JMA00Z撤TD,認定已併入鋒面

JTWC亦30/0300Z撤評

1) THE AREA OF CONVECTION (INVEST 90W) PREVIOUSLY LOCATED
NEAR 26.8N 158.2E HAS DISSIPATED AND IS NO LONGER SUSPECT FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE IN THE NEXT 24 HOURS.

JTWC28/0600Z評級Low

ABPW10 PGTW 280600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
/SOUTH PACIFIC OCEANS/280600Z-290600ZJUL2020//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY: NONE.
   C. SUBTROPICAL SYSTEM SUMMARY:
      (1) AN AREA OF CONVECTION (INVEST 90W) HAS PERSISTED NEAR
24.5N 160.4E, APPROXIMATELY 467 NM NORTHWEST OF WAKE ISLAND. THE
SYSTEM IS CURRENTLY CLASSIFIED AS A SUBTROPICAL SYSTEM, GENERALLY
CHARACTERIZED AS HAVING BOTH TROPICAL AND MIDLATITUDE CYCLONE
FEATURES. RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A
280250Z ASMR2 89 GHZ MICROWAVE IMAGE DEPICT A BROAD OVERALL
STRUCTURE WITH DISORGANIZED CONVECTION AND TWO DISTINCT SMALL
CIRCULATIONS ROTATING ABOUT A CENTROID. ADDITIONALLY, WEAK SHALLOW
BANDING IS PRESENT AND WRAPPING AROUND THE BROAD CENTER. A 272330Z
ASCAT-B IMAGE INDICATES AN ASYMMETRIC WIND FIELD WITH 20-25KT WINDS
AROUND THE NORTHERN SEMICIRCLE WITH A LARGE RADIUS OF MAXIMUM WINDS
(>100NM). UPPER LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH
CYCLONIC EASTERLY FLOW AND MODERATE TO STRONG VERTICAL WIND SHEAR
(20-30KTS). HOWEVER, THE SYSTEM IS CURRENTLY LOCATED OVER WARM (28-
30C) SEA SURFACE TEMPERATURES. MODEL ANALYSIS INDICATES THE SYSTEM
IS LOCATED UNDER THE NORTHERN PERIPHERY OF A 500MB LOW. THE SYSTEM
IS EXPECTED TO RECURVE POLEWARD IN THE NEXT 36-48 HOURS WHILE
BECOMING ABSORBED IN AN APPROACHING FRONTAL SYSTEM. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. FOR HAZARDS AND
WARNINGS, REFERENCE THE FLEET WEATHER CENTER SAN DIEGO HIGH WINDS
AND SEAS PRODUCT OR REFER TO LOCAL WMO DESIGNATED FORECAST
AUTHORITY. THE POTENTIAL FOR THE SYSTEM TO TRANSITION INTO A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.

(1) AN AREA OF CONVECTION (INVEST 90W) HAS PERSISTED NEAR
24.5N 160.4E, APPROXIMATELY 467 NM NORTHWEST OF WAKE ISLAND. THE
SYSTEM IS CURRENTLY CLASSIFIED AS A SUBTROPICAL SYSTEM, GENERALLY
CHARACTERIZED AS HAVING BOTH TROPICAL AND MIDLATITUDE CYCLONE
FEATURES. RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A
280250Z AMSR2 89 GHZ MICROWAVE IMAGE DEPICT A BROAD OVERALL
STRUCTURE WITH DISORGANIZED CONVECTION AND TWO DISTINCT SMALL
CIRCULATIONS ROTATING ABOUT A CENTROID. ADDITIONALLY, WEAK SHALLOW
BANDING IS PRESENT AND WRAPPING AROUND THE BROAD CENTER. A 272330Z
ASCAT-B IMAGE INDICATES AN ASYMMETRIC WIND FIELD WITH 20-25KT WINDS
AROUND THE NORTHERN SEMICIRCLE WITH A LARGE RADIUS OF MAXIMUM WINDS
(>100NM). UPPER LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH
CYCLONIC EASTERLY FLOW AND MODERATE TO STRONG VERTICAL WIND SHEAR
(20-30KTS). HOWEVER, THE SYSTEM IS CURRENTLY LOCATED OVER WARM (28-
30C) SEA SURFACE TEMPERATURES. MODEL ANALYSIS INDICATES THE SYSTEM
IS LOCATED UNDER THE NORTHERN PERIPHERY OF A 500MB LOW. THE SYSTEM
IS EXPECTED TO RECURVE POLEWARD IN THE NEXT 36-48 HOURS WHILE
BECOMING ABSORBED IN AN APPROACHING FRONTAL SYSTEM. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. FOR HAZARDS AND
WARNINGS, REFERENCE THE FLEET WEATHER CENTER SAN DIEGO HIGH WINDS
AND SEAS PRODUCT OR REFER TO LOCAL WMO DESIGNATED FORECAST
AUTHORITY. THE POTENTIAL FOR THE SYSTEM TO TRANSITION INTO A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.

一般大都是擾動熱低壓跟颱風高緯轉變成溫帶氣旋，

溫帶氣旋高緯轉變為擾動熱低壓到是滿少見的，

大概是長時間處在太平洋高亞的熱環帶上，因為長時間在高海溫的環境場導致變質了。

20200727.2310.himawari-8.vis.90W.INVEST.15kts.1010mb.25N.162E.100pc.jpg