Hurricane Hunters from Lakeland and Keesler fly Isaias as Coast Guard and park service brace the Panhandle

The federal response to Tropical Storm Isaias began in the air and on the water Wednesday, well before the storm's expected arrival on the northern Gulf Coast on Friday. Air Force Reserve and NOAA Hurricane Hunter crews, including NOAA aircraft based at Lakeland Linder International Airport in Polk County, were scheduled for round-the-clock missions into the storm, while the U.S. Coast Guard set port conditions for its Mobile sector, which includes Pensacola and Panama City, and the National Park Service closed most of Gulf Islands National Seashore's Florida beaches at noon.

The data those flights collect feed directly into the National Hurricane Center forecasts that Panhandle residents, emergency managers and the region's large military community are using to decide what to secure and when to leave.

Where Isaias stands

As of the hurricane center's 4 a.m. CDT advisory Wednesday, Isaias was centered about 285 miles west of Progreso, Mexico, and 580 miles southwest of the mouth of the Mississippi River, with maximum sustained winds near 40 mph. It was moving east-northeast at 8 mph. The center said rapid strengthening was forecast, that Isaias was expected to become a hurricane by Thursday, and that it was increasingly likely to be a significant hurricane when it reached the coast. Forecasters told residents from Louisiana to the Florida Panhandle to monitor updates and said Hurricane and Storm Surge Watches would likely be needed for part of the northern Gulf Coast later Wednesday.

The hurricane center described track confidence as below average, with a wide spread among computer models. That uncertainty is exactly what reconnaissance flights are meant to reduce.

The first look inside the storm

An Air Force Reserve WC-130J flying mission 0209A, tail number AF304, reached the system Wednesday morning. In a vortex data message sent at 12:33 UTC, or 8:33 a.m. EDT, the crew fixed the center near 22.4 north, 94.0 west and measured a minimum pressure of 1004 millibars, matching the hurricane center's earlier estimate. The highest flight-level wind recorded on that pass was 43 knots, about 49 mph, 32 nautical miles from the center. The crew also released dropsondes, instruments that radio back pressure, temperature, humidity and wind as they fall to the sea.

In its 4 a.m. discussion, the hurricane center had noted that both Air Force Reserve and NOAA Hurricane Hunter missions were scheduled to sample the storm later in the day, after it upgraded the depression to a tropical storm based largely on satellite data and a buoy report.

The flight schedule

The hurricane center's reconnaissance coordination office issued its Tropical Cyclone Plan of the Day on Tuesday afternoon, before the system was named, when it was still listed as suspect area AL92. The plan called for six flights between Wednesday morning and Thursday midday, alternating between Air Force Reserve WC-130J aircraft, which use the call sign Teal, and NOAA aircraft. Departure times below are converted to Eastern Daylight Time and could change as the storm evolves.

The plan's outlook for the following day called for continued fixes every six hours, two more NOAA P-3 tail Doppler radar missions departing Lakeland at 10 a.m. and 10 p.m. EDT Thursday, and another Gulfstream IV-SP surveillance flight leaving Lakeland at 1:30 p.m. EDT Thursday. Air Force Reserve crews were to begin fixing the center every three hours starting at 4:30 a.m. EDT Friday, the day the storm is expected to approach the coast.

The plan also noted that during the NOAA 43 mission overnight Wednesday, crews planned to release two small uncrewed aircraft systems into the storm. The drones were to operate at or below 5,000 feet for about one to two hours, gathering data close to the ocean surface in the storm's lowest levels.

Florida's role: Lakeland and the NOAA fleet

NOAA's Hurricane Hunter aircraft are operated by the agency's Aircraft Operations Center at Lakeland Linder International Airport, part of NOAA's Office of Marine and Aviation Operations. The fleet's crews include NOAA Corps officers, members of one of the nation's eight uniformed services, along with civilian flight engineers, meteorologists and electronics specialists.

