SPAC: VAIANU - Tropical Cyclone

[cycloneye]

91P INVEST 260402 1200 7.8S 176.6E SHEM 15 1009

[cycloneye]

AN AREA OF CONVECTION (INVEST 91P) HAS PERSISTED NEAR 9.0S
173.0E, APPROXIMATELY 590 NM NORTH-NORTHEAST OF PORT VILA. ANIMATED
ENHANCED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 030047Z OCEANSAT
DEPICTS AN AREA OF CALMER WINDS (5-10 KTS) CLOSER TO THE CENTER, WHILE
MORE ELEVATED WINDS (10-15 KTS) ARE OBSERVED ALONG THE NORTHERN FLANK
OF THE CIRCULATION. WITHIN THE STRUCTURE OF 91P, MULTIPLE
MESOVORTICIES ROTATING CYCLONICALLY ARE IDENTIFIABLE. UPPER AIR
ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT FOR FURTHER
DEVELOPMENT WITH LOW (10-15 KTS) VERTICAL WIND SHEAR, WARM (29-30 C)
SEA SURFACE TEMPERATURES AND A MODERATE POLEWARD OUTFLOW CHANNEL
ASSISTING THE SYSTEM. MODEL GUIDANCE IS IN GOOD AGREEMENT ON A
SOUTHWESTWARD TRACK WITH STEADY INTENSIFICATION OVER THE NEXT 24-48
HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 23 TO 28
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1003 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN
THE NEXT 24 HOURS IS LOW.

[cycloneye]

TROPICAL DISTURBANCE TD11F CENTRE [1000HPA] WAS ANALYSED NEAR 11.8S
171.5E AT 031800UTC. POSITION POOR BASED ON HIMAWARI-9 VIS/EIR
IMAGERY. TD11F SLOW MOVING.

DEEP CONVECTION REMAINS TO THE EAST AND SOUTHEAST OF THE SUPPOSED
LLCC. TD11F LIES IN A LOW SHEARED ENVIRONMENT, WITH WEAK UPPER
DIVERGENCE AND MODERATE LOWER CONVERGENCE. SST AROUND 29 DEGREES
CELSIUS.

HOWEVER, DRY AIR INTRUSION FROM THE SOUTHWEST OF THE SYSTEM AND
STRONG WIND SHEAR FROM THE SOUTH CAN HINDER FURTHER DEVELOPMENT.

GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND MOVED IT SOUTHWARDS WITH
LITTLE INTENSIFICATION.

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

[Hurricane2022]

HOWEVER, DRY AIR INTRUSION FROM THE SOUTHWEST OF THE SYSTEM AND
STRONG WIND SHEAR FROM THE SOUTH CAN HINDER FURTHER DEVELOPMENT.

GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND MOVED IT SOUTHWARDS WITH
LITTLE INTENSIFICATION.

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

They're saying this while GFS, Euro, CMC, ICON, HWRF-P & HAFS-P are all showing a decent TS developing in about 24 - 48 hours and a bonafide hurricane-strength TC afterwards... The FMS is acting terribly bad this season. Strange to see such behavior coming from an agency that usually overestimate systems!

[cycloneye]

THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED NEAR
12.4S 170.8E IS NOW LOCATED NEAR 11.7S 171.8E, APPROXIMATELY 347 NM
NORTH-NORTHEAST OF PORT VILLA. MULTISPECTRAL SATELLITE IMAGERY (MSI)
REVEALS A BROAD LOW LEVEL CIRCULATION CENTER (LLCC) WITH AN ELONGATED
BUT SLOWLY CONSOLIDATING CENTER. A RECENT OSCAT-3 PASS REVEALED A
BROAD CIRCULATION WITH A BAND OF ELEVATED WINDS UP TO 30 KNOTS ALONG
THE EASTERN FLANK OF THE ROTATION. ENVIRONMENTAL ANALYSIS REVEALS
FAVORABLE CONDITIONS FOR DEVELOPMENT WITH LOW TO MODERATE VERTICAL
WIND SHEAR (15-20 KNOTS), GOOD DIFFLUENT OUTFLOW ALOFT, AND WARM SEA
SURFACE TEMPERATURES (29-30 C). GLOBAL MODELS ARE IN FAIR AGREEMENT
THAT INVEST 91P WILL CONTINUE TO HAVE STEADY DEVELOPMENT AND A
SOUTHWESTWARD TRACK OVER THE NEXT 24 TO 36 HOURS. 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 UPGRADED TO MEDIUM.

