MET Eireann has issued new warnings for 26 counties across Ireland as the big freeze closes schools and forces airports to cancel flights. Snow has accumulated in parts of Donegal, Derry, Fermanagh, Leitrim, Mayo, Roscommon, Cavan, Tyrone and Antrim – with temperatures set to drop to a biting -5C tonight. Met Eireann has slapped Leinster, Cavan, Monaghan,…