FRIDAY MORNING WEATHER - THE WEATHER TURNING MORE UNSETTLED AND THUNDERY AS WE GO THROUGH THE WEEK

Updated: Feb 18

The weather has finally started to shift in response to the climate drivers turning wetter and that has been covered off enough. Now I will start to focus on how long the drivers will influence weather and where the low pressure starts to emerge across the nation.


If you are living over the north of the nation, there is likely to be increasing showers and thunderstorms across the outlook with the chance of a monsoon trough forming north of the nation and another trough over the tropical inland strengthening, both combining to bring the seasonal rainfall back.


If you are living over the east coast of the nation and inland to the Great Dividing Range, you will see showery periods with onshore winds more often than not. A trough laying over central and northern NSW and extending to the Central Coast of NSW will extend northwest back through southern and western QLD with moderate to heavy falls likely to emerge across the weekend with storms over the inland and near the coast where convergence develops.


If you are living through VIC, SA and WA, quiet for a while with dry air and high pressure close by, BUT, for VIC, the weather is set to turn more unstable as we go through next week with the trough over inland parts of the east dipping down from the north and bringing up the chances of showers and storms. The weather gradually warming up and becoming hot in SA, very hot over in southern WA.


Lets take a look how long the wet phase sticks around for

FORECAST

Rainfall Next 10 Days

The movement to the wet phase begins from the weekend with the SAM starting to impact the rainfall distribution over the south and east, with drier weather for central and western parts of the nation in drier easterly winds, those same winds bringing widespread falls to coastal areas of NSW and QLD. Inland areas of QLD and northern NSW need to watch an upper low which could produce widespread rain and severe storms mid to late week, have to keep an eye on that through the next few days as that could evolve quickly. Up north the MJO is expected to move through the north of the nation from next week and then strengthen over the NT or QLD which may lead to low pressure formation with a developing monsoon trough. This could see the cyclone season come to the peak, but strange that once again, cyclone season which is forecast to be above average again has not eventuated. But none the less further widespread rainfall and heavy falls are possible. Moisture will eventually spread south and southeast through the nation outside of this period.

Thunderstorm Forecast Friday

Thunderstorms will continue to increase over NSW and QLD mainly west of the divide as a trough lingers and is invigorated by a front passing over the southeast bringing more wind shear into the region. Storms may tend gusty during the afternoon and evening over NSW and will track the severe risks in the next day. Scattered showers and thunderstorms over the northwest and north, still at below average thresholds for this time of year.

Thunderstorm Forecast Saturday

Thunderstorm activity is expected to increase over northern NSW and into southern and western QLD as a trough deepens a little and starts to feed off the easterly flow establishing along the east coast. Storms have the potential to produce heavy rainfall leading to flash flooding and damaging winds. Thunderstorms will feature over the northern tropics with some of those gusty with damaging winds possible over the Top End and through the north of WA.

Thunderstorm Forecast Sunday

Thunderstorms are expected to become more widespread over the southeast, east and northeast of NSW and across the ACT, extending back over southern and western QLD and into the NT with some of the storms turning severe. Storms may produce heavy rainfall leading to flash flooding and damaging winds are also a risk over the NT. Thunderstorms near a west coast trough unlikely to be widespread over in northwest WA

CLIMATE DRIVERS

Southern Annular Mode - Next 2 Weeks

The SAM has peaked at the positive phase in this wave and we will start to feel that influence in greater scale over the weekend and into next week and it is now being reflected in the rainfall prognostics. Widespread rainfall is penned in to fall over much of QLD, NSW and then into VIC and eastern SA in response to the broad easterly wind developing. The westerly winds over the south are moving further towards the south by the end of the weekend. There could be a secondary peak next week but only 2 members suggest a neutral phase into early March.

MJO - Next 2 Weeks

The latest guide is pushing through the MJO a little quicker over northern Australia and not as amplified so this is why rainfall is not as heavy or widespread now on some of the models over northern and northwest parts of the nation. Widespread rainfall, thunderstorms and flood risks increasing again for the NT and parts of northern QLD. The north of WA may miss out on the heaviest of the rainfall with the MJO deepening over the NT and QLD. The moisture will spread south from the tropics into the central and eastern parts of the nation with rainfall also increasing in combination with the positive SAM.

DATA - Refer to the video for more details on the daily breakdown for the short and medium term


Euro 12Z - Surface Pressure Pattern and Rainfall Distribution - Next 10 Days

Not a huge amount of change from yesterday and indeed the week of analysis, we are tracking some heavier rainfall over the nation during the coming week as moisture and instability increases over northern and eastern Australia, this then spreading throughout the northern and eastern inland. The weather over the southern and western parts of the nation a lot drier with more stable weather. The key areas to watch is the tropical low off the QLD coast and that feature interacting with an upper trough over inland QLD and whether we see a major weather event next week over northern NSW and much of QLD. The tropical weather over the north, do we see widespread storm activity developing with severe weather risks over the NT and QLD ahead of the monsoon returning? There are many questions including these that need to be answered as we track through the weekend and into early next week. Expect the weather to chop and change in the coming days.

Euro 12Z - Precipitable Water Values - Next 10 Days

The guide is still the same as it has been all week but the specifics will now move around as we see a lot of the weather that was in the medium term move into the short term. A few moving pieces that need to be watched, the tropical low that may form in the Coral Sea which may have moisture drawn into the east coast of QLD and the inland areas via and upper trough/low over western QLD. That could produce very high levels of atmospheric moisture could see well above average rainfall for many in central and northern QLD. Over northern areas of the nation, increasing moisture levels over the NT and WA with more rainfall developing in northern areas spreads south through the outlook. the tropical systems that emerge in the medium term will be the drawing features of that moisture across the nation into the southeast IF they form. And finally the positive SAM phase will slingshot moisture via easterly winds into eastern NSW and then into inland and across to VIC as well. The easterly winds will dry out over land and heat up over SA before hitting WA, so dry and very hot weather over in the west for a while.

Euro 12Z - Rainfall Accumulation - Next 10 Days

Refer to video to compare the model data and my analysis

GFS 12Z - Rainfall Accumulation - Next 10 Days

Refer to video to compare the model data and my analysis

CMC 12Z - Rainfall Accumulation - Next 10 Days

Refer to video to compare the model data and my analysis

Euro 12Z - Rainfall Accumulation - Next 15 Days

Refer to video to compare the model data and my analysis

GFS 12Z - Rainfall Accumulation - Next 16 Days

Refer to video to compare the model data and my analysis

More information coming throughout the day including the 6 week outlook refresher and a national wrap of the weather heading into the weekend.






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