The arrival of a wave of cool air this afternoon may bring with it scattered thunderstorms and the potential for funnel clouds in Ottawa and much of southern Ontario, Environment Canada cautions.

The funnel clouds may make "a brief appearance" Thursday afternoon, according to the national weather agency, in what it describes as an unseasonably cool and unstable air mass.

"These types of funnel clouds are generated by weak rotation under rapidly growing clouds or weak thunderstorms," Environment Canada said in an update published at 11:52 a.m. ET.

"This weak rotation is normally not a danger near the ground. However, there is a chance that this rotation could intensify and become a weak landspout tornado."

These funnel clouds appear with little or no warning, the agency said, and people should take shelter if one develops nearby.

The thunderstorms are expected to end Thursday evening in Ottawa. Some storms could bring dime sized hail and wind gusts of 70 kilometres per hour with frequent lightning.