WDPN32 PGTW 090300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (BOLAVEN)      
WARNING NR 009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.8N 150.3E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 357 NM EAST-SOUTHEAST OF ANDERSEN AFB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
OVER THE PAST DAY, ENVIRONMENTAL CONDITIONS HAVE IMPROVED
SIGNIFICANTLY WITH A ROBUST POLEWARD OUTFLOW CHANNEL INTO THE TUTT
TO THE NORTHEAST AND IMPROVED BROAD EQUATORWARD OUTFLOW NOW
EVIDENT IN ANIMATED WATER VAPOR IMAGERY. ADDITIONALLY, SST VALUES OF 
29-30 C COUPLED WITH A POOL OF DEEP WARM WATER ARE AIDING IN THE 
RAPIDLY CONSOLIDATING LOW-LEVEL CIRCULATION (LLC). ANIMATED 
MULTISPECTRAL SATELLITE IMAGERY SHOWS DEEP CONVECTIVE BANDING 
WRAPPING TIGHTLY INTO A SMALL CENTRAL DENSE OVERCAST FEATURE, WHICH 
IS OBSCURING THE LLC. INTENSE CONVECTIVE BURSTS WITH CLOUD TOP 
TEMPERATURES AS COLD AS -90 C (OVER 55,000 FEET ACCORDING TO THE 
090000Z GUAM SOUNDING) ARE EVIDENT IN ANIMATED ENHANCED INFRARED 
SATELLITE IMAGERY. THESE VORTICAL HOT TOWERS LIKELY SIGNAL AN 
IMMINENT RAPID INTENSIFICATION PHASE. A 082214Z TEMPEST 89 GHZ 
MICROWAVE IMAGE REVEALS CURVED DEEP CONVECTIVE BANDING WRAPPING INTO 
THE CENTER. OVERALL, THERE IS MEDIUM CONFIDENCE IN THE INITIAL 
POSITION WITH UNCERTAINTY IN THE EXACT POSITION. THIS POSITIONAL 
UNCERTAINTY COULD LEAD TO SLIGHT SHIFTS IN THE SHORT-TERM FORECAST 
TRACK OVER THE NEXT DAY BEFORE THE SYSTEM BECOMES MUCH BETTER 
ORGANIZED. THE INITIAL INTENSITY IS ASSESSED AT 55 KNOTS AND IS BASED 
ON THE PGTW AND RJTD DVORAK ESTIMATES AND RECENT CIMSS SATCON 
ESTIMATE WITH MEDIUM CONFIDENCE.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
ENTRENCHED TO THE NORTH AND NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 56 KTS AT 082133Z
   CIMSS ADT: 63 KTS AT 082330Z
   CIMSS AIDT: 57 KTS AT 090130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: HIGH OCEAN HEAT CONTENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: ENVIRONMENTAL CONDITIONS ARE HIGHLY FAVORABLE 
FOR STEADY DEVELOPMENT TO 70 KNOTS BY TAU 24 AS THE SYSTEM TRACKS
NORTHWESTWARD. AFTER TAU 24, POLEWARD OUTFLOW IS EXPECTED TO
IMPROVE FURTHER WITH ENHANCED OUTFLOW INTO THE TUTT POSITIONED TO
THE EAST AND INTO THE MIDLATITUDE WESTERLIES. TS 15W WILL CONTINUE
TO TRACK NORTHWESTWARD THROUGH TAU 48 OVER WARM SST AND OVER A POOL 
OF DEEP WARM WATER, WHICH EXTENDS ALONG THE TRACK TO THE NORTHWEST OF
GUAM. AFTER TAU 24, THE UPPER-LEVEL CENTER AND LOW-LEVEL CENTER WILL 
BECOME VERTICALLY ALIGNED, WHICH WILL FAVOR A SUSTAINED PERIOD OF 
RAPID INTENSIFICATION (RI) DURING THE SYSTEM'S PASSAGE OVER THE 
NORTHERN MARIANAS. PEAK INTENSITY IS FORECAST TO INCREASE FROM 70 
KNOTS TO 85 KNOTS DURING THIS PASSAGE. ADDITIONAL RI WILL OCCUR AFTER 
TAU 36 AS THE SYSTEM RECURVES NORTHWARD TOWARD A BREAK IN THE STR, 
WITH ENHANCED POLEWARD OUTFLOW INTO A MIDLATITUDE SHORTWAVE TROUGH.
AFTER TAU 96, TS 15W WILL BEGIN EXTRA-TROPICAL TRANSITION AS IT
BEGINS TO INTERACT WITH THE MIDLATITUDE WESTERLIES AND BAROCLINIC
ZONE. ALTHOUGH THE CORE OF 15W IS EXPECTED TO TRACK NORTH OF GUAM, 
MESOSCALE MODELS (E.G., HAFS-A) INDICATE GUAM WILL REMAIN UNDER 
SPIRAL BANDING (THROUGH TAU 36) ALONG THE SOUTHERN PERIPHERY OF THE 
SYSTEM WITH INTENSE THUNDERSTORMS PERSISTING WITHIN THE STRONG LOW-
LEVEL CONVERGENT FLOW.      

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, DETERMINISTIC 
GUIDANCE REMAINS IN TIGHT AGREEMENT WITH A 50 NM CROSS-TRACK SPREAD 
IN SOLUTIONS AT TAU 36. ADDITIONALLY, THE MAJORITY OF THE EPS AND 
GEFS SOLUTIONS NOW TRACK THE SYSTEM NORTH OF GUAM. IN GENERAL, THE 
ENSEMBLE SOLUTIONS SHOW A NARROW SWATH FROM ABOUT 14N TO 16N LATITUDE 
THUS THERE IS NOW HIGH CONFIDENCE IN THE JTWC FORECAST TRACK THROUGH
TAU 72. THE MESOSCALE MODELS (COAMPS-TC AND HAFS-A) SUPPORT RI AFTER
TAU 24 CONTINUING THROUGH TAU 72 WITH PEAK INTENSITIES OF 120 KNOTS 
(HAFS-A AT TAU 60) TO 135 KNOTS (COAMPS-TC (GFS VERSION) AT TAU 96).
ADDITIONALLY, RAPID INTENSIFICATION GUIDANCE IS TRIGGERED (CONSISTENT 
OVER THE PAST DAY) REFLECTING THE HIGHLY FAVORABLE ENVIRONMENT. THE 
081800Z COAMPS-TC INTENSITY PROBABILITY DATA ALSO PROVIDES EXCELLENT 
SUPPORT FOR RAPID INTENSIFICATION AFTER TAU 24 WITH PROBABILITIES 
PEAKING AT 85 PERCENT FROM TAU 36 TO TAU 60.  

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
NNNN