Forecast Times
When a program involves viewing forecast information, the ability to determine the forecast time is necessary. This value can also be set with the time resource.
Specifying Forecast Times
There are several ways to specify the forecast time in addition to above menu values. The syntax is:
time[-range][type]
You can specify a time by using entering the time and its units:
| Value | Description |
|---|---|
| init | Initial time |
| anal | analysis |
| obs | observation (same as anal) |
| 12hr | 12 hour forecast |
| h12 | 12 hour forecast |
| 2day | 2 day forecast |
| d2 | 2 day forecast |
| 4.5day | 4 1/2 day forecast |
| e4 | 4 1/2 day forecast |
| time | use the value of the time resource (useful in var files) |
| miss | missing value, take first available |
The range is an hour range that is followed by the type of range. The types of ranges are:
| Value | Description |
|---|---|
| range (default) | |
| avg | average |
| acc | accumulation |
| dif | difference |
| max | maximum |
| min | minimum |
This leads to several possible combinations:
| Value | Description |
|---|---|
| anal-12acc | 12 hour accumulation up to analysis time or 12 hour observed accumulation. |
| anal-24dif | 24 hour difference between current and previous 24 hours. |
| 24hr-12acc | 12 hour accumulation up to the 24 hour forecast time. |
Forecast Times and GRIB Data
Often gridded model data is specified with a complex time. The time and range syntax is a way of solving the problem of accessing these grids. A simpler way is to specify only the valid time.
-ft=24hr -ft=24hr-12acc
The GRIB search algorithm will find the first grid with that valid time. The more verbose method will also work if there is more than one grid matching the same valid time.
Updated January 2021