MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (KHANUN)
WARNING NR 009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 16.3N 133.1E
INITIAL INTENSITY: 45 KTS
GEOGRAPHIC REFERENCE: 680 NM SOUTH-SOUTHEAST OF KADENA AB
MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 08 KTS
SIGNIFICANT WAVE HEIGHT: 20 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A BROAD
LOW-LEVEL CIRCULATION (LLC) WITH MULTIPLE MESOVORTICES ROTATING
CYCLONICALLY ABOUT A DEFINED CENTROID. MSI ALSO SHOWS IMPROVED DEEP
CONVECTIVE BANDING WRAPPING INTO THE EASTERN SEMICIRCLE OF AN
EXPOSED LLC. THE INITIAL POSITION IS BASED ON THE CENTROID AND IS
PLACED WITH MEDIUM CONFIDENCE. A 290455Z ATMS 88.2GHZ IMAGE DEPICTS
A BROAD AND ILL-DEFINED LLCC WITH INTENSE SPIRAL BANDING,
PREDOMINANTLY OVER THE SOUTHERN PERIPHERY. A 290330Z BULLSEYE
SCATTEROMETER IMAGE SHOWS A WELL-DEFINED CIRCULATION ALIGNING VERY
WELL WITH THE CENTROID LOCATION. BASED ON THE AFOREMENTIONED DATA,
THE 290000Z POSITION WAS RELOCATED 65NM SOUTHWEST. THE INITIAL
INTENSITY OF 45 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
KNES DVORAK ESTIMATE AND CIMSS SATCON ESTIMATE. A PREVIOUS 282117Z
SMAP IMAGE DEPICTED A HIGHLY ASYMMETRIC WIND FIELD WITH 40-50 KNOT
(1-MINUTE AVERAGE) WINDS ASSOCIATED WITH THE DEEPEST CONVECTIVE
ELEMENTS, WHICH ALSO SUPPORTS THE INITIAL INTENSITY ESTIMATE.
INITIAL WIND RADII BASIS: SMAP DATA: 34KT WIND RADII WERE
SIGNIFICANTLY EXPANDED BASED ON A DETAILED ANALYSIS OF THE SMAP
DATA.
CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE CENTERED SE OF TOKYO
EXTENDING SOUTH OVER THE NORTHERN MARIANA ISLANDS.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.5 - 35 KTS
RJTD: T2.5 - 35 KTS
KNES: T3.0 - 45 KTS
CIMSS SATCON: 43 KTS AT 290454Z
CIMSS ADT: 32 KTS AT 290530Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 15-20 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
OTHER FACTORS: DRY AIR ENTRAINMENT
ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: MEDIUM
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: SHIFTED FORECAST TRACK WEST DUE TO
SIGNIFICANT RELOCATION.
FORECAST DISCUSSION: TROPICAL STORM (TS) 05W WILL TRACK NNW THROUGH
TAU 24 ALONG THE SW BOUNDARY OF A STRONG ANTICYCLONE CENTERED NEAR
34N 143E. TS 05W IS FORECAST TO SLOWLY INTENSIFY AS IT EXPERIENCES
THE EFFECTS OF MID- TO UPPER-LEVEL DRY AIR ENTRAINMENT AND
NORTHERLY SHEAR, ESPECIALLY APPARENT IN THE NW QUADRANT. AFTER TAU
24, THE SYSTEM IS ANTICIPATED TO TURN MORE NW-WNW DUE TO THE STRONG
INFLUENCE OF A STEERING RIDGE TO THE NORTH. THE NORTHERLY SHEAR IS
ANTICIPATED TO WEAKEN, ALLOWING FOR A MORE FAVORABLE ENVIRONMENT
AND QUICKER INTENSIFICATION. A PEAK OF APPROXIMATELY 85KT WINDS IS
ANTICIPATED TO OCCUR NEAR TAU 72. THE SYSTEM IS EXPECTED TO MAKE
LANDFALL AROUND TAU 96 AND DISSIPATE OVERLAND AFTER TAU 120.
MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT
WITH A CROSS-TRACK SPREAD RANGING FROM 117NM AT TAU 48 TO 135NM AT
TAU 60. WITH THE EXCEPTION OF GFS AND THE GFS ENSEMBLE MEAN (AEMN),
MODEL GUIDANCE INDICATES A TRACK SOUTH OF OKINAWA. GFS AND AEMN
INDICATE A TRACK DIRECTLY OVER OKINAWA WITH A SHARPER POLEWARD TURN
ALONG THE EASTERN CHINA COAST BUT GFS APPEARS TO BE TRACKING THE
SYSTEM DIRECTLY INTO THE SUBTROPICAL RIDGE. THE GFS ENSEMBLE (GEFS)
INDICATES A LARGE SPREAD OF SOLUTIONS FROM A MORE WESTWARD TRACK
INLAND TO A SHARP POLEWARD TURN. THE 290000Z ECMWF ENSEMBLE (EPS)
INDICATES A HIGH PROBABILITY (80 PERCENT) OF A WNW TRACK INLAND AND
DISSIPATION SCENARIO WITH 20 PERCENT OF THE SOLUTIONS SHOWING A
POLEWARD TRACK. THE 290000Z COAMPS-TC ENSEMBLE NOW INDICATES A LOW
PROBABILITY (20 TO 30 PERCENT) OF RAPID INTENSIFICATION OVER THE NEXT
84 HOURS.
FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
TRACK 72-120 HR: MEDIUM
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
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