I'm sure it's a bit selective memory on my part, but in NW it's very
common in the winter months to have altimeter setting swing from 2950
to 3050 in a day or two, and when the next storm comes in a week, the
cycle happens all over again. I'm pretty sure that you can find such
highs and lows in Northeast if you really look into the yearly records.
However the "normal" cycle from low to high is less dramatic.


Icebound wrote:
"M" wrote in message
ups.com...

Anyone knows why the barometric pressure has a much larger swing in
Pacific Northwest (Seattle) than in New Jersey area? I remember
back
in the days when I was flying in NYC area a low pressure day would
have
an altermeter setting of something like 2980, and a high pressue
day
would be something like 3006. .....

I think there is a little bit of selective memory going on, here.

Without trying too hard, I picked up the weekly data archive from
NCDC for
JFK for the first week of January, 2005, and it showed a pressure of
1025mb,
which corresponds to an altimeter setting of about 30.25, a far cry
from the
30.06 that you specified as a "high" pressure day.

I am betting that if someone cares to spend the time to analyse the
NCDC
files

( ftp://ftp.ncdc.noaa.gov/pub/data/globalsod/2005/ )

...for JFK, for example.... then even higher pressures will be found,
and
that the pressure variation is not likely to be all that different
from the
SeaTac regime.

On the "low" side, it is possible that Pacific winter storms
contribute to a
lower-than-normal pressure regime in the Northwest, but it would take
some
analyses of the data to convince me. The Northeast gets some pretty
decent
low-pressure-systems, too.



Here in Seattle the altimeter setting
can go from 2940 to 3050 in about two days when a strong system
passes.


29.40 is approximately 995 mb. That is not a really deep low. I
know the
northeast occasionally sees lows below 990, even below 980mb (which
would
be 28.90) On the high side, 30.50 is about 1032 millibars, not
particularly
excessive.


Is it because of the higher latitude (48 north in Seattle vs. 40
north
in Jersey) or is it because the storms in northeastern Pacific
being a
lot more severe? Temperature wise Seattle is very mild compared
with
the northeast.


Latitude does have a part to play in that, if a serious non-tropical
low
pressure system is moving in some west-to-east path.... and then
starts to
deepen significantly.... its track will almost always curve further
to the
north.... Hence the more northern areas, such as the Gulf of Alaska,
Hudson's Bay, and the Labrador Coast, are often the areas of the
lowest,
lowest pressures. At the same time, the northern continental
interiors...
the Canadian Prairies, US Midwest.... will be the scenes of the
highest,
highest pressures when they get outbursts of the really cold air from
the
Arctic in winter.

It could well be that Seattle's storm-track climate provides for more
rapid
variability of pressure day-to-day...if so it would be because more
low-pressure-systems are passing by... There are climate studies
available
for individual states... some of which are available on the web...and
it
would take somebody some poring over those studies, or over the raw
NCDC
numbers, to convince me one way or the other.