General notes
This site's purpose is to show event path maps
(occultations and eclipses) overlaid directly on
real-time weather forecast maps, to avoid having to flip
between two different maps when checking the weather for
mobile events. This is an evolving site: features
change, and not everything is documented.
Auto-refresh
Weather imagery is automatically refreshed by
default (unless changed in settings -- see below), so
the page does not generally need to be manually reloaded
to get up-to-date imagery.
Auto time seek
Event time is the time set for this map's
event to occur, e.g. the geocentric midtime of an
occultation, or midtime of an eclipse. It is
arbitrarily set for each map, and indicated by a star
(
) on buttons and widgets. On initial load, the
map will automatically show the weather at event time if
possible, i.e. if the default forecast is in range; or
the star button can be pressed to select it. Thus one
does not need to compute and select the correct forecast
time each visit. Some weather pages may not have an
event time defined.
Widgets
Many widgets have a brief tooltip that pops up when they
are hovered over. This may give help and/or status on
the item. This includes some non-clickable items,
like the house and star icons under the imagery slider.
Buttons are white on blue when they are
selected/on, black on white when they are
unselected/off.
Pop-up dialogs can be dismissed by clicking
the
X at upper right (if available),
pressing
Esc, or clicking on the page outside
the popup (except for Help, which stays open).
Bookmarks
Most GUI selections are stored in the URL anchor
(the
#... part). This means that a
particular provider/region/time etc. can be set and the
URL bookmarked or shared, and those selections will be
restored on revisit. (However, this will lose the
default provider/region; see that section below.)
Choosing imagery type (clouds, wind, etc.) and region
Provider selects the overall weather service
provider. This controls not only the type of imagery
(forecast vs. satellite), but also what models, model
runs, products, and regions are available, as different
providers have different offerings. Most providers are
focused on only one or a few continents; hence they are
grouped that way.
Product selects which product to show,
e.g. cloud cover, temperature, wind etc. Total cloud
cover or its equivalent is generally the default/first
product.
Region and the 8 arrows beneath it select
which region to show. The arrows move roughly in the
direction indicated. Note that different
providers/products/etc. have different regions, and they
are rarely due-north/south/east/west of each other, nor
of consistent size. The arrows may thus not always be
reciprocal; e.g. moving southeast and then northwest may
not always return to the same region (or even be
allowed). An arrow with no region reasonably adjacent
in that direction from the current region will be
disabled (greyed out). Note that some regions
may
only be accessible via the select box and not
the arrows; e.g. moving to/from
Contiguous United
States and the various other regions in the
NWS
forecasts provider.
Model selects which forecast model to show.
A forecast model is a statistical tool, run by complex
software, which is used to generate the forecast maps.
Various weather agencies have developed different
models, and their predictions often differ -- so check
multiple models where possible. Some providers only
offer one model, so it is unselectable for them.
Satellite providers do not use any models, as they are
showing observations not forecasts.
Model run selects which model
run
to show. Each model is run several times a day as new
weather information is added, to update the forecasts.
The
(latest) run is typically the most accurate
-- as it incorporates the most recent data -- and thus
is chosen by default. (If model runs are offered but
none say
(latest), then auto-refresh is off;
see settings.) One way to see if a model getting
"confident" about its forecast is to halt the
display on a fixed forecast time of interest (e.g. event
time), and choose different model run dates: if the
weather starts to look consistent across the most recent
several runs for the same forecast time, then the model
is more sure of its predictions. (Be sure that the
selected forecast time is in range of all model runs
being checked: the image timestamp should stay the
same.)
Cascading options
If a used-car website were to have two select boxes
for vehicle make and model, the available model options
would likely change based on the make selected -- i.e.
the make selection "cascades" down to the
model options. Similarly on this site,
Provider,
Model,
Product, and
Region
selections cascade downstream in that order. This means
that selecting the provider will change the available
models, products, and regions; selecting the model will
change the available products and regions but not
providers; etc. The interface will attempt to preserve
downstream selections when their available options
change due to an upstream selection, but this may not
always be possible. In such cases, another upstream
selection may need to be made to restore or change
downstream available options.
