Illuminating the Fog

I've waited almost a month to post this. Mostly because I've been savoring the feeling of having put together information from various sources and all on my own coming up with an explanation for an observed natural phenomenon.

Okay, really? I've waited so long to post this because one of you will probably tell me my explanation is incorrect.

I've been inordinately proud of myself, and I didn't want to pop that bubble.

So here's the deal: Several times over the past six weeks or so -- most recently two mornings ago -- I've noticed some very localized fog over Gulf waters.

In the West Delta field, one drilling rig might be completely in the clear as the sun rose, while another rig two miles away is shrouded in gray.

On the previous boat we carefully logged the dewpoint, relative humidity and temperature each day; I assumed this was to aid in the prediction of fog during the coming 24 hours.

Of course those factors most directly impact the formation of radiation fog, which is mostly a land-based phenomenon.

Of greater concern to mariners is advection fog, or sea fog, which forms when warm, moist air moves across cooler water, causing the warm air to contract and condense.

My question was: why over here, and not over there?

Seawater, particularly deeper water in a relatively large basin such as the Gulf of Mexico, change temperature only slowly. It's one reason coastal South Texas enjoys more moderate temperatures year-round than, say, Dallas or even San Antonio.

One day as we were plunging into the gray, I noticed a "rip," or line of foam that denoted a current in the water. On one side, the opaque green of the nearshore Gulf; on the other, a silty brown. I thought about this, and decided that the brown stuff was Mississippi River water, floating on top of the heavier salt water.

It also occurred to me that these eddies or currents of river water were probably cooler than the surrounding Gulf water. (I could find nothing on the interwebs about river water in the Gulf, or surface water temperatures for the areas I was looking at, by the way.)

And sure enough, that fog bank started on the other side of the rip and appeared to cover only the brown water.

So, that's my explanation for localized advection fog in this part of the Gulf: river water which started as snowmelt in the continent's heartland remains cooler than the Gulf of Mexico as it flows into the sea, and fog forms over it even when the surrounding Gulf waters are not cool enough to support the phenomenon.

Did I get it right?

Small World

A shout-out to my compadre from Florida who sherlocked his way through this blog and correctly deduced not only what company I work for, but what boat I’m on and what field we’re working. Of course, he’s a captain on a sister ship for the same company.

Anyhow, thanks for reading.

More proof that it’s a small world … I’ve been puzzling over why this damned norther just keeps blowing and blowing after the front passed through. Navtex delivered the answer this afternoon:

High pressure well NW of the area is combining with the large wind field of Hurcn Sandy to produce fresh to strong NW to N winds behind the front. These winds will persist thru early Mon over W portions of the Gulf … and linger to the E. Winds will diminish basin wide Tue and Wed as high pres builds SE across the Gulf ….

And here I thought that the late-season hurricane that barely brushed the Gulf was a mid-Atlantic and Northeast problem, one that wouldn’t affect us at all. I looked at the projected track last week and dismissed it from my mind.

“Fresh” and “strong” are adjectives with specific meanings in marine meteorology; they correspond to Force 5 and Force 6 on the Beaufort Wind Scale, or 17-21 knots and 22-27 knots, respectively.

So, thanks Sandy, for the extended cold front. And my very best wishes to the mariners who must deal with the comparably much worse conditions up the east coast and in the Atlantic.

First Week of October

I figured my birdwatching would be curtailed nearly 100 miles offshore in the Gulf of Mexico. And while it’s true that I have no 50 or 60 species days out here, I continue to see interesting birds. Only a cuckoo has been a quick and easy ID.

Apparently, this is wren week out here; I’ve added two to my list – a Winter Wren, distinctively tiny and dark, hopping about the deck with its tail cocked-up, and (tentatively) a Marsh Wren, which took up residence in the wheelhouse last night.

Both are winter residents of the Gulf Coast, and perhaps farther south. Whether these are migrating birds that decided to take a break on one of the many platforms out here, or resident coastal birds that went astray, I don’t know.

I do know a production platform on the outer continental shelf is no happy place for a wren; not a lot of bugs out here, and the platforms themselves have galvanized steel grating on the decks. That means there’s not a lot of fresh water.

On the boat, we have moths and the occasional cricket that ride out with us, and there’s usually a puddle of freshwater somewhere on the deck.

As I write this, the field is coming alive with radio traffic – helicopters up and flying personnel from platform to platform. I’m thinking we’ll probably stand by on our buoy today, as the seas are building in the wake of a front that blew through about two hours ago.

Our dispatcher knew it was coming and had us finish our backload yesterday.

With seas running less than two feet and a couple of hours of standby time at the far south end of the field yesterday morning, I continued work on the top of the wheelhouse; got the handrails whirewheeled and primed, scrubbed the entire surface and put another coat of white on most of it.

The midnight-to-noon watch is a tough one for getting boat projects done on the deck; not enough light to easily work the first half of the watch, and too busy running the second half.

