--It is nearly one week since my last post, so there has been enough time for some of the "dust" to settle with respect to a would-be tropical cyclone. Numerical forecasts that I have seen insinuate that a tropical low now along the east coast will drift west to the eastern Arabian Sea during the next several days. Towards the end of the week, it may become cyclonic as it veers northward and northeastward. Thus, a return to land over India (Gujarat?) seems to be the latest, best idea. And I believe this to be more in keeping with historic behavior of late-season tropical lows.
Indication by the GFS is still that this weather system would unleash heavy falls of rain in select spots along its path. As to Karachi and Sindh, however, I am afraid that the past history will once again show the way. In other words, past history is that little rain falls during October in the city, so it would take some exceptional behavior on the part of any cyclonic weather system to unleash heavy and/or widespread rain over the city. This is not to say that it cannot rain; indeed, the GFS is hinting at scattered showers and thunderstorms in the area.
--Tragic results on Luzon Island, Philippines, with the latest tropical cyclone, T.S. Ketsana. Not wind; rather, it was one month (or more) worth of normal rain within about one day. It was a "perfect storm" for driving torrential rain right into the heart the nation's biggest city. Rainfall over Manila City was on the order of 30 cm. But at nearby Diliman, it was more than 50 cm within the same span of time. At Tanay, rainfall was almost as high.
-Now, Ketsana is a full-fledged typhoon taking square aim upon Vietnam. Landfall of this big storm will be north of Hue, where the coast strikes northwest-southeast. I even wonder if this storm would not try to veer enough to keep its center off shore as far north as, say, Vinh. Timing of landfall will hinge upon how much it veers; I believe that it would be somewhere between Tuesday afternoon and Wednesday morning, local time.
--Presence of two other Western Pacific tropical cyclones, TD 18W and TS 19W, will keep tropical forecasters busy for another week or so. The more easterly system, 18W, seems headed for Guam. TS 19W will track into the Philippine Sea by way of Yap Islands. Of the two, 19W would be the one to watch for those in the Philippines worried about further heavy rain. It may not have much bearing upon rainfall over the archipelago before week's end.
Get a handy weather station and convenient public alert radio, all for one great price.
The Public Alert Docking Weather Station - available at AccuWeather's AccuMall.
© 2009 AccuWeather, Inc.
All Rights Reserved.
AccuWeather.com is a registered trademark of AccuWeather, Inc.
Terms of usage under which this service is provided.
Privacy Statement
192.168.77.149 | IA0111
Subscribers sign-in to AccuWeather Premium | AccuWeather Professional | AccuWeather RadarPlus
Not a Member? Read all about Premium, Professional, RadarPlus, and LightningPlus
RSS Feeds Available 
Podcasts Available 
Blogs Available
This page may contain Mapping and GPS Navigation Systems provided by GeoMicro, Inc.
Dear jim:Any new update about karachi and arabian sea?
Reply:
Nothing meaningful, Shoaib. It is a "waiting game" right now.
Jim
Posted by shoaib | September 30, 2009 3:47 AM
Dear jim:Can we expect heavy rain over karachi within 15 days?
Reply:
Dear Shoaib,
The short answer is "no". However, I qualify this by saying that there is a measurable chance (I can not reckon the odds) for heavy rain happening.
Now I see that the GFS run of 1200 UTC, Tuesday, shows heavy rain over Karachi at about Oct 10. I cannot account for this, nor do I have good reason to believe it will happen.
Jim
Posted by shoaib | September 29, 2009 12:11 PM
I think history of monsoon 2004 will once again repeat, that year too there was a cyclone Onil which was formed on 30 september and dissipated on 3rd october it unleashed heavy rains in Gujrat(india) and some coastal towns of sindh(Pakistan) near Gujrat Border (including Badin),But sadly it made the weather too hot in karachi, This year too the GFS model is showing the same thing.
Reply:
Thank you, Ali. I am looking into Onil. Latest GFS run (1200 UTC on Tuesday) has a cyclone south of Karachi before veering NE to Gujarat.
Jim
Posted by Ali | September 29, 2009 11:48 AM
Hi Jim,
Regarding Ketsana, why was it so destructive? Philippines get hit by typhoons on a regular basis. How can a much weaker storm (given that Ketsana wasn't even a hurricane while hitting Philippines) inflict such a damage?
Reply:
Dear Ahmed,
It was all about extreme rainfall in/near greater Manila. The damage was wrought by flooding. I have heard through the media that rainfall reached 16 inches/40 cm within 12 hours. This is at or above the normal monthly rainfall.
Extreme rainfall stemmed from the storm path. The center tracked east-to-west about 100 km north of Manila city center. This brought a deep sodden southwesterly wind off Manila Bay to bear over the city and against the hills lying to its east.
Jim
Posted by Ahmed | September 29, 2009 4:40 AM