|
|
本帖最後由 dom 於 2021-3-27 16:41 編輯
JTWC09Z發佈TCFAWTXS21 PGTW 270900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 98S)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 10.0S 65.2E TO 10.3S 68.8E 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 28 TO 33 KNOTS. METSAT IMAGERY AT 270830Z
INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 10.2S 65.6E. THE
SYSTEM IS MOVING EAST-SOUTHEASTWARD AT 04 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 98S) PREVIOUSLY LOCATED
NEAR 9.9S 64.9E IS NOW LOCATED NEAR 10.2S 65.6E, APPROXIMATELY 439
NM WEST-SOUTHWEST OF DIEGO GARCIA. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A WELL-DEFINED LOW LEVEL CIRCULATION CENTER (LLCC)
LOCATED NEAR THE NORTHEAST EDGE OF A MASS OF CONVECTION THAT HAS
EXHIBITED PULSING BURSTS DURING THE PAST 6 HOURS. SATELLITE IMAGERY
INDICATES THAT THE MID-LEVEL CIRCULATION CENTER IS DISPLACED WEST OF
THE LLCC AS A RESULT OF 10-15 KTS OF EASTERLY VERTICAL WIND SHEAR,
AND THE LLCC IS PARTIALLY EXPOSED ON THE NORTHEAST SIDE. HOWEVER, A
270533Z ASCAT-C IMAGE REVEALS A COMPACT CIRCULATION THAT HAS SEEN
ITS RADIUS OF MAXIMUM WIND CONTRACT SUBSTANTIALLY TO AROUND 20 NM
DURING THE PAST 12 HOURS, WITH A BAND OF 30 KT WINDS ENCOMPASSING
THE ENTIRE NORTHWESTERN SEMICIRCLE. HEALTHY UPPER-LEVEL OUTFLOW IS
OBSERVED IN ALL QUADRANTS EXCEPT NORTHEAST. INVEST 98S IS LOCATED IN
A MOSTLY FAVORABLE ENVIRONMENT WITH SEA SURFACE TEMPERATURES AROUND
29C AND LIGHT-MODERATE VERTICAL WIND SHEAR. WATER VAPOR SATELLITE
IMAGERY AND PRECIPITABLE WATER DATA INDICATE A BAND OF DRY AIR
LOCATED ABOUT 200 NM SOUTHWEST OF THE SYSTEM, BUT DOES NOT APPEAR TO
BE WRAPPING INTO THE CIRCULATION AT PRESENT. NUMERICAL MODELS HAVE
MIXED OPINIONS ON DEVELOPMENT, WITH MOST SHOWING ONLY SLIGHT
INTENSIFICATION OF 98S IN THE SHORT TERM. HOWEVER, MOST MODELS
DEPICT 98S WITH A BROADER AND WEAKER CIRCULATION THAN IS BEING
OBSERVED, SUGGESTING THAT DEVELOPMENT CHANCES ARE HIGHER. INVEST 98S
IS EXPECTED TO TRACK EAST-SOUTHEASTWARD AND THEN TURN EASTWARD UNDER
THE INFLUENCE OF A WESTERLY WIND BAND TO ITS NORTH. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 28 TO 33 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 HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
280900Z.//
NNNN 
MFR編號熱帶低壓第15號，暫不看好命名
TIO30 FMEE 270647
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 1/15/20202021
1.A TROPICAL DEPRESSION 15
2.A POSITION 2021/03/27 AT 0600 UTC:
WITHIN 20 NM RADIUS OF POINT 10.3 S / 65.4 E
(TEN DECIMAL THREE DEGREES SOUTH AND
SIXTY FIVE DECIMAL FOUR DEGREES EAST)
MOVEMENT: SOUTH-SOUTH-EAST 4 KT
3.A DVORAK ANALYSIS: 2.0/2.0/D 1.0/24 H
4.A CENTRAL PRESSURE: 998 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 30 KT
RADIUS OF MAXIMUM WINDS (RMW): NIL
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 95 SE: 0 SW: 0 NW: 185
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 700 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM
1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/03/27 18 UTC: 10.8 S / 66.4 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 140 SE: 0 SW: 0 NW: 85
24H: 2021/03/28 06 UTC: 11.0 S / 67.4 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 45 SE: 0 SW: 0 NW: 120
