WPAC: Sepat - Post-Tropical

[euro6208]

Huge fail.

[Hayabusa]

Well JMA finally issued gale warning

TD
Issued at 19:10 UTC, 25 June 2019

<Analysis at 18 UTC, 25 June>
Scale -
Intensity -
TD
Center position N19°20' (19.3°)
E128°20' (128.3°)
Direction and speed of movement ENE 20 km/h (10 kt)
Central pressure 1006 hPa
Maximum sustained wind speed 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)

<Forecast for 06 UTC, 26 June>
Intensity -
TD
Center position of probability circle N23°50' (23.8°)
E127°00' (127.0°)
Direction and speed of movement N 45 km/h (23 kt)
Central pressure 1004 hPa
Maximum sustained wind speed 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)
Radius of probability circle 110 km (60 NM)

<Forecast for 18 UTC, 26 June>
Intensity -
Center position of probability circle N28°20' (28.3°)
E128°50' (128.8°)
Direction and speed of movement NNE 45 km/h (24 kt)
Central pressure 998 hPa
Maximum wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 150 km (80 NM)

[wxman57]

I'm not seeing any significant LLC at 19.9N / 128.6E. Looks like an elongated mess heading into increasing shear.

[Nancy Smar]

WARNING.
TROPICAL DEPRESSION 1004 HPA
AT 26.1N 126.5E EAST CHINA SEA MOVING NORTH SLOWLY.
POSITION GOOD.
MAX WINDS 30 KNOTS NEAR CENTER.

[wxman57]

Duplicate thread. See Tropical Depression "a", was 94W.

[Tailspin]

[NotoSans]

(For unknown reasons) Upgraded to TS Sepat by JMA at 09Z. Let’s wait for the 12Z prognostic reasoning.

[Nancy Smar]

(For unknown reasons) Upgraded to TS Sepat by JMA at 09Z. Let’s wait for the 12Z prognostic reasoning.

Because of the following observation data, this system has been upgraded.
和歌山県 和歌山市 友ケ島（トモガシマ） 21.6m/s] 南] 16:38]

[euro6208]

THE AREA OF CONVECTION (INVEST 94W) PREVIOUSLY LOCATED
NEAR 20.7N 128.2E, IS NOW LOCATED NEAR 28.3N 130.3E, APPROXIMATELY
294 NM SOUTH OF SASEBO, JAPAN. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS A BROAD DISORGANIZED CIRCULATION. A 260125Z METOP-B
ASCAT PASS SHOWS SLIGHT TURNING WITH MOSTLY STRAIGHT LINE FLOW ON
THE EASTERN SIDE. THE SYSTEM REMAINS AHEAD OF AN APPROACHING UPPER
LEVEL TROUGH. 94W IS UNDER WEAK UPPER LEVEL OUTFLOW AND NEUTRAL TO
UNFAVORABLE VERTICAL WIND SHEAR (20-25 KTS). SEA SURFACE
TEMPERATURES ARE MARGINAL (24-26 C) FOR DEVELOPMENT. GLOBAL MODELS
ARE IN GOOD AGREEMENT THAT THE SYSTEM WILL CONTINUE TRACKING
NORTHWARD, THEN NORTHEASTWARD ALONG THE COAST OF HONSHU, JAPAN AS IT
INTERACTS WITH THE UPPER LEVEL TROUGH AND UNDERGOES EXTRATROPICAL
TRANSITION. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO
25 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 REMAINS LOW.

[euro6208]

[Hayabusa]

Huge fail.

An epic fail for HWRF for many runs it was forecasting a typhoon.

[Hayabusa]

We are already at the peak shear according to this chart it should go down soon and TC development could finally happen while the shear is down 94W could finally take advantage of the untapped OHC and SST east of the Philippines, though there was no HWRF 18Z run. Interesting how would 94W develop while interacting with the front. Could we finally have Sepat or a subtropical cyclone?

I'm not sure if I welcome that WPAC finally got Sepat after 4 months of no named storm since Wutip, given how Sepat looks even though there is wind support for a TS

[NotoSans]

ASCAT shows 40-45KT winds and a slightly elongated circulation. Naming this system seems fine to me.
On the other hand JTWC classifies it as a subtropical storm.

[euro6208]

94W INVEST 190627 1200 32.6N 134.2E WPAC 35 996

Yup unfortunately JTWC doesn't use this classification.

I reckon if they did. Just imagine how much the numbers will increase considerably.

Lost ACE for the season.

[wxman57]

ASCAT shows 40-45KT winds and a slightly elongated circulation. Naming this system seems fine to me.
On the other hand JTWC classifies it as a subtropical storm.

Looking more like a frontal low than a TS. I don't see any 45kt winds on ASCAT, but I do see southerly winds 35-40kts ahead of the system. That wind is from the SSW east of the low. It's not directed inward toward the low. Poorly-defined LLC, if it has one at all. Winds about 15 kts west of the low pressure area.

[euro6208]

THE AREA OF CONVECTION (INVEST 94W) PREVIOUSLY LOCATED
NEAR 28.3N 130.3E, HAS DISSIPATED AND IS NO LONGER SUSPECT FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE IN THE NEXT 24 HOURS.

[euro6208]

94W INVEST 190628 0600 36.2N 147.1E WPAC 35 996