FARM FOCUS - WHEN WILL WE GET A BREAK IN THE HUMIDITY AND RAINFALL?

Well that is certainly the question on many over the east, not so much for those over central and western parts of the nation, but those who have dodged the high humidity will likely feel the impacts of the humidity this week with a low pressure system rolling through.


The east as mentioned numerous times this morning looking very wet and unsettled with the potential of flash and riverine flooding.


But do we get a break from the humidity and rainfall in the outlook?


The answer is YES, from later this week, a southerly shift in the wake of the low will send up a cooler and drier southerly flow, which will sweep the moisture and rainfall out and likely send temperatures below average for many areas.


Euro 12z - Precipitable Water Anomalies - Next 10 Days

The moisture content over the nation presently is abnormal and leading to the high end rainfall and thunderstorm activity this week. But note by later this week into the weekend, the brown shading, the drier air out of the south in a strong southwesterly flow will bring a pattern shift and a cooler period for the eastern and southern parts of the nation, BUT a drier period for the nation. The drier weather should last 4-5 days for much of the nation before we see the moisture recirculate across the north and west and the humidity and rainfall cycle begins again. Farmers would love to see more brown shadings across the country but that is looking less likely as we get back into the medium term.

GFS 12z - Precipitable Water Anomalies - Next 16 Days

The precipitable water however does return from about this time next week and builds as we go through the period November 18-24 - this is where we will see warmer, more humid weather return. Showers and thunderstorms likely to emerge from the tropics then extending through QLD and NSW with onshore winds feeding a trough over the east. Showers and thunderstorms also likely to emerge from the northwest and north through WA and SA during this period as well. More of what we are experiencing now is likely to impact the same regions for the end of November and December. Finding a dry spell with warmer temperatures is hard at the moment.

Humidity Impacts This Week - November 8-15 2021

The high humidity values are currently in place but will begin to contract north and east through the nation from mid week from west to east. The drier air reaching the southeast by Friday and then the eastern inland during the weekend with the high humidity values remaining over tropical areas as they should until early next week.

Humidity Values Next Week - November 15-22 2021

The humidity should return over northern areas, and begin to shift south from the tropics as a broad easterly flow redevelops, the high pressure over the southern ocean that ridges in from the west this weekend bringing a southwest flow, will move further south and shift the winds into the east. Once that happens, more moisture will be drawn in across the nation via easterly winds over QLD and NSW and then via the northeasterly flow over the tropics. Another surge of moisture should also begin to move south and east from the Indian Ocean with the IOD continuing to influence the moisture content via the jet stream. The IOD is in the process of waning from it's peak last week.

Disease Risk Related to Weather Next 2 Weeks - November 8-22 2021

The risk of all the usual wet weather fungal issues to crops is high for southern QLD, NSW and northern and eastern VIC with a medium risk broadly surrounding this into eastern SA. The high humidity in the short term posing the most serious threat at the moment coupled with the severe weather potential. The humidity will return later in the period bringing a moderate risk of disease risks returning to the eastern inland of the nation.

Harvest Operations Disruption This Week - November 8-15 2021

With the severe weather risks, heavy rainfall, high rainfall and humidity, the daily operations are likely to be retarded and halted through many areas over eastern and southeastern parts of the nation. A small window to dry out with cooler conditions is available this weekend but the weather is expected to be very wet and unsettled this week.

Significant Rainfall Issues - Next 10 Days

A lot of this will come down during the coming 5 days before the rainfall contracts back to the north and then it will return again from later in the period from the northwest of the nation into the southeast as per the above.

FLASH FLOOD RISK THIS WEEK.

Refer to the chart for more details about the movement of severe weather on current guidance from modelling.

THUNDERSTORM OUTLOOK.

Thunderstorm Forecast Tuesday

Scattered to numerous showers and thunderstorms continuing through QLD and the NT, with locally heavy rainfall leading to flash flooding the main concern on Tuesday. Thunderstorms over WA will likely produce heavy rainfall and gusty winds, but marginally severe at this time. They could reach the eastern suburbs of Perth/Darling Scarp later in the day. Heavy rainfall and damaging winds possible over the NT with a deep moisture plume and jet aloft. A few thunderstorms possible along the south coast of NSW with wind convergence east of Canberra.

Thunderstorm Forecast Wednesday

A small low pressure system developing near Tasmania may create more favourable conditions for dangerous thunderstorm activity through southeast QLD and eastern NSW with dangerous flash flooding likely to unfold with the bigger thunderstorms, given the near record PW values. Large to giant hail and destructive winds/isolated tornado activity cannot be ruled out over eastern NSW and southern and southeast QLD. Scattered thunderstorms near a trough and deepening low pressure system over the NT and SA could produce locally heavy rainfall. It is a line ball whether these make it south to the Ag Areas of SA but keep watch of these forecasts. The storms contract out of WA with a drier southerly flow developing in the wake of the low pressure system.

Thunderstorm Forecast Thursday

Scattered to extensive thunderstorm activity likely to develop in the warm sector ahead of a low pressure system through QLD and northeast NSW. Some of the storms likely to produce dangerous conditions with high end flash flood flooding and damaging winds likely to be the main feature though large hail cannot be ruled out. Damaging winds and heavy rainfall leading to flash flooding contracting east through the NT though may continue over much of the Top End. The storm risk contracting east out of SA and through VIC during day as a large rain mass moves through the region with the low pressure system, keeping the surface cool and stable. But where the sun comes out or where it is warmer, severe thunderstorms are likely in advance of this system in the east.

Thunderstorm Forecast Friday

The surge of cooler southerly winds can be see across the country, but ahead of that surge of dry cooler air, showers and thunderstorms will continue, locally severe with dangerous flash flooding possible about parts of the Wide Bay and Capricornia, Central coasts of QLD. Large hail and damaging winds also possible. Damaging winds and heavy rainfall also a risk for the Top End ahead of the dry line. Some chance of marble sized hail over tropical QLD and the NT with robust convection.

The weather eases this weekend and we are likely to see a reduction in the severe weather risks for a period along with the drier and cooler air. But again note the weather does turn warmer then more unsettled into the medium term.

I will have more details on the medium term shortly.