Monday, August 29, 2011

TS Nanmadol and TS Talas Update

Nanmadol (Formerly Bagyong Mina) has made landfall near Hengchun in Southern Taiwan very early this morning (around 3am). It has since weakened to a tropical storm. It has also exited into the Taiwan Strait and regained a little bit of strength as it moved across the waters. Tropical Storm Nanmadol was last located approximately 100km west northwest of Kaohsiung or about 230km southwest of Taipei. Nanmadol is now out of the Philippine Area of Responsbility.

Signal #1 remains in effect for Batanes Group of Islands.

Maximum sustained winds are up slightly to around 95kph gusting to around 140ph. Nanmadol is currently moving west northwestward at 10kph. Weather stations from Taiwan still recording sustained winds of around 65 to 70kph (TS strength) with occasional gusts of as high as 90 to 100kph. Yesterday, just before it made landfall, we saw some reports of gusts as high as 170kph in the southeastern part particularly Lanyu.

Furthermore, there are widespread rainfall reports of 100-200mm in 24 hours. Hengchun actually reported rainfall amounts of near 350mm. Based on the radar image from Taiwan below, there are still bands of light to moderate rain affecting the southeastern areas such as Kaohsiung and Tainan. Other areas reporting windy conditions with mostly cloudy skies.

Radar image from CWB

Forecasts for Nanamdol are generally in good agreement among models and agencies although some discrepancies the timing. We do expect the storm to continue on its present movement at a slow pace. We expect it to make landfall in Fujian Province--approximately 80km south of Xiamen--by late Tuesday night. It will then continue moving across China, weakening rapidly and should dissipate as a depression as early as Thursday.

My Personal Forecast (NOT OFFICIAL):

Tropical Storm Talas

Tropical Storm Talas continues to remain stationary well south of Japan. It remains a tropical storm at the moment as it continues to organize at a slow rate. Latest IR image, though, is now showing improved banding and convective activity especially on the eastern side. A recent microwave image also reveals a very nice organization in the lower levels of the storm structure although the center of circulation still looks elongated. Wind shear is very weak in that area (about 5 to 10knots) and sea surface temperatures remain warm. We expect Talas to slowly intensify over the next 24 to 48 hours.

The Forecast track remains very difficult to pinpoint. I would like to say, however, that Japan's chances of seeing stormy conditions this weekend continue to increase. Model consensus now brings Talas towards Honshu near the Ize Peninsula (southwest of Tokyo) by Friday. The steering patterns in the atmosphere are somewhat complicated and the movements, timing, and eventual positioning of these features are very crucial for Talas' track down the road. Most forecasts by agencies also show a landfall near Tokyo but keep in mind that this is still about four days away and we have seen how Nanmadol's forecast track dramatically changed within 24 hours; those shifts could also happen here with Talas.

Nevertheless, my forecast takes somewhat of a middle track although favoring more on JMA's forecast as well as on the GFS model. If it makes landfall, the strength looks to be around a strong Category 1 or a weak Category 2. Talas is then forecast to continue moving northeastward across Honshu and could exit towards the Sea of Japan by the weekend.

My Forecast (NOT OFFICIAL)

I will have my next update by tomorrow morning.
Issued (0930 UTC) 530pm PhT 082911

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