The Central Weather Bureau (CWB) said Monday that Typhoon Lupit has been strengthening and that it could bring extremely torrential rain to northeastern Taiwan's Yilan County Thursday and Friday. According to the weather bureau, the typhoon was centered some 1,450 km east- northeast of the Philippines capital of Manila as of 8 a.m. Monday, moving in a west-northwesterly direction at 16 kph. The storm was gaining strength and had been upgraded to the level of a strong typhoon, the weather bureau said. The CWB meteorologists forecast that due to the combined effect of the typhoon and the seasonal northeasterly monsoon, rainfall in northern and eastern regions of Taiwan would begin Wednesday afternoon. Although, the typhoon might not hit Taiwan directly, extremely torrential rain -- which is classified as 350 mm of precipitation in 24 hours -- is likely to affect Yilan County and mountainous northern areas Thursday and Friday, the forecasters warned. 