Questions & Answers about لعل الطقس جميل غدا.
How does لعل affect the grammar of the word الطقس?
لعل is one of the sisters of إنّ. This group of particles changes the subject of a nominal sentence from the default nominative case (ending in an 'u' sound) to the accusative case (ending in an 'a' sound). Because of لعل, you pronounce the subject as الطقسَ instead of الطقسُ.
Does لعل express probability like 'maybe', or desire like 'hopefully'?
It does both! لعل expresses a strong probability or expectation. Because the speaker is talking about something positive (beautiful weather), it naturally carries a hopeful tone, making 'Hopefully the weather is beautiful tomorrow' an equally good translation.
Why doesn't the word جميل change its ending to match الطقس?
Because لعل only changes the case of its subject (الطقس). The predicate, which is the word giving us the news about the subject (جميل), stays in the regular nominative case (ending in an 'un' sound).
There is no verb here, so how does the sentence work for the future?
Arabic nominal sentences do not need a present or future tense form of the verb 'to be'. You simply state the subject and the predicate side by side (الطقس جميل). Adding the time word غدا (tomorrow) at the end is all you need to shift the meaning to the future.