[cycloneye]

TROPICAL DISTURBANCE TD11F CENTRE [999HPA] WAS ANALYSED NEAR 12.4S
171.3E AT 040600UTC. POSITION POOR BASED ON HIMAWARI-9 VIS/EIR
IMAGERY. TD11F SLOW MOVING.

DEEP CONVECTION REMAINS TO THE EAST OF THE SUPPOSED LLCC WITH
ORGANISATION ORGANISATION IN THE LAST 6HRS. TD11F LIES IN A LOW TO
MODERATE SHEARED ENVIRONMENT, WITH MODERATE UPPER DIVERGENCE AND
MODERATE LOWER CONVERGENCE. SST AROUND 29 DEGREES CELSIUS.

THE SYSTEM IS EXPECTED TO BE STEERED TO THE SOUTH THEN LATER
SOUTHEASTWARDS BY THE SUBTROPICAL RIDGE.
HOWEVER, DRY AIR INTRUSION FROM THE SOUTHWEST OF THE SYSTEM AND
STRONG WIND SHEAR FROM THE SOUTH MAY HINDER FURTHER INTENSIFICATION.

GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND MOVED IT SOUTHWARDS WITH
SOME INTENSIFICATION.

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

[Hurricane2022]

If HAFS-A is right, we may see a historic duo of C4 Tropical Cyclones spinning in the South-west Pacific. This one should take the name Vaianu.

[cycloneye]

THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED NEAR
12.3S 171.3E IS NOW LOCATED NEAR 12.7S 171.2E, APPROXIMATELY 345 NM
NORTH-NORTHEAST OF PORT VILA. MULTISPECTRAL SATELLITE IMAGERY (MSI)
REVEALS A BROAD LOW LEVEL CIRCULATION CENTER (LLCC) WITH AN ELONGATED
BUT SLOWLY CONSOLIDATING CENTER AND RECENTLY DEVELOPING DEEP
CONVECTION ALONG THE EASTERN SIDE OF THE CIRCULATION. A 040959Z ASCAT
PASS SHOWS A DEFINED CIRCULATION WITH STRONGER WINDS OF 25-30 KNOTS
WRAPPING AROUND THE SOUTH AND EASTERN SIDE OF THE CIRCULATION, WITH A
FEW ISOLATED PATCHES OF 35 KNOTS EMBEDDED UNDER THE DEEPEST CONVECTIVE
CELLS. ENVIRONMENTAL ANALYSIS REVEALS FAVORABLE CONDITIONS FOR
DEVELOPMENT WITH LOW TO MODERATE VERTICAL WIND SHEAR (15-20 KNOTS),
GOOD DIFFLUENT OUTFLOW ALOFT, AND WARM SEA SURFACE TEMPERATURES (29-30
C). GLOBAL MODELS ARE IN FAIR AGREEMENT THAT INVEST 91P WILL CONTINUE
TO HAVE STEADY DEVELOPMENT AND A SOUTHWARD TRACK OVER THE NEXT 12 TO
24 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 28 TO 33
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 UPGRADED TO HIGH

[Hurricane2022]

This may go pinhole soon.

[cycloneye]

[Subtrop]

Tropical Cyclone Naming Bulletin ISSUED FROM RSMC NADI Apr 051222
UTC.

