Hurricane Isaias: What to Expect from Pensacola to Mobile and the Mississippi Coast

Everything forecast-related on this page is as of National Hurricane Center Advisory 4, issued at 10 AM CDT (11 AM EDT) Wednesday, October 7, together with the wind-probability and arrival-time products NHC issued with it and the NWS Mobile products out that morning. NHC's next full advisory is at 4 PM CDT, with an intermediate update at 1 PM, and the track has already shifted between packages. Check the time on this page against the clock. Our tropics tracker mirrors NHC and updates through the day.

This is not an official forecast. It is a local reading of the official one: what the Advisory 4 track usually means for the beaches, bays and sounds from Bay St. Louis to Mexico Beach, and what this coast has learned from storms that took similar paths. For any decision about your home, your boat or your family, the authorities are NHC, your National Weather Service office (NWS Mobile for Mobile and Baldwin counties and Escambia, Santa Rosa and Okaloosa counties; NWS New Orleans for the Mississippi coast; NWS Tallahassee for Walton and Bay counties), and your county emergency management office. When they say something different from an app, including this one, they are right.

Watches now in effect

With Advisory 4, NHC issued the first watches for Isaias:

• Hurricane Watch: Bay St. Louis, Mississippi, to Indian Pass, Florida. That covers every beach from the Mississippi coast through Dauphin Island, Gulf Shores, Orange Beach, Perdido Key, Pensacola Beach, Navarre, Okaloosa Island, Destin, Panama City Beach and Mexico Beach.
• Storm Surge Watch: the mouth of the Mississippi River east to Yankeetown, Florida, including Mobile Bay.
• Tropical Storm Watch: the Jefferson/Plaquemines Parish line in Louisiana to west of Bay St. Louis, and east of Indian Pass to the Aucilla River in Florida.

What the watches mean

A hurricane watch means hurricane conditions are possible. NHC issues it about 48 hours before it expects tropical-storm-force winds, because outside preparations get difficult or dangerous once those winds arrive. A storm surge watch means life-threatening inundation from rising water moving inland from the shoreline is possible in the next 48 hours. Watches usually become warnings as the storm closes in, and NHC said additional watches and warnings could be required later Wednesday.

NHC's discussion asks residents in the surge watch area to follow the advice of local officials and evacuate if told to, and residents in the hurricane watch area to prepare for the possibility of long-duration power outages. Evacuation orders come from your county, not from NHC.

Also in effect Wednesday morning: NWS Mobile had a High Rip Current Risk through late Saturday night for the Mobile, Baldwin, Escambia, Santa Rosa and Okaloosa coasts, and a Small Craft Advisory for the Gulf waters until 3 AM CDT Friday. NWS Tallahassee had a High Rip Current Risk through late Sunday night for South Walton and coastal Bay, Gulf and Franklin counties. NWS New Orleans had Small Craft Advisories on the Mississippi Sound and coastal waters and said they may be replaced with tropical headlines.

Where Isaias is and what NHC expects

At 10 AM CDT Wednesday an Air Force Reserve Hurricane Hunter aircraft found Isaias about 260 miles west-northwest of Progreso, Mexico, and about 540 miles south-southwest of the mouth of the Mississippi River. Maximum sustained winds were 45 mph, pressure 1000 mb, and it was moving east-northeast at 8 mph. NHC's discussion says the center was re-forming a little farther north, closer to the storm's mid-level circulation, a change that could help it intensify rapidly.

NHC expects a turn to the northeast and then north on Thursday and Friday, with the storm speeding up, so that a fast-moving Isaias approaches the northern Gulf coast by Friday afternoon. The forecast has it a hurricane by Thursday and peaking at 110 mph, Category 2, over the central Gulf at 7 AM CDT Friday, then 105 mph at 7 PM CDT Friday about 75 miles off the coast. NHC's key messages call for a strong hurricane approaching the coast. Shear is expected to increase near landfall, but the discussion says it isn't certain how fast the winds will come down, and that Isaias should be growing in size as it nears the coast because of its interaction with a trough. By 7 AM Saturday the center is forecast to be well inland over Alabama at 50 mph.

