Hurricane Gilbert - The flight of the Century
(meteorologically speaking)

As some of you guys know, on Sept. 13, 1988, I was lucky (very, very lucky) enough to be on the research aircraft that flew into Hurricane Gilbert. This flight recorded the lowest barometric pressure ever for a tropical cyclone the the Atlantic Basin (Atlantic Ocean, Caribbean Sea, Gulf of Mexico, etc), 879 mb (unofficial),winds of 175 mph sustained with gusts to 199 mph were also recorded.

In the beginning...
With United and Continental Airlines currently in an airfare war, tickets were easy and cheap to get. We had originally planned on going on a hurricane recon mission earlier in the year, but tickets were $700+, which was too much for my advisor (Dr. Bill Gray CSU) to dig up. In late August I went to AAA travel agency to get tickets to fly home and I was advised of the cheap airfare to anywhere in the U.S. for only $218 round trip with NO restrictions. With the airfare being so cheap and with no restrictions, we were set to make plans for a possible hurricane recon mission.

The day before (Monday Sept. 12 Colorado State Univ.)
Arrangements were made for us to get on a recon mission into Gilbert. We were not guaranteed a seat on the plane, but Dr. McFadden, who is in charge of the Office of Aircraft Operations (OAO) flights, advised us that we would eventually get on one flight during the week. The flights on Tuesday Sept. 13 were scheduled for Noon and 9 PM.

Approximately at 2 PM we left Ft. Collins for Denver to catch a flight to Miami. We got a flight onDelta to Miami with a stop in Atlanta. Unfortunately, a United airliner had a mishap at Stapelton International (Denver) and our Delta plane was late. This in turn caused us to miss our connecting flight in Atlanta. We arrived at Hartsfield International (Atlanta) at midnight and were scheduled to fly out on the next flight to Miami at 6 AM. This meant less than 3 hours of sleep, which to be honest with you, didn't bother me a bit. My adrenaline had been pumping ever since this "possible" hurricane flight became a reality.

During all this time flying, I had not the slightest idea what was happening to Gilbert. When we left CSU at 2 PM the hurricane was just about to pounce on Jamaica. Horrible thoughts crossed my mind - Did Gilbert get hung up in the mountains of Jamaica and weaken to a measly tropical storm? Were we going to fly into a storm instead of a 110 knot hurricane? My nightmares vanished when I got into my hotel room in Atlanta and turned on CNN. "Gilbert flattens Jamaica. Storm in now 115 knots." I was relieved! Gilbert did not weaken but intensified during the time we were flying!! (You can tell that we were in a "cheap" hotel. It did not have the Weather Channel !!)

Thee Day (Tuesday Sept. 13 Atlanta/Miami)
5 AM - The phone rings. I look up and wonder where the Hell I'm at! Then I remember and I'm instantly awake. I flash on the TV set and find out Gilbert is still there in the Caribbean just as strong as before. We get dressed, check out, and get to the airport. At 6:30 AM our flight leaves Atlanta bound for Miami.

9 AM - We arrive at Miami International. We immediately catch a taxi to OAO. When we arrive we are advised that we are on a "waiting list." We will have to wait until 10:30 AM before we know for sure that we can go. Let me tell you, that was the longest hour I ever had to wait! In the meanwhile, we meet Jeff Masters (the flight meteorologist) and Dr. McFadden. Jeff is going on the 11:30 AM flight, the one we hope to be on. Word gets to us that a U.S. Air Force recon just measured 922 mb inside the eye of Gilbert. The thought crosses our minds, "Will we fly into a Cat 5 storm?" The thought of me getting sick on the flight also crossed my mind. So I purchased some Dramamine (air sickness pills), so I wouldn't "blow chow." Wouldn't that be horrible? Flying in a hurricane and hating every second of it because you were sick? The directions on the Dramamine said to take 2 every four hours. I took 4 in the first shot just to be sure I wouldn't lose it!!

To kill time we toured the plane that we were going to fly in, an Orion P3 aircraft with four "Schwartzenegger"-size turboprop engines. This plane is designed to hunt down submarines for the Navy. The plane was fully equipped with plenty of meteorological measuring devices including Doppler radars (which broke down the day before), front and rear radars, wind (u,v,w) measuring devices, radiometers, a downward looking microwave radiometer to estimate wind speed at the surface (which is a new instrument in testing phase) , plus others.

Almost all seats had a console in front of them. Each console had two 8" TV screens that allowed one to select one of thirteen channels per screen. Three of these channels showed the radar from 20, 50, or 200 km radius. Other channels plotted on a graph in real time, temperature, mosture, pressure, etc. as we punched through the moat, eyewall, eye, and back through the eyewall again. The most important channel in my opinion listed time versus the latitude, longitude, surface pressure (calculated from flight-level pressure using a 6.5°C lapse rate), wind direction, temperature, dewpoint, plane track and heading, flight pressure, pressure and radar heights, and liquid water content. All this information was updated every 1 second in real time!!! I called it the "data screen."

