How Inversions Impact High Temperatures

Forecasting high temperatures can sometimes be a little tricky, especially when a warm up is expected after a freshly fallen snow.

For most, highs Monday reached the upper 30's.  This was warmer than what I had thought we would be.  But hey, at least it didn't end up cooler.

A new coating of snow can have an effect on high temperatures during the day, but also low temperatures at night.  Even with sun, afternoon highs will be cooler than surrounding locations with little to no snow.  The reason?  It's a term called: Albedo.  Snow has a high albedo.  This means that most of the shortwave radiation that is produced by the sun and used to warm the surface of the earth is reflected back to space.  Whereas a ground that doesn't have much snow, dirty snow or is bare is able to absorb that radiation.

Temperatures Monday afternoon were cooler than surrounding locations.  Just look at the highs for today.

Strong temperature inversions can also hinder how warm afternoon highs reach.  This happens when warmer air moves in a few thousand feet above the surface of the earth.  Meanwhile, temperatures at the surface don't warm quite as fast.  A perfect example of that happening: snow on the ground and winds within the jet stream shifting around to the southwest.  Similar to what is going to happen the next couple of days.

Noon Tuesday

Look at the image to the left.  This is a model forecast sounding for Tuesday afternoon - Noon.  The red line represents the temperature in the atmosphere while the green line represents the dew point temperature.  What I want you to notice is how the red line begins to shift to the right, or represents a warming temperature with height.  That's a weak temperature inversion.  What's interesting is that this inversion strengthens just a little by 3pm Tuesday (second image to the left).  This would imply that temperatures above the surface are warming, but at the surface they might not be warming as fast.  It doesn't look overly strong, so because of that I'm going to keep my forecast of highs warming into the

3pm Tuesday

middle and upper 30's.  If, however, this inversion does develop and doesn't mix out during the afternoon high temperatures will be lower for Tuesday.