Plot the Advisory 4 forecast points and the line from Friday evening's position (29.2 North, 87.5 West) to Saturday morning's (32.2 North, 87.6 West) runs almost due north and meets the coast near the Alabama-Florida line, around Perdido Pass, between Mobile Bay and Pensacola. At the forecast speed of roughly 17 mph between those points, the center would cross the beach around midnight Friday night. NHC does not publish a separate landfall time or intensity.

The track can still move. NHC nudged it east again with Advisory 4, and the guidance is still split: AI-based models on the east side of the envelope, physics-based models on the west. NHC's discussion notes that many of the stronger solutions sit on the eastern half of the guidance and are faster, which is why the watches cover so much coastline.

When the wind arrives

NHC's public advisory says tropical storm conditions could begin in the watch areas midday Friday and hurricane conditions late Friday. Its two arrival-time maps, issued with Advisory 4 and read here directly from NHC's data files, fill in the detail. The earliest reasonable arrival time is the time before which there is no more than a 1-in-10 chance of sustained tropical-storm-force winds (39 mph) starting; NHC describes it as the window for finishing preparations if you have a low tolerance for risk. The most likely arrival time is the point at which arrival before or after is equally likely.

On the earliest reasonable map, the whole coast from Bay St. Louis to Mexico Beach sits between the Friday 8 AM and Friday 8 PM CDT lines, close to the 8 AM line. In plain terms: plan as if 39 mph winds could start on the beaches Friday morning. On the most likely map, every point from Bay St. Louis to Mexico Beach, including the city of Mobile, sits just inside the Friday 8 PM CDT line, meaning Friday afternoon or early evening.

Those maps only resolve to the lines NHC draws, so treat them as windows, not appointments. The forecast/advisory tells the same story: at 7 PM CDT Friday the center is forecast to be about 85 miles south of Pensacola, with tropical-storm-force winds reaching 140 nautical miles (about 160 statute miles) out on its northeast side and hurricane-force winds about 35 nautical miles (40 statute miles). Anything you need to do outside, from shutters to the boat, should be finished by Friday morning, not Friday afternoon.

The odds NHC gives each town

NHC's wind speed probability table lists the chance that sustained winds of at least 39 mph (tropical-storm force), 58 mph, and 74 mph (hurricane force) occur at each point over the five days. As of Advisory 4, for the coastal points it names:

• Pensacola: 58 percent tropical-storm force, 30 percent 58 mph, 10 percent hurricane force.
• Whiting Field (Milton): 55, 25 and 8 percent.
• Destin Executive Airport: 52, 23 and 7 percent.
• Panama City: 50, 19 and 8 percent.
• Mobile: 42, 17 and 5 percent.
• Apalachicola: 33, 9 and 3 percent.
• Gulfport: 24, 11 and 3 percent.
• Stennis (Hancock County): 15, 6 and 1 percent.
• Over the Gulf at 29 North, 87 West, roughly 100 miles south of Pensacola: 81, 55 and 35 percent.

Why 10 percent is not a small number

A 10 percent chance of hurricane-force wind at Pensacola can read like a reason to relax. It is not. These are odds for one exact point, about two and a half days out, built from NHC's historical track, intensity and size errors. Nearly all of the probability at every coastal point falls in a single 24-hour window, 7 AM Friday to 7 AM Saturday CDT, and the open-water point NHC lists closest to the forecast track, south of Pensacola, carries 35 percent. NHC's own guidance on these products says probabilities that seem relatively small, 5 to 10 percent, may still be quite significant, and asks people to weigh the cost of not preparing for an extreme event. NHC has also put the whole coast from Bay St. Louis to Indian Pass under a hurricane watch. Read the table as "this coast is in play", not as "Pensacola is probably fine".

