MTEOR 417/517 WEEK 1 SUPPORTING MATERIAL

Heavy Snow Forecasting

• University of WI overview of snow forecasting rules
  • FOUS data for Lab 1

    Remember the helpful rules of thumb, but also note when they might fail

    Answer the questions related to the maps below. Be sure your answers describe the full time period covered by the maps

    Do you see any features on the 500 mb map that would raise concern about a significant winter precipitation event? If so, what and where?

  • 24hr 500 mb Heights
  • 36hr 500 mb Heights
  • 48hr 500 mb Heights

    Do you see any features on the surface map that would raise concern about a significant winter precipitation event? If so, what and where?

  • 24hr MSLP and 1000-500 mb thickness
  • 36hr MSLP and 1000-500 mb thickness
  • 48hr MSLP and 1000-500 mb thickness

    The above maps may have looked pretty tame to you. Look at the 850 maps below with wind and height information. You now should be able to see something that could result in a bad winter storm. Describe it.

  • 24hr 850 mb Heights and wind
  • 36hr 850 mb Heights and wind
  • 48hr 850 mb Heights and wind

    Look at the Eta prediction of precipitation. Describe how it fits with your answers above. If you didn't think this precipitation area would be present before, now offer a reason for it.

  • 24hr Accumulated precip in the last 12 hours
  • 36hr Accumulated precip in the last 12 hours
  • 48hr Accumulated precip in the last 12 hours

    Look back at your surface map. What would the 1000-500 mb thicknesses indicate the form(s) of precipitation to be in your forecast city

    Explain your answer

    Use the 850 mb, 700 mb and surface temperature maps below and the data you have already seen to issue a precipitation forecast (type and amount) for your city over this period.

  • 24hr 850 mb Heights and T
  • 36hr 850 mb Heights and T
  • 48hr 850 mb Heights and T
  • 24hr 700 mb Heights and T
  • 36hr 700 mb Heights and T
  • 48hr 700 mb Heights and T
  • 24hr Sfc T
  • 36hr Sfc T
  • 48hr Sfc T

    Now, look at a different case to determine where heavy snow will fall

  • MSLP (12,24,36,48 hrs)
  • 850mb Heights (12,24,36,48 hrs)
  • 850mb Temperatures (12,24,36,48 hrs)
  • 700mb Heights (12,24,36,48 hrs)
  • 700mb Temperatures (12,24,36,48 hrs)
  • 500mb Heights/Temperatures (24,36 hrs)
  • 200mb Temperatures/Winds (Cook Method - 24hrs)
  • Approximate use of Garcia Method (850 mix ratio, winds - 24 hrs)

    If you are lucky, when the arctic air moves in behind the storm, you may see:

  • Optical phenomena over Ames in December 2000 - partly due to extensive blowing snow in very cold air.