JERUSALEM (Reuters) - A rare snowstorm on Wednesday blanketed Jewish, Christian and Moslem holy sites in Jerusalem's walled Old City as well as covering parts of the West Bank and Jordan The snow, at the threshold of spring, caught many Israelis, Palestinians and Jordanians by surprise just two days after sandstorms that blew up from Saudi Arabia had covered towns and villages in a fine yellow dust. The wintry sleet and snow paralysed Jerusalem for hours and signalled it was too early to break out the suntan lotion. Israeli authorities said the main Tel Aviv-Jerusalem highway was blocked until late morning after eight hours of snow that began falling overnight. Most schools cancelled classes and public transport went on emergency schedule. In Jordan, the government announced a public holiday in the largely desert kingdom because of the severe weather conditions. Snow ploughs cleared main highways and blizzards cut off many side roads. The inclement weather forced the Israeli cabinet to postpone a scheduled discussion on proposals to withdraw Israeli troops from south Lebanon, an official in Prime Minister Benjamin Netanyahu's office said. In Jerusalem's Old City, the gold-tipped Dome of the Rock mosque atop the Temple Mount was dusted with a fine white powder. At the nearby Wailing Wall, Judaism's holiest shrine, ultra-orthodox Jews prayed in the wet slush with plastic bags protecting their fur-trimmed black hats. In a rare show of Jewish-Arab unity, Palestinian and Israeli children hurled snowballs at passing cars. A trace of snow falls nearly every year in Jerusalem but usually melts within an hour. This year it has snowed twice.