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Jim, you wrote:
"I hear from an astronomer friend of mine that the moon  is lining up around
summer solstice to produce unusually big tides June 22  this year.  Can
anyone shed light on that?"

It's full moon, near  perigee, and the declination of the Moon and Sun are
both high (Sun at 23N, Moon  at 28S). So that adds up to a maximal set of
astronomical factors. The tidal  range at Cape Hatteras will be over four feet on
June 22 compared with a range  of about two feet on June 15 (the preceding neap
tide).

These things  often get exaggerated. The main thing here is perigee spring
tides. But they  occur often. Compared to other dates with perigee spring tides,
the tides on  June 22 will have an additional inch or so of predicted range
at Hatteras (out  of four feet). The natural daily variation from
meteorological factors such as  low barometric pressure is larger than this additional inch
from the  astronomical factors so it's not really an observable difference.
In areas with  diurnal or mixed tides, the difference may be more noticeable.

If you  want to run some comparisons for different dates, I've written a
small tide  calculator web page (I've mentioned it before, I think). It's designed
small so  that it fits onto my cell phone's display. You can calculate the
tides for a set  of locations that happen to interest me personally. If there's
interest I can  add others. You can access it at http://fer1.com. I mention my
calculator  primarily because I can answer questions about how it calculates
things (having  written it and all...). There is also the widely-available
XTide program  (http://www.flaterco.com/xtide/) which makes larger graphs and
accesses a large  set of tidal harmonics. It has the small disadvantage of using
old  pre-calculated tables for the astronomical factors which limits its time
range.

-FER
42.0N 87.7W, or 41.4N  72.1W.
www.HistoricalAtlas.com/lunars

   

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