New Jersey will experience a brief return to spring this afternoon, with partly sunny skies and temperatures warming up to the high 60s, but a surge of colder air from Canada later Wednesday will make it feel more like early March instead of late April. Forecasters say temperatures will likely drop below the freezing mark overnight Wednesday into early Thursday in northern sections of the state, posing a threat to sensitive outdoor plants and outdoor pipes during the early phase of the growing season. As a result, the National Weather Service has issued a freeze watch for five counties — Morri…