The right side of the storm

Hurricane winds blow counterclockwise. In a storm moving north, the east side is where the forward motion adds to the rotation and where the wind blows from the south, straight off the Gulf and onshore. That right-front quadrant usually carries the strongest wind, the highest surge and most of the tornadoes. The west side gets winds from the north and east, blowing off the land, which can push water out of the bays.

Isaias is forecast to be lopsided in exactly that direction. At 7 PM CDT Friday NHC forecasts tropical-storm-force winds out to 140 nautical miles on the northeast side but only 80 on the southwest. NHC's surge statement says the deepest water will be along the immediate coast near and to the east of where the center comes ashore. NWS New Orleans said the same from the other end on Wednesday morning: the strongest impacts are expected along and east of the center, with a sharp drop-off to the west, though the west side still gets wind and marine impacts.

On the Advisory 4 line crossing near Perdido Pass, Perdido Key is about 5 miles east of the center, Pensacola Beach about 25, Navarre Beach about 40, Okaloosa Island and Destin about 55 to 60, Panama City Beach about 105 and Mexico Beach about 125. Gulf Shores would be about 10 miles west, Dauphin Island about 35, Pascagoula about 60, Biloxi about 80 and Bay St. Louis about 105. Shift the track 40 or 50 miles in either direction and those numbers, and which side of the storm you are on, change. That is ordinary: NHC's 2026 cone is built so that two-thirds of 60-hour forecasts land within 77 nautical miles (about 90 statute miles) of the forecast point, which means one in three miss by more. That is why everyone from Bay St. Louis to Mexico Beach is under a hurricane watch, not just the towns near the line.

Storm surge: NHC's first numbers

Advisory 4 carries NHC's first surge forecast for Isaias. It is the height the water could reach above normally dry ground somewhere in each area if the peak surge arrives at high tide:

• Ocean Springs, Mississippi, to Indian Pass, Florida: 5 to 7 feet. That covers Pascagoula, Dauphin Island, Gulf Shores, Orange Beach, Perdido Key, Pensacola and Pensacola Beach, Navarre, Fort Walton Beach and Destin, Panama City Beach and Mexico Beach.
• Mobile Bay: 5 to 7 feet.
• Mouth of the Mississippi River to Ocean Springs: 3 to 5 feet. That covers Bay St. Louis, Gulfport and Biloxi.
• Indian Pass to the Aucilla River: 3 to 5 feet.
• Aucilla River to Yankeetown: 2 to 4 feet.
• Lake Pontchartrain: 1 to 3 feet.

How surge behaves in these bays and sounds

Those are ranges for long stretches of coast. NHC adds that surge varies greatly over short distances and that the deepest water, with large and dangerous waves on top, will be near and east of landfall. How each bay behaves is a big part of that.

Mobile Bay is a funnel. It is wide at the mouth between Dauphin Island and Fort Morgan and narrows north toward downtown Mobile, the Causeway and the Delta. A south wind pushes Gulf water in and the shape of the bay stacks it higher toward the head. Zeta in 2020 shows it in NHC's own numbers: the open-coast gauge at Dauphin Island peaked at 2.4 feet above Mean Higher High Water (roughly, above the normal high-tide line), while inside the bay the West Fowl River Bridge gauge reached 5.9 feet and Coast Guard Sector Mobile 5.3 feet. In Katrina, which came ashore at the Mississippi-Louisiana line, NHC found 8 to 12 feet of surge along the northern and western shores of Mobile Bay, several miles inland from the Gulf.

The bay can also empty. On Sally's back side in 2020, once the wind turned out of the north, nearly every tide gauge around Mobile Bay fell below Mean Lower Low Water. The Coast Guard Sector Mobile gauge dropped about 10.6 feet in roughly 20 hours to 7 feet below that datum, exposing parts of the bay floor. If you see that, the water is not done. It returns when the wind swings back.