Default provider/region
Some maps have one or more default providers and
regions defined, which are selected if none are set in
the URL (no
#... anchor info) on
initial page load. These defaults (especially region)
are defined to best fit the event map; e.g. an event
that mostly occurs over the eastern US might have
CMC and
Eastern United States defined
as its default. Since the preferred/"best"
provider might not have the longest forecast range,
alternate defaults may also be defined, which will be
selected if the event time is out of range of the
most-preferred provider. For example, many US event
maps have
Wetterzentrale forecasts /
North
America as a secondary default for a more-preferred
default of
CMC /
Eastern United
States: the former is lower-resolution but
longer-range, the latter is higher-resolution but
shorter-range. On such maps, the provider and region
may thus change from one default to another on a later
visit, when the event time becomes in range of the
more-preferred provider.
KML (event overlay) controls
The pin button (or pressing
k) toggles whether
the KML (occultation/eclipse event map) overlay is shown
or not. Turning it off can make the underlying weather
more visible when the KML lines are close together.
The letter-
A button (or pressing
l /
"el") toggles whether labels for KML points
are shown or not.
The inward-pointing-arrows button (or
pressing
i) toggles the size of KML icons. By
default they are shown normal size, but toggling the
button makes them smaller, revealing more of the
surrounding weather map.
The overall KML name and description are show to
the lower left of the map (below the imagery
timestamps). Hovering or clicking on a map KML element
(e.g. a line or icon/point) highlights it on the map,
and adds its details -- layer name/description and
placemark name/description -- to the lower left info
area.
Setting imagery date/time range
The
Show imagery for widget set controls
what date/time to try to show imagery for. Clicking
on the date/time button will pop up a calendar/time
widget, and the date and time can be selected. Clicking
a day selects that day, but does not yet apply it;
clicking a time selects that time and also applies it
(closing the dialog). Closing the dialog (by
pressing
Esc or clicking a time) applies the
selected date/time, which now becomes the (approximate)
center of the desired imagery range. On the calendar,
the current date is indicated with a small home icon,
and the event date (if defined) with a small star.
The home button (to the right of the date/time button)
sets
Now as the date/time to show, and will
also automatically track it, updating once a minute.
This is indicated by the home button turning blue
(selected). (To pick the current date/time
but
not track it, select it via the
calendar/time widget: press the home button, then
date/time button, then highlighted time.) Selecting the
home button also makes
Now the
(approximate)
start of the imagery time range
for forecast providers, and the
end time for
satellite providers.
The star button (to the right of the date/time button
and home button) sets event time as the date/time to
show, and (roughly) centers the imagery range on it.
This is indicated by the star button turning blue
(selected). This is generally the default date/time
selected, if it is defined. If the current map does not
have an event time defined, this button is disabled.
Duration selects how long to show imagery
for. The available options are determined by the
provider and model selected; different ones have
different maximum durations.
Desired vs. displayed time range
Note that while
Show imagery for
and
Duration together select the
desired
date/time range, the actual
displayed range may
differ, depending on the current data available for the
selected provider and model. If the selected range is
partially or wholly beyond available data, the displayed
range will be altered to fit. Looking at where the
home/star time ticks are (see below) can quickly
indicate whether the displayed range matches the desired
range.
Stepping/animating imagery
The 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 5-hour range (duration),
1-hour interval images will show a narrower handle than
3-hour interval images. Thus a wider handle can
indicate coarser/larger steps between forecast
times.
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 image times, even if those
are not integral (e.g.
GOES satellite shows
time ticks like
18:01). However not all images
may have ticks (e.g. if there are many images for a
large duration range). 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 to identify specific points in time:
-
A home icon appears beneath the current time.
-
A star 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 home or star icons left
or right of the slider is a quick indication that
"now" and/or event time are out of range.
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.
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 home/star icons and their time offsets
indicate how far the image is from "now" and
event time, respectively.
Help and settings
The question-mark help button displays this help popup.
The gear-icon settings button shows a popup that
controls some settings:
-
Use UTC shows times in UTC; when unchecked,
the local (browser) timezone is used. Note that
using local times can lead to more confusing or
verbose tick labels on the imagery slider, as the
local time offset may not be an even multiple of the
imagery interval. (This setting does not affect the
two image timestamps below the imagery slider, as
they always show both UTC and local time.)
-
Weekdays shows weekdays in the imagery slider
tick labels when days are shown; when unchecked,
months are shown. The day of month is shown next to
both.
-
Scale images scales the weather map so its
height fills the browser's viewport without
scrolling. When unchecked, weather images are shown
at native scale.
-
Auto refresh automatically refreshes imagery,
as well as updating model runs. This is the
default, thus it is generally not necessary to
manually refresh the page to keep imagery
up-to-date.