EAS 270: What You Should be able to Deduce from Weather Maps (by the end of term!)

• Surface Analysis
  • From station report/symbols (Appendix C of Aguado & Burt) decode
    • temperature T and dewpoint temperature T_d
    • fraction of sky covered (recognize qualitative degree of cover: none, less than half, half, almost overcast, overcast)
    • the most common and significant present weather symbols (intermittent drizzle, rain, snow; continuous drizzle, rain, snow)
    • wind direction & speed
    • local sea-level-corrected pressure
    • 3 hour pressure tendency
  • approximate estimate of direction of motion of surface system (inferred from pressure trends)
  • determine dominant system (if any) for local weather
  • judge whether local weather is static ("no weather") or in state of development
• 850 mb Analysis
  • from station report
    • height of the 850 mb surface
    • wind direction and speed aloft
    • T, T-T_d
  • identify whether there is substantial spatial variation of T... which potentially could imply rapid temperature changes if the winds were to develop
  • are there regions where isotherms are packed so tightly that we might speak of a ``front''?
  • identify regions of strong positive (warm) or negative (cold) temperature advection
• 750 mb Analysis
  • decode station report
  • identify regions of strong positive (warm) or negative (cold) temperature advection
  • identify regions of high humidity and/or strong humidity advection
• 500 mb Analysis
  • from station report
    • height of the 500 mb surface
    • wind direction and speed aloft
    • T, T-T_d
  • identify whether there is substantial spatial variation of 1000-500 thickness.
  • identify regions of strong positive (warm) or negative (cold) thickness advection
  • positions of ridges and troughs affecting local weather
  • distinguish long waves and short waves
• Satellite Photographs
  • identify higher (colder) and lower (warmer) clouds, and cloud-free regions
  • relate cloud patterns to maps
• Thermodynamic chart (skew T - log P diagram)
  • be able to plot T and T_d versus p; be able to read off T, T_d at any given p
  • diagnose proximity to saturation of any layer
  • identify the families of lines on the diagram - lines of constant pressure (isobars), isotherms, dry and moist adiabats
  • diagnose the stability of any specified layer
  • recognise inversion layers
  • recognise well-mixed layers
• From the ensemble of maps
  • what is/are the dominant systems as far as Alberta's weather is concerned
  • what are the probable short term trends, given what you estimate to be the likely nature of the diurnal cycle and the existing synoptic patterns?

Last Modified: 6 Oct. 2006