850 mb Temperature Advection
an indicator of surface changes to come

Warm advection at 850 mb is often indicative of rising temperatures at the surface, while cold advection at this level often precedes falling temperatures. Regions of strongest temperature advection are found where geopotential height contours (blue) and isotherms (red) are nearly perpendicular to each other. For example, on the following 850 mb surface, the strongest cold advection is occurring from Montana to New Mexico, while the strongest warm advection is occurring from eastern Texas into Illinois.

The influence of thermal advection at 850mb is typically felt at the surface about a day later (map below).

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Credits and Acknowledgments for WW2010.
Department of Atmospheric Sciences (DAS) at
the University of Illinois at Urbana-Champaign.