Forecasting Tips: High

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Forecasting Tips High Low Temperatures

• Metr2413
• March 12, 2004

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Low Temperatures (not always overnight lows)

• Dependant mostly on radiational cooling really a
  balance of many factors
• Cloud cover insulation vs. radiational cooling
• Moisture Dew point can act as a lower boundary
• Topography upsloping/downsloping winds
• Low level winds vertical mixing
• Location climate proximity to bodies of water

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Low Temps - Cloud Cover
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Low Temps - Moisture
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Busted
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Low Temps - Topography
Steep topographic changes can influence adiabatic
compression (downsloping warming) or adiabatic
expansion (upsloping cooling)
warming
cooling
Also affected are valleys and ridges cooler air
(higher density) due to radiational cooling at
the surface can converge at the base of the
valley basecooler, ridgewarmer
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Pueblo, CO
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Low Temps - Mixing

• Sustained overnight winds create turbulent mixing
  allowing the boundary layer to maintain a
  well-mixed profile and suppressing some
  radiational cooling
• Overnight look for low level jet (common in the
  Southern Plains)
• Daytime look for strong radiational heating with
  a capped boundary layer

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High Temperatures (not always during the daytime)

• Also a balance of many factors
• Cloud cover insulation vs. radiational heating
• Moisture Surface energy budget effects
• Topography upsloping/downsloping winds
• Low level winds vertical mixing
• Location climate proximity to bodies of water

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All about balance

• If you notice that your forecast area will likely
  experience upslope winds overnight (cooling), but
  also will have cloud cover (insulation), the two
  processes may balance each other.
• If you notice that your forecast area has a high
  dewpoint, but also a high about of clearing
  overnight, the radiational cooling may be slowed
  due to condensation (fog).
• Again, watch out for EOP/BOP highs and lows

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Lab Assignment 9 (optional 10pts)

• If you are participating in the LFC
• Summarize your high and low temperature forecasts
  for Oklahoma City (KOKC)
• 1) Why was your reasoning behind your high/low
  temperature forecasts?
• 2) How correct were your numbers? If they were
  spot-on, explain why. If they were off, explain
  why, and dont spare the details. In this
  assignment, details win points!
• If you are not in the LFC
• Over the break, pick two consecutive days and
  make a high/low temperature forecast for KOKC.
• Verify and summarize your forecasts as described
  above.
• Once again, this assignment is optional, and is
  due on Friday, March 26.