36H: 2021/03/28 18 UTC: 10.7 S / 68.6 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 155 SE: 0 SW: 0 NW: 85
48H: 2021/03/29 06 UTC: 10.0 S / 69.4 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 165 SE: 0 SW: 75 NW: 85
60H: 2021/03/29 18 UTC: 9.6 S / 69.7 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 175 SE: 0 SW: 75 NW: 85
72H: 2021/03/30 06 UTC: 9.2 S / 69.6 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 175 SE: 0 SW: 75 NW: 85
2.B LONGER-RANGE OUTLOOK:
96H: 2021/03/31 06 UTC: 8.7 S / 68.4 E, VENT MAX= 025 KT, REMNANT LOW
120H: 2021/04/01 06 UTC: 9.1 S / 66.1 E, VENT MAX= 025 KT, REMNANT
LOW
2.C ADDITIONAL INFORMATION:
FT=2.0+ CI=2.0+
THE MINIMUM MONITORED SINCE THURSDAY FAR EAST OF AGALEGA HAS
GRADUALLY GAINED IN ORGANIZATION DURING THE LAST 48 HOURS. THE
SATELLITE IMAGERY AND THE RECENT SCATT PASSES SHOW THAT THE
DEFINITION OF THE LOW LEVEL CENTER HAS IMPROVED AND THAT THE
CONVECTIVE ACTIVITY HAS STRENGTHENED NEAR THE CENTER. THIS ONE IS
HOWEVER ASYMMETRICAL BEING LOCATED MAINLY IN THE WESTERN SEMICIRCLE,
SUGGESTING THE EXISTENCE OF A SHEAR CONSTRAINT FROM THE EAST. THE
WINDS DISPLAYED ON THE ASCAT-B OF 0438Z GIVE NEAR GALE FORCE WINDS IN
THE NORTHERN SEMICIRCLE AND LOCALLY WINDS APPROACHING GALE IN THE
NORTHEAST QUADRANT. THE SYSTEM IS CONSEQUENTLY ANALYZED AS A TROPICAL
DEPRESSION AT 06Z.
THE CURRENT AND FORECAST ENVIRONMENTAL CONDITIONS FOR THE NEXT FEW
DAYS ARE MIXED TO UNFAVORABLE: THE LOW LEVEL CONVERGENCE IS CURRENTLY
GOOD ON THE NORTHERN AND SOUTHERN SIDES OF THE SYSTEM. IT WILL BECOME
VERY INDIRECT FROM MONDAY, WHERE THE STRENGTHENING OF THE EQUATORIAL
WESTERLIES IS NOT EXPECTED TO FEED THE CIRCULATION DIRECTLY. THE
SYSTEM IS CURRENTLY EXPERIENCING AN EASTERLY SHEAR AT THE NORTHERN
EDGE OF THE UPPER LEVELS RIDGE. THIS CONSTRAINT SHOULD CONTINUE
DURING THE NEXT FEW DAYS AND EVEN STRENGTHEN FROM MONDAY ONWARDS
DEPENDING ON THE FORECAST TRACK (POSSIBLE NORTHEASTWARD TREND KEEPING
THE SYSTEM OUT OF PHASE WITH THE UPPER LEVELS RIDGE FURTHER SOUTH).
IN THIS SHEAR CONTEXT, THE MID-LEVELS DRY AIR OF AVERAGE COULD ALSO
THWART THE INTENSIFICATION. THE OCEANIC POTENTIAL IS SUFFICIENT OVER
WATERS AT 28-29C AT THE SURFACE WITHOUT HOWEVER A DEEP WARM WATER
RESERVE. THE CURRENT FORECAST CALL FOR A LEVELING OFF OF THE CURRENT
INTENSITY AND A TENDENCY TO DISSIPATE IN THE FIRST PART OF NEXT WEEK,
MAINLY DUE TO THE STRENGTHENING OF THE EASTERLY SHEAR. ALL THE
GUIDANCE DOES NOT NECESSARILY FOLLOW THIS SCENARIO, SOME MODELS
INTENSIFY AND MAINTAIN THE SYSTEM AT THE STAGE OF TROPICAL STORM OVER
THE ENTIRE PERIOD BUT THIS POSSIBILITY IS NOT CONSIDERED THE MOST
LIKELY SCENARIO AT PRESENT.
IN TERMS OF TRACK, THIS ONE IS DRIVEN OVER A GOOD PART OF THE PERIOD
BY THE DYNAMIC OF THE NEAR EQUATORIAL WESTERLY FLOW WHILE THE
SUBTROPICAL RIDGE, TO THE SOUTH, IS NOT VERY MARKED, NOT VERY THICK
AND TENDS TO WEAKEN IN THE SHORT TERM, BEFORE STRENGTHENING DURING
THE PERIOD. A SIGNIFICANT DISPERSION EXISTS AROUND THIS SCENARIO
AMONG THE GUIDANCE AND THE UNCERTAINTY ON THE FUTURE TRACK IS HIGHER
THAN NORMAL. THE SYSTEM COULD THUS MOVE MORE DURABLY EASTWARD (WITH
EVEN LESS CHANCE OF INTENSIFYING). OVERALL THE EVOLUTION OF THIS
SYSTEM IS MORE UNCERTAIN THAN NORMAL.
THIS SYSTEM HAS NO IMPACT ON THE INHABITED LANDS OF THE BASIN DURING
THE NEXT 5 DAYS.= 
|
|