When we got back to OAO it was "destiny time" and the answer was "Yes." We were to leave at 11:30 AM (15:30 Z) for Gilbert. We 'bumped off' a CBS news crew. Too many TV cameras and not enough windows.

On the plane (Tuesday Sept. 13, 1988 on N43RF)

As the plane was warming up on the taxiway, our pilot warned us of a few things, where the 'barf bags' were located, the emergency doors, and the codes. Code 1 meant to put on your harness and safety belt, which was 4 inches FAT and sighed 50 pounds (or at least felt it weighed that much!) Code 4 meant to just put on your safety belt (for eye penetrations.) Code 5 meant we could walk around once we were airborne and talk our visitors, A CNN crew, a PBS crew, the CSU crew (Chris Landsea, Jim Kossin, and myself), along with the flight crew. Code 3 meant to start praying because we were going for a swim whether we liked it or not!!

The PBS crew was there to do a documentary on hurricanes for "NOVA." It will be similar to the NOVA program "Tornado." It will be shown next summer. It was only coincidental that they got to fly on the strongest storm ever!! They got lucky just like myself.

By Noon we were airborne and I was pinching myself because I did not believe that I was about to fly into a hurricane. I always had two meteorological dreams, see a tornado and to fly into a hurricane. I saw six tornadoes during the spring of '88 (two at once during the Denver outbreak of June 15, 1988.) Now my second dream was about to come true.

As we left the runway, the city of Miami became visible. All of southern Florida was under the influence of Gilbert. Winds were gusting to gale force in the Miami area and the first rainband was over the Florida Keys. As I looked out, the sea was already full of white caps. About 40-45 minutes passed by and we were over Cuba. Usually the Cuban government does not allow overflights, but this was an exception to say the least. By this time we were in and out of CBs with light turbulence and heavy rain showers. Gilbert's eye started to come clearly into view on the radar. It looked like a small, dark dot surrounded by brilliant reds and yellows on the radar screen. It would not be long before we 'punched' into the eye.

As one would expect, everything is bolted down scarily for the flight. The pilot warned us about our cameras and such, "If you don't hold on to them, you'll lose 'em." He also warned us of unexpected turbulence. A metal bar was strung lengthwise along the central path of the aircraft. At times, I was walking using my arms instead of my legs. The best part was people who were droning a beverage and a good bump hit. "@#&%!!" would fill the cabin and everybody would get a good laugh!

Finally the message I was waiting for, "Ladies and Gentlemen, Code 4." I popped into a window seat next to Chris (who I share an office with at CSU.) He popped on the the radar channel and my 'data screen' channel. As I looked outside, I could definitely tell I was in the moat. There were stratocumulus (SQ) below in a spiral pattern and dense cirrus aloft. Out ahead of me I could see IT, the eyewall, a large, gray mass of heavy rain, extreme wind, and good turbulence!! The plane was equipped with fish eye windows, you could see above, below, and to the sides. The radar showed the eye surrounded by a brilliant red circle, the highest level on the radar screen. It was also obvious that the eye was small, 10 nautical miles across, a good sign that the storm would be very intense. At this time, I put on my headphones and listened in on the pilots'/crew's conversation. Suddenly, visibility went to zero, we were punching the eyewall. "Pressure 960 wind,damn, where is it? Oh, 126 kts … 947 mb *BUMP* 4.6 m/s updraft." The equipment on the plane is shaking, people are excited, one lady grabs a barf bag and … no fun! "Pressure 943, winds 159.6 kts (184 mph)" I look over at Chris with a huge smile on my face, he looks back with the same reaction. The cabin brightens up, the winds go from 160 kts to 14 kts in 90 seconds. The pilot searches for dead calm, "the center of a toilet bowl" as some call it. He finds it. Winds drop to 3.7 kts. Pressure on the first eye penetration is 903.1 mb! Gilbert is now a Category 5 storm. I look up at the sun and blue sky and wonder in amazement. Then I look down to the sea, hugh waves approximately 50 feet high and 200 yards across cover the ocean. The look like pancakes from our vantage point, 2322 meters about, flying at the 650 mb level. Then I look down and to the left where the sea is under the eyewall. Streaks of foam circle the eyewall, in seconds visibility drops to zero, winds pick up to 132 kts in 80 seconds. This was our first eye penetration and we still had four to go!

Unfortunately, we have to go 100 nautical miles west past the eye, then turn around and travel 141 nmi southeast, then 100 nmi north. As strange as this might seem, you can get bored, especially when you do it 10 times!

It is not long before we leave the eyewall, the captain announces "Code 5" and we get up and look around. The CNN cameraman has a smile on his face, for he knows he's getting excellent video. The PBS crew is built chattering away with Jeff Masters. The others walk around and grab lunch (believe it or not.) Chris and I are babbling a mile a minute about the experience we just went through. It wasn't as bad as I thought. The turbulence was more like a roller coaster than choppy or washboard-type turbulence. Our strongest updrafts were +18 m/s (40 mph straight up!) The experienced crewmen mentioned earlier before that it is better to fly into well-developed storms than those rapidly intensifying. Storms that are rapidly intensifying are known for extreme turbulence.

