Imagery Animation

The prediction page horizontal slider controls stepping through imagery a frame at a time; [ and ] (square bracket) keys can also be used. (Curly braces -- { and } -- also step, but wrap around at the end of the range.) The slider handle is centered at the date/time being displayed, and its width indicates the image interval (time step to next image), relative to the time tick marks or overall range. E.g. for the same 6-hour range (duration), 1-hour interval images will show a narrower handle than 3-hour interval images. Thus a wider handle can indicate larger steps between forecast images.

The time ticks are labelled with time, and/or day of month (with month or weekday -- changeable in settings), by default in UTC (also changeable in settings). Day-only labels imply a time of 00:00. Ticks are always aligned with specific image times, even if those are not integral (e.g. GOES satellite shows time ticks such as 18:01). However not all images may have ticks (e.g. if there are many images for a large Duration).

Note that sometimes the displayed range will have two different image intervals; late in a forecast's available range it may switch from e.g. 3-hour interval images to 6-hour intervals. The handle will stay the same size, while the time ticks will generally be denser for the longer-interval portion of such a range, indicating where the interval change occurs.

Just below the imagery slider, two icon ticks may appear, identifying specific points in time:

•    A now icon appears beneath the current time.
•    An event time icon appears beneath the event time (if an event time is defined).

If either of these times are out of the display range, their icons may appear left or right of the slider, with an arrow indicating what direction they lie out of range. (Hovering over them gives a tooltip as to how far away.)

Thus, seeing the now or event time icons left or right of the entire slider range -- with an arrow -- is a quick indication that "now" and/or event time are out of range. And when the event time icon has a tick mark that touches the slider handle, the currently displayed image is for event time.

Progress/status bars

While loading imagery, a grey progress bar appears beneath the slider, showing the fraction of images completed (whether successful or not). The bar disappears when loading is finished, so it may not be visible if loading is rapid.

The inside of the slider span serves as a status bar: images that successfully load have their slider location colored green, failed images show red, and pending images white. So a mix of loaded and failed images can produce a green and red stripe. Images can fail to load for various reasons, besides just connectivity problems. A common reason is that images for the failed dates are simply not available yet. The GUI makes an educated guess as to when each model run or satellite image is available, but it could be wrong, e.g. there is a delay in the provider's processing. Failed images will automatically retry; there is no need to continually refresh via the browser.

Animation buttons

The step-backward, play/pause, and step-forward buttons control animation of the weather images. The step buttons move a step in the indicated direction (stopping animation first); as noted above, [ and ] (square brackets) also do so. The play/pause button (or = key) starts or stops the animation. Speed and animation style can be configured in settings.

Below the animation buttons, the date/time of the currently displayed image is shown, in both UTC and local time. An Image link is given to display just the raw weather image in a separate tab, e.g. for downloading. The now/event time icons and their time offsets indicate how far the image is from "now" and event time, respectively.