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>Path: infoac!unido!mcsun!uunet!elroy.jpl.nasa.gov!sdd.hp.com!uakari.primate.wisc.edu!ames!ucsd!news-mail-gateway
>From: oler@HG.ULeth.CA (CARY OLER)
>Newsgroups: rec.radio.amateur.misc
>Subject: MINOR GEOMAGNETIC STORM ALERT AND INFORMATION UPDATE
>Message-ID: <910609202342.272003c4@HG.ULeth.CA>
>Date: 10 Jun 91 02:23:42 GMT
>Sender: daemon@ucsd.Edu
>Organization: UCSD Usenet Gateway
>Lines: 74


                       /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

                            GEOMAGNETIC STORM ALERT

                       /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

                          Issued:  02:00 UT, 10 June

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


ATTENTION:

     A minor geomagnetic storm has been in progress since 00:40 UT on 09
June.  The activity has been rather weak in nature.

     Another weak interplanetary shock was observed at 16:15 UT on 09 June,
which measured only 15 nanoteslas (nT).  It was followed by a weak increase
in geomagnetic activity.

     An interplanetary shock from yesterdays large X12+/3B flare is expected
to arrive sometime near 12:00 UT on 09 June.  There is uncertainty regarding
the possible impact of this shock.  We believe the ensuing geomagnetic
activity will remain at minor storm levels with possible periods of major
storm level excursions.  Major to severe geomagnetic storming is not
expected, but can't be entirely ruled out due to the uncertainties which
exist.

     The satellite proton event continues in progress.  A gradual decay in
the proton flux began near 17:00 UT on 09 June and is continuing at the
present time.  The proton flux at greater than 10 MeV is currently near 70
pfu.  The satellite proton event is expected to continue for at least the
next 24 hours.  Further major flaring could enhance these levels
significantly.

     The Polar Cap Absorption (PCA) event weakened significantly following
the large shock which occurred early in the UT day on 09 June.  Absorption
levels are also decaying in tandem with reduced proton activity.  The PCA is
technically almost over, although renewed activity can be expected should
another major flare erupt.

     Solar activity has been moderate to high over the past 24 hours.
Several minor M-class flares occurred following yesterdays powerful class
X12+/3B event.  The largest minor flares occurred at 13:19 UT and 20:05 UT on
09 June.  Both of these events were class M1.3 flares.  Another major flare
is expected to occur within the next 24 to 48 hours.  Region 6659 is
extremely complex.  Significant shearing is taking place in this region,
which now spans an area well over 6,000 million square kilometers.  A strong
delta configuration continues in this region.

     The Low Latitude Auroral Activity Warning will remain in effect for
another 24 hours.  If an interplanetary shock fails to arrive from the large
X12+/3B flare of 09 June, the Warning will be downgraded to a Watch.  This
continues to be a high-risk period.

     HF propagation conditions will continue to remain only fair to good
throughout the next 24 hours.  Some improvements in polar propagation has
been observed recently, although conditions are still well below normal
there.  Full ionospheric recovery is not expected until later this week at
the earliest (barring further major flaring).  Degradation can be expected on
10 and possibly 11 June.  Some recovery should occur later in the UT day of
11 June and 12 June.  Further strong solar flare activity could continue to
produce occasional major shortwave blackouts and strong SIDs.

     There will be a chance for VHF auroral backscatter on 10 June and the
early part of 11 June.  This is dependent on how strong the terrestrial
impact is from the major flare of 09 June.  There is uncertainty regarding
how strong the impact might be.  At the present time, we continue to believe
the impact will be moderate, although probably won't be sufficient to produce
widespread backscatter opportunities.


**  End of Alert  **
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