Fog

1
Fog Low Cloud Forecasting- the Victorian
Approach

• Harvey Stern, Kevin Parkyn, Peter Newham
• Victorian Regional Office

Aviation Weather Services Workshop Thursday 23
May, 4.15pm-5.00pm
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Part 1 Harvey Stern- Historical
BackgroundPart 2 Kevin Parkyn- Bob
Jacksons Fog/Stratus Forecasting ProgramPart 3
Peter Newham- Towards Timing Fog
Onset and Clearance
Presentations
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Outline of Part 1

• Early work in fog and low cloud forecasting
• (concentrating on Melbourne Airport).
• More recent developments using synoptic
  climatologies.
• The current operational WEB-based technique.
• A recommendation.

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Background- Fog Forecasting

• In 1978, Harry Goodhead developed an objective
  aid to the forecasting of fog onset at Melbourne
  Airport.
• Development of the aid followed a synoptic
  approach.
• Inputs were the previous afternoons pressure
  gradient, in addition to some temperature and
  surface moisture data.
• Goodheads aid became Victorian forecasters
  primary tool in their endeavours to predict fog
  at Melbourne Airport.

Goodhead H M (1978) An objective method for
predicting fog and mist at Melbourne Airport.
Airmet Conference Papers, Canberra Meteorological
Society Royal Meteorological Society (Australian
Branch) Canberra, 1978, pp 27-38.
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Background- Low Cloud Forecasting

• Also in 1978, Ross Keith developed an objective
  aid to the forecasting of low cloud onset at
  Melbourne Airport.
• Development of the aid followed a synoptic
  approach.
• Inputs were the previous afternoons pressure
  gradient, in addition to some temperature and
  surface moisture data.
• Keiths aid became Victorian forecasters primary
  tool in their endeavours to predict low cloud at
  Melbourne Airport.

Keith R (1978) Formation of low cloud at
Melbourne Airport in a lee trough. Airmet
Conference Papers, Canberra Meteorological
Society Royal Meteorological Society (Australian
Branch) Canberra, 1978, pp 39-44.
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Background- Synoptic Classification

• In 1993, Andrew Treloar Harvey Stern developed
  a classification of synoptic situations over SE
  Australia.
• The classification was based upon the direction,
  strength and cyclonicity of the surface flow.
• The work enabled a synoptic classification of
  Victorian severe thunderstorms to be established.

Treloar ABA and Stern H (1993) A climatology and
synoptic classification of Victorian severe
thunderstorms. Fourth International Conference on
Southern Hemisphere Meteorology and Oceanography,
March 29 to April 2, 1993, Hobart, Australia,
American Meteorological Society.
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More Recent Developments- Fog

• In 1998, Harvey Stern Kevin Parkyn carried out
  a synoptic classification of fog situations at
  Melbourne Airport.
• The fog classification utilised the Treloar
  Stern synoptic types.
• This classification was followed by the
  development of an aid to the assessment of fog
  risk (probability of occurrence).
• Development of the aid utilised a regression
  approach, stratifying the data according to the
  synoptic classification.

Stern H and Parkyn K (1998) Synoptic climatology
of fog at Melbourne Airport. Abstracts, ANZ
Climate Forum, Perth, 1998. Stern H and Parkyn K
(1999) Predicting the likelihood of fog at
Melbourne Airport. 8th Conference on aviation,
range and aerospace meteorology, Amer. Meteor.
Soc., Dallas, Texas, 10-15 Jan., 1999.
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Recent Developments- Low Cloud

• Stern and Parkyn then developed an aid to the
  assessment of low cloud risk (probability of
  occurrence) at Melbourne Airport.
• Development of the low cloud aid also utilised a
  regression approach, stratifying the data
  synoptically.

Stern H and Parkyn K (2000) Low cloud at
Melbourne Airport A synoptic climatology leading
to a forecasting technique. AMOS Annual
Conference, Melbourne, 2000.
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Recent Developments- the WEB

• The fog and low cloud forecasting aids were then
  combined into a WEB-based technique, utilising
  JavaScript.
• The WEB-based nature of the technique, renders it
  accessible to people who wish to explore its mode
  of operation.
• In applying the technique, the user inserts MSL
  pressure data, the, and today's 3pm dewpoint and
  temperature.
• The aid returns the probability of fog and low
  cloud, and various synoptic information.

Stern H and Parkyn K (2001) A web-based Melbourne
Airport fog and low cloud forecasting technique.
2nd Conference on Fog and Fog Collection, St
John's, New Foundland, Canada 15-20 Jul.,2001.
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Example of WEB Output
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Concluding Remarks Recommendation

• Computerised half-hourly hourly METAR data is
  generally only available for recent years.
• Development of fog low cloud forecasting
  techniques has been greatly restricted by this
  deficiency of computerised historical data.
• It is therefore recommended that funds be set
  aside for a major effort to computerise
  historical half-hourly hourly METAR data.

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End of Part 1