Weathering Irma: September 10 Forecast Update
Breezy with a lower-than-expected high tide (at least in Charleston)
At 3:35 PM, Hurricane Irma made a second landfall at Marcos Island, FL, packing winds of 115 MPH. It is currently moving through Naples, FL, with the eyewall steadily raking up the west coast of the state.
Thus far for Charleston, Hurricane Irma feels more like a wintertime setup than your typical tropical cyclone. It’s been rather cloudy, and temperatures have been held in the low 70s under the influence of dry high pressure wedging down from the Great Lakes. Dewpoints have been steadily climbing as 700mb flow continues to pump moisture in, and while there have been a few showers, today has been mostly dry thus far.
Tides underperform (that’s good, by the way)
The high tide just before noon came in at 7.39'; this is well under the 8'+ that was forecasted. Despite the tide being lower than normal, there were still impacts, including numerous closed roads and some beach erosion.
What to expect tonight
- Tides: The next high tide comes around 11:55 PM. Latest guidance continues to suggest that moderate to possibly major tidal flooding will be possible with this tide cycle. Tidal departures have increased to 2' and this should continue to increase as the center of Irma approaches. Major flooding begins after 8' and this will need to be watched closely. Park vulnerable vehicles in city and Charleston County downtown garages, which with the exception of the garage at the Galliard, is free.
- Winds: Expect winds to steadily increase as the center of Irma moves closer to the area and interacts more with the high pressure to the north. The resulting gradient winds will increase with tropical storm force gusts expected by morning.
- Tornado threat: Nil. With the high pressure wedge hanging on, the tornado threat has remained suppressed. The tornado threat should increase for the Tri-County around sunrise tomorrow.
- Rainfall: Expect steady rain to start to move in later tonight from the south. A half-inch of rain is possible through morning before the heaviest rain moves in for Monday. That being said, the Flash Flood Watch goes into effect at 8PM.
Facebook Live
Join me on The Post & Courier’s Facebook page at 8:30PM for a Facebook Live update.
Next Update
Expect the next full Medium post tomorrow morning.
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