Alpena is heading into a stretch of unusually mild fall weather, with weekend highs expected to reach the upper 60s and lower 70s. But residents may see a sharp difference between temperatures near Lake Huron and those farther inland, especially Friday morning.
Patrick Bak, a meteorologist with the National Weather Service office in Gaylord, said temperatures across the region should remain near or above normal for the next week or so. The normal high temperature in the Alpena area at this time of year is about 60 degrees.
“Right now, we do not have any significant precipitation events coming,” Bak said. “For the next several days temperatures will be near or above normal.”
Weekend forecast stays warm
The short-range forecast calls for mostly sunny conditions and a high near 67 on Tuesday. A chance of showers is expected to return Wednesday night into Thursday, although rainfall amounts are not expected to be heavy.
Thursday’s high is forecast near 59 degrees, closer to the seasonal average, before temperatures rise again. Bak said the weekend should be the warmest part of the near-term forecast.
“This weekend looks pretty warm with highs in the 70s,” Bak said.
The weather service forecast calls for a mostly sunny Saturday with a high near 69, followed by a mostly sunny Sunday with a high near 74. Columbus Day on Monday is expected to be partly sunny, with a high near 67.
Overnight temperatures through the weekend are forecast to remain well above freezing along the shore, ranging from the upper 40s to the upper 50s.
Inland locations could still see frost
The mild outlook will not affect every part of Northeast Michigan equally. Bak said Friday morning lows are expected to fall into the 30s, although the Alpena area probably will not experience a hard freeze.
“However, there is a big difference between the areas near the coast and the areas inland,” he said.
A hard freeze is generally defined as a temperature of 28 degrees or lower, a level cold enough to end the growing season for many plants. Some locations may have already recorded their first hard freeze this fall, particularly areas farther from Lake Huron.
Clear, calm nights allow heat to radiate away from the ground, while cold air settles into low-lying areas. That process can make inland fields and gardens considerably colder than locations closer to the water.
For Alpena-area residents, the difference may be noticeable Friday morning. Gardens and low-lying fields west of town could see frost while lawns closer to the shoreline remain above freezing. Inland locations have a better chance of dropping into the 30s than the city itself.
Lake Huron is moderating shoreline temperatures
The lake is expected to remain the main reason coastal areas stay milder. Bak said water temperatures around Alpena are still close to 60 degrees, allowing the relatively warm lake to hold nighttime temperatures higher near the bay and Lake Huron shoreline.
“The lakes are still relatively warm so that helps the coastal areas,” Bak said. “The water temperature around Alpena is still close to 60 degrees.”
That lake effect can also influence when the first frost arrives. Shoreline lawns may avoid freezing conditions that affect areas only a few miles inland, while the temperature difference becomes more pronounced during clear, calm nights.
Early October has already been mild in Alpena. Preliminary weather service climate data show highs of 67, 64, 61 and 66 degrees during the first four days of the month. Overnight lows ranged from 36 degrees on Oct. 3 to 54 degrees on Oct. 1.
Measurable rainfall totaled 0.28 inches through Oct. 4, slightly below normal for that period.
Fall color is building across northern Michigan
The mild and dry pattern is arriving as fall color develops across northern Lower Michigan. Bak said peak color typically arrives during the second or third week of October, although shoreline forests often lag behind inland hardwoods by several days because lake-moderated air remains warmer.
Cool nights above freezing combined with sunny days generally provide conditions for reds, oranges and yellows to develop before a hard freeze or strong wind and rain strip leaves from the trees. A hard freeze can damage leaf tissue, while a prolonged mild spell can slow the loss of green chlorophyll, especially near the lakes.
For now, the forecast does not point to an abrupt end to the fall display around Alpena. The key difference to watch is between the coast and inland cold spots, rather than a regionwide freeze. Residents farther from Lake Huron may still see patchy frost Friday morning, while the warmer lake and mild air mass should keep the first widespread hard freeze away from the shoreline for now.