Pensacola, Escambia and Blackwater bays, Santa Rosa Sound, Big Lagoon and Perdido Bay are a maze of back bays behind Perdido Key and Santa Rosa Island, and that is where Sally did its worst surge damage. NHC found 5 to 7 feet of inundation above ground along the coasts of Baldwin, Escambia and Santa Rosa counties, the Pensacola tide gauge peaked at 5.6 feet above Mean Higher High Water, and NHC's model put the upper reaches of Escambia and Blackwater bays at 6 to 7 feet. Water in these bays drains out through Pensacola Pass and Perdido Pass, and when surge holds the passes shut the rain has nowhere to go.

The Mississippi Sound is shallow and wide, with the barrier islands well offshore, and the back bays behind the mainland shore flood deep. In Zeta, a USGS gauge on Old Fort Bayou in Ocean Springs reached 9.5 feet above Mean Higher High Water, a Biloxi gauge on the Back Bay 7.2 feet, Bay Waveland Yacht Club 8.2 feet and the Pascagoula NOAA Lab 7.1 feet, with NHC estimating up to 10 feet above ground in the back bay around St. Martin. Zeta came ashore in Louisiana, and the Mississippi coast was on its east side.

The tide clock this weekend

NHC's surge ranges assume the peak arrives at high tide, and this time that is close to the forecast. Tides here are small and mostly once a day, and NOAA's predictions put the Friday high tide at Dauphin Island around 10 PM CDT and at Pensacola around 11 PM CDT, within an hour or two of when the Advisory 4 track brings the center ashore. Each night's high runs a little higher than the last through the weekend. The range is under a foot, so the surge dwarfs the tide, but the two are lined up rather than working against each other. Our tide pages carry the NOAA predictions for each station.

What past storms on this track did

No two storms are the same, and none of these is a forecast for Isaias. They are the reason local emergency managers say not to judge a storm by its category or by the last one you rode out.

Ivan, 2004, is the closest match for track. NHC's report puts its landfall just west of Gulf Shores at about 1:50 AM CDT on September 16 as a 120 mph Category 3, with an eye 40 to 50 nautical miles across, then north-northeast across eastern Mobile Bay. The strongest winds likely fell on Perdido Key and Perdido Bay, east of the eye. NHC reports storm surge of 10 to 15 feet from Destin west to Mobile Bay and Baldwin County, and 6 to 9 feet from Destin east to St. Marks. Perdido Key was essentially leveled. Waves on top of the surge knocked as much as a quarter mile of the Interstate 10 bridge across the upper bay (NHC's report calls it the I-10 bridge system across Pensacola Bay) into the water, and the U.S. 90 causeway across the north end of the bay was heavily damaged.

Sally, 2020, peaked at 110 mph, the same as Isaias's forecast peak, and came ashore at Gulf Shores at about 4:45 AM CDT on September 16. What made Sally was speed, or the lack of it: steering currents nearly collapsed and it crawled ashore, with its northern eyewall over coastal Baldwin County for about three hours before landfall. NHC's report has 29.99 inches of rain at Orange Beach, 29.30 inches near Fort Morgan and 24.88 inches just west of Naval Air Station Pensacola, plus 2 to 4 feet of combined freshwater and surge flooding in parts of downtown Pensacola. Isaias is forecast to be moving much faster at landfall than Sally was, which helps on rain, but NHC still forecasts 3 to 6 inches with localized 10.

Sally also carries a forecasting lesson. NHC's report says many of its own forecasts, and the major models, showed landfall in southeast Louisiana or Mississippi as late as 36 hours before it came ashore in Alabama, and that the forecasts made about three days out, when people make their decisions, may have given a false sense of security in the hardest-hit areas. For Isaias the guidance splits the other way, with the eastern and faster solutions tending to be the stronger ones. Either way, a few days out is exactly when tracks are still moving.

