Friday, September 2, 2011

JTWC - Tropical Cyclone Advisory 31 - Tropical Storm Talas

WTPN32 PGTW 012100
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL STORM 15W (TALAS) WARNING NR 031
01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
011800Z --- NEAR 29.5N 135.5E
MOVEMENT PAST SIX HOURS - 355 DEGREES AT 07 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 210 NM NORTHEAST QUADRANT
190 NM SOUTHEAST QUADRANT
190 NM SOUTHWEST QUADRANT
210 NM NORTHWEST QUADRANT
REPEAT POSIT: 29.5N 135.5E
---
FORECASTS:
12 HRS, VALID AT:
020600Z --- 31.2N 135.3E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 210 NM NORTHEAST QUADRANT
190 NM SOUTHEAST QUADRANT
190 NM SOUTHWEST QUADRANT
210 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 355 DEG/ 11 KTS
---
24 HRS, VALID AT:
021800Z --- 33.4N 135.1E
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT
120 NM SOUTHEAST QUADRANT
120 NM SOUTHWEST QUADRANT
100 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 015 DEG/ 12 KTS
---
36 HRS, VALID AT:
030600Z --- 35.7N 135.8E
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 48 HR POSIT: 025 DEG/ 15 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
031800Z --- 38.4N 137.5E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
BECOMING EXTRATROPICAL
RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT
080 NM SOUTHEAST QUADRANT
080 NM SOUTHWEST QUADRANT
080 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 030 DEG/ 16 KTS
---
72 HRS, VALID AT:
041800Z --- 43.8N 141.8E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
EXTRATROPICAL
---
REMARKS:
012100Z POSITION NEAR 29.9N 135.5E.
TROPICAL STORM (TS) 15W (TALAS), LOCATED APPROXIMATELY 315 NM
SOUTHEAST OF IWAKUNI, JAPAN, HAS TRACKED NORTHWARD AT 07 KNOTS OVER
THE PAST SIX HOURS. TS 15W HAS TURNED TOWARD THE KANSAI REGION OF
JAPAN WHILE MAINTAINING A STEADY INTENSITY. RECENT ANIMATED INFRARED
IMAGERY SHOWS TOPS WARMING AROUND AN EXPANSIVE AND NEARLY CLOUD-FREE
LOW LEVEL CIRCULATION CENTER (LLCC). THE OUTERMOST RAINBANDS ARE
ALREADY PELTING THE KYUSHU AND WAKAYAMA PREFECTURES. A 011135Z ASCAT
IMAGE CAPTURES THE EXPANSIVE NATURE OF THE SYSTEM, SHOWING GALE
FORCE WINDS EXTENDING OVER 200 NM OUTWARDS IN THE NORTHERN
SEMICIRCLE. THE 011200Z SOUNDING FROM SHIONOMISAKI (WAKAYAMA
PENINSULA, WMO 47778) CONFIRMS 50 KNOT WINDS BEGIN AT 1K FT. CURRENT
SURFACE REPORTS FROM SHIKOKU INDICATE NEAR GALE FORCE WINDS ALONG
THE COAST. THE CURRENT INTENSITY IS BASED ON A COMBINATION OF
SURFACE REPORTS, UPPER AIR SOUNDINGS FROM SHIONOMISAKI AND HAMAMATSU
AIR BASE, AND THE MOST RECENT ASCAT IMAGE. THE EXPANSIVE AND
ELONGATED NATURE OF THE LLCC ARE RESULTING IN DVORAK ESTIMATES THAT
