Happy Valentine’s Day! Now, please get the sweaters ready. A pair of chilly cold fronts is slated to push through southwest Florida the next several days. These will knock temperatures down from their lofty pedestal into well-below seasonal averages by Sunday. When coupled with gusty northerly winds, Sunday promises to feel like one of the coldest days so far this 2012-2013 winter season (Fig. 1).
The initial cold front arrived early Thursday morning, along with some much needed precipitation (Fig. 2). Naples Airport logged about four-tenths of an inch by 5:00 a.m. E.S.T.; Fort Myers reported a quarter of inch.
However, the big news was the drop in dew point temperature readings in just a few hours from around 70 degrees to the upper 50’s. The dew point is a measure of the water vapor in the atmosphere. At readings above 70, it feels humid; dew points below 60 are considered comfortable. Note that falling precipitation and atmospheric water vapor are two very distinct weather parameters. It can still rain or snow, even when water vapor values are low.
Looking ahead, the air mass that arrived this morning will allow for a gradual cool down the next few days. Highs today should top out in the mid-70’s, unless the clouds and showers overpower daytime solar heating (Fig. 3). Friday should be even a little cooler.
On Saturday, however, the next, stronger cold front arrives. This one brings a dramatic drop in dew points, colder air and gustier north and northwesterly winds. By Sunday, Naples-Fort Myers area high temperatures may only reach into the low 60’s. Those northerly winds, blowing straight down the Florida peninsula, will make it feel even colder (Fig. 4). The predicted daily average temperature on Sunday could be as much as 10 degrees below seasonal average!
It will get meteorologically dry with dew points tumbling into the 30’s as far south as Miami. Compare that forecast value to the 65 dew point temperature observed at Miami this Thursday morning.
By Monday, as winds begin their usual migration back to northeasterly (allowing some Atlantic moisture and warmer air back into the Naples-Fort Myers area), temperatures will return to near or slightly above average readings.
Right now, it looks as though dew points and winds will be high enough to preclude any risk of frost here in southwest Florida. Further north along the peninsula, frost or freezing conditions may become a risk during the weekend.
However, along coastal areas and across inland lakes, winds this weekend will be approaching small craft advisory levels and waters will be rough.
© 2013 H. Michael Mogil