Katrina, 2005, is the Mississippi coast's benchmark: NHC's report has 24 to 28 feet of storm surge across a 20-mile swath centered on St. Louis Bay, including Waveland, Bay St. Louis, Pass Christian and Long Beach, a high water mark of 27.8 feet at Pass Christian, 17 to 22 feet from Gulfport to Pascagoula and 10 to 15 feet in Mobile County, including Dauphin Island. Katrina had weakened from Category 5 to Category 3 before landfall, but NHC notes it stayed very large, with its tropical-storm and hurricane-force wind field nearly as big at landfall as the day before. A storm that weakens just before landfall does not take its surge with it, and NHC expects Isaias to be growing in size as it comes in.

Michael, 2018, shows how sharp the left-right difference is. It came ashore near Mexico Beach as a Category 5, and NHC estimates up to 14 feet of inundation in Mexico Beach and 9 to 14 feet from just southeast of Tyndall Air Force Base to Port St. Joe. West of the center, from west of Panama City to near Pensacola, inundation was 2 to 4 feet.

Rain and flooding

As of Advisory 4, NHC forecasts 3 to 6 inches of rain from Friday through the weekend, with localized totals up to 10 inches, across the central Gulf coast from far southeastern Louisiana to the Florida Panhandle, and 1 to 3 inches, locally 5, farther inland across the Southeast. It expects flash and urban flooding and isolated river flooding. NWS Tallahassee's Wednesday morning discussion forecast a similar 3 to 6 inches with isolated amounts near 10 for its area, including Panama City Beach and Mexico Beach, and noted the ground there is already soggy.

The compounding problem on this coast is surge holding the bays and passes high while the rain falls. NHC's Sally report says exactly that: storm surge kept rainwater from draining into the rivers, bays and the Gulf, which is how the Styx, Fish, Blackwater and Shoal rivers and several Walton County creeks reached major or record flood. Low streets near the bays can flood from rain even where surge never reaches.

Never drive into water over the road. You cannot see how deep it is or whether the road under it is still there.

Tornadoes in the right-front bands

The National Weather Service's description of tropical tornadoes is plain: they most often form in rain bands well away from the center, and most occur in the right-front quadrant. On the Advisory 4 track that puts the Florida Panhandle and south Alabama under the bands. NWS Mobile's discussion mentions the potential for tornadoes, mainly during the day Saturday, with timing and placement depending on the track.

Ivan is the local example. NHC's report lists an F2 tornado near Panama City Beach on September 15, the day before Ivan made landfall west of Gulf Shores, that killed one person and injured seven, another F2 near Blountstown that killed four, and a third tornado that killed two people in Panama City about an hour later. Panama City Beach was more than 100 miles from where the center came ashore.

Tropical tornadoes are usually brief and often wrapped in heavy rain, so you will rarely see one coming. Keep Wireless Emergency Alerts on, keep a weather radio or a loud alert app on overnight Friday into Saturday, and know which interior room you would use.

Surf, seas and rip currents: the danger that starts first

The water turns dangerous long before the wind does, often under blue sky. NWS Mobile's beach page says it directly: hurricanes that are far away can still create deadly rip currents and waves. A High Rip Current Risk was already in effect Wednesday through late Saturday night from Dauphin Island to Destin, and through late Sunday night from South Walton to Franklin County.

The NWS Mobile surf zone forecast issued at 4:32 AM CDT Wednesday called for 3 to 4 foot surf Wednesday and Thursday, 5 to 7 feet Friday, 13 to 15 feet Friday night with winds around 45 mph, 8 to 10 feet Saturday and still 5 to 7 feet Saturday night, from Dauphin Island and Gulf Shores across to Pensacola Beach, Navarre and Destin. Offshore, NWS Mobile expected seas of 4 to 8 feet even before Isaias arrives. Expect those numbers to change now that watches are up.

