NSW - SHOWERS ALONG THE COAST TENDING TO HEAVY RAINFALL THIS WEEKEND IN THE SOUTHEAST.

Still showery over the east coastal districts with the southerly flow and the low pressure system offshore driving the unstable airmass. A high ridging in from the west will work with the low in the east and strengthen that pressure gradient and strong to gale force southerly winds and heavy surf is expected for much of the remainder of this week and into the weekend.


The low pressure system could begin to retrograde back to the west on Saturday morning and may even cross the coast during Sunday south of Batemans Bay and clearly that would bring the chance of severe weather for the Southeast of NSW with damaging winds and heavy rainfall.


If the low does move back over land, this will increase the risk of showers and thunderstorms, some severe, developing for northern and northeast NSW into the Central Coast on Sunday. All modes of severe weather would be possible under such circumstances, however the pattern is complex and there is a high degree of uncertainty so keep watch.


Once the low moves out the region from Sunday afternoon, conditions will ease over the state as a whole.


The next upper trough will move through mid to late next week with showers developing for the eastern third of the state with moderate falls for the coastal areas once again before it clears once again by next weekend.


Inland areas should be dry for the coming 10-15 days with no real strong opportunity for rainfall. Temperature for areas west of the Great Dividing Range will tend warmer than average as we track through the coming week and potentially some late season heat for the northwest and far west is quite possible ahead of a change in conditions mid month.


Lets take a look

FORECAST

Rainfall Next 10 Days

Rainfall remains heaviest along the coastal fringe and through to the eastern side of Great Dividing Range in the short term. Rainfall could turn heavier down along the southeast regions over the coming 2-3 days with that Tasman Low heading in from the east. How heavy the rainfall becomes is in direct relation to the low's position to the coast. There may also be a surge of showers and thunderstorms over the northern and northeast inland during Sunday as the low and trough once again tries to move eastwards. So some moderate to heavy falls with thunderstorms on Sunday is not out of the question for the north and northeast but all of this carries a low confidence. Now next week does look drier, apart from a surge of showers and maybe some thunder for the coastal areas and adjacent inland on Wednesday or Thursday. But other areas should be dry and stable throughout the next 10 days or so.

Zoomed in view on the heavy rainfall potential through the southeast.

Thunderstorm Forecast Friday

There is a low chance of a few claps of thunder along the extreme coastal fringe among the showers throughout the coming 24hrs.

Severe Weather Risks - Saturday through Sunday

The severe weather risks associated with a low pressure system moving back to the coast could result in damaging winds and heavy rainfall leading to flash flooding through areas south of the Batemans Bay around the bend into Eastern Victoria. This is conditional however and will come down to the proximity of the low pressure system to the coastal fringe over the weekend.

Damaging Winds Risk - Saturday through Sunday

With the low moving closer to the coast, damaging winds of up to 100km/h are forecast to develop for coastal areas and about the coastal ranges and Alpine areas above 500m. Strong squalls on the western face of the low moving into the coast will also bring heavy squalls if the system is close enough to the coast.


Flash Flood Risk - Saturday through Sunday

Heavy rainfall developing with the approach of the low may lead to pockets of flash flooding along parts of the coast, with the highest risk in the region between Merimbula to Orbost and the adjacent inland. Be weather aware as with the higher SSTs in the region we could see some areas collect 200mm in 24hrs. Once again this is conditional in direct relation to the position of the low pressure system.

Riverine Flood Risk - This Weekend

There could be renewed minor to moderate flooding in the zones identified. The risk is moderate at the moment given the degree of uncertainty surrounding the position of the low pressure system to the coast among the modelling.

MEDIUM TERM FORECAST - April 7th-14th 2022


Moisture Watch

Moisture remains hard to find for inland areas through this time so the drier picture should continue for much of the nation as a whole. We should start to see moisture roll through the northern waters of the country with a tropical wave moving west. The onshore winds may also produce low moisture through QLD and over parts of NSW with some light falls, moderate over the tropics. Moisture coming through the jet stream from the Indian Ocean may hold the key to the drier pattern breaking down through this period with increasing falls over the southwest and possibly western interior of WA. That may have some chance of linking up with troughs or frontal weather mid month.

Rainfall Anomalies

Even though it is a drier picture it does fall within seasonal expectations for this time of year. The drier spell is part of the transition process and should not prove to be the start of a drought, rather than a movement away from warm season conditions and rainfall distribution to the cooler season and the cooler distribution of rainfall. The sub tropical ridge moving over the south of the nation is a part of the process and should actually be an alert to those watching the patterns that the heat is behind us until about October/November.

Temperature Anomalies

Above average temperatures are forecast to feature through this period with a large and stagnant area of high pressure leading to days of sunshine, warming the land and the airmass and this will see most areas over the period remaining in above average temperatures. No searing heat is forecast at this time, but will keep watch, but be advised that conditions will continue to transition out of the cooler than normal weather being experienced right now.

DATA - Refer to the video for further information and it is critical to keep check of the data sets to understand where the next major weather events are emerging from outside of this period. It may be quiet now but I am all about preparation and ensuring that information is shared with you as soon as it is available.


00Z GFS - Surface Pressure Pattern and Rainfall Distribution - Next 2 Weeks

More details can be found in the video - weather settling down after the next 4 days. You can see the daily breakdown in the video on this information below.

00Z GFS - Precipitable Water Anomalies - Next 2 Weeks

The moisture content over Australia is starting to wane with a drier gusty southerly flow moving through the east of the nation, being rotated around a high and bringing a drier phase for much of the next 2 weeks. You can see that by the drier air continuing through the next 2 weeks into the middle of the month.

00Z GFS - Rainfall Accumulation - Next 10 Days

Refer to the video for more context and analysis

00Z CMC - Rainfall Accumulation - Next 10 Days

Refer to the video for more context and analysis

00Z GFS - Rainfall Accumulation - Next 2 Weeks

Refer to the video for more context and analysis

A closer look in - rainfall over the southeast is highly variable with regards to the placement of the low in the short term, the drier air will take over from early next week and clear conditions. Also watch carefully the storm risk of the northeast of the state with the trough amplifying as that moves eastwards during Sunday into Monday.

More coming up after 8am EDT. Have a great evening.




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