Matt Lanza

One-sentence summary

Final preparations in advance of expected major hurricane Idalia should be made by tomorrow morning on the Florida coast, as the storm’s impacts will begin spreading that way by Tuesday afternoon or evening.

Idalia right now

Idalia has been battling some shear today that has held it back a bit in terms of significanr intensification and organization. To be clear, this was expected, and even in the face of this Idalia has held its own and added some lower pressure and stronger wind. As shear moves around a bit tonight and tomorrow and Idalia begins to advance northward, it should begin the process of rapid intensification, just in time for its arrival in Florida. The general rule of thumb in recent years has been that if anything can go wrong in the Gulf of Mexico, it will, and Idalia may add to that list. Let’s focus on impacts today.

Idalia has not moved a whole heck of a lot today, sitting generally just southwest of the western tip of Cuba.

Max winds are currently 70 mph, and Idalia should become a hurricane tonight. Hurricane warnings are in effect for western Cuba. As noted above, wind shear has inhibited Idalia a bit to this point, but we expect that to loosen up some tonight and tomorrow.

Forecast track & uncertainties

Idalia will broadly come north-northeast toward the Big Bend of Florida. There’s still a good deal of uncertainty on the exact landfall point. Because of the angle of approach from Idalia and the unique geography of Florida, a slight shift in track could yield a decent shift in surge impacts. As we’ll note below, the impacts beyond surge should be relatively baked in now for most spots, with a few exceptions.

You can see the ensemble spread here from the European model is still considerable, with a handful of ensemble members close to Tampa and many more spread across the Big Bend, as well as a couple as far west as Apalachicola. Recall, the Euro ensemble consists of 51 model runs “tweaked” at initialization slightly to produce some goal posts for outcomes. We need this in tropical situations.

In terms of wind and rain, the forecast will be fairly straightforward regardless of track. The exceptions to this will be the core maximum winds that extend out 10 to 20 miles from the center. We still need to fine tune that. But a broad swath of tropical storm or even hurricane force winds will be possible along much of the west coast of Florida and a bit inland from there.

In terms of storm surge, things get a lot trickier. As we saw with Ian last year, the track south of Tampa led to catastrophic surge in Fort Myers and an empty Tampa Bay. Initial forecasts were calling for significant surge flooding in Tampa. We will have to watch the exact track of Idalia closely to determine exactly where the worst surge occurs and where the inflection point between onshore and offshore winds occurs. But in general, significant, damaging, dangerous storm surge is likely in the Big Bend and along the Nature Coast south to near Tampa Bay. Surge impacts in Tampa should be considerable but not quite as serious as farther north. And surge impacts south of Tampa will be modest but notable. Moderate surge is possible on the South Carolina and Georgia coasts as well into Wednesday.

It cannot be overstated that everyone from Apalachee Bay to Sarasota needs to prepare for the reasonable worst case scenario surge, understanding that if the track shifts, conditions could get worse or better depending on that exact track. There will be some element of overpreparation in some communities, which is an outcome you need to accept. Wind is a concern with this storm, rainfall a secondary concern. Surge? The biggest concern I have with this thing. Please take it very, very seriously. There is no modern analog to this storm in the Big Bend, and the surge impacts are likely to be dire.

Intensity

The current National Hurricane Center forecast brings Idalia ashore as a major, category 3 hurricane with maximum winds of 120 mph. We could see a slightly stronger storm (or even a weaker storm!) depending on the track and how efficiently Idalia can undergo its expected rapid intensification.

For folks along the coast from Sarasota north, expect hurricane force gusts possible and sustained tropical storm force winds. Inland, including the west side of Orlando will see tropical storm force wind gusts. The core hurricane conditions will follow near and east of Idalia’s center, likely impacting the Big Bend, Nature Coast counties north of Tampa and perhaps grazing Ocala. Inland hurricane conditions are likely for Gainesville, Lake City, and perhaps the western side of Jacksonville, as well as in extreme southeast Georgia. As long as the storm stays on its current forecast track, Tallahassee should be spared significant impacts.

For the east coast, tropical storm watches are in effect from Sebastian Inlet, FL north past Savannah and Charleston to the South Santee River in South Carolina. Storm surge watches cover the area north of the Florida/Georgia line to the South Santee River.

Rainfall

In terms of rain, anywhere from 4 to 8 inches will be possible along the track of Idalia across North Florida, into southeast Georgia and South Carolina as well as southeast North Carolina. Flooding is possible in any of these locations, but the increasing forward speed of Idalia will hopefully help mitigate severe freshwater flooding concerns.

