Multiple Tropical Lows Bring Heavy Rainfall Threats For Vietnam and Philippines Possible Nepartak

The tropics look like a pan of oil that has been lit on fire today with wide spread convection being seen from Yap and Palau through the South China sea stretching across the Philippines.



The thing is at least at this time this is a uncontrolled burn with wide spread monsoonal storms concentrated near two low pressure areas. A tropical depression (invest 96w) in the South China Sea and another invest area which could become a TD over Yap and Palau.


First we start with our Tropical Depression, officially this is expected to become a tropical storm in the next 24hrs as it tracks north towards Vietnam and Southern China.  Before this happens it will need to re-organize a little since as of Friday morning wind shear and multiple low level vorticies has turned this once decent looking TD in to a mess of scrambled eggs.

Most numerical guidance also continues to struggle on the handling of this storm, which further supports my ideas from yesterday, that is that this Tropical low regardless on if it becomes a named storm or not will be more of a Monsoonal Gyre which are notorious for bringing wide spread long lasting rainfall to locations they come near.  Thus heavy rainfall is to be expected in Vietnam and eventually China this weekend in to early next week.  For those in Hong Kong I wouldn’t worry as much about this though as our friends to the South as it does look like this low will be a very slow moving storm and Hong Kong remains just north of the extent of the Monsoonal rains.


72hr Rainfall Outlook

72hr Rainfall Outlook

For the Philippines though this could spell some long lasting intense rainfall heading through the weekend. Wide


spread swaths of Southern Luzon Visayas and Mindanao could see over 50mm of rainfall but parts of Visayas including the Cebu area might top 200mm this weekend. This in short means there is the chance of river flooding and landslides.


This is a combination of the TD and the Invest area now over Yap and Palau. That area already is bringing Thunderstorm alerts and Prolonged rainfall warnings for those islands as it slowly tracks over head over the next 48hrs carrying an abundance of moisture with it. Like a giant water balloon this will track west towards the Philippines bringing rainfall with it as well.


Can we see a Typhoon?


As I wouldn’t go ruling that out I would say there is an abundance of disorganized convection here which can put strain on developing storms as the energy in the area is unable to consolidate, still though lets continue to watch both areas, for those in the Philippines and Vietnam the threat of heavy rain and the chance of flooding.




After this burst of activity models do not show much, but the yearly outlook and climatology suggest that things should start to pick up quickly as we head in to July. So right now do not trust long range models so much and keep a open mind for pending storms.
Some good news maybe not for these storms but in the near future may be happening.

For those who track and forecast storms in the western pacific there is a extra challenge in doing so compared to our friends in the Eastern Pacific and Atlantic and that is a lack of aircraft recon.

Consistent typhoon reconnaissance ended nearly 30 years ago in 1987 with the closing of the 54th Weather Reconnaissance Squadron base in Guam.


The squadron was responsible for some of the lowest official pressure readings in history in a tropical cyclone and was key in forecasting the storms for a half a century.


In 2010 a hurricane hunter ventured in to the western pacific to study the Impact of Typhoons on the Ocean in the Pacific or “ITOP”.   The last flight to punch a eye wall in the Western Pacific was on October 18th 2010.


Taiwan still does flights on a irregular basis around storms to get steering flow information but never near the storms core.


This could be changing in the near future though thanks to a Japanese Research team from Nagoya University, the University of the Ryukus and the Japan Meteorological Agency.


They have purchased a Lear Jet and equipped it with observational equipment including drop sondes. These are a type of equipment that are launched from the bottom of aircraft to get a gauge of the atmosphere inside a typhoon.


Flights are expected to start in 2017 and continue through 2020 with hopes of extending if funding remains suitable.


The Jet is likely to be stationed in Okinawa in southern Japan a location that is hit often several times a year by typhoons.


Due to the small size of the aircraft compared to its cousin the C-130 hurricane hunters it may not be able to punch the eye wall on significant typhoons, but one of the researchers during a interview with NHK TV stated they will try to get as close as possible to the storms center as safety permits.



The information gathered during flights will primarily be used for research purposes but since JMA is also working in the program it is apparent that it will also be used in directly nowcasting and forecasting typhoons tracks and strength.


Intensity forecasting is a bullet point for the agency since in recent years we have seen a surge in “Super Typhoons” in the western pacific.  Many people arguing it would have made a massive difference if there was recon during Typhoon Haiyan in 2013.


This is why the announcement of recon in to typhoons next year comes with such applause.

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