLEND OF AGENCY DVORAK FIXES AND OBJECTIVE ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: 041800Z RCM-2 SAR DATA

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE CENTERED TO THE
NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T6.0 - 115 KTS
   RCTP: T5.0 - 90 KTS
   PHFO: T3.0 - 45 KTS
   CIMSS ADT: 99 KTS AT 042330Z
   CIMSS AIDT: 102 KTS AT 042330Z
   CIMSS D-MINT: 95 KTS AT 042146Z
   CIMSS D-PRINT: 114 KTS AT 042330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 15E IS FORECAST TO CONTINUE
WEST-NORTHWESTWARD OVER THE NEXT 12 HOURS UNDER THE STEERING
INFLUENCE OF THE SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST.
TRACK SPEED WILL TEMPORARILY SLOW AS 15E REACHES A WEAKNESS IN THE
STEERING RIDGE, HOWEVER, BY TAU 24 THE STR IS EXPECTED TO REBUILD
TO THE NORTHWEST OF 15E AND CONTINUE STEERING THE TRACK WESTWARD.
BETWEEN TAUS 72 AND 96 NOLO IS FORECAST TO TURN NORTHWESTWARD AS IT
BEGINS TO ROUND THE AXIS OF THE STR. REGARDING INTENSITY, TY 15E IS
FORECAST TO MAINTAIN AN INTENSITY OF AROUND 100 KTS FOR THE NEXT 24
HOURS AS IT MAINTAINS FAVORABLE OUTFLOW ALOFT, LOW VWS, AND GOOD
MOISTURE CONTENT. AFTER TAU 24, A WEAKENING TREND IS EXPECTED AS
VWS BECOMES INCREASINGLY HOSTILE, OUTFLOW WORSENS, AND DRY AIR
BEGINS TO ENTRAIN INTO THE CORE. NEAR THE END OF THE FORECAST
PERIOD, THERE IS A SLIGHT WINDOW IN WHICH TY 15E IS EXPECTED TO
REINTENSIFY AS IT ROUNDS THE STR AXIS AND NEARS THE UPPER-LEVEL
JET, PROVIDING STRONG POLEWARD OUTFLOW ALOFT. HOWEVER, THE
MAGNITUDE OF THIS REINTENSIFICATION IS UNCERTAIN AND LARGELY
DEPENDENT ON HOW THE AFOREMENTIONED DETRIMENTAL ENVIRONMENTAL
CONDITIONS WILL IMPACT 15E AND THE DEFINITION OF ITS STRUCTURE BY
THIS POINT.

MODEL DISCUSSION: TRACK MODEL GUIDANCE IS IN GOOD AGREEMENT WITH
NEARLY ALL AIDS DEPICTING A GENERALLY WESTWARD TRACK AND
RECURVATURE SCENARIO BEGINNING BETWEEN TAUS 72 AND 96. THE MAIN
OUTLIERS ARE NAVGEM AND THE AIGFS MEAN ENSEMBLE WHICH DEPICT A
FASTER RECURVE, PUTTING 15E POLEWARD OF THE STR AXIS BY TAU 120, AS
WELL AS THE AIGFS DETERMINISTIC SOLUTION WHICH DOES NOT DEPICT A
POLEWARD TURN BY TAU 120. ENSEMBLE MODEL ANALYSIS REVEALS A HIGHER
SPREAD IN REGARDS TO THE TIMING OF THE RECURVATURE SCENARIO ACROSS
BOTH PHYSICS AND AI BASED MODELS. THE OFFICIAL JTWC FORECAST TRACK
IS THUS PLACED WITH HIGH CONFIDENCE OUT TO TAU 72 AND MEDIUM
CONFIDENCE THEREAFTER DUE TO THE UNCERTAINTY DEPICTED BY ENSEMBLE
GUIDANCE, BUT IN GOOD AGREEMENT WITH THE MULTI-MODEL AND AI
CONSENSUS TRACKS THROUGHOUT AND DISREGARDING THE AFOREMENTIONED
OUTLIERS. MODEL INTENSITY GUIDANCE IS IN FAIR AGREEMENT ON A
GENERAL WEAKENING TREND OUT TO TAUS 60 TO 72, FOLLOWED BY SLIGHT
REINTENSIFICATION THEREAFTER, BUT MAINTAIN A SPREAD OF 30-40 KTS
THROUGHOUT THE FORECAST PERIOD, WITH THE HIGHEST OUTLIER BEING
HAFS-A AND THE LOWEST BEING THE GFS SOLUTION. THE OFFICIAL JTWC
INTENSITY FORECAST IS ASSESSED WITH MEDIUM CONFIDENCE OUT TO TAU 72
AND LOW CONFIDENCE THEREAFTER DUE TO THE SPREAD IN THE GUIDANCE
PACKAGE, CLOSELY IN LINE WITH THE MULTI-MODEL CONSENSUS THROUGHOUT.

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