NSW - SEVERE WEATHER SET TO REDEVELOP THIS WEEK IN THE EAST.

The pattern that refuses to let go, upper low after upper low combining with the easterly wind regime bringing up rainfall chances. Once again we see this take place during the next week with a slow moving upper low over inland areas leading to significant rainfall and flood potential.


The western areas for now look dry, but do not rule out a rogue shower or thunderstorm during this period, especially Thursday through Saturday.


The bulk of the wet weather will be about the central and eastern districts with storms turning severe also a moderate chance at this stage with heavy rainfall, strong winds and small hail. With an upper low in the region, that will lead to large accumulations of small hail with slow storm movement.


Along the coast, the showers could turn to areas of heavy rainfall, with the risk of flash and riverine flooding for the coast, some pockets already on current guidance under a high risk of this occurring.


Into the weekend, conditions should start to ease with the high in the Bight ridging through and leading to clearing conditions from west to east. The coast won't totally clear but will likely clear of severe weather potential.


Another change is forecast to approach from Monday or Tuesday next week.


Lets look at the latest

FORECAST

Rainfall Next 10 Days

No change to the guidance from this morning. Rainfall remaining very much above average for the eastern third of NSW and into the ACT if the data sets do verify. Some modelling has rainfall further west, however that idea is not as supported like the rainfall being heavy along the coast. The zone of the heaviest rainfall is forecast to be between Newcastle and Narooma at this time. The northeast should also remain on alert, but current trends are pushing the heaviest of the rainfall further south at this time. Inland areas, you rainfall numbers will vary with thunderstorms, with the uneven distribution of rainfall likely under this upper low. Conditions should ease by Sunday but not totally clear with another system likely to emerge early next week.

Severe Weather Watch - Wednesday through Saturday

Areas of heavy rainfall likely to develop in association with a deepening upper trough and low through inland NSW. This will likely link into a moist onshore easterly flow and increase rainfall over saturated catchments leading to additional flood risks. Thunderstorms will also form over inland areas, leading to scattered thunderstorms, some of these could be severe and the colour of green over inland areas could be expanded and increased in chances in the next day or so.

Heavy Rainfall Leading to Additional Flooding

Heavy showers developing on Tuesday night will likely turn to areas of rain with thunderstorms with moderate to heavy falls accumulating from Wednesday through Saturday. Daily rainfall totals of 50-100mm for some parts of the southern and central coast could see weekly totals clear 300mm in areas that are saturated. A major flood event is possible over these areas, but will come down to placement of the upper level system. So if you are living in the zones identified here, be aware of the risk developing and stay close to forecasts, official warnings and advice from authorities. I am giving you a heads up well ahead of the authorities, not to hype the event but to risk assess and mitigate danger.

Heavy Rainfall Leading to Flash Flooding

With the saturated soil and catchments, the rainfall forecast will result in the rivers and streams/creeks responding rapidly to moderate to heavy rainfall. Some areas could be upgraded to very high to dangerous flash flooding based on some of the data coming in so these forecasts will be updated and more localised forecast charts will be drawn if required.

MEDIUM TERM FORECAST - April 11th-18th 2022

Moisture Spread

Great odds of seeing the last of the tropical waves passing through the tropics in the medium term with some heightened risk of showers and thunderstorms. There may be moisture remaining in place for eastern areas of the nation in weak onshore winds for NSW but a stronger flow for QLD where the trade winds could bring in some heavier falls. Moisture may also begin to be drawn into the westerly wind belt leading to more rain and cloud cover over much of southwest and southern Australia.

Rainfall Anomalies

Rainfall anomalies for this period are remaining fairly neutral for most areas away from the northern tropics where there is evidence of that lingering wet season influence via the tropical wave. The bias for drier weather remains over inland areas however, has been softened to reflect the uncertainty surrounding the development of moisture out of the northwest and north of the nation feeding into weather systems moving through the Southern Ocean. Timing is everything.

Temperature Anomalies

No change to the temperature anomalies through the nation for the second week of April. Above average temperatures will continue for large sections of interior Australia with a broad high pressure ridge in place and slowly moving through and extending through the southeast of Tasman Sea leading to a warm northwest to northerly flow establishing over the southern parts of the country. Pockets of the nation, being the southwest, the far east and northeast of QLD could see below average temperatures, but the nation as a whole seasonal to above seasonal temperatures.

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 at the top of the page.

00Z GFS - Precipitable Water Anomalies - Next 2 Weeks

There is some seriously dry air being forecast across the middle and upper portions of the nation that will not only suppress rainfall chances moving forward beyond the next severe weather potential for the east, but could also lead to a prolonged period of below average rainfall for some locations into the latter part of the month if this was to verify. So will be watching keenly to see how that plays out. You can see the tropics are very much quiet (not dead) and the Indian Ocean only having influence in the short term on the back of the week long storm event.

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 totals for the east are set to be volatile with each model certainly showing a range of options. More coming up tomorrow morning once we get better upper air data into the modelling overnight and into Tuesday.

I will have the Climate Outlook Update tomorrow and a look at the weather once again from 8am EST. Have a great evening.

0 views0 comments