Saturday, November 19, 2011

Eerie Similarity In LRC Feature Occurring on October 19th

There is a very eerie similarity we have discovered in today's new 0z GFS. We have been closely following a pattern called the LRC (Lezak Recurring Cycle). Here's the gist of it:

-Observation period between October 1-November 10.
-Look for features present in weather over period.
-After November 10, look for repetition in weather from observation period to present time.
-Pattern different every year.
-Pattern repeats on 40-60 day cycle through winter, into spring.

This year, a dominant feature was a strong trough of low pressure in the Ohio Valley. See the below example from October 19th.
We see a strong low pressure system in the Midwest into Ohio Valley. A ridge was present in the west, holding up the jet stream in that area. Now see the forecast from the freshly-printed 0z GFS for the final days of November.
Look at just how similar this is: A strong low pressure system sets up in almost the exact same place as October 19th. A high pressure system sets up in the west US. The only difference is a low pressure system present just offshore the West Coast. However, we prefer to focus on the presence of a trough in the Midwest.

Now, according to LRC 'guidelines', the pattern typically does not appear this soon after it happens. If this was to verify, the cycle would happen every 39 days. That would be an extremely short cycle. However, seeing as how this is a very similar forecast to what happened on the 19th, it is possible that this LRC will turn out that way. Let's not get ahead of ourselves- this forecast is for November 27th.
It is definitely something to watch, though.

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