“At First”

[CJ1]

Hello Everone,

What exactly does the expression “at first” mean in a shipping forecast?

Recently I was planning an 0700 departure, but the 0600 shipping forecast said “Visibility: Good.Very poor at first”.

So I delayed my departure by 5 hours, leaving in clear skies at 1200 hrs. But two hours (1400) later I was in dense fog, which lasted for another 2 hours.

I know a forecast is never 100% accurate, but I’d like to know the precise definition so I can better judge the risk I’m taking in future.

 

[Fr J Hackett]

As I remember them the terms are:

Immanent, within 6hours

Soon 6 to 12 hours

Later 12 hours or later after issue

I would interpret at first to be immediately after issue and up to 6 hours after.

 

[Boathook]

Hello Everone,

What exactly does the expression “at first” mean in a shipping forecast?

Recently I was planning an 0700 departure, but the 0600 shipping forecast said “Visibility: Good.Very poor at first”.

So I delayed my departure by 5 hours, leaving in clear skies at 1200 hrs. But two hours (1400) later I was in dense fog, which lasted for another 2 hours.

I know a forecast is never 100% accurate, but I’d like to know the precise definition so I can better judge the risk I’m taking in future.

Poor visibility to start with and then becoming good. The timeliness can be vague though from a few hours onwards .....

 

[johnalison]

I would guess that it means that although it will be there at the beginning of the forecast they don’t know for sure when it will pass, though I would expect it to do so during the ‘imminent’ time period. Just a thought.

 

[Black Sheep]

Interesting question.
The Met Office site doesn't define the term "at first".
But slide 12 from this Met Office presentation defines "at first" as: "within the first 12 hours".
So it seems to be an amalgamation of "imminent" and "soon".

 

[jon and michie]

Is the Forecast given for the general outlook of the day so in the OP's case "Visibility - Good but very poor at first" as in the start of the day or First light but then improves

 

[CJ1]

Interesting question.
The Met Office site doesn't define the term "at first".
But slide 12 from this Met Office presentation defines "at first" as: "within the first 12 hours".
So it seems to be an amalgamation of "imminent" and "soon".

Looks like the forecast was accurate then. I consulted the Met office web site, but didn’t find this presentation, and couldn’t find a definition so wrongly assumed that it was probably shorter than imminent.

 

[wonkywinch]

I've got the T shirt ..

 

[dunedin]

Looks like the forecast was accurate then. I consulted the Met office web site, but didn’t find this presentation, and couldn’t find a definition so wrongly assumed that it was probably shorter than imminent.

The main difference between At First and Imminent is that with the former the condition (strong winds, fog etc) is already there at the start of the forecast period, whereas with Immininent it has not yet started.
So not to do with time interval but a departing orcarriving weather condition.
PS Currently got extremely biblically wet as Imminent :-(

 

[Malish]

I'm sure that (early) autumnal fogs are a challenge to predict..... Saturday on the Orwell gave a pleasant early morning thin mist, nothing more, although it did provoke a following yacht to make radio contact because they were concerned about the amount of steam / 'smoke' being emitted from our engine .... a raw water cooled Bukh.... I was readily able to set their mind at ease