Theta and Theta e for Estimating Areas of Maximum Thermal Lift

Equivalent Potential Temperature (Theta e) and its abbreviated counterpart, potential temperature (theta), are important parameters that determines relative buoyancy of airmasses. Identifying where maximum surface theta e is often correlates with areas of strongest convective lift. If there is good capping aloft but good lapse rates and dewpoints are not too high these parameters that helps identify where zones of good thermal lift can be found. Here is a good description of Theta e and theta from meteorologist Jeff Habby

and more on Potential temperature:

Theta is temperature simply adjusting for pressure altitude, discounting the adjustment for water vapor. From a practical standpoint, theta can be used in place of theta e for estimating thermal heights for general soaring conditions atmospheres that are capped and not inclined to overdevelopment. Until LcL or CcL is reached and the latent heat is released, the influence of atmospheric moisture on density/buoyancy is small. Estimates of surface theta can be easily made from surface reporting stations where the elevation is known.  Here are two useful sites for obtaining these data:
http://forecast.weather.gov/MapClick.php?lat=36.88181755936464&lon=-121.40853881835937&site=mtr&unit=0&lg=en&FcstType=text

http://www.wrh.noaa.gov/mesowest/frame.php?map=mtr&limit=1
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With the paradigm shift occurring with interactive forecast tools on the Internet, it is possible to get broad based estimates of where maximum surface theta is both forecast and reported along with forecast or current surface dewpoints.  These data can then be used in conjunction with forecast soundings from NOAA FSL to determine thermal heights and cloudbase.  Here is a link to the site with a sample location near Hollistere, CA: http://rucsoundings.noaa.gov/plot_soundings.cgi?data_source=Op40;latest=latest;n_hrs=8;airport=36.881818,-121.401672;plot=Java-based%20plots&start=latest

The interactive soundings allow for determination of boundary layer (BL) tops quickly with simple inputs of the temperature and dewpoint.  The value of using estimates of potential temperature is that by adjusting for elevation/altitude, the  BL tops can rapidly by assessed simply by observing where the sounding at a particular location intersects the isentrope lines (lines of equal theta) on the SkewT.  In addition, once the theta is estimated, one does not need to click on the specific height and .

.temperature to obtain the BL mixing profile, but anywhere on the estimated potential temperature line.

Finding a sounding location:
Kurt Thames created an interactive Googl;e Map that links ot the FSL Forecast sounding for a selected location by clicking the the location.  This map allows close correllation with the NWS interactive Google Maps for both forecast and current temperature. http://thams.com/flying/skewTmap.html

Sources of Theta on FSL Soundings and how to use: < to be created>