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UKMET

A medium-range numerical weather prediction model operated by the United Kingdom METeorological Agency.

Ultraviolet radiation

Electromagnetic radiation with wavelengths shorter than visible light, but longer than x-rays. Exposure to too much UV radiation can cause skin cancer.

Unsettled

Changeable or variable weather.

Unstable air

Air in which static instability exists. This condition is determined by the vertical gradients of air temperature and humidity.

Updraft

A small-scale current of rising air. If the air is sufficiently moist, then the moisture condenses to become a cumulus cloud or an individual tower of a towering cumulus or Cb.

Updraft base

Alternate term for a rain free base.

Upper level

The portion of the atmosphere above the lower troposphere. It is generally applied to levels above 850 hPa.

Upper level system

A general term for any large-scale or mesoscale disturbance capable of producing upward motion (lift) in the middle or upper parts of the atmosphere. This term is sometimes used interchangeably with impulse or shortwave.

Upslope flow

Air that flows toward higher terrain, and hence is forced to rise. The added lift often results in widespread low cloudiness and stratiform precipitation if the air is stable, or an increased chance of thunderstorm development if the air is unstable.

Upslope fog

Fog that forms when warm moist air is forced up a slope by wind.

Upstream

Toward the source of the flow, or located in the area from which the flow is coming.

Upwelling

The rise of colder, deep ocean waters along a coast due to the movement of surface water away from the coast.

UTC

Abbreviation for Universal Time Coordinate. See also Zulu, GMT.

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Weather News

Farm Management Deposits changes will give farmers chance to help themselves, once they have cash to spare

16:23 EDT

The Federal Government has introduced legislation to overhaul the Farm Management Deposits scheme, which it says will help farmers to help themselves.

Perth weather: Temperature hits 40C for fourth day, equalling record from 1933

15:57 EDT

Perth has recorded its fourth consecutive day of temperatures above 40 degrees Celsius, equalling a record that has stood for more than 80 years, as a heatwave continues to grip the city.

Hobart set to cool after a warm start to February

14:50 EDT

The first ten days of February have set a new record for Hobart with each day breaking the 21 degree mark, although a series of fronts on the forecast will bring a cooler change.