NSW - SEVERE WEATHER OVER THE NORTHEAST BACK TUESDAY - SHOWERS INCREASING IN THE REMAINDER EAST.


It has been a very active day of weather for the northeast with severe thunderstorms continuing tonight and that will be back again during Tuesday.


We have a mid level trough over the south, you may have noticed the increase in thick high cloud this afternoon and a few showers and storms have now started for some across the south. Albury picking up a quick fire 11mm this afternoon.


The weather turning cooler and showery for the southeast overrnight and into the ACT during Tuesday with that rain and thunderstorm activity moving up the NSW coast during the day. Mostly dry weather further west.


Then from Wednesday on and west of the divide should have a dry spell, something that has not been said for a while, with warmer weather developing.


A trough is likely to form west of the state and that is where the weather turns tricky to forecast with a bit of madness going on.


Lets take a look

Rainfall for the next 10 days

Rainfall is heaviest and more concentrated over the northeast tonight and again tomorrow with thundery areas of rain with moderate falls. Another area of rain will develop over the southeast overnight and during Tuesday, this area of unstable weather passing up the NSW coast with a southerly change with some moderate falls. The inland areas will remain mostly dry through this period until about the weekend, when the forecast becomes really tricky. The forecast trough over the weekend could spark more storms for the state, but where that kicks off is yet to be determined but it may be further west than advertised so watch this space. Otherwise no major rainfall events on the board until the very end of the month at this time.

Thunderstorm Forecast Tuesday.

Showers and thunderstorms tonight will continue to be ongoing and flatten to areas of rain with moderate falls. Another round of thunderstorms may form in QLD overnight and move southeast into northeast NSW and then clear by late morning or early afternoon. This will be along the trough. A southerly change moving up the NSW may trigger a separate batch of showers and thunderstorms during the day.

Large Hail Risk Tuesday

Large hail is a moderate to high chance with the fresh thunderstorm development overnight and during Tuesday morning along the trough as it passes from the inland through to the coast and then offshore. The risk will diminish once the trough passes through.

Damaging Winds Risk Tuesday

Damaging Winds remaining a high risk overnight and during Tuesday morning with fresh thunderstorms that develop and emerge out of QLD. The trough passing through will carry the highest risk of damaging winds IF thunderstorms form from late morning or early afternoon.

Flash Flood Risk Tuesday

Heavy falls today have brought flash flooding to scattered communities and this risk will continue on and east of the trough overnight and again during Tuesday before the trough lifts offshore. Falls of 50mm in an hour possible.

DATA


Euro 00Z - Surface Pressure Pattern and Rainfall Distribution - Next 10 days

Severe thunderstorms have broken out along a trough today and as expected bringing high impact weather, that will return again on Tuesday before moving offshore. The ridge over the southeast will continue to hold firm for much of this week, cradling weakening low pressure troughs passing through from WA bringing unsettled rounds of weather for NSW and QLD in particular. The odd low pressure system is expected to form offshore the NSW coast through this week, enhancing coastal showers. During the weekend, a large upper high is expected to form. On the periphery of that ridge you can see troughs producing showers and thunderstorms, one in the east, one over the west and over the north throughout the period. Under that ridge the southeast will warm up a bit this week too, even following the front passing over later this week, the winds are not cold as they have been in previous weeks. Out west, perhaps the last strong cold front of the season is coming through tomorrow before being shunted south of SA due to the blocking pattern in the east. Over the north the tropical easterly winds are likely to move further south in the coming 10 days and this is where you can see the moisture now running into the west coast trough into the medium term. All signals the weather is starting to shift further. The forecast overall is indicating a low confidence on rainfall spread and intensity across the nation.

Euro 00Z - Precipitable Water Anomalies - Next 10 days

As outlined in the video, you can point out the amount of moisture coming through in the sequence and not being reflected in the pattern at the surface in showers and thunderstorms. That is the power and suppression of the large scale upper high on GFS but other models are more generous in introducing rainfall back through the nation from next week. You can see the role of the low pressure in the Tasman Sea not only acting to block the passage of the frontal weather and troughs out of the west with deeper moisture and rainfall chances, but note the injection of dry air over the east and southeast inland through the period, as the system oscillates through the region. Meanwhile, deep moisture over WA will bring extensive cloud and rain areas for Tuesday which may run across the south of the nation before moving offshore the coast from Wednesday. The north, above average humidity values as expected with that playing out with more widespread falls further south throughout the north than usual, the early onset rainfall unfolds. And the east will see showers and thunderstorms with troughs from time to time, the moisture over QLD remains near seasonal for most of the period so seasonal rainfall expectations can be forecast for now. Much of the inland looks stable, dry and warm.

Euro 12Z - Rainfall Accumulation - Next 10 days

The GFS is keen on enhancing the upper ridge over the south and upper high over the north of the nation throughout this period, with the rainfall strictly coastal over the east and southeast, through the tropics and over in the west tomorrow with widespread falls. The major rainfall event for this week is over the in the west. The major storm outbreak is expected in QLD tonight and tomorrow and again over the weekend ahead of the next middle level trough coming out of SA. That leaves a good chunk of NSW, SA and VIC relatively dry with stable air in place, but I do think this forecast will resolve and rapidly shift wetter looking at the PW Values available on modelling tonight not being picked up by the heat lows at the surface. That to me makes no sense.

Let us have a closer look in.

GFS 00z - Rainfall Accumulation - Next 16 days

Refer to the video for more.

CFS 18z - Rainfall Accumulation - Next 6 Weeks

Refer to the video for more.

More details on all things rainfall coming up from 9pm EDT



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