JTWC 02Z取消評級。

(1) THE AREA OF CONVECTION (INVEST 90P) PREVIOUSLY LOCATED
NEAR 19.6S 176.8E IS ASSESSED AS A SUBTROPICAL CYCLONE AND IS
LOCATED UNDER THE SUBTROPICAL JET, THEREFORE, 90P IS NO LONGER
SUSPECT FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE IN THE
NEXT 24 HOURS.

JTWC於07/20Z取消TCFA，降評為Medium。

(1) THE AREA OF
CONVECTION (INVEST 90P) PREVIOUSLY LOCATED NEAR 14.5S 175.8W, IS NOW
LOCATED NEAR 18.0S 176.7W, APPROXIMATELY 210 NM NORTH-NORTHWEST OF
TONGA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS DEEP CONVECTION
ASSOCIATED WITH THE LOW LEVEL CIRCULATION (LLC) SHEARED TO THE WEST
WITH ADDITIONAL DEEP CONVECTION TO THE NORTH. A 071731 GMI MICROWAVE
PASS CONFIRMS THE ASYMMETRIC CONVECTIVE STRUCTURE AND COMPARING THE
37 AND 89GHZ REVEALS THE GROWING INCLINATION THROUGH THE ATMOSPHERE.
90S IS CURRENTLY IN AN UNFAVORABLE ENVIRONMENT FOR DEVELOPMENT AS A
TROPICAL CYCLONE WITH VERY HIGH (40 TO 50 KNOT) VERTICAL WIND SHEAR
(VWS) AND MODERATE (27 TO 29 CELSIUS) SEA SURFACE TEMPERATURES (SST).
90P CURRENTLY HAS GOOD RADIAL OUTFLOW WITH A STRONGER POLEWARD
OUTFLOW CHANNEL AS IT BEGINS TO TAP INTO THE POLAR JET. GLOBAL MODELS
ARE GENERALLY IN GOOD AGREEMENT THAT 90P WILL CONTINUE TO TRACK
SOUTHWARD AND CONTINUE AS A SUBTROPICAL CYCLONE WITH MINIMAL FURTHER
INTENSIFICATION. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25
TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 997
MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS IS DOWNGRADED TO MEDIUM. SEE REF A
(WTPS21 PGTW 072000) FOR FURTHER DETAILS.

JTWC:TCFA

WTPS21 PGTW 062130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 90P)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 13.7S 175.6W TO 19.0S 176.8W
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 23 TO 28 KNOTS. METSAT
IMAGERY AT 061800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 14.5S 175.8W. THE SYSTEM IS MOVING SOUTH-SOUTHWESTWARD AT 18
KNOTS.
2. REMARKS:
THE AREA OF CONVECTION (INVEST 90P) PREVIOUSLY LOCATED NEAR 9.7S
174.9W, IS NOW LOCATED NEAR 14.5S 175.8W, APPROXIMATELY 295 NM WEST-
NORTHWEST OF PAGO PAGO, AMERICAN SAMOA.  ANIMATED MULTISPECTRAL
SATELLITE IMAGERY SHOWS A PERSISTENT BALL OF DEEP CONVECTION
OBSCURING THE LOW LEVEL CIRCULATION (LLC). A 061644Z SSMIS F-18
91GHZ MICROWAVE IMAGE SHOWS DEEP CONVECTION OVER AN ASYMMETRIC LLC
WITH A BROAD AREA OF DEEP CONVECTION TO THE NORTH BEGINNING TO WRAP
INTO THE LLC. 90P IS IN A MARGINAL ENVIRONMENT WITH STRONG POLEWARD
AND MODERATE EQUATORWARD OUTFLOW OFFSET BY MARGINAL (26 TO 28
CELSIUS) SEA SURFACE TEMPERATURES (SST) AND HIGH (30 TO 40 KNOT)
VERTICAL WIND SHEAR SURROUNDING THE SYSTEM. GLOBAL MODELS ARE IN
GOOD AGREEMENT THAT 90P WILL TRACK SOUTHWARD, INTENSIFYING AS A
SUBTROPICAL SYSTEM. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT
23 TO 28 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR
998 MB.  THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.

FMS 強度升熱帶低壓，緩慢南下。

GALE WARNING 001 ISSUED FROM RSMC NADI Feb 061951 UTC.

TROPICAL DEPRESSION, 06F CENTRE [997HPA] WAS ANALYSED NEAR 14.4S 176.0W AT
061800UTC. POSITION POOR. TD06F MOVING SOUTHWEST AT 15 KNOTS.

EXPECT CLOCKWISE WINDS UP TO 35 KNOTS WITHIN 60 TO 180 NAUTICAL MILES AWAY FROM
THE CENTRE OF TD06F CENTRE IN THE EASTERN SEMI-CIRCLE

AREA OF GALES MOVING WITH DEPRESSION.

THIS IS THE FIRST WARNING FOR THIS SYSTEM.

FMS 06F最新定位已經接近90P。

Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI Feb 052322 UTC.

TROPICAL DISTURBANCE 06F [1000HPA] WAS ANALYSED NEAR 10.8 174.4W AT
052100UTC. TD06F SLOW MOVING. POSITION POOR BASED ON HR HIMAWARI-8
VIS/EIR IMMAGERY AND PERIPHERAL SURFACE REPORTS.

CONVECTION REMAINS PERSISTENT OVER LOW LEVEL CIRCULATION CENTRE
[LLCC] IN THE LAST 24 HOURS. CYCLONIC CIRCULATION EXTENDS UPTO
700HPA. SYSTEM LIES UNDER AN ANTI-CYCLONIC CIRCULATION WITH GOOD
OUTFLOW IN A LOW SHEARED ENVIRONMENT. SST AROUND 30 DEGREES CELCIUS.

MOST GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND MOVE IT TOWARDS THE
SOUTHWEST WITH SOME INTENSIFICATION.

THE POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN
THE NEXT 24 TO 48 HOURS IS LOW.

90PINVEST.25kts-999mb-97S-1749W.100pc.jpg

JTWC於02052000Z評級Medium。

(2) AN AREA OF CONVECTION (INVEST 90P) HAS PERSISTED NEAR
10.0S 174.3W, APPROXIMATELY 333 NM NORTHWEST OF PAGO PAGO, AMERICAN
SAMOA. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A 051741Z
89GHZ GMI MICROWAVE IMAGE DEPICT DEEP CONVECTIVE BANDING OVER THE
NORTHERN PERIPHERY ASSOCIATED WITH A BROAD LOW LEVEL CIRCULATION. A
050835Z ASCAT PASS SHOWS 25-30 KNOT WINDS ON THE NORTH SIDE OF THE
CIRCULATION WRAPPING DOWN THE EAST SIDE. UPPER LEVEL ANALYSIS SHOWS
FAVORABLE CONDITIONS FOR DEVELOPMENT WITH LOW VERTICAL WIND SHEAR
(10-15 KNOTS) AND STRONG POLEWARD OUTFLOW. SEA SURFACE TEMPERATURES
ARE ALSO FAVORABLE (28-30C) FOR DEVELOPMENT. GLOBAL MODELS ARE IN
GOOD AGREEMENT WITH THE SYSTEM REACHING WARNING STATUS IN 36-48
HOURS AND TRACKING SOUTHWARD. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1000 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS MEDIUM.