Sydney- get ready to shiver in the water this weekend!

The summer-like weather is continuing for Sydneysiders for the best part of the weekend but before you dive straight into the ocean to cool off, be prepared for some icy ocean temperatures! Saturday will bring another great beach day with 27 degrees for the coast and a balmy 31 degrees in the west. There’s a slight chance of afternoon storms in the west but beaches should remain dry. But while it’s simmering outside, the ocean may feel like an ice bucket as sea surface temperatures take a dive over the next few days! You’ll need a wetsuit to swim at Bateman’s Bay on the NSW South Coast where the ocean temperature has already dropped from 19 degrees to a chilly 14.9 degrees this week! And the cooling is starting to show in Sydney’s waters which are sitting at 19.4 degress right now and falling. Note that Sydney’s ocean temperature is taken offshore so it’s probably even colder than that.

Why is the ocean so chilly? The cold ocean temperatures are a result of “upwelling.” Basically we’re seeing a consistent stream on north-easterly winds along the Sydney and South Coast which actually work to drag the surface water away from the coast. When this water gets dragged away something has to replace it, so the colder bottom ocean waters rise to the top resulting in a rapid cooling of sea surface temperatures on our coastline. Next week we’ll get southerly winds coming in which should allow sea surface temperatures to warm up again.

Sunday will start off well in Sydney with a high of 25-27 degrees before widespread rain and possible storms develop in the afternoon. Try and make the most of the sunny skies until then as once the rain rolls in on Sunday it will persist right through into next week.

Another spring soaking heading straight for eastern Australia this weekend

The year 2010 has been nothing short of extraordinary when it comes to rainfall, with rain records smashed across much of northern and eastern Australia. The August to October period this year has been our wettest on record (from 111 years of record keeping) across the entire country- and there is another big soaking on the way this weekend. This will be the fourth, widespread, soaking deluge across eastern Australia this spring.

Thanks to a moderate to strong La Nina which is well established in the Pacific Ocean, we have very warm waters off the northern Australian coastline- this is the moisture source for all the rain that we’ve been seeing through northern and eastern Australia in recent months. This week northerly winds across the east have been funnelling very warm and humid conditions across the region so the moisture source for widespread heavy rain is back- all that’s needed now is a trigger! Tomorrow, this trigger comes in the form of a cold front. So the warm and moist tropical airmass from the north will clash with this colder airmass coming up from the south, resulting in an extensive area of rain that will move slowly eastwards. Far eastern SA, western QLD, central and northern VIC and much of NSW could see 50mm of rainfall from this system. Isolated falls of 100mm are also possible which could renew flood warnings across many already saturated catchments.

Of the capital cities, it’s Adelaide and Melbourne that will bear the brunt of this rain event over the weekend. Adelaide will experience a big temperature drop on Friday going from around 30 degrees in the morning to 20 degrees in the afternoon, accompanied by rain. The weather rollercoaster is also heading to Melbourne with the temperature dropping from 32 degrees on Friday to 23 degrees on Saturday. Rain and storms will develop during Friday afternoon and evening with the heaviest day of rain on Saturday. Melbourne could pick up around 50mm from this system.

Severe storms to hit Sydney and NSW again!

Sydneysiders, along with most of NSW and the ACT, got a taste of summer yesterday as warm and humid blue skies turned to severe storms in the afternoon. The three ingredients that constitute a severe thunderstorm accompanied the massive and prolonged lightning display: flash flooding, large hail and damaging winds. Sydney's southern and south-western suburbs were hardest hit with 65mm at Holsworthy, 47mm of that falling in just one hour. Other rain totals included 47mm at Cronulla and 29mm at Sydney Airport. Sydney Harbour was whipped by a 100kmh wind gust.

Most of NSW, except for the far west, should brace again for summer-like temperatures and storms this afternoon. While Sydney's storms shouldn't be as widespread or intense as yesterday, severe storms are still possible although more likely Sydney's western suburbs. Both Wednesday and Thursday are set to deliver another round of Spring heat and severe storms, but this time both Sydney's western and coastal subrubs may be affected (like yesterday).

The state will continue to heat up towards the weekend with Sydney's west set to peak at a hot and sticky 34 degrees on Sunday.

Another rainy race day? Here's your Melbourne Cup forecast

The last three major race days at Flemington have been a washout and the odds for the Melbourne Cup are favouring wet conditions- but don't worry it will nothing like the Derby Day deluge!

On Saturday, Flemington was awash with heavy rain and Melbourne city picked up 55mm, almost a month's worth of rain and it's heaviest day of rain in 5 years. Yesterday (October 21, 2010) Melbourne's storages reached 50% for the first time in 4 years. But according to Melbourne Water this is still low in historical terms considering that only 19 of the past 50 years have seen Melbourne's storages slip below 50%.

The morning of Melbourne Cup day should be mostly dry, with scattered showers developing around midday. But the totals will be much lighter than previous race days with around 1-5mm expected. It will also be cool with a maximum of 18 degrees.