MORNING WEATHER WRAP - ALL EYES ON THE DEVELOPING RAINFALL EVENT FOR THE SOUTHEAST. DRY SOUTHWEST.

The nation is caked in a lot of unstable air, especially over northern and eastern areas. The weather dominated by troughs does not always equal rainfall everywhere, and as in this case, the west and far south of the nation remains dry and stable nearer to high pressure. The weather is expected to turn more unstable over the southeast inland with one of these troughs, invigorated by deeper moisture pooling in from the northeast and an upper trough from SA.


This will lead to widespread showers and thunderstorms developing during mid to late week, some of the storms likely severe with an overarching riverine flood risk as well to watch out for.


The north of the nation remains very unstable with a developing trough and heat low over the central NT. This will support multiple rounds of showers and thunderstorms throughout the coming few days. Some of these also tending severe.


Into the weekend and next week, the trough over the southeast will slowly lift north into QLD and then back southwest into eastern SA and western NSW, meaning the showers and storms will dance around large parts of the interior with a soupy airmass. Up north, we will have to keep watch on the developing trough and if any tropical waves can become more organised in the medium term, offering some chance of cyclone weather for QLD, NT and WA.


Lets take a look

FORECAST

Rainfall Next 10 Days

Rainfall still fairly heavy and widespread in the short term with a decent supply of moisture running from north to south into a trough coming into the eastern inland of NSW through VIC producing severe weather potential. We have another port of moisture sitting over the northern tropics near a heat low and trough producing scattered to numerous showers and thunderstorms once again during the coming days, as per the tropical rainfall guide, near impossible to draw how much rainfall you will see up there, but some places could see 70-120mm per day with large thunderstorms. Beyond these two features in the short term the area to watch coming into next week will be the developing tropical lows across the north embedded within the trough. With tropical waves passing through, each of these will need to be watched for development into cyclone activity. The higher chances still exist for the Coral Sea, over Cape York and across the Top End, lesser risks for the Kimberly and Northwest. Any cyclone that forms, crosses the coast and then gets pulled south or southeast into the mid latitude westerly flow will clearly form major rainfall events across Australia, there is a very high risk of this occurring, but a very low confidence in predicting where.

Thunderstorm Forecast Tuesday

The trough over southern NSW will lift to central and northern NSW on Tuesday, but stall out, resulting in storms relocating out of the southeast of NSW for a period. The trough over the north is set to deepen with multiple heat lows involved over the interior sparking showers and thunderstorms over a wide area of the NT and WA. The storms could be gusty over the north with damaging wind gusts as we have seen today with damaging winds reported from multiple areas over the tropics.

Thunderstorm Forecast Wednesday

Showers and thunderstorms become more widespread during Wednesday with storms tending severe with heavy rainfall leading to flash flooding the main concern. The storm coverage over the north and northwest also on the increase with storms tending severe, gusty damaging straight line winds are possible. Thunderstorms may also produce heavy rainfall.

Thunderstorm Forecast Thursday

The trough over the east amplifies in response to the approach of an upper feature from SA and the absorption of Seth in the east so widespread showers and thunderstorms with heavy rainfall leading to flash flooding the main concern. Thunderstorms extend through inland QLD, though more scattered, may be gusty and heavy also. For the northern tropics, the thunderstorms will likely trend more gusty once again during the afternoon and evening with dry high based storms extending southwest from the tropics into the Pilbara.

SEVERE THUNDERSTORM OUTBREAKS TO WATCH

Currently tracking severe thunderstorms today with an organised batch of severe weather already observed overnight through northwest QLD and now rolling up through the Barkly and into the Katherine region at the time of this update. The Daly including Darwin can expect some relief later this afternoon with a severe thunderstorm likely. There will be multiple rounds of severe weather to come through to about Thursday. Right now will focus on today and tomorrow. Damaging winds are the main concern over the interior and additionally, heavy rainfall leading to flash flooding for Darwin and Palmerston this afternoon and this evening. This activity may be repeated again on Thursday into Friday across the region with another surge of southeasterly winds from the trough.

SEVERE THUNDERSTORM OUTBREAK - OVERALL THREAT WEDNESDAY THROUGH FRIDAY.

Thunderstorms are likely to increase from Wednesday but more likely Thursday and Friday with areas of heavy rainfall leading to flash flooding the main concern. I will review the flash and riverine flood risk later tonight and have a first forecast on those details tomorrow morning at some stage to pin down who is at the greatest risk of disruptive weather.

Tropical Depression Risk - January 10-17th 2021

There is a heightened risk of tropical activity across northern Australia throughout the next week. This will lead to enhanced rainfall risks near any low pressure that forms, and this will then feed troughs over the nation seeing rainfall increase over central and eastern parts of the nation primarily. However, a tropical low that runs further west of the modelling, may bring up rainfall chances for areas over WA and SA. This will be a focus of the medium term forecast packages this week. Once again, these tropical lows can whip up very quickly in the short term forecasts so make sure if you are living or have interests in the region, pay attention to forecasts.

DATA - Refer to the video to see GFS for comparison against the Euro.


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

Pressure pattern remains largely unchanged from yesterday. The ghost of Seth meandering offshore the east coast will be drawn into the coast by northeast winds, picked up by a trough and utilised to create showers and thunderstorms for a number of days through VIC, NSW and QLD. Some heavy to very heavy falls are possible. Much of southern SA and WA remains dry and warm through SA, hot to very hot over WA with a persistent easterly flow. The rainfall opportunities limited to none through this period. The main precipitation lay further north with a trough and heat low lifting the moisture over the northern NT and WA, showers and thunderstorms to feature most days this week, they could be gusty and severe at times. An area of tropical interest remains over the Coral Sea on the general charts. This could form into a cyclone in the medium term and run west over the nation's north producing widespread rainfall and heavy falls, but also act to help drag in the monsoon over northern Australia once again. The further west the system were to go, the wetter the nation will be for the end of January.

Euro 12Z - Precipitable Water Values - Next 10 Days

A very deep rich moisture supply continues to build over much of VIC, NSW and through QLD and the NT into northern WA. That is where you will find the higher rainfall chances for the coming 3-4 days. For southern areas of SA and through much of central and southern WA, the air is drier, and more stable with high pressure ridging. So rainfall opportunities remain limited. Areas to watch are the remains of Seth wafting offshore, being absorbed into the trough over the east later this week with heavy rainfall increasing through the eastern states (La Nina 101) and the northern tropics, seeing a larger increase in moisture and low pressure leading to higher rainfall chances. Watching very closely the potential for a tropical feature to run west through the north and then spread moisture over the interior from mid month.

Euro 12Z - Rainfall Accumulation - Next 10 Days

More information in the video

CMC 12Z - Rainfall Accumulation - Next 10 Days

More information in the video

GFS 12Z - Rainfall Accumulation - Next 10 Days

More information in the video

Euro 12Z - Rainfall Accumulation - Next 15 Days

Note the presentation of the tropical low over the northern inland being swept up by the upper northwest winds and then propelled southeast through the outback. A very plausible idea in the medium term.

GFS 12Z - Rainfall Accumulation - Next 16 Days

Today the GFS runs a cyclone through the Coral Sea east and another down the west coast. As I keep reminding you, do not go for the bogus tropical systems and clickbait on social media, it is important to read the longer term as follows, the monsoon trough and MJO are returning mid to late month and the models can see it, but do not know how to handle it.

More coming up today including a refresh on the 6 week outlook into mid February and further updates on the severe weather potential across the nation as well.


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