Display Screen or Portion Thereof with Transitional Graphical User Interface

This application incorporates by reference the following application in its entirety: U.S. patent application Ser. No. 29/698,824, filed Jul. 19, 2019. All disclosure and subject matter, including all figures, of the 006' ans '824 application are specifically incorporated by reference in this application as if set forth fully herein. It is understood that any material in the 006' and '824 applications which is not present in the application forms no part of the claimed design.

FIG. 1 is a front view of the first image in a sequence of a display screen or portion thereof with transitional graphical user interface showing our new design according to a first embodiment;

FIG. 2 is the second image thereof;

FIG. 3 is a front view of the first image in a sequence of a display screen or portion thereof with transitional graphical user interface showing our new design according to a second embodiment;

FIG. 4 is the second image thereof;

FIG. 5 is the third image thereof;

FIG. 6 is a front view of the first image in a sequence of a display screen or portion thereof with transitional graphical user interface showing our new design according to a third embodiment;

FIG. 7 is the second image thereof;

FIG. 8 is a front view of the first image in a sequence of a display screen or portion thereof with transitional graphical user interface showing our new design according to a fourth embodiment;

FIG. 9 is the second image thereof;

FIG. 10 is a front view of the first image in a sequence of a display screen or portion thereof with transitional graphical user interface showing our new design according to a fifth embodiment;

FIG. 11 is the second image thereof; and,

FIG. 12 is the third image thereof.

The dashed broken line perimeter in the drawings illustrates a display screen or portion thereof and forms no part of the claimed design. The remaining dashed broken lines in the drawings illustrate portions of the graphical user interface that form no part of the claimed design.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1 - 2 , 3 - 5 , 6 - 7 , 8 - 9 , and 10 - 12 , respectively. The process or period in which one image transitions to another image forms no part of the claimed design.