Advisories

WDPN31 PGTW 052100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15E (NOLO) WARNING NR 061//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.8N 174.7E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 595 NM NORTHEAST OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TIGHTLY
CURVED BANDING WRAPPING INTO A 21 NM DIAMETER EYE, WITH WARMING
CLOUD TOPS AND A NOTABLE DEGRADATION OF PRIOR SYMMETRIC STRUCTURE
OF TYPHOON (TY) 15E (NOLO) UNDER THE INCREASING INFLUENCE OF
NORTHWESTERLY VERTICAL WIND SHEAR. THE ENVIRONMENT IS ASSESSED AS
MARGINAL, WITH MODERATE POLEWARD OUTFLOW AND WARM 28-29 DEGREE
CELSIUS WATERS OFFSETTING MODERATE (20 KNOT) ASSESSED VERTICAL WIND
SHEAR (VWS) AND SIGNIFICANT DRY AIR. A 200MB TROUGH BRANCHING
EQUATORWARD OFF THE SUB-TROPICAL JET IS INCREASING THE VWS ALONG
THE WESTERN FLANK. ADDITIONALLY, SUBSIDENT OUTFLOW FROM TYPHOON
26W WELL TO THE WEST IS AIDING TO SUPPRESS ENVIRONMENTAL MOISTURE.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON
MULTI-AGENCY FIXES ON THE EYE FEATURE. THE INITIAL INTENSITY OF 105
KTS IS ASSESSED WITH LOW CONFIDENCE, BASED ON THE RANGE OF
SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES, AS OBJECTIVE
ESTIMATES ARE MORE QUICKLY ADJUSTING TO THE DECLINING PRESENTATION.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: THE AXIS OF A DEEP-LAYER SUBTROPICAL
RIDGE (STR) TO THE NORTH


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T5.5 - 102 KTS
   PHFO: T6.0 - 115 KTS
   CIMSS SATCON: 106 KTS AT 051637Z
   CIMSS ADT: 94 KTS AT 051730Z
   CIMSS AIDT: 98 KTS AT 051730Z
   CIMSS D-MINT: 101 KTS AT 051639Z
   CIMSS D-PRINT: 86 KTS AT 051840Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: LOW
   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 TRACKING
GENERALLY WESTWARD TO WEST-NORTHWESTWARD WHILE IT REMAINS ON THE
SOUTHERN PERIPHERY OF THE STRONG STEERING STR DURING THE FIRST 72
HOURS OF THE FORECAST. AFTER TAU 72, A WEAKNESS IS EXPECTED TO
DEVELOP ALONG THE WESTERN PERIPHERY OF THE RIDGE AND ALLOW FOR A
SLOW POLEWARD TURN INTO THE BREAK BETWEEN THE STR AND A BUILDING
LOW- TO MID-LAYER RIDGE CENTERED OVER JAPAN. FORWARD SPEEDS ARE
EXPECTED TO SLOW DURING THIS PERIOD DUE TO COMPETING STEERING
INFLUENCES, AS THE SUBTROPICAL RIDGE, ANCHORED WELL TO THE NORTH AT
THIS POINT, IS NOT EXPECTED TO DYNAMICALLY AID IN THE INITIAL TRACK
RECURVATURE. FORECAST INTENSITIES HAVE BEEN ADJUSTED DOWNWARD, AND
FURTHER ADJUSTMENTS MAY BE NECESSARY. OVER THE NEXT 36 HOURS, THE
ALIGNMENT OF THE UPPER-LEVEL TROUGH WILL BECOME EVEN MORE
UNFAVORABLE, ADDING ADDITIONAL VWS OVER THE SYSTEM AND DECREASING
THE OVERALL OUTFLOW. AT AROUND TAU 72, TY 15E IS EXPECTED TO BE IN
A MORE FAVORABLE POSITION, WITH THE ENTRANCE REGION OF THE JET
BEGINNING TO PROVIDE ADDITIONAL OUTFLOW AND SLIGHTLY RELAXING THE
VWS TO ALLOW FOR A PERIOD OF SOME RE-INTENSIFICATION THROUGH THE
END OF THE FORECAST PERIOD. 


MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGH TAU 72, WITH MINIMAL ALONG-TRACK OR
CROSS-TRACK DEVIATION. AFTER TAU 72, HOWEVER, MODEL GUIDANCE
SPREAD BECOMES SIGNIFICANT, WITH A NOTABLE BIFURCATION BETWEEN THE
TRADITIONAL PHYSICAL MODELS AND THE AI SOLUTIONS. HOWEVER, EVEN THE
AI ENSEMBLES THEMSELVES, SUCH AS THE GOOGLE DEEP MIND ENSEMBLE, ARE
DEPICTING THE LARGE SPREAD IN POSSIBLE SCENARIOS ASSOCIATED WITH
UNCERTAINTIES IN WHETHER THE STR WILL WEAKEN AS FORECAST, OR REMAIN
STRONG ENOUGH TO CONTINUE PROJECTING A MORE WESTWARD TRACK. THE
JTWC TRACK FORECAST IS PLACED WITH HIGH CONFIDENCE FROM TAU 0-72.
AFTER TAU 72, THE JTWC TRACK FORECAST IS PLACED WITH LOW
CONFIDENCE, BETWEEN THE MULTI-MODEL CONSENSUS AND THE AI ENSEMBLE
MEAN CONSENSUS. RELIABLE INTENSITY MODELS DEPICT THE WEAKENING TREND
THROUGH TAU 72 FOLLOWED BY A SLIGHT REINTENSIFICATION. THE JTWC
INTENSITY FORECAST IS IN CLOSE AGREEMENT WITH THE MULTI-MODEL
CONSENSUS WITH OVERALL LOW CONFIDENCE. 


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