Aviation Climatology

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Aviation Climatology
Andrew Rorke WFO LOX Los Angeles / Oxnard
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What Is Aviation Climatology

• A database of observations for a given TAF site
• The database contains Ceiling, Visibility, Wind
  Speed and Wind Direction data for every day and
  hour for (hopefully) the past 30 years.

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What Good Is Aviation Climatology?

• Given a fairly normal climatological day,
  climatology is probably the best forecast tool
  for ceiling and visibility changes.
• For any given ceiling and visibility aviation
  climatology will produce a cig/vis forecast for
  the next 1 to 6 hours.

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Drawbacks of Aviation Climatology

• The day has to fairly normal.
• There has to be low ceiling (040 AGL or less) or
  a low visibility (5SM or less)
• It does not predict good flying weather turning
  to bad flying weather
• It does, however, predict, bad weather getting
  worse

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Aviation Climatology in the NWS

• Consists of two programs
• Ceiling and Visibility Distribution
• Determines how normal the day is
• Ceiling and Visibility Trend
• Forecasts changes in Cig and Vis based on current
  conditions and climatology

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Ceiling and Visibility Distribution
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Ceiling and Visibility Distribution
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Ceiling and Visibility Distribution Visibility
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Ceiling and Visibility Distribution Joint Ceiling
and Visibility
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Ceiling and Visibility Trend
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Ceiling and Visibility Trend
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Ceiling and Visibility Trend

• Pick The TAF Site
• Pick the Element
• Visibility only
• Ceiling only
• Joint (combined to flight cat)
• Chose the number of hours ahead to forecast

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Ceiling and Visibility Trend

• Chose a range of dates to pull data from
• Smaller range might be more accurate, but might
  not sample low frequency events
• Defaults to /- 30 days from current

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Ceiling and Visibility Trend

• Choose your start hour for initial conditions
• Default may be too much try to use 1 or 2 hours

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Ceiling and Visibility Trend

• Enter the wind information
• Again a smaller range will be more accurate
  provided there is enough data to sample

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Ceiling and Visibility Trend

• Enter the Ceiling and Visibility information
• Unlike this example try not to cross flight
  categories

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Ceiling and Visibility TrendThere Must Be An
Easier Way!
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Ceiling and Visibility Trend
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Ceiling and Visibility Trend Results
Vis Only VFR is inferred Count refers to
total data points
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Ceiling and Visibility Trend Results
Cig Only VFR is inferred Count refers to
total data points
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Ceiling and Visibility Trend Results
Both Cig and Vis VFR is inferred Count refers
to total data points Note that the data points go
down
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Ceiling and Visibility TrendSummery

• A great forecast tool when properly used.
• Best for predicting burn off or changes to a
  pre-existing ceiling or fog obscuration
• Works best during normal conditions

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Aviation Climatology In The Southwest

• Ceiling based Aviation Climatology is not ideally
  suited for the Southwest
• The vast majority of Ceiling and Visibility
  restrictions occur on the coast
• Aviation Climatology gives very little
  information on arrival times of lower flying
  conditions
• Aviation Climatology does not make wind
  predictions (important to many SW airports)

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KLAX Los Angeles International

• Concerns
• Ceiling Visibility Arrivals
• Ceiling Visibility Changes
• Ceiling Visibility Improvement
• Sea Breeze Front
• East Winds
• Traditional Climatology only helps with 2 of the
  five problem areas

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Need To Look For Something New
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Pressure Gradient Aviation Climatology

• Stratifying the observational data base using
  pressure gradients.
• Would generate wind forecasts
• Would give information on ceiling and visibility
  arrivals
• Initially it might provide information on not
  events, but hopefully when combined with other
  information will be able to provide arrival
  forecasts.(KPRB combined with KSNS ceiling info)

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Pressure Gradient Aviation Climatology

• Which Gradient Values to use?
• Must be chosen for each TAF site
• Look At
• The Current Gradient
• The 24 hour Change
• The 12 hour Change (how different is it from the
  normal diurnal change)
• The 3 hour change

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Pressure Gradient Aviation Climatology

• Calculate these gradients and trends and link
  them to their corresponding observational values
• Use a database program such as Filemaker Pro
• Use the database to search and sift the data
• Use the databases GUI creation capabilities to
  design a front end for the aviation desk

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Pressure Gradient Aviation Climatology

• KLAX

• KPRB

• Use LAX-DAG and LAX-BFL
• Good with not forecast of sea breeze front
• Good with east wind forecast with rain
• So-so results with summertime east winds

• Use SNS-PRB and SFO-SBA
• By itself good with no cig forecast
• Needs to be linked with current conditions at
  KSNS for better arrival time forecast

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Questions?

• Andrew Rorke
• andrew.rorke_at_noaa.gov