Halloween forecast: Coolest air in 6 months to hit South Florida this weekend

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The coldest air of the season is forecast to ooze through the Sunshine State late this week, sweeping in low temperatures not seen since early spring and gifting a temporary reprieve from the gummy tropics.

Meteorologists caution the front could stir storms Thursday and Friday depending on its arrival time, but the punch will be feeble compared to its related bomb cyclone that walloped the northwest Monday with high winds and a firehose of rainfall.

A buoy offshore of Washington State measured a low pressure of 943.5 millibars for the storm that underwent a rapid deepening called bombogenesis. The National Weather Service in Seattle said it was the lowest pressure recorded off the Washington coast.

In comparison, Hurricane Wilma made landfall as a Category 3 hurricane on Florida’s southwest coast in 2005 with a pressure of 950 millibars. At its most intense, Wilma’s central pressure was 882 millibars.

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“They are two different types of storms, but they have similarities,” said Bob Oravec, a lead forecaster with the Weather Prediction Center about tropical and mid latitude cyclones. “Winter storms can have rapid deepening, high winds, heavy rains and storm surges just like tropical systems.”

Oravec said while the storm that hit the West Coast will be tamed and modified from its travels east, it’s the same energy that that will be responsible for the cool front late this week.

When does cold front move into Palm Beach County?

Low temperatures at Palm Beach International Airport are forecast to dip to 64 degrees Friday night and 63 degrees Saturday night into Sunday. If the 63 verifies, it will be the coolest temperature measured since April 13.

High temperatures in West Palm Beach on Saturday and Sunday are expected to be near 80 degrees. The normal low temperature at PBIA this time of year is 69 degrees with a normal high of 83.

Melbourne’s temperature is forecast to fall to 62 degrees Friday night and 60 degrees Saturday into Sunday – a reading not seen at the NWS gauge there since May 8.

“This will be our first real taste of fall,” said Kole Fehling, a meteorologist with the NWS in Melbourne. “Saying it’s the coolest air of the season is accurate.”

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Areas of Central Florida and the western reaches of Palm Beach County could feel temperatures fall to the upper 50s with high temperatures Saturday and Sunday struggling to reach 80 degrees.

A weaker front is forecast to push through the Peninsula on Tuesday and Wednesday increasing rain chances for South Florida.

The stronger front is expected to herald a days-long flow of drier air.

Coldest temperatures of the fall season so far

“There’s no mention of rain whatsoever for the weekend,” said Paxton Fell, an NWS meteorologist in Miami. “It will be the coldest temperatures of the fall season so far, but it’s still a very young season.”

Meteorological fall begins Sept. 1 and runs through Nov. 30. Astronomical fall began this year on the Sept. 22 equinox and runs through Dec. 20.

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Fell said it’s too early to predict whether the late-week cool front will come with severe thunderstorms, but she is expecting marine conditions to deteriorate with building winds and rising seas.

It’s a raucous weather week nationwide with the bomb cyclone in the west dumping double-digit rainfall north of San Francisco, wind advisories in Nevada, a forecast for more than a foot of snow in the Utah mountains, and potentially two robust storm systems whacking the northeast.

But the wintry storms don’t signal the end of hurricane season just yet. The National Hurricane Center says a non-tropical area of low pressure that was consolidating Monday off the northeast coast of the US has a 40% chance of forming into a subtropical or tropical cyclone near the end of the week.

The next, and last, name on 2021’s traditional list of hurricane names is Wanda.

Kimberly Miller is a veteran journalist for The Palm Beach Post, part of the USA Today Network of Florida. She covers weather, climate and the environment and has a certificate in Weather Forecasting from Penn State.  Contact Kim at kmiller@pbpost.com