The transcription /oː‖əʊ‖oʊ/ or {oː} represents the diaphoneme descended from the ancestral Old English phoneme /oː/, which is preserved in Irish English as [oː] but has become [əʊ] in Received Pronunciation and as [oʊ] in General American.
Source: wiktionary
The series with the long a as a point of departure…today has the diaphoneme /o‖u/, and to be exhaustive the diaphoneme should be rendered /o‖u‖au‖oi/, for in western Yiddish there are also the articulations /šlaufn/ and /šloifn/ (sleep). From the point of departure of long e (Early Vowel E₂) Yiddish arrived at the diaphoneme /ei‖ai/, for example in veynik (little) (cf. MHG wênic). In groys (big; Early Vowel O₂) (cf. MHG groȥ), Yiddish has the diaphoneme /ei‖oi/; with the variant of Samogitia–Latvia (7.35), the symbolization will become still more complicated: /ei‖øu‖oi‖ou/.
Source: wiktionary