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>Path: infoac!unido!mcsun!uunet!zaphod.mps.ohio-state.edu!usc!ucsd!news-mail-gateway
>From: oler@HG.ULeth.CA (CARY OLER)
>Newsgroups: rec.radio.amateur.misc
>Subject: POTENTIAL MAJOR TO SEVERE GEOMAGNETIC STORM WARNING
>Message-ID: <910611120818.27200bab@HG.ULeth.CA>
>Date: 11 Jun 91 18:08:18 GMT
>Sender: daemon@ucsd.Edu
>Organization: ucsd usenet gateway
>Lines: 83


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                  POTENTIAL SEVERE GEOMAGNETIC STORM WARNING

                               18:00 UT, 11 JUNE

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WARNINGS ISSUED OR IN PROGRESS:

  - POTENTIAL MAJOR TO SEVERE GEOMAGNETIC STORM WARNING
  - POTENTIAL MAJOR SOLAR FLARE WARNING (PROTON)
  - SATELLITE PROTON AND PCA ACTIVITY ALERT
  - POTENTIAL MAJOR GIC ANOMALY WARNING


ATTENTION:

     The major class x12+/3B tenflare which occurred on 11 June is expected
to have a major to severe terrestrial impact.  Already, significant protons
have arrived.  The greater than 10 MeV proton levels gradually increased to a
peak of 4,400 pfu at 14:25 UT on 11 June.  The greater than 100 MeV protons
increased to a peak of 66 pfu at 12:45 UT on 11 June.  Protons at these
energy levels have been decaying since that time.  Another increase in
protons should accompany the flare shock.  A significant increase in greater
than 1 MeV protons should also be witnessed concurrent with the shock
arrival.

     At the present time, geomagnetic activity has subsided.  The last
disturbance appears to be waning.  Significant increases in activity should
therefore accompany the approaching flare shock.

     The shock from this major event is in transit at the present time and is
expected to arrive here at the Earth anytime near or after 06:00 UT on 12
June.  Conditions thereafter will deteriorate very rapidly.

     Geomagnetic activity is expected to reach at least major storm levels
with a very real possibility for severe storming (A-indices > 100).  Very
intense geomagnetic activity should occur later in the UT day on 12 June and
throughout most of the UT day on 13 June.  Conditions should begin to recover
on 14 June, although recovery will be long and slow.

     Significant HF degradation is expected.  There is a risk for widespread
HF blackouts when the main phase of this storm begins.  Severe levels of
fading, distortion and absorption can be expected to accompany this storm
event.  Conditions should begin to improve on 14 June, although a full
recovery will take quite a few additional quiet days.  The ionosphere will be
very stressed during this period and will not be in good shape for
communications.

     A very high probabiliby (> 80%) exists for widespread VHF backscatter
communications later in the UT day of 12 June and on 13 June.  Conditions
should be very favorable for backscatter from the low and middle latitudes on
these dates.  High latitudes will also have significant opportunities for VHF
backscatter, although the geometry required for backscatter will become
increasingly unfavorable as geomagnetic activity approaches or surpasses
severe storm levels.

     Extensive and widespread low-latitude auroral activity should become
visible late in the UT day of 12 June and throughout most of the UT day of 13
June.  If the impact from this flare event is as large as predicted, auroral
storming may be observed as far south or perhaps even further south than
Florida.  Continent-wide sightings may also be possible over Australia and
New Zealand.

     This is a significant storm warning.  There is a risk that this storm
event could be the largest since 1989, and may in fact become the largest
event so far this solar cycle.


PLEASE SEND ANY REPORTS OF DEGRADED RADIO PROPAGATION CONDITIONS, SIGHTINGS
OF AURORAL ACTIVITY, VHF BACKSCATTER COMMUNICATIONS OR OTHER ANOMALIES TO:
OLER@HG.ULETH.CA (INTERNET), OLER@ALPHA.ULETH.CA (USENET), OR (SNAIL-MAIL)
TO: SOLAR TERRESTRIAL DISPATCH, P.O. BOX 357, STIRLING, ALBERTA, CANADA,
T0K 2E0.  PLEASE INCLUDE THE DATE AND TIME (LOCAL AND UT) OF THE OBSERVATION,
THE APPROXIMATE LATITUDE/LONGITUDE OF THE OBSERVATION LOCATION, AND A BRIEF
DESCRIPTION OF THE PHENOMENA OBSERVED.  WE THANK ALL THOSE WHO TAKE THE TIME
TO SEND IN OBSERVATIONAL REPORTS.


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