Places like Jacksonville, Savannah, and Charleston will want to prepare for a combination of surge flooding, worsened by rainfall, which will prevent water from draining as quickly as usual. In those areas, flooding could be a little more noteworthy. We’ll touch on that some more tomorrow.

As is always the case with landfalling tropical systems, isolated tornadoes are possible across Florida and into southeast Georgia and the southeast Carolinas.

So, to summarize:

• Idalia is likely to lead to dire storm surge impacts in the Big Bend of Florida with no real good modern analog.
• Surge is highly likely south and east of where Idalia comes ashore, far from the center, but the landfall point matters significantly in determining who sees the worst surge. All of Gulf Coast Florida between Apalachicola and Sarasota should prepare for surge impacts.
• Idalia’s strongest winds will impact the Big Bend and just inland, but gusts to hurricane-force are possible for Tampa and Ocala, and sustained hurricane-force winds may impact Gainesville and the western side of Jacksonville. Idalia’s wind field will extend well east of where it comes ashore.
• Rainfall is a secondary impact in most spots in this particular storm, but still 4 to 8 inches of rainfall could cause flooding in Florida, southeast Georgia, coastal SC and southeast NC.
• Places on the East Coast like Charleston, Savannah, and JAX could be dealing with some moderate surge flooding exacerbated by rainfall that limits drainage.

Our next full update will be on Tuesday morning. Look for a video update this evening on our social channels and follow our Twitter feed and Instagram stories for some other notes this evening.

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One-sentence summary

Hurricane and storm surge watches are now posted along much of Florida’s west coast and parts of the Panhandle as Idalia is expected to bring impacts by Tuesday.

Tropical Storm Idalia

Tropical Storm Idalia (pronounced “ee-DAL-ya” for those that were not sure) formed this morning, and quite frankly it looks no better organized now than it did then. So in essence, not a whole lot has changed from our morning post.

This was mostly expected. Idalia is unlikely to really get moving in terms of intensity until it start getting a lift north, meaning a lot of the intensification we see from this storm may not occur until it’s rather close to land. Idalia is not exactly a small system, with thunderstorms extending from the Yucatan to east of the Isle of Youth in Cuba, which is about 400 to 500 mile wide swath of unsettled weather. To underscore, while the track of Idalia does matter, one need not be close to the center to feel the impacts of this storm as it comes north.

The track forecast today has not seen any dramatic changes, so, broadly we still expect a hurricane approaching the eastern Panhandle, Big Bend, Nature Coast, or Tampa area by Tuesday night. Again, given the size of Idalia and the geography of Florida, hurricane impacts may touch the coast well south of wherever Idalia comes ashore. So, it’s entirely conceivable that (hypothetically) Idalia makes landfall, say, near Cedar Key, while producing hurricane impacts as far south as Sarasota.

Indeed, the biggest change this evening is that we now have a broad swath of the Florida coast under Hurricane Watches and Storm Surge Watches.

Storm Surge Watch: Indian Pass on the Panhandle south to Chokoloskee on the southwest coast.
Hurricane Watch: Indian Pass south to Englewood, between Sarasota and Fort Myers
Tropical Storm Watch: Englewood south to Chokoloskee and for the Dry Tortugas.

On the map below I have overlaid the watches for Florida, in addition to the probability of 60 mph winds and the most likely arrival time of those tropical storm force winds. You can see how wide the berth is for potential strong wind.

The storm surge forecast from the NHC is somewhat aggressive, and it seems warranted given Idalia’s current forecast intensity. The map below shows the reasonable maximum surge above ground level in the impacted areas.

One important note: During Irma and last year during Ian, because of the wind direction, surge was directed out of Tampa Bay. With Idalia currently forecast to pass west and north of Tampa, this would direct surge *into* Tampa Bay. So please don’t go storm chasing this to see a dry Tampa Bay. Another important note: As Idalia’s forecast is revised, this forecast will be revised too, and you should be following forecast progress closely. Florida’s geography and the unique interaction with storms coming from this direction can lead to some substantial forecast impact changes with surge in particular.

So, for folks along Florida’s west coast, the Big Bend, and parts of the eastern Panhandle: You will need to be ready for potential hurricane impacts, regardless of exactly where Idalia comes ashore.

The rainfall forecast has not changed a ton. Idalia keeps moving at a good clip once it gets north of Florida. While this will by no means prevent flooding in spots, it does help to probably limit flooding concerns a bit. We’ll watch the situation in Carolinas a bit closely, as some heavy rain will front run Idalia today and tomorrow, and flood watches are already posted in eastern North Carolina. If I were watching some place closely for flooding risk, it would be there right now.

