Fewer locations for observations than forecasts?

[magics...@gmail.com]

Hello all,

I've started reading/experimenting with the API today and one question I'd appreciate some help with is why when I request forecasts do I have access to many more discrete location id's, then I do when I want to track historical/current observations? I may be missing something simple, and if so I apologise, but when I extract the site lists resource for wxobs, and wxfcs - the wxobs list is far shorter?

Can I therefore, somehow acquire recent observations and forecasts for the same location somehow? Take Withernsea on the east cost for example - location ID 354267 here is an example,

When I grab the observation - as follows I get no data returned, just headers:

http://datapoint.metoffice.gov.uk/public/data/val/wxobs/all/json/354267?res=hourly?key=MYKEY

{"SiteRep":{"Wx":{"Param":[{"name":"G","units":"mph","$":"Wind Gust"},{"name":"T","units":"C","$":"Temperature"},{"name":"V","units":"m","$":"Visibility"},{"name":"D","units":"compass","$":"Wind Direction"},{"name":"S","units":"mph","$":"Wind Speed"},{"name":"W","units":"","$":"Weather Type"},{"name":"P","units":"hpa","$":"Pressure"},{"name":"Pt","units":"Pa\/s","$":"Pressure Tendency"},{"name":"Dp","units":"C","$":"Dew Point"},{"name":"H","units":"%","$":"Screen Relative Humidity"}]},"DV":{"dataDate":"2016-03-12T22:00:00Z","type":"Obs"}}}

but when I get the forecast:

http://datapoint.metoffice.gov.uk/public/data/val/wxfcs/all/json/354267?res=3hourly&key=MYKEY

I successfully retrieve the result

{"SiteRep":{"Wx":{"Param":[{"name":"F","units":"C","$":"Feels Like Temperature"},{"name":"G","units":"mph","$":"Wind Gust"},{"name":"H","units":"%","$":"Screen Relative Humidity"},{"name":"T","units":"C","$":"Temperature"},{"name":"V","units":"","$":"Visibility"},{"name":"D","units":"compass","$":"Wind Direction"},{"name":"S","units":"mph","$":"Wind Speed"},{"name":"U","units":"","$":"Max UV Index"},{"name":"W","units":"","$":"Weather Type"},{"name":"Pp","units":"%","$":"Precipitation Probability"}]},"DV":{"dataDate":"2016-03-12T21:00:00Z","type":"Forecast","Location":{"i":"354267","lat":"53.7363","lon":"0.0349","name":"WITHERNSEA (BEACH)","country":"ENGLAND","continent":"EUROPE","elevation":"0.0","Period":[{"type":"Day","value":"2016-03-12Z","Rep":[{"D":"SE","F":"5","G":"16","H":"80","Pp":"0","S":"9","T":"8","V":"MO","W":"2","U":"0","$":"1080"},{"D":"SSE","F":"3","G":"13","H":"92","Pp":"0","S":"9","T":"6","V":"MO","W":"2","U":"0","$":"1260"}]},{"type":"Day","value":"2016-03-13Z","Rep":[{"D":"SSE","F":"1","G":"20","H":"96","Pp":"0","S":"9","T":"4","V":"MO","W":"2","U":"0","$":"0"},

........

I'd really appreciate any thoughts on this - is it the case that forecasts are provided for far more locations then those at which observations are acquired?

Thanks

Stew

[mike]

Yes, it seems odd at first. 

NWP (numerical weather prediction) means the Met Office forecasts are for the entire surface of the earth, land and sea, and right up through the atmosphere to the edge of space.  Observations to initialise come from various sources including satellites, radiosondes, aircraft, ships, buoys...  The upshot is that there are only a small number of locations, mostly airports and airfields, that provide official UK land observations.   Some sites are operated for climate monitoring purposes to ensure the long term record is maintained.

Michael

[magics...@gmail.com]

Thanks for replying so quickly, it makes sense although I'm just a little surprised at the relative scope. That said I get the point about official observations versus mathematical extrapolations and the reduction in scope that entails.  

Cheers

Stew