TROPICAL DEPRESSION TD11F LOCATED NEAR 14.9S 172.2E AT 051200UTC HAS
BEEN NAMED VAIANU.

[Hurricane2022]

 https://x.com/i/status/2040785112183263665


 https://x.com/i/status/2040773484788216014

[cycloneye]

[Hurricane2022]

As of 1630z today, FMS still stuck at 40 kt while we're starting to see the first signs of a pinhole eye clearing. IMD is proud of them!
 https://x.com/i/status/2040762992384418043

The posts in this forum are NOT official forecasts and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the NHC and NWS.

[sasha_B]

Eye pattern isn't applicable because the 24h FT was 2.0, but the eye is obviously there and seems to be warming; DT would be 4.5 otherwise. W eye surrounded by B = E#5.5, －1.0 for W or CMG = DT4.5; PT agrees. Convection wraps >1.0 around the center, in any case, so FT 4.0 (65 kt, roughly 978～980 hPa) would be a fine conservative estimate for 18z, IMO. It would also be only slightly higher than objective intensity estimates from UW-CIMSS (CI 3.8, 61 kt / 986 hPa), though ADT has been missing the center position and should probably be taken with a grain of salt.

The posts in this forum are NOT official forecasts and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the NHC and NWS.

[sasha_B]

B. 05/1730Z
C. 15.08S
D. 172.55E
E. FIVE/HMWRI9
F. T4.5/4.5/D2.5/24HRS STT: D1.0/03HRS
G. IR/EIR
H. REMARKS: 38A/PBO SBC/ANMTN. B EYE SURROUNDED BY B YIELDS AN E#
OF 5.5. SUBTRACTED 0.5 EYE ADJUSTMENT FOR CMG TO YIELD A DT OF
5.0. MET YIELDS 3.5. PT YIELDS 4.5 ADJ +0.5 FOR WH. DBO PT.

Vaianu is catching up to Maila in strength: the JTWC has them at 80 kt and 90 kt respectively, as of 18z. Not every day we get to track two rapidly-intensifying cyclones in (relatively) close proximity.

[cycloneye]

TROPICAL CYCLONE VAIANU CENTRE 975HPA CATEGORY 2 WAS LOCATED NEAR
15.1S 172.6E AT 051800 UTC. POSITION POOR BASED ON HIMAWARI IR
IMAGERY AND PERIPHERAL SURFACE REPORTS. CYCLONE MOVING SOUTHEAST AT
ABOUT 04 KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE
ESTIMATED AT ABOUT 55 KNOTS.

EXPECT WINDS OVER 47 KNOTS WITHIN 40 NAUTICAL MILES OF CENTRE AND

EXPECT WINDS OVER 33 KNOTS WITHIN 120 NAUTICAL MILES IN NE QUADRANT
AND WITHIN 110 NAUTICAL MILES IN SE QUADRANT
AND WITHIN 90 NAUTICAL MILES IN SW QUADRANT
AND WITHIN 70 NAUTICAL MILES IN NW QUADRANT

DEEP CONVECTION REMAINS PERSISTENT AND ORGANIZATION REMAINS GOOD
ORGANISATION WITH EYE DISCERNIBLE ON HIMAWARI IR IMAGERY. CYCLONIC
CIRCULATION EXTENDS UP TO 300HPA. SYSTEM LIES IN A GOOD UPPER
DIVERGENT AREA WITH A GOOD POLEWARD OUTFLOW. CYCLONE LIES IN A LOW
SHEARED ENVIRONMENT AND IS MOVING IN TO AN AREA OF DECREASING SHEAR.
SST AROUND 29 DEGREES CELSIUS. DVORAK ANALYSIS BASED ON W EYE AND CMG
SURROUND THUS YIELDS DT=4.5, PT=4.0 MET=3.0. FT BASED ON PT. THUS,
YIELDING T4.0/4.0/D1.5/24HRS. DVORAK FT CONSTRAINT BROKEN.