std_oler@HG.ULeth.CA (Cary Oler) (02/08/91)
-- MAJOR SOLAR FLARE ALERT --
FEBRUARY 07, 1991
Flare Event Summary
Potential Impact Forecast
--------
MAJOR ENERGETIC EVENT SUMMARY
Two major flares erupted off the sun today. The first, rated a class
M8.8/1F flare was spawned by departing Region 6471 (which has now rotated
beyond view around the west limb). The flare began at 14:54 UT, peaked in
intensity at 15:14 UT and ended at 15:40 UT on 07 February. The location
of this flare was S10W86 and was associated with minor radio emissions.
No sweeps were observed from this flare.
The second major energetic event began at 21:18 UT, peaked in intensity
at 21:23 UT reaching an x-ray level of M5.3 and ended at 22:46 UT. This
flare was optically uncorrelated but is strongly suspected of being
associated with departed Region 6471. Some significant radio emissions
were observed from this flare, although no sweeps were detected. Radio
emissions at 245 MHz reached 38,000 sfu. This flare was associated with
a 1,900 sfu Tenflare at 21:20 UT, lasting 7 minutes.
A third M-class event almost made the major-flare category today. At
17:12 UT, a class M4.9 x-ray flare (again, optically uncorrelated) was
observed. However, unlike the second major flare, this event was not
associated with any significant radio emissions or sweep frequency events.
The effects from M-class flaring (and possible major flaring) may remain
noticable for about the next 12 to 24 hours as Region 6471 continues to move
beyond influential range. The effects of flaring behind the western limb will
become unnoticable on 09 February.
Other regions now worth noting are Regions 6480 (S10W15), 6484 (N14E25),
and 6487 (N15E40). Region 6487 is perhaps the most newsworthy region
currently visible. It has exploded in growth over the past 24 hours and has
managed to spawn two low-level class M1 flares. This region is also the
largest presently visible, now covering an area of 2,040 million square
kilometers encompassing 22 spots within its boundaries. This region is
presently holds a magnetic Beta configuration and is not regarded as
a potential major flare producer yet. The optical configuration of this
region is a type DKO group and has an angular extent of 8 degrees.
The potential major flare warning remains in effect for 08 February.
It will probably be cancelled on 09 February, unless the regions currently
visible begin to exhibit potential major activity.
The stratospheric warming alert remains in effect. Stratospheric
warming is continuing over Siberia and is spreading polewards in the lower
and middle stratosphere. The temperature gradient has reversed between
60 degrees north latitude and the pole. In addition, a weak mean zonal
wind near 60 degrees north latitude is persisting. We are now into
day 36 of this major stratospheric warming event.
POTENTIAL TERRESTRIAL IMPACT PREDICTIONS
Although flare activity was high today, none of the energetic events
will have a terrestrial impact.
A large polar coronal hole extension exists throughout much of the
northern solar hemisphere. At the present time, the furthest southward
extension of this hole occurs at N28W69, which appears to be the westernmost
edge of the extension. No significant structural changes have been observed.
However, grazing effects are possible. Geomagnetic activity is expected to
increase to mostly Unsettled levels over the next two to four days. Auroral
activity over high latitudes is likewise expected to increase. No significant
auroral activity is expected over middle latitudes, although the notherly
middle latitudes should witness the low to moderate auroral activity
occurring over the high latitude zones. No geomagnetic or auroral storming
is expected.
** End of Alert **