TD WIPHA(08W) forecast to dissipate near Hanoi in 36h. 09W: slowly intensifying

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WESTERN NORTH PACIFIC

TD WIPHA(08W)
As of 18:00 UTC Aug 01, 2019:
Location: 21.4°N 109.4°E
Maximum Winds: 30 kt ( 55km/h)
Gusts: 45 kt ( 85km/h)
Minimum Central Pressure: 991 mb
WDPN31 PGTW 012100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 08W (WIPHA)
WARNING NR 09//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 08W (WIPHA), LOCATED APPROXIMATELY 197 NM
EAST OF HANOI, VIETNAM, HAS TRACKED WESTWARD AT 08 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
SHOWS THE SYSTEM HAS DEGRADED AS IT TRACKED ACROSS THE LEIZHOU
PENINSULA AND INTO THE GULF OF TONKIN. THE ASSOCIATED CONVECTION HAVE
BEGUN TO COLLAPSE AS EVIDENCED BY WARMING TOPS, AND UNRAVEL. HOWEVER,
THE LOW LEVEL CIRCULATION CENTER (LLCC) REMAINS INTACT, BASED ON A
COMPOSITE RADAR LOOP FROM CHINA. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE RADAR LOOP AND FROM NEARBY SURFACE
OBSERVATIONS, INCLUDING THOSE FROM BEHAI, 15 NM NORTHWEST OF THE
LLCC. UPPER-LEVEL ANALYSIS INDICATES A MARGINALLY-FAVORABLE
ENVIRONMENT WITH LOW TO MODERATE VERTICAL WIND SHEAR OFFSET BY GOOD
POLEWARD AND EQUATORWARD OUTFLOW. TS 08W IS TRACKING UNDER THE
STEERING INFLUENCE OF THE LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR)
TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 08W WILL GRADUALLY TURN WESTWARD TO WEST-SOUTHWESTWARD AS
IT TRACKS UNDER THE STR. THERE IS UNCERTAINTY IN THE TIMING OF
THIS WESTWARD TURN, WHICH ALSO INTRODUCES UNCERTAINTY IN THE
INTENSITY
FORECAST AND EXACT TRACK OVER THE GULF OF TONKIN. THE CURRENT JTWC
FORECAST TRACK SKIRTS THE SOUTHERN COAST OF CHINA WITH LANDFALL
ALONG THE NORTHEAST COAST OF VIETNAM NEAR TAU 18 AND DISSIPATION BY
TAU 36 EAST OF HANOI. DYNAMIC MODEL GUIDANCE REFLECTS THIS
UNCERTAINTY
WITH SOME SOLUTIONS FURTHER SOUTH OVER WATER, WHICH COULD LEAD TO A
PROLONGED LIFESPAN. DUE TO THIS UNCERTAINTY, THERE IS LOW CONFIDENCE
IN THE JTWC FORECAST TRACK.//
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TD 09W
As of 18:00 UTC Aug 01, 2019:
Location: 19.5°N 153.3°E
Maximum Winds: 25 kt ( 45km/h)
Minimum Central Pressure: 1002 mb
WDPN32 PGTW 012100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 09W (NINE)
WARNING NR 01//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 09W (NINE), LOCATED APPROXIMATELY 501 NM
EAST-NORTHEAST OF SAIPAN, CNMI, HAS TRACKED NORTHWESTWARD AT 04 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY SHOWS A CONSOLIDATING SYSTEM WITH DEEP FLARING CONVECTION
SHEARED EAST-SOUTHEASTWARD OF A PARTLY OBSCURED LOW LEVEL CIRCULATION
(LLC). THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED ON
THE EIR LOOP AND LINED UP WITH A NOTCH FEATURE IN THE 011651Z SSMI
MICROWAVE IMAGE. THE INITIAL INTENSITY OF 25 KNOTS IS BASED ON THE
DVORAK ESTIMATE OF T1.5/25KTS FROM PGTW AND CONSISTENT WITH RECENT
ASCAT DATA. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA
OF MODERATE (20-25 KNOT) VERTICAL WIND SHEAR (VWS) AND SUBSIDENCE
CAUSED BY AN ADJACENT TUTT CELL TO THE NORTHWEST. HOWEVER, THESE ARE
PARTLY OFFSET BY EXCELLENT POLEWARD OUTFLOW AND WARM (3OC)
ALONG-TRACK SSTS. THE CYCLONE IS TRACKING ALONG THE SOUTHWEST
PERIPHERY OF THE STR TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE ON THIS SYSTEM
AND SETS THE FORECAST PHILOSOPHY.
   B. TD 09W WILL CONTINUE ON ITS CURRENT TRACK THROUGHOUT THIS
FORECAST. THE AFOREMENTIONED MARGINAL CONDITIONS WILL PREVAIL OVER
THE NEXT 36 HOURS RESULTING IN A SLOW OR EVEN SUSTAINED
INTENSIFICATION. AFTERWARD, VWS WILL RELAX AND THE TUTT CELL WILL
PROPAGATE WELL AHEAD OF THE CYCLONE, ALLOWING FOR A MORE GRADUAL
INTENSIFICATION. BY TAU 72, TD 09W WILL BE APPROXIMATELY 200 NM
NORTH-NORTHWEST OF IWO TO AND WILL HAVE REACHED 55 KNOTS.   
   C. BEYOND TAU 72, 09W WILL CONTINUE ON A NORTHWESTWARD TRACK UNDER
THE STEERING STR TOWARD KYUSHU, JAPAN. THE FAVORABLE ENVIRONMENTAL
CONDITIONS WILL STRENGTHEN THE SYSTEM TO A PEAK OF 70 KNOTS BY TAU
96. AFTERWARD, LAND INTERACTION AND INCREASING VWS WILL BEGIN TO
ERODE 09W, REDUCING IT TO 55 KNOTS BY TAU 120 AS IT TRACKS JUST SOUTH
OF SASEBO. THE AVAILABLE NUMERICAL MODELS ARE IN UNUSUALLY GOOD
AGREEMENT FOR A DEVELOPING SYSTEM. HOWEVER, GIVEN THE DEGREE OF
UNCERTAINTY IN THE INITIAL POSITION, STORM MOTION, AND
INTENSIFICATION, THERE IS LOW CONFIDENCE IN THIS FIRST TRACK FORECAST
TRACK FROM JTWC.//
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