WTPN31 PGTW 242100
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL STORM 20W (NESAT) WARNING NR 006
02 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
241800Z --- NEAR 15.0N 132.3E
MOVEMENT PAST SIX HOURS - 265 DEGREES AT 13 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 - 020 NM NORTHEAST QUADRANT
020 NM SOUTHEAST QUADRANT
020 NM SOUTHWEST QUADRANT
020 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
080 NM NORTHWEST QUADRANT
REPEAT POSIT: 15.0N 132.3E
---
FORECASTS:
12 HRS, VALID AT:
250600Z --- 15.1N 129.8E
MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 095 NM NORTHEAST QUADRANT
085 NM SOUTHEAST QUADRANT
085 NM SOUTHWEST QUADRANT
105 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 275 DEG/ 11 KTS
---
24 HRS, VALID AT:
251800Z --- 15.2N 127.6E
MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT
020 NM SOUTHEAST QUADRANT
020 NM SOUTHWEST QUADRANT
020 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT
055 NM SOUTHEAST QUADRANT
055 NM SOUTHWEST QUADRANT
055 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT
105 NM SOUTHEAST QUADRANT
105 NM SOUTHWEST QUADRANT
125 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 290 DEG/ 10 KTS
---
36 HRS, VALID AT:
260600Z --- 15.8N 125.7E
MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
035 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 065 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
065 NM SOUTHWEST QUADRANT
065 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT
115 NM SOUTHEAST QUADRANT
115 NM SOUTHWEST QUADRANT
130 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 295 DEG/ 09 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
261800Z --- 16.5N 124.0E
MAX SUSTAINED WINDS - 120 KT, GUSTS 145 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 075 NM NORTHEAST QUADRANT
075 NM SOUTHEAST QUADRANT
075 NM SOUTHWEST QUADRANT
075 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT
120 NM SOUTHEAST QUADRANT
120 NM SOUTHWEST QUADRANT
125 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 295 DEG/ 09 KTS
---
72 HRS, VALID AT:
271800Z --- 17.8N 120.7E
MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 96 HR POSIT: 300 DEG/ 09 KTS
---
LONG RANGE OUTLOOK:
---
96 HRS, VALID AT:
281800Z --- 19.6N 117.6E
MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 120 HR POSIT: 305 DEG/ 08 KTS
---
120 HRS, VALID AT:
291800Z --- 21.4N 114.7E
MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT
WIND RADII VALID OVER OPEN WATER ONLY
---
REMARKS:
242100Z POSITION NEAR 15.0N 131.7E.
TROPICAL STORM (TS) 20W, LOCATED APPROXIMATELY 650 NM WEST OF
MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 13 KNOTS OVER THE PAST
SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS EXPANDING
DEEP CONVECTION AROUND THE ENTIRE SYSTEM AND CONSOLIDATING DEEP
CONVECTION AROUND THE CORE. THE ANIMATION ALSO CONFIRMS THAT STORM
MOTION HAS BACKED SLIGHTLY TOWARDS THE WEST, AS EXPECTED. THE LATEST
AMSUB RADIAL CROSS SECTION REVEALS THAT THE MID-LEVEL WARM ANOMALY
IS INTENSIFYING. A 241630Z AMSRE IMAGE INDICATES TIGHTENING IN THE
