Why is it so cold these days? Meteorologist explains

Unaccustomed to the cold, many people in the Commonwealth are wondering about the persistence of the chilly weather in the last several weeks.

National Weather Service meteorologist William Brandon Aydlett told Saipan Tribune yesterday that the CNMI has been experiencing a modified mid-latitude air mass, which equates to drier air and slightly cooler temperatures.

Aydlett said cold fronts routinely exit the Japanese coast and move eastward. Often the very southern tail end of cold fronts will drop down over the Mariana Islands and bring increased cloudiness, showers, and gusty winds, he said.

To the north, Aydlett said, is the cooler and drier air—and lower dew points—which leads to lower humidity, cooler nights, and high day time temperatures without the fangs of a high heat index.

He said such conditions are quite typical for the far Northern Islands, especially north of Pagan, this time of year.

This month, Aydlett said, the shear lines have been consistently dropping well south of Guam.

“Before one drier air mass becomes adjusted by the inherent tropical climate of our region, the next shear line drops south, and so we’ve been in that cycle for a few weeks now,” he said.

This explains, he said, why nighttime lows have been in the low 70 degrees, and even 69 degrees on Feb. 18.

As to when the hot and humid weather will return, Aydlett said the Mariana Islands is in the heart of the dry season now and that will continue for another few months.

He, however, stated that in the latest model runs, he has been noticing the next cold front, now over Japan, doesn’t drop as far south later this week.

At the same time, he said, dew points are expected to increase from the mid-60 degrees early this week into the low 70 degrees around midweek and stay there for the remainder of February.

“Low 70s are more typical for this time of year. So I’m thinking we will be going from our ‘abnormally dry’ of the past few weeks to the ‘normal dry’ of dry season later this week,” Aydlett said.

The meteorologist said it sounds like a really big deal for a 6-7 degree dew point swing, but for islanders who are acclimatized to nighttime lows of upper 70 degrees and daytime highs of upper 80 degrees, it will feel much more normal and less like Hawaii weather.

“We’re still expecting very little rainfall for at least the next week or so, though,” he added.