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>Path: infoac!unido!mcsun!uunet!elroy.jpl.nasa.gov!ames!ucsd!news-mail-gateway
>From: oler@HG.ULeth.CA (CARY OLER)
>Newsgroups: rec.radio.amateur.misc
>Subject: MAJOR GEOMAGNETIC STORM UPDATE - LOW LAT. AURORAL UPDATE - 14 JUNE
>Message-ID: <910613160934.272015cd@HG.ULeth.CA>
>Date: 13 Jun 91 22:09:34 GMT
>Sender: daemon@ucsd.Edu
>Organization: UCSD Usenet Gateway
>Lines: 57


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                            GEOMAGNETIC STORM UPDATE

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                               22:00 UT, 13 June

                                 -------------


STORM UPDATE INFORMATION:

     Major to severe geomagnetic storming has been observed over the past 12
to 18 hours (since approximately 07:00 UT on 13 June).  Storming intensified
after a second sudden magnetic impulse was observed at 06:52 UT on 13 June.
Activity since then has ranged from minor to severe storm levels.
Magnetopause crossings of several geosynchronous satellites was observed
between approximately 18:30 UT and 19:30 UT on 13 June, corresponding to a
major to severe geomagnetic activity period.  A Forbush decrease of between
10 to 15 percent has been observed with this disturbance.

     The A-indices for 13 June are at high-intensity major storm to
low-intensity severe storm levels (near 100).

     Geomagnetic activity is expected to begin subsiding later in the UT day
of 14 June, with a more complete return to generally active levels by 15
June.

     Auroral activity over North America on the evening of 12/13 June was
disappointingly low.  High levels of activity were observed over the
northerly middle and high latitude regions, but equatorward expansion and
luminosity of the auroral activity was insufficient to provide widespread
observations over the lower latitudes.  However, this may change on the
evening of 13/14 June.

     The Low Latitude Auroral Activity Warning remains in effect for the
local evening hours of 13/14 June (for North America, between approximately
04:00 UT and 12:00 UT on 14 June).  If the present disturbance persists long
enough, auroral activity over the lower latitudes may be possible.  This is
expected to be the last evening for a good chance to view auroral activity
over the lower latitudes.  The Low Latitude Auroral Activity Warning is
expected to be downgraded to a Watch (or possibly even cancelled) for 15
June.

     Ionospheric storming has strongly degraded HF radio propagation
conditions over the middle to low latitudes.  High and polar latitudes are
experiencing blackout conditions due to the ionospheric storming, and PCA
activity.  Conditions will gradually improve for the low and middle latitudes
later in the UT day of 14 June and throughout the entire day of 15 June,
while high latitudes will continue to experience fairly strong degraded
conditions.  A return to more normal ionospheric conditions is not
anticipated for the remainder of this week.


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