Čemu se smiješ? Meni se ova prognoza uopće ne sviđa.

Because the verb is smijati se and it normally takes the dative for the thing or person being laughed at.

• što = what in the nominative/accusative sense
• čemu = to what / at what in the dative

So:

• Čemu se smiješ? = What are you laughing at?

This is one of those verbs where English and Croatian structure things differently.

In both cases, se is part of the verb.

• smijati se = to laugh
• sviđati se = to be pleasing to / to appeal to / to be liked

Even though se often looks like oneself, here you should learn these as whole verb expressions, not as literal reflexives.

So do not translate them word-for-word as:

• smiješ se = you laugh yourself ❌
• prognoza se meni sviđa = the forecast likes itself to me ❌

Instead, learn them as fixed patterns.

Smiješ is the 2nd person singular present tense of smijati se.

So:

• ja se smijem = I laugh
• ti se smiješ = you laugh
• on/ona se smije = he/she laughs

Since the question is addressing you, Croatian uses smiješ.

Meni is the dative form of ja and means to me.

The verb sviđati se works like this:

• the person who likes something = dative
• the thing that is liked = nominative

So:

• Meni se ova prognoza ne sviđa. = I don’t like this forecast. = literally, This forecast is not pleasing to me.

Meni can also add emphasis or contrast, something like:

• As for me, I don’t like this forecast at all.

Because with sviđati se, the thing liked is the grammatical subject.

In English, we say:

• I don’t like this forecast.

In Croatian, the structure is closer to:

• This forecast is not pleasing to me.

So:

• meni = dative experiencer
• ova prognoza = nominative subject
• sviđa agrees with ova prognoza

That is why ova prognoza stays in the nominative.

Because the verb agrees with ova prognoza, not with meni.

Here:

• prognoza is singular
• therefore the verb is sviđa = is pleasing

Compare:

• Meni se ova prognoza sviđa. = I like this forecast.
• Meni se ove prognoze sviđaju. = I like these forecasts.

So the verb changes according to the thing liked, not the person who likes it.

Uopće here means at all.

With negation, it often strengthens the negative meaning:

• uopće ne sviđa = don’t like at all

So:

• Meni se ova prognoza uopće ne sviđa. = I don’t like this forecast at all.

Depending on context, uopće can also mean generally in other sentences, but here at all is the natural meaning.

Croatian word order is fairly flexible, but clitics like se usually go near the beginning of the sentence, often in the second position.

So:

• Čemu se smiješ?
• Meni se ova prognoza uopće ne sviđa.

This is very normal Croatian word order.

You may also hear other versions depending on emphasis, for example:

• Ova mi se prognoza uopće ne sviđa.

Here mi is a shorter clitic form of meni.

The sentence in your example sounds natural and slightly emphasizes meni.

Yes.

You can say:

• Ova prognoza mi se uopće ne sviđa.
• Ova prognoza se uopće ne sviđa ❌

Normally, with sviđati se, you need the person in the dative, so the natural short form is:

• mi = to me

So the most everyday version is often:

• Ova mi se prognoza uopće ne sviđa.

Using meni instead of mi adds emphasis:

• Meni se ova prognoza uopće ne sviđa. = I, for one, really don’t like this forecast.

Both can sometimes translate as to like, but they are not used the same way.

• voljeti = to love / to like
• sviđati se = to appeal to / to be pleasing to

For objects, opinions, appearances, choices, and first impressions, sviđati se is very common.

So:

• Sviđa mi se ova prognoza. = I like this forecast.

Voljeti with prognoza would sound less natural in this context, because a weather forecast is something you find appealing or not, not usually something you love in a strong sense.

Yes. Ova is the feminine singular nominative form of ovaj = this.

Because prognoza is:

• feminine
• singular
• nominative

the demonstrative must match it:

• ova prognoza = this forecast

Croatian adjectives and demonstratives agree with the noun in gender, number, and case.