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Fog & Low Cloud Forecasting - the Victorian Approach

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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Fog & Low Cloud Forecasting - the Victorian Approach

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  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

  2. Part 1 Harvey Stern- Historical BackgroundPart 2 Kevin Parkyn- Bob Jackson’s Fog/Stratus Forecasting ProgramPart 3 Peter Newham- Towards Timing Fog Onset and Clearance Presentations

  3. 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.

  4. 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 afternoon’s pressure gradient, in addition to some temperature and surface moisture data. • Goodhead’s 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.

  5. 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 afternoon’s pressure gradient, in addition to some temperature and surface moisture data. • Keith’s 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Example of WEB Output

  11. 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.

  12. End of Part 1

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