04W Advisories

...04W strengthens very slightly...

Center Track Forecast

12 hours: 30 knots; 35 mph; 55 km/h24 hours: 25 knots; 30 mph; 45 km/h (Open wave)

Advisory 2


1-minute sustained wind: 35 knots; 40 mph; 65 km/hEstimated minimum pressure: 1002 mbCurrent position: 16.3N, 129.1E

Public Advisory

04W, currently east of the Philippines, is expected gradually travel towards the Luzon Strait before degenerating into a cluster of thunderstorms. The tropical storm currently has 1-minute sustained winds of 35 knots, or 65 kilometers per hour. The primary impact expected from 04W is enhancement of the monsoonal flow.

Scientific Discussion

The satellite presentation of 04W has organized somewhat, though its low-level circulation remains elongated, indicated by low-level cloud patterns and ASCAT passes. The ADT is currently depicting a current wind speed of 53 knots, but this is currently being considered as erroneously high as ASCAT passes depict peak winds of 30 to 35 knots; SATCON shows a 1-minute sustained wind of 40 knots, and AMSU remains at 35 knots. Subjective Dvorak estimates are currently at CI2.5/35 knots, but the current T-number is 1.5, or 25 knots. Based on this data, 04W is only being upgraded to 35 knots, or bare tropical storm intensity.
The forecast logic has not changed much compared to yesterday's. 04W is expected to gradually make its way towards the Luzon Strait, degenerating into an open tropical wave along the way. This mostly follows the ECMWF, which has split from its northward trajectory and is now following the middle ground between the UKMET, NAVGEM, CTCX, and GFS models. The intensity forecast mostly follows the logic from yesterday as well, predicting a degeneration into an open wave in 24 hours.
It should be noted that this system's moisture may contribute to a gyre-like cyclone expected to form in the South China Sea between the Philippines and Vietnam. This cyclone is not expected to become a tropical cyclone, though it is expected to enhance rainfall across the Philippines.

Forecaster ID

MCK

Advisory Archive

Below is an archive of previous advisories for 04W.

...04W forms east of the Philippines...

Center Track Forecast

12 hours: 35 knots; 40 mph; 65 km/h24 hours: 40 knots; 45 mph; 75 km/h36 hours: 40 knots; 45 mph; 75 km/h48 hours: 35 knots; 40 mph; 65 km/h (Open wave)

Advisory 1


1-minute sustained wind: 30 knots; 35 mph; 55 km/hEstimated minimum pressure: 1007 mbCurrent position: 13.3N, 132.7E

Public Advisory

04W has been officially designated by the JTWC at 18z, and GWES-TCD is following suit as available data supports the upgrade from an open wave to a tropical depression at this time.
04W currently has 1-minute sustained winds of 30 knots, or 55 kilometers per hour, and is expected to strengthen only slightly more before decaying prior to reaching either the Philippines or Taiwan. The primary impact from this system is expected to be heavy rainfall across the Philippines as a result of the enhancement of the monsoon.

Scientific Discussion

Current satellite imagery suggests the closing of the low-level and mid-level circulation of 04W, and ASCAT passes depict a ring of winds of at least 15 knots, peaking at 30 knots with a few pockets of 35 knots (though these pockets are surrounded by flagged data), strongly suggest that 04W has closed into a tropical depression. Shear of up to 25 knots is currently impacting this system, fanning the cloud tops towards the southwest, while most of its circulation is currently moving northwestward. Given this data I am setting the intensity estimate at 30 knots for this advisory.
The forecast reasoning is coming from a particularly complicated divergence of scenarios. Some models forecast that 04W will simply fizzle out as it moves towards the west (suggested by the GFS and NAVGEM), or further northward into Taiwan (suggested by UKMET and ECMWF). The HWRF, though on its 12z run, suggests that 04W will pass just north of Luzon Island and peak prior to making a particularly major landfall in China. However, the HWRF is the only model that makes this suggestion, and furthermore, as of the writing of this discussion, the 18z run has not completed yet. As a result of this, a consensus of the four global models will be used for this advisory, with 04W remaining as a fairly minimal tropical storm before opening into a wave in 48 hours to the east of the Luzon Strait. However, this forecast is likely to change as more models initialize.

Forecaster ID

MCK