Thunderstorm warning issued for weekend

In its seventh warning on summer thunderstorms issued at 5am on Saturday, the Meteorological Department said the thunderstorms were being caused by a high pressure system from China that covers the upper part of the Northeast and the South China Sea, while the southeasterly winds prevailed across the lower North, the Northeast, the Central and the East.
The high pressure or cold weather would hit hot spells that cover upper Thailand, resulting in thunderstorms, gusty winds, and possible hailstones, the warning said.
The affected areas are:
Saturday:
North: Chiang Mai, Chiang Rai, Phayao, Phrae, Nan, Lamphun, Lampang, Tak, Sukhothai, Uttaradit and Phitsanulok.
Northeast: Loei, Nong Bua Lamphu, Udon Thani, Nong Khai, Bueng Kan, Khon Kaen, Chaiyaphum, Nakhon Ratchasima, Buriram and Surin.
Central: Nakhon Sawan, Lop Buri, Saraburi, Uthai Thani, Chainat, Sing Buri, Ang Thong, Phra Nakhon Si Ayutthaya, Suphan Buri, Kanchanaburi and Ratchaburi including Bangkok and its vicinity.
East: Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chon Buri, Rayong, Chanthaburi and Trat.
Sunday and Monday:
North: Tak, Sukhothai, Uttaradit, Phitsanulok, Kamphaeng Phet, Phichit and Phetchabun.
Northeast: Loei, Nong Bua Lamphu, Chaiyaphum, Khon Kaen, Nakhon Ratchasima, Buriram and Surin.
Central: Nakhon Sawan, Uthai Thani, Chainat, Suphan, Kanchanaburi and Ratchaburi including Bangkok and its vicinity.
East: Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chon Buri, Rayong, Chanthaburi and Trat.