By GARLAND KENNEDY
Sentinel Staff Writer
While a predicted heat wave might push temperatures in parts of Southeast to record highs next week, Sitka is likely to be spared the worst of it, the National Weather Service says.
“Widespread hot temperatures are expected this weekend with highs in the 70s into the 80s for much of Southeast Alaska,” the NWS special weather statement reads. “Starting Monday and continuing through the first half of the week, some locations of the Inner Channels could reach upper 80s with a few registering 90 degrees or hotter. Daily high temperature records will likely fall in some areas.”
The hottest weather is expected for the Ketchikan-Hyder area, Juneau-based NWS meteorologist Aaron Jacobs told the Sentinel. Sitka is likely to experience a dense marine layer and temperatures in the 70s, Jacobs said.
“The 90s are going to be closer to the inner channels, away from the open gulf and stuff like that,” the meteorologist said. “There’s going to be a marine layer that’s going to be developing over the late week and into the weekend over the gulf, and that’s going to be pushed up against the coast there. And so the Sitka area will be not as warm as other places across Southeast Alaska.”
While the current forecast calls for highs in the upper 60s and low 70s in coming days in Sitka, Jacobs said, some things remain up to chance.
“It depends on how the marine layer sets up, so it’s still kind of up in the air how warm this area will get because of that marine layer, how persistent it could be, and if it gets pushed off during the day,” he noted.
While a high pressure front currently building over the Gulf of Alaska will generate cloudless and hot conditions across the Panhandle next week, an atmospheric inversion around Sitka is likely to generate that cooling marine layer.
“You have all this sinking air over the Gulf of Alaska. It’s cooler towards the ocean surface compared to the air above. It causes moisture to condense and you have a lot of this sinking air that traps a lot of that moisture in the lowest levels of the atmosphere. So (it can be) a couple thousand feet or even can be just a couple of hundred feet thick – it compresses all that moisture into the small area and produces this marine layer,” Jacobs said. “And it’s clear above and there’s no wind down low because there’s no temperature gradient or temperature differences. Essentially, the high pressure is just compressing all the moisture and everything into the lowest portions of the atmosphere and the coolness of the ocean.”
Earlier this month poor visibility resulting from a marine layer that hung over Sitka for more than a week caused airlines to cancel a number of flights.
Whether next week’s marine layer over Sitka will cause similar air travel disruption can’t be predicted, NWS meteorologist Nicole Ferrin said.
“It’s really difficult to predict if it’s going to be at the surface like that last event was or if it’s just going to be a low cloud deck at a thousand feet, and Alaska Airlines has no problem flying, they’re pretty resilient in that way,” Ferrin said.
While the low clouds will shield Sitka from warming sunlight, Jacobs said, a hiker climbing above the marine layer can expect the high temperatures.
He credited much of the uncertainty and variability of weather in Southeast to the complex nature of terrain in the Tongass.
“It’s due to the mountains and everything in the complex terrain that we have in Southeast Alaska,” he said. “We have a lot of different microclimates and different reasons for why certain areas may get certain weather conditions, while maybe 50 miles east or west they have drastically different things.”
While some record highs might fall next week, that’s unlikely in Sitka under the current forecast. Sitka peaked at 88 degrees on July 31, 2020, and July 30, 1976, Weather Service records show. For June, Sitka’s record high was set in 2001 and stands at 78 degrees.
He advised the public to keep a watch on the well-being of the elderly during the heat wave.
“Stay tuned to the National Weather Service for more updates on the developing weather conditions, and if people have elderly folks across the region, just check up on them. Just make sure they’re OK,” Jacobs recommended.
National Weather Service forecasts can be viewed on forecast.weather.gov, and the NWS Juneau office posts updates on its Twitter page.
