Tuesday, July 12, 2011

Tropical Storm Ma-On Update #3

Formerly TD 08W, has just been upgraded into a Tropical Storm and was named "Ma-On" by the JMA. JTWC, is yet to upgrade the storm, although we believe they will be following soon, perhaps on their 09z update.

Latest IR image, shows convection building, especially on the eastern and southern sides of the storm, and slowly wrapping into the circulation center. ASCAT pass reveals a closed circulation with winds of 30-40kts, with the strongest winds NE of the center. For the past 12 hours, a TUTT cell northwest of the system has been hindering outflow on the western flank although recent images suggests this impediment may soon be over. Maximum sustained winds as of the moment are around 65kph with gusts of up to 85kph. TS Ma-On is moving westward at 20kph.

Computer models are somewhat in good agreement regarding the forecast track. Furthermore, most of them are expecting this storm to blow up and become a major typhoon in 3 to 4 days. Considering the favorable environment that Ma-On is in, it is likely that it will go into a period rapid intensification beginning sometime tomorrow. The presence of Upper-level Lows and/or TUTTs will be key as they can either aid or impede a cyclone's intensification.

As for the track, most models show the storm hitting an area from Okinawa to Southern Japan (Kyushu). NOGAPS is the northern outlier while the GFS is the southern outlier. Many factors play into the eventual northward turn of Ma-On such as the Subtropical Ridge (STR), troughs, or other potential cyclones. A disturbance east of the Philippines is expected to influence, albeit just a little, Ma-On which will make it turn southward, but only for a brief moment. It will then turn northward towards Japan. Of course this will mainly depend on the strength of this disturbance and its proximity to Ma-On.

As of right now, Ma-On is still in the middle of the Pacific and it is not forecast to affect Japanese territories until the end of the week so obviously still expect lots of changes with regards to the forecast in the coming days.

As for us, based on computer models and forecasts from JMA and JTWC, we will be taking a middle stance. As a preliminary forecast, we think Ma-On will eventually strengthen to Typhoon strength and pass through the Ryukyu Islands, around Okinawa, on either Monday or Sunday.
Meanwhile, in the Philippines, the SW Monsoon has weakened a bit and is now affecting mainly Luzon. There will still be increased chance of rainfall especially on the northern and western side of the Island, including Manila. Latest 24-hour rainfall reports in the region are around 50-100mm. Elsewhere in the country, expect clearer skies, especially on Visayas. Mindanao, on the other hand, will experience cloudy skies with light rain at times due to the disturbance in the Philippine Sea. As always, never rule out strong thunderstorms, mainly in the afternoon.

Issued (0730 UTC) 330pm PhT 071211

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