NSW - SHOWERS AND STORMS INCREASING FOR THE STATE WEDNESDAY

A deep trough is set to sharpen overnight with moisture surging in from the north and west ahead of a system moving in from the south tonight to start the first wave of severe weather with heavy rainfall and severe thunderstorms leading to pockets of flash flooding, that will kick off the riverine flooding.


A secondary low will bring a more widespread area of rain with heavier totals with the chance of moderate to major inland flooding. This is a high impact event and I have been very persistent in my stance about preparing your property for flooding this Spring and here we are. So enough said on that...good luck to you all.


Lets take a look at the drier spell from the weekend and into next week but also when rainfall and humidity returns.

FORECAST

Rainfall Next 10 Days

The rainfall is excessive as stated for the past 10 days, when you have record humidity values and deep and unstable atmospheric instability, heavy rainfall is likely to unfold with flooding. So we are nearly here for this event to get underway. Heaviest rainfall is due in Wednesday through Friday with significant falls over 100mm likely for many locations. Catchments have already seen 50-150mm in recent weeks so this is a primed event for those on and west of the divide. Flash flooding also possible with thunderstorms may be dangerous. The rain and storms contract to the southeast during Friday and clears the inland from Saturday but showers and windy weather continues for southern inland and southeast areas before easing Sunday. Next week starting out dry but then humidity with showers and thunderstorms return in the day 8-10 period. The drier spell will assist in reducing the flooding over inland areas but the catchments won't have enough time to dry out.

Central West NSW

Southeast NSW

Northeast NSW

Northwest NSW

Southwest NSW

Thunderstorm Forecast Wednesday

A high risk day for thunderstorms with a near certainty of thunderstorms forming within 25km of a given point over the northeast of NSW and southeast QLD. Severe thunderstorms are a high chance over these regions extending south to the central districts. Flash flooding and damaging winds the main risk. Thunderstorms will continue into the night

Flash Flood Risk Wednesday

Flash flooding a very high risk over northeast NSW and southeast QLD with very heavy rainfall rates expected with thunderstorms that form. There could be flash flooding risks over central and southern inland NSW but it is considered a low chance with thunderstorms initiating overnight ahead of the sharp trough moving through. I have not drawn it in but the risk could extend through Wagga to Canberra, but it is very low risk. Worth mentioning in these wet catchment areas.

Damaging Winds Risk Wednesday

Damaging winds are a very high chance over northern and eastern NSW and through southern QLD with strong winds aloft being drawn to the surface, especially with discrete storms that form ahead of areas of rain developing later in the day. Damaging winds also possible in the early morning over Central NSW as storms kick off.

Large Hail Risk Wednesday

A low chance of large hail with strong storms through parts o northern NSW and southern QLD. The chance of damaging hail is small but not 0.

Riverine Flood Risk Wednesday through Sunday.

A plethora of flood watches are in force for inland NSW, southern QLD and likely to be issued for parts of VIC in the coming day. Please be weather aware and prepare for flooding over the risk areas.

DATA - Refer to Video For the Analysis


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

The pressure pattern is similar to GFS and introduces the humid air following the cold drier snap over the southeast this weekend, across the nation much more quickly now and this time next week I suspect we are already talking about rain and thunderstorms once again. I have been warning of this lack of a break in rainfall for a while now and it appears that idea is on the table.

00z Euro Precipitable Water Anomalies - Next 10 Days

Significant PW Anomalies continue ahead of a nice pop of drier air working through this weekend into next week, but as mentioned, note the moisture surging from the Indian Ocean and then through the easterly wind shift over the tropics which shift south through the nation.

00z Euro Precipitable Water Anomalies - Next 10 Days

Note the very high PW values over the nation's north and east. I want to point out there is a very high region of PW that comes down with the low pressure system between Wagga and Canberra which could trigger torrential rainfall Friday and serious flash flooding there as well as most of QLD and the outback

00z Euro Rainfall Accumulation - Next 10 days More can be found in the video

00z GFS Rainfall Accumulation - Next 10 days

More can be found in the video

A full wrap of the rainfall and flood potential after 9pm.

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