NATIONAL WEATHER PICTURE - PM EDITION - MONDAY 12TH OF JULY 2021

Headlines


  • Heavy rainfall and strong winds, thunderstorms and hail continue to impact large parts of WA with a strong front and moisture infeed moving east.

  • Moisture spreading east during Tuesday with widespread falls developing for the southern states with the eastern inland receiving moderate rainfall Wednesday.

  • A colder shift later this week, to bring another band of rain through southeastern states and snowfalls back to the Alpine areas after a rainy spell.

  • More rainfall developing for WA next week, can that bring follow up for southern areas of the nation next week?

  • Above average temperatures with severe fire dangers over the NT and WA, leading to an early shift to the dry season, responding the the negative IOD.


Satellite Picture - Valid Monday 12th of July 2021.

Quite a dramatic satellite imagery today, zooming out to look at the influences right across the nation. The moisture in feed we spoke about at length last week is now infiltrating the jet stream ahead of a cold front bringing widespread falls to the west and south of WA. That will spread east tomorrow and bring the wet weather east. A weak trough and a little low pressure system moving over southeast Australia triggering scattered showers and a few rumbles through VIC this afternoon. A large high keeping the rest of the nation dry and the weather well behaved.

Clearly the most dramatic weather today through the southwest of the nation with 20-40mm widespread so far from this event and further falls to come. Widespread showers and scattered thunderstorms passing through the southwest around lunchtime with a pool of colder air to continue the unsettled weather over the region tonight and another front to surge through on Tuesday. Widespread light rainfall is extending inland and bringing a cooler shift.

Weak trough passing through the southeast with a small scale low bringing showers and a few thunderstorms to the southwest of VIC and clearing out of southeast SA. Some isolated moderate falls have been observed. The weather set to clear for a period during Tuesday before more cloud increases later ahead of rain areas on Wednesday.

Temperatures - Valid Monday 12th of July 2021

A warm day across the nation for mid July with above average temperatures winning out which was a good pick by GFS last week, I did not side with GFS so it was well forecast. The warmer air filtering into the southeast with a northwest flow, but where the rain is falling and cloud is thicker, you can see the temperatures are lower. But nothing brutally cold on the board this afternoon after a foggy cold start for many locations.

This is a SIGNIFICANT sign of what is happening climatically for the medium to long term. More heat is no necessarily a bad thing, especially if you are looking for more widespread rainfall and weather events coming into August and beyond. Well above average temperatures today over inland areas of the NT and WA with that hot air being drawn south interacting with some moisture and unstable air to produce the rainfall that southern and eastern areas are crying out for (well some are crying out for). I will be talking more about this during the coming days.

Radar - Valid Monday 12th of July 2021

A broader view of where the rainfall is, an a lot is sitting through the inland of WA and offshore with the front passing through. Isolated showers in weak convection over parts of inland NSW and showers are more scattered across the southwest of VIC. And showers have cleared off the east coast in a weak southerly, though a few may come onshore tonight and tomorrow with a weak southeast to easterly.

Clearly the most active weather is in the southwest with the rainfall heading inland, and a small break mid afternoon, but more rainfall sitting offshore signifies the cold unstable air that is expected to drift in from the west tonight with further squalls and hail and thunder. There has been isolated tornado damage down through parts of the far southwest this morning.

Rainfall for the coming 10 days - Valid Monday 12th of July 2021

Rainfall active through the southern parts of the nation with extensive falls expected for the southern states. Moisture profile a little deeper tonight in the modelling so again, may increase those falls in NSW, VIC and SA Tuesday morning if that continues to strengthen. Rainfall expected to ease later this week for WA with another rainfall event next week. Dry weather under the upper high over the north and it is getting hot there.

00Z GFS - Rainfall for the coming 10 days - Valid Monday 12th of July 2021.

Rainfall again largely unchanged for this week coming in tonight's latest data set, however I will point out that there has been a shift to absorb the next wave of moisture into the frontal weather coming over southern waters next week into SA and VIC at the end of the period, which is highly plausible, in association with that next rainfall event over WA early next week.

00Z Euro - Rainfall for the coming 10 days - Valid Monday 12th of July 2021.

Euro maintaining a persistence forecast for the week with no changes anticipated from the flow pattern in the coming 7 days rain wise. Widespread falls for southern WA, SA, VIC, NSW, ACT and TAS The fun part of forecasting this week will be the follow up rainfall that many are eyeing off west of WA, tonight it places that system through the Bight at the end of the run. It is a bit slower than this morning.

00Z CMC - Rainfall for the coming 10 days - Valid Monday 12th of July 2021.

CMC not as aggressive in the rainfall event next week, but ahead of it, some great rainfall prospects for the Ag areas of SA and for VIC too. Southern NSW which missed out last week gets some follow up falls this week as well, with heavy falls in excess of 100mm possible for Alpine areas. Wet weather continues for WA for a number of days, with more rainfall next week.

Model Discussion and Analysis


00Z GFS - Upper level flow pattern at 18000ft with surface pressure pattern to follow with rainfall distribution - Valid Monday 12th of July 2021.


Tuesday 13th of July 2021

Upper trough leave the east coast, upper high moving steadily east towards the eastern inland from SA. A strong long wave trough will be the dominant force on Tuesday with more cold wintry weather in place. Upper high building over the NT will keep temperatures above average for a number of locations.

Tuesday begins dry over much of the east and southeast, maybe some coastal showers for NSW and QLD with offshore thunder. Showers increasing over WA with another front passing through the region. Local hail and thunder to continue for southwest and southern coastline of WA. Warm and windy over SA and VIC with temperatures well above average this afternoon. Fine and hot over the north with light winds out of the east.