CONVECTIVE BANDING AROUND THE LOW LEVEL CIRCULATION CENTER (LLCC). A
241155Z ASCAT IMAGE REVEALS AN EXPANDING AREA OF GALES OVER THE
NORTHERN SEMICIRCLE. THE 241200Z PGTW UPPER LEVEL STREAMLINE
ANALYSIS DEPICTS AN ANTICYCLONE EAST OF THE LLCC AND A DIFFLUENT
ASYMPTOTE OVER THE TOP OF THE SYSTEM. TS 20W EXISTS IN A HIGHLY
DIFFLUENT REGION WITH ONLY 5 TO 10 KNOTS OF VERTICAL WIND SHEAR. SEA
SURFACE TEMPERATURES ARE 30 DEGREES AND INCREASING SLIGHTLY ALONG
TRACK. ANIMATED WATER VAPOR IMAGERY SHOWS OUTSTANDING RADIAL
OUTFLOW, WITH EQUATORWARD OUTFLOW VENTING ALL THE WAY INTO THE
SOUTHERN HEMISPHERE. THE OUTFLOW CONDITIONS AND WARM SEA SURFACE
TEMPERATURES WILL ALLOW THE STORM UNIMPEDED DEVELOPMENT DURING THE
NEXT 24 HOURS. THE INTENSITY RAMP-UP OVER THE NEXT 24 HOURS IS
SLIGHTLY MORE THAN ONE DVORAK VALUE PER DAY, WHICH IS NOT AGGRESSIVE
CONSIDERING THE CURRENT SYNOPTIC SITUATION. TS 20W WILL STEER ALONG
THE SOUTHWESTERN FLANK OF THE SUBTROPICAL RIDGE FOR THE NEXT 24
HOURS. NEAR TAU 24, THE RIDGE WILL WEAKEN AND RETRACT JUST ENOUGH TO
ALLOW THE STORM TO VEER TO THE NORTHWEST THROUGH LANDFALL. TS 20W
WILL ENCOUNTER EVEN WARMER SEA WATER OFF THE NORTHEAST COAST OF
LUZON WHILE REMAINING IN A LOW SHEAR ENVIRONMENT AND NEAR TAU 60, IT
WILL PEAK AT SUPER TYPHOON INTENSITY JUST BEFORE IT MAKES LANDFALL.
ENTRY POINT WILL BE OVER THE DIVILACAN BAY REGION, SOMEWHERE BETWEEN
AUBAREDE POINT AND ILIGAN POINT. ONCE INLAND, TOPOGRAPHY WILL FORCE
THE TRACK A LITTLE MORE WESTWARD AND DRIVE THE STORM ACROSS THE
RUGGED TERRAIN OF THE NORTHERN SIERRA MADRES. LAOG LOOKS LIKE A
REASONABLE EJECTION POINT, WHICH WOULD KEEP THE STORM OVER LAND FOR
ROUGHLY 15 HOURS. ACCORDING TO STATISTICAL ANALOGUES, A 15 HOUR OVER-
LAND TRACK RESULTS IN A FORTY PER CENT REDUCTION IN STORM INTENSITY,
WHICH WOULD RESULT IN NESAT EJECTING INTO THE SOUTH CHINA SEA (SCS)
AT 80 KNOTS. ONCE IN THE SCS, TS 20W WILL BE OVER WARM WATERS BUT IN
A HIGHER SHEAR ENVIRONMENT, AND THUS UNDERGO ONLY MODERATE RE-
INTENSIFICATION. THE TRACK OVER THE SCS WILL TAKE THE STORM CLOSE TO
HONG KONG, WITH A SECOND PEAK INTENSITY NEAR 100 KNOTS. WHILE
INTENSITY GUIDANCE IS TYPICALLY WEAK IN RAPID INTENSIFICATION
SCENARIOS AND THUS FAR HAS BEEN SEVERELY LACKING, TRACK GUIDANCE HAS
BEEN IN EXCELLENT AGREEMENT ON THE OVERALL SCENARIO. DISCREPANCIES
EXIST IN THE ALONG-TRACK SPEEDS AND THE DISTANCE FROM HONG KONG, BUT
CONSIDERING THE EXTENDED RANGE OF THE HONG KONG THREAT AND THE OVER-
LAND ROUTE BETWEEN THEN AND NOW, THOSE DISCREPANCIES ARE MINOR. THE
TRACK FORECAST STAYS CLOSE TO AND SLIGHTLY FASTER THAN CONSENSUS,
WHILE THE INTENSITY FORECAST IS BASED ON OBSERVED ENVIRONMENTAL
CONDITIONS FACTORED WITH A CLIMATOLOGICAL RATE OF DEVELOPMENT FOR A
SYSTEM OF THIS TYPE, TRACK, AND SEASON. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 241800Z IS 14 FEET. NEXT WARNINGS AT 250300Z, 250900Z,
251500Z AND 252100Z. REFER TO TROPICAL DEPRESSION 21W (TWENTY-ONE)
WARNINGS (WTPN32 PGTW)
FOR SIX-HOURLY UPDATES.//
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