Indonesia FM radio stations detected in Alor Setar, Kedah, Malaysia?

On 31st August 2019, it was Malaysia national day, I traveled Alor Setar for personal vacancy. Around 6pm, I detected two Indonesia radio stations signal in Alor Setar, Kedah when I was driving along Alor Setar town, Kedah, Malaysia, these stations are:

1. Radio Boss FM 102.8MHz from Pematangsiantar, Indonesia
2. RPC FM 105.4MHz from Binjai, Indonesia

For Radio Boss FM 102.8MHz, I suddenly received the signal when Perlis FM 102.9MHz from Padang Pauh was facing interference while I was tuning the station. When Perlis FM 102.9MHz Padang Pauh was interfered by another station, I tried to inspect Thailand 4th army radio station FM 103.0MHz from Trang province, but FM 103.0MHz was nothing. Next, I touched the radio dial, it stopped at FM 102.8MHz, the frequency was speaking in Indonesian language.

Two of them are transmitted from North Sumatra province of Indonesia, received during tropospheric condition on hot weather, but these Indonesia radio stations cannot be received anymore later, regardless nighttime or next day.

Again, I traveled to Alor Setar town on next day, Radio Boss FM 102.8MHz and RPC FM 105.4MHz cannot be received anymore.

Distance from two Indonesia radio stations to Alor Setar, Malaysia:

1. Radio Boss FM 102.8MHz Pematangsiantar, Indonesia: 379km
2. RPC FM 105.4MHz Binjai, Indonesia: 350km