ABPW10 PGTW 170200
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
/SOUTH PACIFIC OCEANS REISSUED/170200Z-170600ZJUL2021//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/161951ZJUL2021//
AMPN/REF A IS A TROPICAL CYCLONE WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 16JUL21 1800Z, TROPICAL DEPRESSION 09W (NINE) WAS
LOCATED NEAR 19.9N 134.1E, APPROXIMATELY 527 NM SOUTHEAST OF KADENA
AB, AND HAD TRACKED NORTH-NORTHWESTWARD AT 07 KNOTS OVER THE PAST
SIX HOURS. MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 25
KNOTS GUSTING TO 35 KNOTS. SEE REF A (WTPN31 PGTW 162100) FOR
FURTHER DETAILS.
(2) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY:
(1) AN AREA OF CONVECTION (INVEST 99W) HAS PERSISTED NEAR
18.8N 115.5E, APPROXIMATELY 224 NM SOUTH-SOUTHEAST OF HONG KONG.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS BROAD TURNING WITH
FLARING CONVECTION OVERHEAD. A 161402Z METOP-B ASCAT IMAGE REVEALS
15KT WIND BARBS OVER THE NORTHERN SEMICIRCLE AND WEAKER WINDS
ELSEWHERE, WRAPPING INTO A BROAD LOW LEVEL CIRCULATION (LLC).
ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS FOR
DEVELOPMENT WITH STRONG WESTWARD OUTFLOW ALOFT AND WARM (31-32C) SEA
SURFACE TEMPERATURES, OFFSET BY LOW TO MODERATE (10-20 KTS) VERTICAL
WIND SHEAR. GFS HAS BEEN CONSISTENT WITH FORMATION OF A TROPICAL
CYCLONE NEAR THIS LOCATION FOR THE LAST TWO MODEL RUNS AND DEPICTS
INVEST 99W TRACKING SOUTHWEST OVER THE NEXT 24-48 HOURS. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 5 TO 10 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1014 MB. THE POTENTIAL FOR
THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS LOW.
(2) NO OTHER SUSPECT AREAS.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY: NONE.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.
3. JUSTIFICATION FOR REISSUE: ADDED AREA IN PARA 1.B.(1) AS LOW.//
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(1) THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED
NEAR 18.8N 115.5E IS NOW LOCATED NEAR 18.4N 115.4E, APPROXIMATELY
245 NM SOUTH-SOUTHEAST OF HONG KONG. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY DEPICTS BROAD TURNING WITH FORMATIVE CONVECTIVE
BANDING OVER THE NORTHEAST QUADRANT. A 170232Z METOP-B ASCAT IMAGE
REVEALS 15KT WIND BARBS IN THE NORTHERN SEMICIRCLE AND WEAKER WINDS
ELSEWHERE, WRAPPING INTO A BROAD LOW LEVEL CIRCULATION CENTER
(LLCC). ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS WITH
GOOD WESTWARD OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR AND
WARM (31-32C) SEA SURFACE TEMPERATURES. GFS AND ICON BOTH INDICATE
INVEST 99W WILL CONSOLIDATE AND INTENSIFY AS IT TRACKS TO THE WEST-
NORTHWEST OVER THE NEXT 24-48 HOURS. MAXIMUM SUSTAINED SURFACE WINDS
ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1002 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO
MEDIUM.
WTPN21 PGTW 172300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
100 NM EITHER SIDE OF A LINE FROM 19.2N 115.5E TO 21.1N 113.2E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS
IN THE AREA ARE ESTIMATED TO BE 13 TO 18 KNOTS. METSAT IMAGERY AT
172050Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 19.4N
115.4E. THE SYSTEM IS MOVING NORTH-NORTHWESTWARD AT 06 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 18.4N
115.4E IS NOW LOCATED NEAR 19.4N 115.4E, APPROXIMATELY 188 NM SOUTH-
SOUTHEAST OF HONG KONG. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
DEPICTS BANDING WITH FLARING CONVECTION OVERHEAD. A 171805Z AMSR2
89GHZ MICROWAVE IMAGE REVEALS DEVELOPING LOW LEVEL BANDING WRAPPING
INTO A LOW LEVEL CIRCULATION CENTER (LLCC) WITH CONVECTION OVER THE
NORTHEAST QUADRANT. A 171225Z ASCAT-A IMAGE SHOWS A BROAD
CIRCULATION WITH 15-20 KNOT WINDS IN THE NORTHEAST QUADRANT.
ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS FOR
DEVELOPMENT WITH WESTWARD OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL
WIND SHEAR, AND WARM (31-32C) SEA SURFACE TEMPERATURES. NUMERICAL
MODEL GUIDANCE SHOWS INVEST 99W TRACKING NORTHWESTWARD AS IT
CONSOLIDATES AND INTENSIFIES OVER THE NEXT 24 HOURS. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 13 TO 18 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1009 MB. THE POTENTIAL FOR
THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
182300Z.//
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