Snöglopp is ’sleet’. Snö is ’snow’ of course. Glopp is related to glåpord – ‘jeer’, ‘abusive word’ and the verb glupa ‘to gobble’, ‘scoff’, with the adjective glupsk ‘voracious’. There is also Swedish dialect glåp and Norvegian glop ‘gaping mouth’ So glopp is originally something which comes from a big mouth or hole (Hellquist: Svensk etymologisk ordbok). So far I have found only Scandinavian relations, but guess it could be related to English glut 'to swallow too much' which comes via Old French gloter from Latin gluttire 'swallow', 'gulp down' from the Indoeuropean root *gwele- ‘to swallow’.
This was taken from my window a few hours ago. Now it is almost white outside:
Addition 2012-04-09: More snow, sleet and rain today again. And more birds (or the same probably): Herr och Fru Domherre, 'Mr and Mrs Bullfinch.