CEE POWER-Czech, Slovak spot tumbles on weak holiday demand

* Renewables forecast higher

* CEZ reports 700 MW in unplanned outages

* Hungary spot price diverges

PRAGUE, Oct 2 (Reuters) - Czech and Slovak spot prices plunged on Tuesday ahead of a national holiday in Germany that sapped demand in the region while Hungary day ahead surged as the central European country remained short of supply, traders said.

Electricity for Wednesday delivery tumbled 40 percent to 29.76 euros ($38.41) on Czech and Slovak regional exchanges but soared to 71.33 euros on Hungary's HUPX. The German spot price cleared at 29.75 euros on EPEX.

An uptick in renewables also helped weigh down the Czech and Slovak price, traders said. Data from Thomson Reuters Point Carbon showed forecasts for wind generation in Germany rising to 6.9 GW and solar production climbing to 3.4 GW.

"It is the holiday and the wind," one trader said.

The three central European countries combined their day ahead markets last month and since then Hungary has often traded higher, helping to erase the typical Czech and Slovak discount to Germany.

Day ahead in Poland, which one day hopes to join its day ahead market with those of the other central European neighbours, fell to 170.84 zlotys ($53.84) from 182.02 zlotys ahead of the Reunification Day holiday in Germany.

"We will see Hungary decoupled more often in the future because Romania is quite short these days and there are expensive exports from Hungary to Romania," another trader said.

Further along the curve, the front month fell more than 2 percent to 48.50 euros and Cal '13 baseload shed 15 cents to 46.90 euros on the Prague-based Power Exchange Central Europe.

Around the region, the benchmark German Cal '13 contract fell 3 cents to 47.70 euros on Germany's EEX exchange in afternoon trade.

Czech utility CEZ reported unplanned outages of a 500 MW unit at Melnik 3 and a 200 MW unit at Chvaletice with both blocks expected to be running at midnight on Tuesday.

Serbian water levels for power generation will fall through Oct. 9 on all rivers except the Tisa and Morava after they mainly declined last week, Serbia's hydrometeorological service said in a weekly forecast.

Serbian grid operator Elektromreza Srbije announced the total cross-border power capacity available for allocation in November through a joint auction with Hungary.

In Poland, a court ordered the re-examination of a block on an 11.6-billion zloty ($3.7 billion) power investment by utility PGE

in a setback to environmentalists opposing the project.

The country's gas monopoly PGNiG

will offer 30 percent of its sales on the nation's fledgling gas exchange to fuel the liberalisation of central and eastern Europe's largest gas market, a ministry official said.

Brent crude oil slipped to around $112 a barrel as investors weighed a weaker outlook for fuel demand and sluggish economic growth against the risk of possible supply disruptions.

EUAs for December delivery , the benchmark EU carbon contract, had fallen 5 cents to 7.90 euros a tonne at 1239 GMT. ($1 = 0.7749 euros) ($1 = 3.1733 Polish zlotys)

(Reporting by Michael Kahn; editing by James Jukwey)

((michael.kahn@thomsonreuters.com)(+420 224 190 443)(Reuters Messaging: michael.kahn.thomsonreuters.com@reuters.net))