ARE BELOW ACTUAL INTENSITY. THE SIZE OF THE LLCC AND THE UPPER LEVEL
CYCLONE HAVE PREVENTED CONVECTION FROM CONSOLIDATING OVER THE
SYSTEM. THE MOST RECENT MICROWAVE IMAGERY, A 011620ZZ AMSRE, SHOWS
AN ELONGATED, RELATIVELY CLOUD FREE LLCC WITH A 150 NM DIAMETER.
MICROWAVE IMAGERY ALSO SHOWS THAT ALTHOUGH THE LOW LEVEL BANDING
AROUND THE LLCC IS THICK AND CONTIGUOUS, THE CONVECTION IS SHALLOW.
THE 011200Z PGTW UPPER LEVEL STREAMLINE ANALYSIS STILL REVEALS A
HIGH ALTITUDE CYCLONE ABOVE THE SYSTEM, AND THE LATEST AMSUB RADIAL
CROSS SECTION REVEALS THE MID-LEVEL ANOMALY HAS BEGUN TO COOL AND
SINK. VERTICAL WIND SHEAR REMAINS UNDER 10 KNOTS AND SEA SURFACE
TEMPERATURE (SST) HAS INCREASED TO 28 DEGREES. SST IS EXPECTED TO
INCREASE ANOTHER 1 TO 2 DEGREES AS THE STORM CROSSES THE KUROSHIO
CURRENT BEFORE MAKING LANDFALL. ANIMATED WATER VAPOR IMAGERY REVEALS
THAT A POLEWARD OUTFLOW CHANNEL HAS BECOME WELL-ESTABLISHED ON THE
NORTHEAST QUADRANT AS THE STORM TAPS INTO AN UPPER LEVEL TROUGH
APPROACHING THE TSUSHIMA REGION. TS 15W IS BEING STEERED ALONG THE
WESTERN FLANK OF A BLOCKING RIDGE THAT HAS SET UP OVER WESTPAC. THE
OMEGA BLOCK IS DRIVING TS 15W TOWARDS THE KANSAI REGION OF HONSHU.
ENVIRONMENTAL CONDITIONS WILL REMAIN STABLE THROUGH LANDFALL AND THE
STORM MAY INTENSIFY SLIGHTLY BEFORE LAND INTERACTION WITH THE RUGGED
TERRAIN OF SHIKOKU AND THE WAKAYAMA PREFECTURE WEAKEN THE STORM. THE
BLOCK WILL DRIVE THE SYSTEM POLEWARD AND INTO THE SEA OF JAPAN NEAR
TAU 36, WHERE IT WILL HAVE A BRIEF PERIOD OF FAVORABLE CONDITIONS TO
RE-GROUP. BY TAU 48, HOWEVER, TS 15W WILL ENCOUNTER A SHARP INCREASE
IN VERTICAL WIND SHEAR, A SHARP DROP IN SEA SURFACE TEMPERATURE, AND
INTERACTION WITH A BAROCLINIC BOUNDARY IN A VERY BRIEF PERIOD. TS
15W WILL THEN GO THROUGH A RAPID EXTRATROPICAL TRANSITION PROCESS
(XTT) WHILE ACCELERATING TO THE NORTHEAST. THICKNESS PROGS ARE
BECOMING MORE AGGRESSIVE IN INDICATING COMPLETION OF XTT WELL BEFORE
TAU 72. THE UPSTREAM ENERGY ASSOCIATED WITH THE ENCROACHING SHORT
WAVE FORESHADOWS THAT THE XTT PROCESS WILL BE VIGOROUS, AND TS 15W
WILL TRANSITION INTO AN EXPANSIVE, GALE FORCE MID-LATITUDE LOW.
MODEL GUIDANCE IS COMING INTO BETTER AGREEMENT, BUT MOST VORTEX
TRACKERS ARE STILL FOLLOWING THE 500 MB HEIGHT FALLS AND STEERING
THE SYSTEM TOO FAR WEST. THE ONLY DYNAMIC MODEL THAT IS HANDLING THE
XTT PROCESS CAPABLY IS ECMWF. JTWC FORECAST STAYS RIGHT OF, AND
FASTER THAN CONSENSUS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 011800Z IS
40 FEET. NEXT WARNINGS AT 020300Z, 020900Z, 021500Z AND 022100Z.//

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