Tropical Storm KULAP Advisory Mo, 26.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (KULAP)
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 22.8N 143.3E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 163 NM SOUTHEAST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 19W HAS CONTINUED TO STEADILY CONSOLIDATE AS
INDICATED IN ANIMATED ENHANCED INFRARED SATELLITE IMAGERY, WHICH
SHOWS DEEP CONVECTIVE BANDING OVER THE EASTERN SEMICIRCLE WRAPPING
INTO THE NORTHERN QUADRANT. A 260024Z MHS 89GHZ MICROWAVE IMAGE
PROVIDES CLEAR EVIDENCE THAT A DEFINED LOW-LEVEL CIRCULATION CENTER
HAS FORMED WITH EXTENSIVE DEEP CONVECTIVE BANDING LOCATED OVER THE
EASTERN SEMICIRCLE. ADDITIONALLY, A 260028Z ASCAT-B BULLSEYE IMAGE
SHOWS A SYMMETRIC CIRCULATION WITH A SWATH OF 30-35 KNOT WINDS OVER
THE EASTERN SEMICIRCLE, WHICH SUPPORTS THE INITIAL POSITION AND
INITIAL INTENSITY WITH HIGH CONFIDENCE. ENVIRONMENTAL CONDITIONS ARE
FAVORABLE WITH ROBUST EQUATORWARD AND POLEWARD OUTFLOW CHANNELS AND
LOW VERTICAL WIND SHEAR (VWS).
INITIAL WIND RADII BASIS: SCATTEROMETER DATA
CURRENT STEERING MECHANISM: COMBINED STEERING INFLUENCE WITH A DEEP-
LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST AND A WEAK STR
TO THE NORTH.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 36 KTS AT 252159Z
   CIMSS ADT: 35 KTS AT 260140Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: MEDIUM
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TS 19W IS FORECAST TO TRACK GENERALLY
NORTHWESTWARD THROUGH TAU 24 WITHIN THE COMBINED STEERING INFLUENCE
OF THE BROAD STR TO THE EAST AND THE WEAK STR POSITIONED TO THE
NORTH. AFTER TAU 24, A DEEP MIDLATITUDE SHORTWAVE TROUGH WILL
APPROACH CENTRAL JAPAN AND WEAKEN THE STR TO THE NORTH ALLOWING THE
SYSTEM TO TURN POLEWARD THROUGH TAU 36 THEN RECURVE NORTHEASTWARD
ALONG THE NORTHWESTERN FLANK OF THE RE-ORIENTED STR TO THE SOUTHEAST.
BY TAU 48, TS 19W WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT
INTERACTS WITH THE MIDLATITUDE WESTERLIES AND BAROCLINIC ZONE. THE
SYSTEM WILL COMPLETE ETT BY TAU 72 AS IT GAINS FRONTAL
CHARACTERISTICS AND BECOMES EMBEDDED WITHIN THE MIDLATITUDE
WESTERLIES. TS 19W SHOULD INTENSIFY STEADILY THROUGH TAU 48 UNDER
FAVORABLE CONDITIONS TO A PEAK OF 70 KNOTS. AFTER TAU 48, COOLER SEA
SURFACE TEMPERATURE VALUES (26C) AND MODERATE VWS WILL WEAKEN THE
SYSTEM. HOWEVER, THE SYSTEM IS EXPECTED TO REMAIN A LARGE STORM-FORCE
EXTRA-TROPICAL LOW.
MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH
A SPREAD OF LESS THAN 90NM THROUGH TAU 48. AFTER TAU 48, MODEL
GUIDANCE DIVERGES SLIGHTLY WITH NAVGEM THE PRIMARY OUTLIER OVER THE
SOUTHERN EDGE OF THE AIDS ENVELOPE. THE REMAINDER OF THE GUIDANCE IS
IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH OVERALL CONFIDENCE IN THE
JTWC FORECAST TRACK. ADDITIONALLY, THE 251800Z ECMWF ENSEMBLE (EPS)
AND GFS ENSEMBLE (GEFS) ARE IN GOOD AGREEMENT SUPPORTING THE JTWC
FORECAST TRACK. THE 251800Z COAMPS-TC ENSEMBLE INDICATES A MODERATE
PROBABILITY (40 TO 60 PERCENT) FOR RAPID INTENSIFICATION PEAKING IN
THE TAU 36 TO TAU 60 TIMEFRAME.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
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