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People ice fish on West Grand Traverse Bay on Feb. 29, 2003. 2015 is the seventh year the bay has frozen over since 1990, according to the Watershed Center.

(Garret Ellison | MLive)

TRAVERSE CITY, MI -- It took a little longer, but for the second time in as many years, West Grand Traverse Bay has frozen-over.

The Watershed Center Grand Traverse Bay declared the bay frozen-over on Monday, Feb. 16. The large Northern Michigan water body is considered frozen when ice reaches Power Island, seven miles north of downtown, for at least 24 hours.

Related: Ice grows rapidly: Lake Michigan ice nearly doubles in 1 week

This is the seventh year the bay has frozen over since 1990, according to the Watershed Center. The last time the bay froze-over two years back-to-back was 21 years ago, in 1993 and 1994.

In 2014, the bay remained frozen for 80 days, the longest iced-in period since 1926. The bay was declared frozen-over last year on Feb. 3.

This year's freeze-over comes amid a cold snap that plunged Michigan into record-level subzero temperatures over the weekend.

Temperatures reached negative double digits this weekend, dropping to -31 degrees in Baraga. On Monday morning, wind chills in most of Lower Michigan were between 15 and 25 degrees below zero. Grand Rapids broke a 52-year temperature record.

Low temperatures expected Thursday morning will again be well below zero. Southern Lower Michigan will cool to -5deg to -10deg in most places at sunrise Thursday.

According to MLive meteorologist Mark Torregrossa, the polar vortex -- a semi-permanent low pressure system aloft around the north pole -- will bring another round of dangerous cold to Michigan mid- to late week.

Baykeeper John Nelson said a frozen-over bay usually results in cooler water through the spring and summer and less evaporation in the fall.

Watershed Center director Christine Crissman cautioned that it's not known how thick the ice throughout the bay.

Garret Ellison covers business, government and environment for MLive/The Grand Rapids Press. Email him at gellison@mlive.com or follow on Twitter & Instagram