Wednesday 14th of July 2021

Rain moves from WA into SA, with the rainfall become more widespread as it meets up again with a cold front through southern SA. Some moderate totals are possible about the YP, KI and the eastern districts including Adelaide. That rainfall makes it into western VIC with moderate falls on and north of the divide. Fine weather for NSW to start with though cloud increasing and much warmer than average ahead of the rain commencing. Showers continue for the southwest of the nation with onshore winds continuing. Fine weather for most elsewhere with a strong high in the east.

Rain moves from SA into inland NSW and through much of VIC with moderate to heavy falls over the northern slopes of the divide in central and eastern VIC. Heavy falls possible about the Alpine areas of NSW. Moderate falls expected from the VIC border through to the QLD border on and west of the divide, with lighter falls on the plains. Dry weather for much of the coastal communities with increasing cloud cover for the east of NSW. Fine weather over QLD with warm temperatures for July. The GFS printing out light rainfall but I am not so sure on that. Fine weather over the north and hot! Showers increasing for southwest WA with another strong cold front passing through with local hail and thunder developing into Thursday morning.

Thursday 15th of July 2021

Deep upper trough and long wave moving from WA into SA with an impressive gradient and zonal flow developing through the middle of the country. This will be where cloud will continue to develop to signify the boundary between the hot air to the north and colder air to the south. Upper high building further over northern Australia sending temperatures well above average. Colder than average temperatures starting to carve out the warmth moving into the south.

An impressive long wave with multiple cold fronts impacting large parts of the nation with strong and gusty westerly winds producing widespread showers and storms for southern areas. The coldest air is still back in WA so there will be rainfall for Alpine areas through this period, with moderate falls continuing. Showers with the chance of a thunderstorm for parts of inland NSW in unstable northwest winds, the most frequent rainfall on and west of the GDR. Fine through QLD, though will keep an eye on that rainfall running the stateline with NSW. Showers and windy over the southwest of WA with local hail and thunder. Fine and hot over the north.

Friday 16th of July 2021

Deep long wave with significant weather, possibly severe weather through southeastern areas, with all modes of wintry weather developing, snowfalls returning for the Alpine areas, but up north the weather still supporting above average temperatures. Some dynamic weather may unfold in the battle zone if moisture gets involved. Thunderstorms could break out through NSW in that set up.

Showery weather through SA, VIC and TAS with moderate falls developing for those areas exposed to a southwesterly airstream. Showers and thunderstorms developing for NSW mainly in southern and central areas with moderate falls on and west of the divide. Fine weather back through the NT and QLD with hot weather continuing under an upper high. Conditions slowly starting to ease for WA with an upper high ridging in and so the showers contracting towards the east.

Saturday 17th of July 2021

An sharp upper low with cold weather moving through the southeast with significant weather quite possible. An upper ridge moving into WA with a stable airmass developing. Strong upper high over the north bringing more above average temperatures, which may play out into the next system over the south and east next week.

Showers, with local hail and thunder over SA, VIC and TAS, extending into southern NSW, with those wintry conditions easing much later in the day now, with the cold air hanging back a bit. Fine weather back over WA with high pressure, extending a stable ridge to the remainder of the nation to kick off the weekend. Hot and sunny over the north.

Sunday 18th of July 2021

Showers and hail over the east clearing during the afternoon, with showers clearing from the coast of SA and southwest VIC later as winds turn northwesterly with high pressure moving into the central parts of the nation. Strong southerly winds and colder air rolling up the NSW coast with high seas developing. Fine weather almost everywhere else, but another front looks to surge rapidly northeast to be in Bight waters later in the day. Moisture offshore WA leading to increasing clouds later. Hot and dry over the north.

Monday 19th of July 2021

Front surges north and begins to cut off in the upper atmosphere leading to broadly unstable cold air drifting north rather than east. So showers increasing over much of the southeast with local thunder possible. Cloud increasing over the west, with a trough and low bringing widespread elevated moisture levels to the region, rain likely to break out later. Above average temperatures are expected to continue for northern Australia with sunny dry weather persisting, though temperatures may come down a touch through northern NSW and southern QLD.

Tuesday 20th of July 2021

Cold pool and upper low moves over eastern Australia, first time we have seen this in the modelling, but showers continuing for the southeast. Of higher confidence is the movement of that rain event over southwest WA with a trough, strong cold front and deep low dragging in moisture from the northwest. Heavy falls are possible along with gusty winds. Otherwise the rest of the nation stable and dry under large high pressure.

Wednesday 21st of July 2021.

The upper level trough and low moves east with high pressure taking control of the east. Large scale rainfall event over WA continues and spreads east, though this run a little slower in bringing the system through a day later than this morning in line with other modelling. So some agreement there on timing. The coverage of rainfall moving more east than south tonight which brings up rainfall chances now for southern parts of the nation.

Thursday 22nd of July 2021.

We will take it out one day further and now the GFS prints rainfall still in the medium term for southern parts of the nation with inland falls to come under this scenario, potentially moderate to heavy falls thanks to a larger thermal gradient in play adding energy to systems coming out of the west. So the heat over the north, not always a bad thing for those looking for rainfall.

Rainfall Outlook - July 19th-26th 2021.

Rainfall continuing above average over the west coast with another major rainfall event, that may creep across to southern and southeastern areas during the outlook period. Dry weather under the upper high but it is dry season over the north and inland parts of QLD.

Temperature Outlook - Valid July 19-26th.

Temperatures expected to be well above average through most of the nation.



That will be a system to keep watching and I will have more on that system later tonight. Otherwise any specific details and forecasting you need - email me at karllijnders@weathermatters.org - for tailored forecasting solutions.

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