Stay out of the Gulf. Do not wade out to look at the surf, and stay off jetties and piers. If you are caught in a rip current, do not fight it: float, then swim parallel to the beach.

Bridges and causeways

Almost every barrier island and beach town on this coast is reached by a bridge or causeway, and those are the routes that close or fail first. We are not going to quote closure wind speeds here, because they are set by each road agency and we could not verify them for every bridge. The rule is simpler: if you are leaving Perdido Key, Pensacola Beach, Navarre Beach, Okaloosa Island, Dauphin Island or Pleasure Island, leave while the bridges are open and the wind is calm, which means by Friday morning at the latest, and earlier if you are told to.

The history is in NHC's reports. Ivan's surge and waves dropped part of the I-10 bridge into the bay and heavily damaged the U.S. 90 causeway. During Sally a section of the U.S. 98 Three Mile Bridge between Pensacola and Gulf Breeze collapsed when a construction barge struck it, and flooding closed the I-10 bridge over the Shoal River in Okaloosa County. Zeta completely flooded the U.S. 90 Causeway across the top of Mobile Bay and submerged part of Water Street in downtown Mobile, and Katrina's surge crossed I-10 in many places in Mississippi.

What to do today

• Look up your evacuation zone now, while the roads are quiet. Zones are drawn around storm surge, not wind. Escambia County says plainly that if you live on a barrier island or in a mobile home, you will always be asked to evacuate. Baldwin County's Zone 1, called for even a Category 1, is all of Pleasure Island (Fort Morgan, Gulf Shores, Orange Beach and Ono Island) plus manufactured homes and low-lying flood-prone areas countywide.
• Sign up for your county's alerts, and turn on Wireless Emergency Alerts in your phone settings.
• Decide today where you would go if your zone is called, and plan to be there by Friday morning. Friends or family inland on high ground beat a shelter, but know where the shelters are. If you are told to evacuate, go.
• Plan for a long power outage, as NHC's key messages say: water, food that needs no cooking, medications, batteries, and a safe place outdoors for a generator, never in the house or garage.
• Boats: haul out or move to your hurricane hole now, not Friday. Bridges, ramps and haul-out lists all close up before the wind arrives. Our boat prep guide was written for Charlotte Harbor in Southwest Florida, so skip its local specifics, but the general steps (haul out if you can, double up lines, strip canvas and anything that can catch wind, plan for higher water) apply here too.
• Once the storm is on you, do not go out to check on a boat. Of Sally's four direct deaths, NHC's report attributes two to hazardous marine conditions, including a man who took a jon boat out on Perdido Bay to look for a pontoon boat that had broken loose.
• Bring in or tie down anything that can fly: patio furniture, kayaks, paddleboards, trash cans.
• Clear gutters and the storm drain in front of your house. Rain arriving while the bays are high is when low streets flood.
• Fill prescriptions, fill the car, charge phones and battery packs, and get cash. Check on neighbors who may need a ride.
• If you are on vacation here, check your rental's cancellation terms today, and if the county orders an evacuation of the beaches, go.
• Check back after each advisory. Full advisories come at 4 PM, 10 PM and 4 AM CDT, with intermediate updates in between, and the watches will likely become warnings.

Where to get the official word

NHC owns the track, intensity, watches, warnings and surge forecasts. Your NWS office owns everything local: tornado warnings, flood warnings, beach and marine forecasts, and the hurricane statements that break the NHC forecast down by county. NWS Mobile covers the Alabama coast and Escambia, Santa Rosa and Okaloosa counties in Florida; NWS New Orleans covers Hancock, Harrison and Jackson counties in Mississippi; NWS Tallahassee covers Walton and Bay counties, including South Walton, Panama City Beach and Mexico Beach. Your county emergency management office owns evacuations and shelters.

Conditions at the spots we cover

Our spot pages carry the live wind, radar, tides and marine forecast for each stretch of this coast. Use them to watch the wind build and the water rise, and use the official sources above for every decision.