Potential for northeast flow blocked by terrain - Albany forecast soundings

Notes:

The data on these slides show model forecast soundings at Albany from 18z through 06z. At 18z, the Froude number is 1.4 indicating that some blocking could be possible. However, note that the flow is from the northeast at the elevation of the Catskills. With northeast flow, the Catskills would be upstream from northeast Pennsylvania, but not central New York. Note also that northeast flow would be parallel to the ridges in northeast Pennsylvania, which could be favorable for channeling of winds in the valleys of northeast Pa, as opposed to blocking by the terrain. By 00z, the model forecast Froude number was up to 2.2, which was in excellent agreement with the observed sounding, and is somewhat high for blocked flow. Finally, by 06z, the flow is east-southeast, however the Froude number is up to 4.3 in the destabilized air mass, which is generally considered to be too high for blocking.

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[1800 UTC 29-Oct-2012]  [0000 UTC 30-Oct-2012]  [0600 UTC 30-Oct-2012] 
slide 37


Slide 37