Note that all times are the clock
time in force in the relevant state or territory
Go here for information on how to save the Daily Weather Summary on
your computer.
The National Daily Weather Summary summarises significant,
unusual and noteworthy weather around Australia on a day-by-day
basis. While the format has evolved, AWN has been providing a daily
summary since it began in 1996 -- archives are available off the Daily
Weather Summary index pages.
While the graphics and statistical information is updated
automatically, the Weather Events section
is written in my spare time so,
unfortunately,
doesn't
always
get updated to a strict schedule and there are gaps at times
that I am busy. Graphics: These are sourced from the Bureau of Meteorology.
See today's summary for the times
they become available. Click on the charts or the links under them
to open full-sized versions. These open in separate windows, allowing
you to click between them to make comparisons.
Statistics: It takes until the afternoon of the
following day for all the information to become available (see today's
summary for the times). I source this information
from synoptic and automatic weather station reports from the Bureau,
but it is also supplemented with daily downloads of information from
the Bureau's National Climate Centre and the SILO
rainfall database, which is the most complete Australian real-time
rainfall database on the web. Some important points to note:
- Records set today: These are currently entered
manually, usually a day or two after the event. I use a computer
program to check the day's temperatures and rainfall against a database
of
high daily rainfall, and high maximum and low minimum temperature records. As
part of the current improvements to AWN's data management, I hope
to automate and broaden the scope of this section soon.
- Minimum and grass (or terrestrial) minimum readings are for the
24 hours to 9am and are initially received to the whole degree. These
are replaced with more accurate readings later in the day.
- Maximum temperatures are for the 24 hours FROM 9am.
Observers report an interim maximum to 3pm, but this is replaced
with the official more accurate figure when the instruments are read
at 9am the next morning. It frequently gets hotter after 3pm local
time (especially when daylight savings time is in force), so the
interim figures are often revised upwards.
- Rainfall, evaporation and wind run are recorded by observers for
the 24 hours to 9am and are available same day.
- Maximum wind gust and sunshine are recorded for
the 24 hours midnight to midnight, and are reported by observers
at their 9am observations
on the following day.
- Wind run is measured by a cup anemometer and represents
the length of air passing the station over 24 hours. Divide by 24
to get an average speed.
- Downpours are measurements of short-term heavy
rainfall (periods of 6 hours down to 1 minute). These are calculated
from AWS routine and special reports and 3-hourly synoptic reports.
The criteria for inclusion vary depending on the duration reported;
for example, durations of less than 5 minutes are reported if the
rainfall rate exceeds 80mm/hour while durations of 3 hours are reported
if rainfall rate exceeds 5mm/hour. There is inevitably some duplication
within time periods, but this helps to define the timing of the heavy
rain. While AWSs are programmed to send special reports during heavy
rain, this list is not an exhaustive one.
- Highest gusts and Gales and gusts seem
to be reporting the same thing, but there are a few differences. Highest
gusts are the official maximum wind gust reported for the
24 hours midnight to midnight. At manual observing stations, such
as airports, a Dines Anemograph is used providing an extremely accurate
measurement that the observer reads off a chart. At AWSs, the maximum
gust is recorded by a cup anemometer. Gales and gusts are
reported from routine and special reports received from AWSs through
the day. Note that two measures are given, the gust speed , usually
measured over a few seconds, and the average or sustained speed,
which is usually the average over
a 10-minute
period. Variations between the reported maximum gust in the two parts
of the Daily Weather Summary can happen for a variety of reasons.
The top gust may not have been reported in the routine or special
reports through
the
day,
but is picked up in the whole-of-day statistics. Or the top gust
reported in real time through the day from an airport may have been
measured by a cup anemometer while the whole-of-day reading is from
a Dines.
- Late rainfall reports. Australia is fortunate
in having thousands of voluntary rainfall observers that read gauges
at 9am daily, record the rainfall on a form and post the form off
the the Bureau at the end of the month. This data is entered into
the computer and becomes available some time afterwards. While about
2000 rainfall observations are reported daily to the Bureau, another
6000 or so come later by post. Rainfall is the meteorological element
that is most variable over space and time, so these additional reports
add immensely to the weather record. I re-run the program that produces
the Daily Weather Summary several months after each day to pick up
these late reports -- check the date of the latest run at the top
of the statistical section.
- Quality control. The data is automatically processed
when first entered, and no quality control is undertaken. When I
replace the Weather
Events text with weather news or any other comment, I look
through the data and remove or correct any obvious errors, but others
may remain. When the program is re-run several months later to pick
up late rainfall reports, it also picks up any quality control work
that has been undertaken to that time by the Bureau.
Weather events: The day's significant,
newsworthy or major
weather events are described here, but there are a few caveats:
- AWN is a spare-time activity of one individual. There will be blanks
in the record. Some events will produce a sizable story
while equivalent events at another time
will just get a few lines. I would love to
consistently and accurately report all events, but time doesn't always
allow that.
- Stories tend to be written a day or more after the event. I find
that it takes that long for sufficient accurate information to become
available and for facts to be confirmed by more than one source.
For weather
news as it
happens, your best sources are ABC
News and the very active breaking
weather forum on Weatherzone.
- Sometimes, well after an event, I will incorporate additional
or corrected information that I become aware of. These stories are
marked as
for
a few weeks in the headline indexes.
- Where possible, I add links
to more detailed reports of events on other sites if I am aware
of them.
- The sources I use to prepare weather event stories, in addition
to the ABC and the Weatherzone forums, include all Australian press
available via Google News, the websites of numerous government agencies,
personal contacts and of course the huge resources of the Bureau
of Meteorology.
If you want to save the Daily Weather Summary
to your computer:
You have two options. The following apply to Internet Explorer, but
the situation is similar with other browsers.
- Save the whole page, together with the
graphics. Click File, then Save As. In the
Save as type selection box, make sure that "Web page, complete"
is selected. Navigate to the folder where you want to store the page,
rename it if you wish, then click Save. The document and graphics
will take up about 250kb on your hard disk for an average day.
- Save the page without the graphics.
If you follow the directions in 1, but select "Web page, HTML only",
you will save the full page without the graphics, but it will look
terrible. That's because it is missing the stylesheet that contains
font and formatting information. If you download the stylesheet and
place it correctly on your hard disk, the page will look the same
as it does on the Web (minus the graphics, of course.) Do the following:
-
Create a folder structure like the one at right. You can call the
folders anything, but the "styles" folder must be called "styles".
- Right click this link,
and save the stylesheet file into the "styles" folder you have
just created.
- Finally, save each day's summaries into a subfolder under the
summaries folder. Now when you open them, they will read the
style sheet in the styles folder and will look ok. Each day's
DWS, without the graphics, takes up between 40 and 80kb, depending
on the amount of data. If you save the files using
their original filename rather than the one that Internet Explorer
suggests, you will be able to use the links on the calendar on
the left of the screen to navigate. The original filename is
always in the format yymmdd.SHTML, e.g. 050128.SHTML for 28 Jan
2005.
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