Typhoon Yagi Ramps Up; India Stays Unsettled
September 19, 2006
The atmosphere has wasted little time in replacing Shanshan with another typhoon, the present storm being Yagi. Right now, Typhoon Yagi is a long way from any land--970 miles, or 1560 kms, east-northeast of Guam, for instance. Nearer is Wake, at 580 miles to the east. But Yagi is a west-bound storm, at least for the next two to three days. By the way, I exclude tiny Minami Tori Shima, which is barely more than a shoal, I believe.
Near term, the key steering influence upon Yagi will be a big sub-tropical ridge, aloft, straddling the 30th parallel between 140º and 170º East longitude. Clockwise wind flow about the big ridge, or high, will swing Yagi westwards over seas warm enough to favor further strengthening. Late Thursday, Yagi could approach the northern end of the Northern Mariana Islands. However, at this time, another influence will come to bear upon Yagi, this being the southern edge of the jet stream from the East China Sea to Japan. Dipping southwards in the area of 120ºE-130ºE to define an upper trough, the upper westerly winds of the jet stream will help to veer Yagi northwestwards and, later, northwards. Details of this veering will determine which, if any, of the Bonin (Ogasawara) and Volcano (Kazan) Island take a hit from Yagi. The Nampo Islands, which reach southward from Japan along 140º East longitude, are also in the possible path of Yagi.
At this time, consensus of numerical forecast models (that I have seen) is that Yagi will veer northwards and later northwards in a textbook recurving path. Dissagreement is upon how far west the recurving storm gets. The GFS would allow the storm to threaten mainland Japan in the area of Tokyo as it makes its way back to the north and east. Satellite imagery and the Joint Typhoon Warning Center forecast path are to be found here: http://www.nrlmry.navy.mil/tc_pages/tc_home.html
As I wrote Monday, things aside from Yagi are looking quiet for the time being along the Asian Pacific Rim. There are still hints of locallized torrential rains on Taiwan on each of the next few days.
Speaking of torrential rains, I see that Sandakan, Sabah State, Malaysia (that is the northern end of Borneo), picked up 15.4 inches, or 39 centimeters, of rain within 36 hours as of this morning, local time. Normal monthly rainfall for Sandakan, as given in our climatology reference book, is 9.5 inches.
--South Asia:
Things are looking wierder by the day. Have a look at these Monsoon lows, one to either side of India.
To the east:
...and to the west:
I see that the western (Arabian Sea) low has an obvious anti-clockwise swirl to it that bears watching, as the possibility of it reaching tropical storm, or cyclone, status cannot be precluded. I reader from greater Mumbai, Tejas, has weighed in on this today.
Widen out to the whole Subcontinent and this is how things look (on the infrared band via Kalpana-1) as I write:
The two Monsoon lows can be seen as part of a higher scale belt of disturbed weather bridging Arabian Sea with Bay of Bengal and having northerly limits to nearly 25ºN latitude. Indeed, at the 500-millibar height, there is a continuous trough stretching west to east along either side of 20ºN.
Where to go with the two Monsoon lows along with the widespread, active rains stretching between them? One suggested solution cranked out by the GFS model is for slow evolution: an eastern low drifting ever-so-slowly inland (northwestwards); a western low spinning over the open Arabian Sea. This is through at least the start of next week.
Then there is the NOGAPS, which sends the western low back to the east and a landfall near Mumbai by early Saturday; the eastern low is drawn northwards towards a collision with the eastern Himalaya at the weekend. This latter solution, while posing the threat of heavy rain to the east of the Subcontinent and to the area of depression landfall in the west, would also lead to much quieter weather with the start of next week. The GFS solution would drag out the unsettled, actively rainy weather right into next week for the southern and eastern two-thirds to three-fourths of the Subcontinent.
Hot spots for heavy to excessive rainfall? Through Friday, the northern Deccan, the east north of the coastal bend, the eastern lowland of the River Ganga, also much of Nepal. If the eastern low heads bodily northwards, the Himalayan slope of Nepal could get inundated late in the week. Also, the area near and south of any landfall of the western low (Maharashtra?).
--Southern South America:
This is interesting. An outbreak of strong to severe thunderstorms is in the works for the eastern near south of the continent. It hot to the north (northern Chaco, western Brasil) and a vigorous low pressure wave in the upper atmosphere is aimed out of the northern Pampas (Argentina) for southern Brasil. Primary target for this outbreak looks to me to be: southern Brasil, beginning in western and northern Rio Grande do Sul and western Santa Catarina; southeastern Paraguay; and the far northeast of Argentina (mostly Misiones). The first of the strong thunderstorms seem to be bubbling up right now, but the outbreak is set to proceed overnight and Wednesday from southwest to northeast. Wednesday, the focus will shift to the Brasilian states of Parana and Sao Paulo. It looks prime to me for at least isolated instances of hail, damaging wind and--maybe--tornadoes.
Time is short, so I`ll post the COLA link for those interested in further detail to peek at the GFS plots:
http://www.wxmaps.org/pix/sa.fcst.html