According to NOAA, its two four-engine P-3 turboprops, nicknamed Kermit (N42RF) and Miss Piggy (N43RF), fly 8 to 10 hour missions through a storm's eyewall, deploying GPS dropsondes while tail Doppler and lower fuselage radars scan the storm vertically and horizontally. Their stepped frequency microwave radiometers measure surface wind speed and rain rate over the ocean, which NOAA says are key indicators for storm surge forecasting. NOAA marked the 50th anniversary of the P-3 program's first hurricane flight this year; N42RF first flew into a tropical cyclone, Hurricane Bonny in the eastern Pacific, on June 27, 1976.

The Gulfstream IV-SP, flying as NOAA 49, has a range of about 4,000 nautical miles and cruises at 45,000 feet. NOAA says that since 1997 it has flown around nearly every Atlantic hurricane that posed a potential threat to the United States, mapping the upper-level steering currents that determine where a storm goes. With Isaias expected to turn north toward a coastline where the difference between a Mississippi and a Panhandle landfall matters greatly, those steering observations are a priority.

The Air Force Reserve's 53rd Weather Reconnaissance Squadron, part of the 403rd Wing, flies its WC-130J aircraft out of Keesler Air Force Base in Biloxi, Miss. The squadron is the only Defense Department unit that still flies into tropical storms and hurricanes. Biloxi itself sits within the hurricane center's forecast cone for Isaias.

Coast Guard sets port conditions

On the water, the Coast Guard captain of the port for Sector Mobile issued a marine safety information bulletin, MSIB 120-26, at 8 p.m. Tuesday setting port conditions for portions of its area of operations. The bulletin said Tropical Depression Nine, now Isaias, was forecast to bring gale-force winds of 39 to 73 mph to the sector within 72 hours. That threshold corresponds to Port Condition Whiskey, the first of the Coast Guard's escalating hurricane readiness levels, under which ports remain open but vessel operators and facilities must begin preparations.

As the forecast arrival time of gale-force winds draws closer, the Coast Guard typically moves ports through Conditions X-Ray, Yankee and Zulu, which tighten restrictions on vessel movements and cargo operations and end with ports closed to traffic. Mariners and recreational boaters in Pensacola Bay, Choctawhatchee Bay, St. Andrew Bay and the Intracoastal Waterway should watch for further bulletins from the sector.

Gulf Islands National Seashore closes Florida beaches

The National Park Service closed most of the Florida district of Gulf Islands National Seashore at noon Wednesday, citing possible severe weather in Florida and Mississippi. The closures covered:

• The Fort Pickens Area and Fort Pickens Campground on Santa Rosa Island
• The Okaloosa Area and Crab Island near Destin
• The Opal Beach Area between Pensacola Beach and Navarre Beach
• The Perdido Key Area, including Johnson Beach

The Naval Live Oaks Area in Gulf Breeze was to remain open, the park said. In Mississippi, the barrier islands were closed until further notice, and the Davis Bayou Area and campground in Ocean Springs were set to close at 4 p.m. Wednesday.

Military bases in the cone

The forecast cone for Isaias covers a heavy concentration of military installations, including Naval Air Station Pensacola, Naval Air Station Whiting Field in Milton, Eglin Air Force Base, Hurlburt Field and, at the eastern edge, Tyndall Air Force Base near Panama City. No installation had publicly announced aircraft evacuations or closures in information available Wednesday morning. Bases in the region have flown aircraft out of the path of past storms, and the Panhandle's military community remembers Hurricane Michael, which devastated Tyndall in October 2018.

Service members and families who live on or near those installations should follow their base's official channels, as well as county emergency management, for decisions on hurricane conditions, liberty restrictions and any authorized departures.

What's next

Reconnaissance flights will continue through Friday, increasing to every three hours as Isaias nears the coast, and each flight will feed the hurricane center's advisories at 10 a.m., 4 p.m., 10 p.m. and 4 a.m. CDT, with intermediate updates once watches are posted. The hurricane center expected to issue Hurricane and Storm Surge Watches for part of the northern Gulf Coast later Wednesday. If tropical-storm-force winds draw within 48 and then 24 hours, the Coast Guard is likely to tighten port conditions for Pensacola and Panama City, and more federal and state closures could follow.