An Astronomical Summer: WeatherTiger's Weekly Column for June 22nd
Heat will give way to a more active Tropics in the last week of June.
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On Earth, there are 86,400 seconds in each day, give or take one additional millisecond during El Niños and one fewer during La Niñas. Around this week’s summer solstice, the Sun is up in Florida for roughly 50,000 of those seconds, for 45,000 of which it is basically a McDonalds fry lamp broiling everything in sight.
Meteorological summer includes all of June, July, and August, but June 21st, the year’s longest day, marks the beginning of astronomical summer. In 2022, Florida’s summer has already been both astronomical and retrograde, and not just because a rare pre-dawn alignment of five planets is delighting skywatchers and changing the numbers beneath scratch-off ticket foil. Rather, the state remains in the grip of a massive heat wave and will be for a few more days.
The reason for this Kenny Rogers-level roasting is the same as it was last week: a Brobdingnagian ridge of high pressure extending across the Southern Plains and Deep South. This sinking airmass is unusually dry, preventing afternoon storm activity. Low humidity also allows temperatures to rise more quickly, as less solar energy is required to heat a dry airmass than a saturated one. Look for mid-to-upper 90s in Central Florida and triple digits in North Florida through Friday, with an outside shot of Tallahassee tying or cracking our all-time record high of 105 degrees on Thursday. Be sure to observe extreme heat safety, including remaining indoors, proper hydration, and not throwing pots of boiling water in the air to see if it will flash-freeze. It will not work.
As expected, this pattern has put the kibosh on tropical activity over the last week, and no development is likely through the weekend. However, as the ridge goes west like Fievel and more typical summer temps and rain chances return to Florida, the winds of change may usher in a more active close to June in the Tropics.
Mid-summer is a transitional time in hurricane season. The favored regions for June tropical storm formation, the Gulf and Caribbean, are less common points of origin in the first half of July. Meanwhile, the frequency of development east of the Carolinas increases, and the “Cape Verde” season of tropical waves developing as they move west across the tropical Atlantic sputters to life as sea surface temperatures warm.
As this climatological baton exchange takes place, Florida (and U.S.) landfall risks temporarily drop. While Gulf impacts like last year’s Tropical Storm Elsa or 2005’s Hurricane Dennis are possible, total tropical storm or hurricane landfalls between North Carolina and Texas in the last 135 years are about 40% lower in the first half of July compared to the last half of June.
This year, there are signs of a galloping handoff, with three features worth monitoring in the Tropics over the next ten days. The first area will be in the eastern or central Gulf, as a cluster of thunderstorms forming over the Carolinas dives south, then possibly stalls over water this weekend. Gulf temperatures are in the mid-to-upper 80s, so if convection meanders there through mid-next week, slow tropical development is possible. However, this mode of genesis is notoriously fickle, and an organized system remains a slim chance until there is something to assess. Still, it bears watching, perhaps at one bear on a scale of zero to five bears.
The second and third features to monitor are a pair of unusually well-developed tropical waves emerging from the West African coast by Friday. While tropical development east of the Lesser Antilles is rare prior to July 1, with a named storm only forming three times since 1900, these waves are expected to track south of 10°N where water temperatures are passable, shear is relatively low, and mid-level moisture is decent.
As occurred with Elsa last year, the western wave of the two may be a sacrifice bunt that moistens the atmosphere enough for the second wave to develop in five to eight days. There is some model support for slow organization of the second wave, and looking under the hood of those models, that outcome is not unrealistic in terms of the atmospheric environment. This system is at least 12 days out from any potential threat to the U.S., an eternity to watch steering patterns evolve. But this system, too, merits a precautionary lone bear, watching.
In summary, the David Lee Roth-echelon heat insanity Florida is currently experiencing will break over the weekend, giving way to more typical summer weather. While tropical trouble is not expected to immediately follow, the mischievous stars and planets tell us such an outcome is unlikely, though not completely impossible. Keep watching the skies.
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