Gilbert's eye, being so small, had a few drawbacks. One of them was you were in and out within seconds. This also led to lousy photographs (unless you had a fisheye lens) because you couldn't get the blue sky, eyewall, and ocean in one photo. On the other hand, the small eye was probably the reason Gilbert was so intense (beside the excellent outflow pattern at 200 mb.) The most astonishing aspect of the whole trip was being able to actually see the curvature of the clouds inside and outside the eyewall. A synoptic-size cyclone, as we all know, has curvature to it, but you only visually see it on a satellite photograph. Even chasing supercells on the northeast Colorado High Plains doesn't even come close to the rotation and curvature that Gilbert had. But then on the other hand, you would not see me in an aircraft punching a supercell!!

It wasn't long before we were about to make the second penetration into the eyewall. The eye was just as small on radar and we were expecting to go below 900 mb. Gilbert was moving about 290°, we were expecting wind to be strongest on the northern side of the storm. but the question was "How strong?"

Chris and I again grabbed our seats. This time I took control of the data screens and he had the window seat. "Code 4, ladies and gentlemen" here we go again! "Winds 99 … 116 … 127 … 101. Pressure 927 … 915 … 910 … 907. Winds 50 … 28. Pressure 903 … 901 … 899 … 894. Winds 15. Pressure 893. Winds 46 … 84 … 117 … 153 … 157 … 165 kts (190 mph) Not bad!!

The third penetration, the one that broke the pressure record (888.7 mb.) The old record was 892 mb from the Labor Day storm of 1935. Since this was a west to east pass, the winds only got up to 150 kts (only?). But the winds in the center were only 1.5 kts.

The fourth penetration was the 199 kts gust and lowest pressure. This was a north to south Penetration, so we were expecting high winds on the north quadrant. At 21:52:50 Z we recorded an unofficial 879 mb. We were at 630.9 mb level (2091 meters above the sea surface.) The reason why it is unofficial is rather obvious. To calculate sea-level pressure, the algorithm used a -6.5°C/km lapse rate. In the eye of the storm, there is no lapse rate, it's isothermal for a good ways up. The first few hundred meters it's moist adiabatic then a very strong inversion, and isothermal the rest of the way up. In the eye on this pass, the dewpoit depression was 26°C!! The downward looking radiometer measured 23.2°C and our temperature outside the aircraft was 25.6°C.

The saddest part about all of this controversy is that a dropsonde would have answered the sea-level pressure question. The dropsondes were taken off the plane the night before and they forgot to bring them back on. But on second thought, the dropsonde might not have helped. Why? The eye was too small. What are the odds of dropping a pressure device out of an aircraft moving at 300 kts in a 10 nmi eye and having it land at the lowest pressure? They tried it five times on the succeeding flight (the 9 PM one) and missed the eye (landed in the eyewall) every time!!

NHC used a more realistic temperature field to calculate SLP and it went officially at 885 mb. None-the-less, a western hemispheric record! The fifth penetration was anticlimactic, 888 mb and 187 mph winds. Not bad! It was time to go home.

When we landed, we were in for a slight surprise. I walked out of the plane and it wall lit up. I thought this was normal procedure so we could see waling down the ladder, but to my surprise it was the media! They got word of the record braking storm and they were waiting for us. Dr. McFadden greeted us all and shook our hands, congratulating us all fro breakage the record. It was a rush!!

At the National Hurricane Center (9:30 PM Tuesday Sept. 13th, 1988 Coral Gables)
Boy, was this a mad house. There were more cameras in that place than there were people! Poor Dr. Sheets was being hounded by question after question!! I only wonder how they get any work done in that place. I was surprised at where NHC was located. I thought it would be one building where NHC was the sole occupant. In reality, it's in a ~10 story office building on one floor. It's not like NCAR folks, NOT AT ALL!! None-the-less, NHC was impressive with all the equipment they have.

At Chris Landsea's parent's house (Tuesday Sept. 13, 1988 Coral Gables, FL)
The first thing we were told when we got to Chris' place is Dr. Gray wants us to call. I've never heard a man who so happy for us. He was more excited than we were. He had already told everybody (including the local press in Denver and Ft. Collins) that we were onboard THE flight. We had press briefings waiting for us when we got back, talks to give to the faculty and students, etc. etc.!

Soon things calmed down and I had a chance to turn on the Weather Channel and CNN. Sure enough the video from the CNN crew member was on the air every half hour. The Weather Channel was giving its Tropical Discussion in Spanish(!) warning of the imminent doom and gloom which never came to the United States. All three of us retired to sauna, talked about a day we would never forget for the rest of our lives, had a beer, and went to bed.

The next day (Wednesday Sept. 14, 1988 Miami/Ft. Collins)
It was pretty much "pack up and leave" time. But we couldn't get a flight to Denver until 6 PM EDT. So we went back to OAO and thanked Dr. McFadden for the flight of our lives, stopped at NHC to see what was going on, and then headed to the beach for a few hours and body surfed the afternoon away. Thanks to Gilbert, the waves were great! What a way to end a great trip.

Steve Hodanish