Ian’s threat zone shifts north, putting eastern Gulf coast on high alert

Latest update on the tropics provided by Local 10 Hurricane Specialist and Storm Surge Expert Michael Lowry

Tropical Storm Ian (NOAA)

Saturday’s forecasts signaled a trend northward in Ian’s potential U.S. strike area, decreasing the odds of a direct run-in with southeast Florida, but placing areas from southwest Florida to the Florida panhandle on high alert for what’s forecast to be a very powerful and impactful hurricane this week.

Tropical Storm Ian forecast cone (WPLG)

The risk for inclement weather in South Florida remains – including the possibility of localized flooding from heavy rainfall and periods of gusty winds – beginning as early as late tomorrow and especially by Tuesday into Wednesday, depending on Ian’s exact track.

Rainfall forecast through Wednesday morning for South Florida from the National Weather Service shows the possibility of heavy rainfall from Ian’s moisture surge across much of the local area. (WPLG)
Guidance from the National Weather Service shows South Florida under a slight risk for flash flooding through Wednesday morning. (NOAA)

We’re only a few days removed from a potential hurricane strike in Florida and track forecasts continue to show a wide range of possibilities. South Floridians should check back frequently on the forecast today and tomorrow.

For now, Ian is still surprisingly disorganized given the conducive upper-level wind pattern, but recent surveillance from ongoing hurricane hunter flights indicates an improving vertical structure which should allow for a period of rapid strengthening to commence today. Our most reliable intensity guidance are in unanimous agreement strengthening Ian very quickly into a powerful hurricane in the coming days, so it’s a matter of when not if Ian takes off. It’s worth noting the rate of strengthening forecast by the National Hurricane Center in the coming days is historically high, indicating their confidence in the risk of rapid intensification.

The National Weather Service, which typically sends up weather balloons twice daily from around 100 locations around the country to capture upper-air observations, initiated special weather balloon releases at many of these same locations to beef up its observation network and hopefully improve Ian’s forecast. Additionally, the high-altitude Gulfstream jet operated by NOAA hurricane hunters began its flights yesterday to sample the environment around and ahead of Ian to help improve model forecasts.

Despite the additional data ingested in the overnight computer model runs, forecast track uncertainty remains high. The European camp of models, including the ECMWF and UKMET, are to the east, showing a sharper turn over the southeastern Gulf and toward southwest Florida, while the American models, which include the GFS and its HWRF counterpart, take Ian toward the Florida panhandle. The NHC splits the difference and tracks Ian generally toward Florida’s big bend this week.

Global forecast models and their ensemble track for Ian from overnight Saturday. The blue ellipse shows the possible scenarios out to Friday morning. Credit: Tomer Burg/University of Oklahoma. (NOAA)

There are a few important caveats to the forecast worth noting. Ian could be both a large and powerful hurricane in the eastern Gulf. Even if its center tracks west of the western Florida peninsula, major impacts – including life-threatening storm surge and flooding rains – could occur across a wide stretch of Florida’s Gulf Coast. The western Florida peninsula and big bend is one of the most storm-surge prone regions of the country, so if you’re reading this and have interests here, please finalize your preparations and listen carefully to instructions from local officials in the hours ahead.

Additionally, while Ian is forecast to weaken as it nears landfall, it won’t change the threat for significant impacts. Even a slowing locomotive carries a tremendous force. Many weakening but powerful Gulf Coast hurricanes of the past like Ivan in 2004 or Katrina in 2005 delivered historic and devastating blows, so don’t focus on the late weakening right now.

Everyone in Florida needs to be watching this one closely, not just at the coast but inland. For us in South Florida, the direct threat may have decreased, but we’ll need to monitor the trends, especially into the lower Keys, with the threat of heavy rainfall from abundant moisture surging northward ahead of Ian starting tomorrow.


About the Author:

Michael Lowry is Local 10's Hurricane Specialist and Storm Surge Expert.