A tropical low (10U) was located about 260 kilometres southeast of Christmas Island at 1300 WST Tuesday 19 January. It is forecast to continue moving generally west. Guidance generally indicates an unfavourable environment which means there is only a Low risk of 10U reaching tropical cyclone intensity from Thursday.
Although there is currently only a Very Low risk of 10U being a tropical cyclone on Wednesday the Cocos (Keeling) Islands could experience heavy rainfall and squally strong winds as the low moves past during Wednesday and early Thursday. There is also the potential for a north to northwesterly swell impacting Flying Fish cove on Christmas Island over the next week as a result of persistent northwesterly winds between the islands and Indonesia.
Likelihood of this system being a tropical cyclone in the Western Region on:
Wednesday:Very Low
Thursday: Low
Friday: Low
(2) AN AREA OF CONVECTION (INVEST 93S) HAS PERSISTED NEAR
12.0S 109.0E, APPROXIMATELY 380 NM SOUTH-SOUTHEAST OF JAKARTA,
INDIA. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A 191715Z
GMI 89GHZ MICROWAVE IMAGE DEPICT LOWER LEVEL BANDING WITH CONVECTION
OBSCURING THE LOW LEVEL CIRCULATION CENTER (LLCC). ENVIRONMENTAL
ANALYSIS DEPICTS A FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH LOW
(<15 KTS) VERTICAL WIND SHEAR, POLEWARD OUTFLOW, AND WARM (30-31C).
GLOBAL MODELS ARE IN GOOD AGREEMENT THAT INVEST 93S WILL TRACK
WESTWARD AS IT CONSOLIDATES AND STRENGTHENS. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1007 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.
(2) THE AREA OF CONVECTION (INVEST 93S) PREVIOUSLY LOCATED
NEAR 13.4S 104.5E IS NOW LOCATED NEAR 12.8S 100.9E, APPROXIMATELY
235 NM EAST-SOUTHEAST OF COCOS ISLANDS, AUSTRALIA. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY AND A 200222Z MHS 89GHZ MICROWAVE
IMAGE DEPICT A CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC)
WITH FLARING DEEP CONVECTION, PARTICULARLY SOUTHEAST OF THE LLCC. A
PARTIAL 200607Z ASCAT-A PASS SHOWS A WELL-DEFINED CIRCULATION WITH
20-25KT WIND BARBS IN THE SOUTHERN SEMI-CIRCLE AND 15-20KT WINDS IN
THE NORTHERN SEMI-CIRCLE. ENVIRONMENTAL ANALYSIS DEPICTS A FAVORABLE
ENVIRONMENT FOR DEVELOPMENT WITH LOW (<15 KTS) VERTICAL WIND SHEAR,
POLEWARD OUTFLOW, AND WARM (30-31C)SEA SURFACE TEMPERATURES. GLOBAL
MODELS ARE IN GOOD AGREEMENT THAT INVEST 93S WILL TRACK GENERALLY
WESTWARD AS IT CONSOLIDATES AND STRENGTHENS. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS UPGRADED TO MEDIUM.
WTXS21 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 93S)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 12.8S 100.8E TO 13.4S 95.2E
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 25 TO 30 KNOTS. METSAT
IMAGERY AT 201200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 13.1S 99.3E. THE SYSTEM IS MOVING WESTWARD AT 16 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 93S) PREVIOUSLY LOCATED
NEAR 12.8S 100.9E IS NOW LOCATED NEAR 13.1S 99.3E, APPROXIMATELY
153NM ESE OF COCOS ISLANDS, AUSTRALIA. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY SHOWS DEEP CONVECTION OVER A CONSOLIDATING LOW LEVEL
CIRCULATION CENTER (LLCC). ADDITIONALLY, 201202Z SSMIS 91 GHZ MICROWAVE
IMAGE DEPICTS CONVECTIVE BANDING WRAPPING INTO THE LLCC. ENVIRONMENTAL
ANALYSIS REVEALS A FAVORABLE ENVIRONMENT FOR DEVELOPMENT CHARACTERIZED BY
POLEWARD OUTFLOW AND WARM (30-31C) SEA SURFACE TEMPERATURES OFFSET BY
MODERATE (15-20KTS) VERTICAL WIND SHEAR. GLOBAL MODELS ARE IN GOOD
AGREEMENT THAT INVEST 93S WILL TRACK GENERALLY WESTWARD AS IT
CONSOLIDATES AND STRENGTHENS. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 25 TO 30 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 HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
211500Z.//
NNNN
IDW27700
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 0632 UTC 22/01/2021
Name: Tropical Low
Identifier: 10U
Data At: 0600 UTC
Latitude: 13.2S
Longitude: 97.2E
Location Accuracy: within 10 nm [20 km]
Movement Towards: southwest [232 deg]
Speed of Movement: 2 knots [5 km/h]
Maximum 10-Minute Wind: 40 knots [75 km/h]
Maximum 3-Second Wind Gust: 55 knots [100 km/h]
Central Pressure: 994 hPa
Radius of 34-knot winds NE quadrant: 80 nm [150 km]
Radius of 34-knot winds SE quadrant:
Radius of 34-knot winds SW quadrant:
Radius of 34-knot winds NW quadrant: 110 nm [205 km]
Radius of 48-knot winds NE quadrant:
Radius of 48-knot winds SE quadrant:
Radius of 48-knot winds SW quadrant:
Radius of 48-knot winds NW quadrant:
Radius of 64-knot winds:
Radius of Maximum Winds:
Dvorak Intensity Code: T2.0/2.0/W0.5/24HRS STT:S0.0/06HRS
Pressure of outermost isobar: 1006 hPa
Radius of outermost closed isobar: 240 nm [445 km]
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+06: 22/1200: 13.3S 97.3E: 025 [045]: 035 [065]: 995
+12: 22/1800: 13.5S 97.4E: 040 [075]: 035 [065]: 995
+18: 23/0000: 13.8S 97.4E: 050 [095]: 035 [065]: 995
+24: 23/0600: 14.2S 97.5E: 070 [130]: 035 [065]: 995
+36: 23/1800: : : :
+48: 24/0600: : : :
+60: 24/1800: : : :
+72: 25/0600: : : :
+96: 26/0600: : : :
+120: 27/0600: : : :
REMARKS:
The low level centre of tropical low 10U remains well exposed from the deep
convection that is displaced to the west of the system and as a result the
position accuracy is good. The latest Dvorak analysis was based on a shear
pattern with less than three-quarters of a degree between the low level centre
and the deep convection, giving a DT of 2.5. MET and PAT were both 2.0. FT was
based on MET.
An ASCAT pass at 0206UTC showed a swath of gales within about 110nm of the
system centre in the northern semicircle, with maximum winds of 35-40 knots. As
of 0600UTC, gales were continuing about the Cocos Island National Tidal Centre
Automatic Weather Station [AWS] and winds remained below gale force at the Cocos
Island Airport AWS.
Tropical low 10U is currently in an area of strong vertical wind shear on the
northern side of the upper ridge, under a divergent easterly flow. The middle
level circulation is weak, and displaced well to the west of the low level
circulation. As a result, the system will likely take some time to reconsolidate
into a deep circulation [if it does at all], and therefore it is rated a low
chance of forming into a tropical cyclone from Sunday.
At the moment the system is slow-moving but it should start to be guided in a
general southerly direction into Saturday by a low to mid-level ridge situated
to the east.
提升卡
千斤頂