The other watch got our two new deck lights up a couple of days ago, and yesterday evening replaced one of our old Carlisle & Finch searchlights with a brand-new, but not much brighter Perko light.

If the sky clears, I’ll try to finish up the top of the wheelhouse and get our sidelight boxes painted this morning. We also have half a cable of 2-inch polypro that needs to be made up into a couple of mooring lines.

Last time we were at the dock, we received a large pallet of really useful supplies. It’s nice to be finally getting some of what we need.

Isaac

Forgive me for saying so, but it was a pretty good hurricane, so far as those things go. For me, anyhow.

That's the status I posted on Facebook earlier today.

When I was younger, I took a guilty pleasure in tropical weather. As I grew older and began to understand better the utter devastation these storms often cause, my feelings changed. My complicated relationship with cyclones is chronicled here.

So, by virtue of not having family in harm's way of this storm, by the good fortune of not being stuck in Port Fourchon or -- God forbid -- offshore, I stand by my midday statement.

Turns out a boat is not a bad place to be during a hurricane, provided you have a good hurricane hole. The dock we chose on the ICW in Morgan City was a pretty good spot.

Double-up the lines, lash down the life rafts, stow the life rings, bind the cargo and make sure the hatches are dogged tight. Then, throw a peach cobbler in the oven. That's the routine, apparently.

We didn't have to worry about the electricity going out (it's always provided by our generators), we had plenty of good food on board, and when the water rose we rose with it.

The idle time gave our crew a chance to get to know each other better; normally, we are all awake at the same time only a couple of hours a day and then we're likely pretty busy.

The eye of Isaac, still a hurricane, passed about 40 miles east of us, which meant we never saw the calm in the center of the storm.

We got some serious wind, quite a bit of horizontal rain, and in fact as late as this afternoon we're still getting some bands that make us wonder if the storm really passed. Inconveniently, one of those squalls slammed into us just as I was about to put our boat on the fuel dock.

Morgan City is hosting more work boats than usual; eight of Seacor's pretty, orange and black crewboats are rafted-up down at the Halliburton dock, and a variety of utility boats and offshore supply vessels we don't normally see are in port.

The Coast Guard did not allow any of us to move until after 1400 today, when it began reopening waterways section by section.

The bulkhead at the dock where we usually load has caved-in, and the word is that we'll be offloading and backloading at a different location tomorrow morning.

Seas are still a bit steep out there, if the National Weather Service is to be believed, so I'm happy to wait.

Don't Forget to Turn Out the Lights

Monday

It's 0500 Monday and the latest forecast from our Navtex is headed: "Hurricane Warning."

Isaac is on his way, pushing across the northern Gulf of Mexico, bulking up on a steady diet of warm water.

AIS shows just two other boats in our field and only six within range (usually a little more than 20 miles). That's a stark contrast with yesterday morning when there were more than 30 boats on the display.

It's a little lonely out here.

The radios, usually at least sporadically alive overnight with chatter between boats and platforms, have been eerily silent.

Except for some wit, who just blasted a stanza from the Scorpions' mixed-metaphor megahit: "Here I am, rock you like a hurricane ..."

Ensco Rig 75 has gone dark, the derrick now lit only by a few flashing red lights. Many of our platforms are shut-in, and only a skeleton crew remains in the field.

There are three helicopters overnighting out here, and the word is that as soon as they are loaded up with the last of the production operators, we'll be released to head in sometime after dawn.*

*Update: Our early morning release got stretched to "a couple more hours" and finally 1400. We were the very last boat out of our field, though we crossed paths with a jumbled fleet of crewboats, OSVs and ROV/dive vessels once we got close to shore -- they were all evacuating Grand Isle and Port Fourchon, headed for safe(r) harbor.

Debby does Florida

Well, Debby apparently decided on Florida, and what we thought would be a couple of valuable days at the dock with clear deck space (valuable because we would be able to get some painting done) ended abruptly when our customer called us back out to stand by in a field about 30 miles farther inshore (and 200 feet shallower) than the one we usually work.

It’s crowded here. Platforms and satellites everywhere Lots of bugs and birds, too, which we don’t see too much of out at the edge of the shelf.

Because a lot of these little satellites don’t have helipads on them, the guys in this field move around by boat a lot more. I accomplished my first six swing rope (think Tarzan with a hard hat)  personnel transfers in a side sea and 3-knot current today and only smacked one platform. No damage, thankfully.

Tomorrow sometime, certainly not before the field boss wakes up and maybe not until the end of the day, we’ll head in. As soon as my relief arrives, I head home. Anxious to see my boys and long-suffering spouse, wear flip-flops and sleep in a bed I can really stretch out in.

But, I’m also not dreading coming back to work. It’s not always fun, but it’s usually interesting and the rest of this crew has been good company so far.