NSW - SHOWERS, HAIL AND THUNDER CONTINUES WITH A COLD WINDY AIRMASS.

The cold airmass leading to widespread rainfall with snowfalls welcomed over the Alpine resorts with open arms. The band of rain that brought the significant rainfall to parts today is moving through to the east and north and will clear the coast tonight with widespread showers ongoing in a cold and unstable airmass.

Showers may be heavy at times over the Southwest Slopes and Plains and through the Southern Interior west of the divide. Showers more scattered through Central areas and isolated over the north. The better rainfall chances will be along the windward slopes of the Great Dividing Range.

As we track into Tuesday, the showers will begin to contract further south through the state with drier but colder weather developing over northern areas. The clearer skies and lighter winds over northern areas will support severe frost development in some areas.

Wednesday will be the day that the showers decrease and largely clear the state, with cold nights and mostly sunny weather to return with the westerly winds easing.

Now the tricky part of the forecast will be how much moisture comes into the next cold front coming through later this week and/or on the system developing over the weekend, with the high moisture loads over the northern and western parts of the country, this does open the door for more widespread rainfall chances beyond this short-term system which is quite a punch.

The following systems look to offer more broad areas of rain with not as colder airmass which represents the issues talked about today, more humidity in the air leads to warmer weather overall, warmer moist air at this time of year leads to above average rainfall potential.

Let’s take a look

FORECAST

Rainfall Next 10 Days

Extensive rainfall has been spreading throughout today and then into tonight, the rainfall is forecast to spread further to the coast but the rainfall rates coming way down. Showers with some thunderstorms also possible overnight in the west with an area of cold air following the widespread rainfall so far today. The showery airmass continues through Tuesday before clearing Wednesday, most areas should be dry by the end of Wednesday. We may have some thicker high cloud and the chance of a bit of patchy rainfall Thursday or Friday over the northern areas of the state bordering QLD, but this should scoot through with not too much in the way heavy rainfall. Another front is forecast to approach the region from the weekend with a broad area of mainly light rainfall forecast but my confidence levels on this feature are not especially high right now, and I will be waiting for this current event to conclude before focussing more specifically on this feature. There is also a signal that rainfall could become more widespread over northern areas during the medium term as well, with further moisture running through the jet stream. Some of what you see here tonight, has already fallen as is reality in real time rain events.

Rainfall for much of the southern and southeast inland not welcome and quite frankly, retarding the ability for crops to be planted in many areas. The rainfall below thresholds for flood issues at this time, but a reminder that it is the incremental rainfall events like this that stops the catchments from drying out, leading to the impacts of flooding down the track as move into Spring and the heavier rainfall events on the go.

The rainfall over the northern parts of the state is lighter but be on the lookout for rainfall across the weekend and into next week, as we track a few cloud bands over the interior. Rainfall has been up and down in recent runs and will continue to chop and change as we move through the outlook period but better guidance likely to come from Thursday.

Thunderstorm Forecast Tuesday

Thunderstorms are present tonight and again tomorrow with a risk of damaging winds and small hail possible. Thunderstorms are forecast to contract eastwards during the afternoon, so the risk clearing through Victoria by nightfall and NSW southeast and the ACT by overnight with more stable air by Wednesday.

Severe Weather Watch - Damaging Winds

Damaging winds have already been observed Sunday and today with that very tight pressure gradient leading too strong to gale force wind gusts on and with a front moving through NSW expected to move further east on Monday. A strong cold front to follow up the low-pressure system could also produce strong squalls with showers and thunderstorms on Monday night and into Tuesday morning. Conditions should ease from the west on Tuesday.

Hail Risk - Monday to Tuesday

Small hail is likely with scattered to widespread showers and thunderstorms with wind squalls of up to 100km/h, the combination could lead to crop damage, especially of young vulnerable plants.

Farmers and Graziers

We are already experiencing the major airmass change through the coming week, with cold and wet conditions and high wind chill developing over thre southeast overnight and into this morning. Only 5C about the Tablelands in NSW and VIC with windy weather and rainfall underway. Conditions peak on Tuesday before the weather warms somewhat on Wednesday and the winds ease.

Frost Risk Mid-Week

The cold air is forecast to be trapped under a weak ridge mid week, and as skies clear and winds drop out, there is an elevated risk of frost forming, especially about elevated terrain and away from the coast. Some of the frost could be severe in and around the ACT and southeast NSW, extending into northeast VIC.

MEDIUM TERM

June 6th-13th 2022

Rainfall Anomalies

Rainfall anomalies through this period largely unchanged, the moisture over the northern tropics is of great interest to me where we could see more above average moisture content. But as mentioned, this rainfall over this part of the world is going to show up as green on this chart, as this area should be dry. Mostly seasonal rainfall expectations elsewhere but the confidence is not especially high right now. Will have to see what that moisture does over the northwest and whether it comes southeast with any northward approaching frontal feature.

Temperature Anomalies

The cooler signal remains in place and relates to the cloud cover running through the nation and the colder air left over from the dual cold outbreaks taking a while to clear the country's interior. But the day time temperatures will be below average where the night time may move above the average. The overall pattern is connected to the developing IOD and the ongoing negative SAM phase.

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

I have more to say in the video but be aware that the forecasts will keep jumping around nationally. The cold outbreak should be on the way out tomorrow night and a drier pattern establishes across the inland and southeast for a period. But it does not look to last as more moisture runs through the northwest of the nation through Central Australia and into the southeast states. Some of this could be caught up into the westerly wind belt and further rain could develop this weekend but it is not clear yet on how that looks with the current system needing to be off the board before I can be specific about this. Over the north and northwest, the weather is forecast to turn humid and more unsettled with that moisture possibly moving south and southeast throughout the country, but once again how that looks is up in the air, so another day before we get better guidance.

00Z GFS - Precipitable Water Values - Next 2 Weeks

The moisture values are coming down through the south and southeast as the dry southwest to southerly flow develops behind the large mass of rain in the southeast and east tonight. Drier air extends back over the southwest and west of the nation where high pressure is ridging through. Another pulse of tropical moisture is expected to sweep in from the Indian Ocean and race into the jet stream, spreading widespread cloud and potential rain across the nation. Some of this moisture may be swept into the cold fronts trying to approach the southeast but the timing is all over the shop. The pattern is of low confidence and will have consequences across the nation.

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 Euro - 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 - this forecast is changing erratically and I will continue to add that the forecast confidence remains low beyond this current event over the southeast.

More coming up from 8pm EST with a look at the models and rainfall.

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