So, to summarize:

• Idalia is still forecast to become a hurricane as it comes north into Florida Tuesday night.
• Storm surge and hurricane watches are posted along much of Florida’s west coast indicating that surge and hurricane conditions are possible.
• The forecast storm surge will be contingent on exactly where Idalia comes in but a substantial surge event is possible for the Nature Coast and Big Bend. Folks in Tampa Bay should watch this closely as well.
• While portions of SW Florida impacted so badly by Ian last year are unlikely to take a direct hit from Idalia, there will likely be impacts there from high water, rough surf, and some gusty winds and some vulnerable portions of the waterfront still not fully recovered may see some issues.
• Heavy rain will follow Idalia inland and North Carolina may be in line for the greatest inland flooding risk as it stands right now.
• The forecast IS going to change in the coming days so check back for more.

We will have our next update for you as usual on Monday morning.

One-sentence summary

Tropical Depression 10 continues to slowly organize off the Yucatan, and it continues to look to come north as a hurricane, impacting somewhere in Florida by Tuesday night.

Tropical Depression 10 Tropical Storm Idalia

Editor’s Note: Tropical Depression 10 was upgraded to Tropical Storm Idalia immediately after pressing “Publish.” While the content is unchanged, “TD 10” should now be referred to as Idalia.

One look at TD 10 this morning on satellite allows for two thoughts for me as a meteorologist. First, where is the center? Second, that’s a *lot* of thunderstorms.

In terms of the first point, the center seems to be located near Cozumel. The NHC just placed the center about 75 miles ESE of Cozumel. It’s been doing a bit of a loop, but it remains in tact at least. TD 10 is expected to drift north over the next 24 hours, slowly organizing as it does so. We could have a tropical storm by later today or tomorrow.

Thereafter, steering currents should direct this north/north-northeast toward the Florida coast. There are two important changes today in terms of track outlook that may not be obvious from the NHC outlook. First, the organization of TD 10 is still an issue. Until this thing can really wrap up and get going, there is some risk that the center tries to “reach” for the thunderstorms, which is to say, it’s entirely possible the center relocates at some point today. Second, model consensus on TD 10’s future track has shifted a little to the right (or east) since yesterday. This keeps the west coast, especially north of Tampa along the Nature Coast in play, as well as the Big Bend and Panhandle. Basically, everyone from about Destin to Sarasota should continue monitoring TD 10’s progress closely.

The reason you may be hearing a lot about TD 10 and its future is because of where it’s located. It’s over deep, rich warm water, an untapped resource it can probably tap into as it organizes. If and when that happens, TD 10 could quickly go from funky to formidable. And it remains likely that portions of the Florida coast will be dealing with hurricane impacts by Tuesday night. The NHC forecast brings maximum winds to 90 mph as TD 10 (then Idalia) comes ashore. It’s possible it could be stronger than that. In addition to wind, storm surge will probably be an issue as well as this storm comes ashore. The West Coast of Florida will need to watch this, as well as the Big Bend area, where surge could be maximized depending on the exact track of the storm.

In addition to wind and surge, there is always the rainfall. A general 3 to 6 inches is likely along TD 10’s track as it comes north. Areas to the east of the track may also see some enhanced rain. Higher amounts are likely in spots and the potential for inland freshwater flooding is possible for Florida into Georgia and the Carolinas.

Bottom line on TD 10:

• Gradual organization is expected today and tomorrow, leading to a hurricane impact by Tuesday night somewhere on the west coast or Panhandle of Florida.
• Rapid intensification is possible as TD 10 enters the Yucatan Channel or Gulf.
• Storm surge flooding will likely be an issue on Florida’s west coast or in the Big Bend area.
• Specific track details still need to be ironed out.
• Heavy rainfall from TD 10 will lead to localized flooding concerns from Florida and Georgia through the Carolinas.

Our next update on TD 10 will be Monday morning, unless things change or become sharply clearer later today.

Hurricane Franklin

Meanwhile, in the Atlantic, Franklin had become a bit of a curiosity and afterthought yesterday as it looked to pass west of Bermuda as a hurricane. That has since changed some.

While Franklin should still miss Bermuda comfortably to the northwest, it may be large enough to produce fringe impacts on the island, including gusty winds and heavy rain, in addition to rough surf, rip tides, and beach erosion (something we may also see on the U.S. East Coast later this week). Franklin is forecast to peak in intensity before passing Bermuda, but still a decent, large-sized hurricane passing 100 to 150 miles away is capable of producing some impacts. Folks in Bermuda will want to monitor Franklin’s progress closely. For Newfoundland, this should mean fewer impacts ultimately.