This Week in Walt Disney World Weather — September 16, 2019

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Happy Monday, Walt Disney World! It’s been another wild week of tropical maybes around Central Florida. If you love a lot of “high uncertainty” around your weather forecasts, maybe Orlando is the right place for you!

This week we’ve got more peak-hurricane season shenanigans, some progress on the slow march into fall, and the summer 2019 climate report. Let’s go.

Dorian Out, Humberto In (Sort Of)

Last Sunday we were watching Hurricane Dorian speed up the Atlantic coastline without so much as waving goodbye. The storm was remarkably disruptive for a cyclone which didn’t make landfall in Florida, and its effects on our local weather were pretty long-lasting. Dry air left in the hurricane’s wake was slow to be replaced by more typical humidity. We had a run of extremely hot, dry days with low humidity and no rain. Here’s why that happened:

Florida’s rainy season climate is self-fueling—once it’s humid enough to rain every day, the daily rain keeps it humid enough to continue raining every day. It’s a perpetual rain machine… until something interrupts it. Hurricanes leave dry air in their wake. Earlier in the summer, when daytime heating is at its most intense, all it takes is the repeated influx of the sea breeze and lake breezes from our larger lakes to get the humidity levels back up and storms firing again.

Deep blue skies over Frontierland during our hot, sunny week post-Dorian.
Deep blue skies over Frontierland during our hot, sunny week post-Dorian.

When the rain machine is interrupted later in the season, like mid-September, it takes a little help from the outside to get the humidity back up to levels that support daily rain. We’ve lost two hours of sunlight energy since the summer solstice. Things are starting to get creaky. The tropical air associated with the wave that became Tropical Storm Humberto was the instigator, in this case. But as Humberto pulls away, we are going to see a few more dry days.

This Week in Walt Disney World Weather

As Humberto moved away through last night, the quickly moving rain bands we’ve been experiencing all weekend will subside. In its place? You guessed it: fairly dry air. An uneventful week is expected, with dry air holding on through Tuesday, and just a 30-40% chance of afternoon storms for Central Florida Wednesday-Thursday. Highs will be around 90-92 daily, with higher heat index readings, and around 75 at night.

By the end of the week and into the weekend, a surface ridge should develop which will bring onshore winds from the Atlantic. This will boost our rain chances back to normal scattered activity. Atlantic flows often bring us late-day storms which cluster close to the western side of property, so while it’s too soon for a weekend forecast, that’s my speculation. Highs should moderate to around 88 degrees once some cloud cover and showers return. Lows will drop to 70-73 at night.

Tropical Update

September is peak hurricane season, and the Atlantic, Gulf of Mexico and Caribbean are definitely in production mode. The National Hurricane Center is watching two areas of development outside of Tropical Storm Humberto, which is moving away from Florida.

This week's map looks active, but only one disturbance is of interest to Florida weather. Courtesy NOAA
This week’s map looks active, but only one disturbance is of interest to Florida weather. Courtesy NOAA

Of these, only one is of interest to Florida, and that’s a broad area of disturbed weather over the central Atlantic. As it tracks slowly west-northwestward over the coming week, this disturbance will find favorable conditions for development. It’s expected to become a tropical depression by the end of the week. Long-range models have had a lot to say about this storm, but I think we’re all learning that unless we’re within the 1-3 day model, it’s just not worth getting fussed about. Check back in a week.

The Gulf of Mexico disturbance is expected to move inland over Texas without further development.

Summer Climate Report

Anyone who visited Walt Disney World this summer will agree with this statement from the National Weather Service in Melbourne: “summer 2019 was warmer and generally wetter than normal across east central Florida.”

Influenced by a ridge which remained parked over south Florida most of the summer, a moist flow of tropical air from the southwest kept most of our summer days extra-stormy. It also pushed back the east coast sea breeze or at least delayed it on many days, which meant the temperature kept rising when cooler ocean air should have been flooding our area in mid-afternoon. All of those days when it was 94 and still getting hotter at 4 p.m.? That’s when the southwest wind was in control.

And so for most of the summer, temperatures were near or above normal, with some records broken for both high temperatures as well as warm minimum temperatures. Orlando’s average temperature for the season was 83.3 degrees — this includes both high and low temperatures for one daily average, and it’s one degree above normal.

The rainfall for Orlando in particular was just about on target, with 22.25 inches of rain recorded at Orlando International Airport. Here are some more fun stats from the airport’s reporting station from 92 days of summer:

Thunderstorms were reported on 68 days

Party Cloudy conditions were reported on 75 days

Fair conditions were reported on 3 days

The average relative humidity was 74%

The highest wind gust was 67 mph and it was recorded on June 12 in a regular, every day thunderstorm… not a tropical system!

While summer might technically be over on the calendar, it’s still rainy season in Florida for another month. But temperatures are starting to moderate already. With the days beginning to shorten, nights will begin to cool more and it will take longer to heat up during the morning. “Very light jacket every now and then” season is almost here!

What questions do you have about fall or winter weather at Walt Disney World? Ask them here!

Natalie Reinert

One of those Florida locals who can usually tell you if it's going to rain by the sun angle and the feel of the air, I'm an avid weather fan and a certified weather spotter for the National Weather Service's SkyWarn program. I tweet about Central Florida weather at @WeatheratWDW. As I work for Walt Disney World, please note all of my views are my own, and do not represent the views of The Walt Disney Company. All information shared in my posts comes from publicly available sources.

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