West Singapore
Bukit Batok weather
Western inland town. Catches many southwest-monsoon morning squalls.
How rain usually arrives here
Bukit Batok is inland enough to heat up, and west enough to catch Sumatra squalls after they have made landfall at Tuas. The nowcast often flips from Fair to Showers while the city is still dry.
Open the 240 km radar if a line is over the Strait. The 50 km view of an empty island is too late once the squall is already over Tuas.
West Singapore
Western towns are first in line when a Sumatra squall crosses the Strait of Malacca. Rain often arrives before dawn or in the morning, then clears as the line races east. Over a year this side of the island is wetter than the east coast.
How a Sumatra squall crosses the island
A line of storms that forms over Sumatra, then rides southwest monsoon flow across the Strait. Typical window is 2am to 10am, June to September.
1. Strait
Watch 240 km radar
A solid line west of Tuas is the tell. The 50 km view is still empty at this point.
2. West
Tuas, Jurong, Choa Chu Kang
First landfall. Wind jump, brief heavy rain, then it keeps moving.
3. Central
Bukit Timah, Toa Payoh, City
Often 30 to 60 minutes after the west. Not every line still has punch here.
4. East
Tampines, Bedok, Changi
Last to arrive, often weaker. Some squalls die over the catchment before they get here.