[HCDX] Major Storm Alert

[Tomas Hood - NW7US <nw7us@xxxxxxxxxxx>]

Folks, we are in for an interesting week!

Minor to major storm levels of geomagnetic disturbances are
expected as early as in the late afternoon on July 24 over North
America, with increases in geomagnetic activity starting today
(July 23).  The next week may see extreme solar flare activity.

Region 10039 (Catania sunspot group #35), which produced the X3.3
flare of July 20, struck again on July 23, producing an X4.8 flare
with the X-ray flux peaking at 0035Z.  This solar flare is a
proton-producing flare and the energetic protons are expected to
reach the Earth and begin slowly enhancing the radiation in the
near-Earth space environment by the end of today (July 23).

Region 10039 has rotated fully into view at the southeast limb. 
This region has the potential to produce occasional X10+ flares. 
During the X4.8 flare, a large and fast full halo Coronal Mass
Ejection (CME) was observed with a leading edge speed above
1700km/s.  Although the fastest part of the CME headed eastwards,
Earth should receive an impact on July 24, resulting in a severely
disturbed geomagnetic field for 12 to 24 hours after the impact. 
This event is very similar to the eruption of July 20, probably at
the origin of the geomagnetic disturbances of yesterday (July 22)
around noon (Zulu).  But this one will be stronger and more
geoeffective.  Minor to major storm levels of geomagnetic
disturbances are thus expected as early as in the afternoon of July
25 (late afternoon on July 24 over North America).

Additional major X-class solar flares from this Region over the
next two weeks might produce very active and geomagnetically stormy
conditions, the likes of which we have not observed in over 10
years.  If Region 10039 holds true to its potential, the spot
complex will continue to produce very energetic solar activity
about once every 2 to 3 days as it rotates across the face of the
Sun.  The Region is well-placed for producing large, geoeffective
impacts on the earth, and it will remain visible for about another
12 to 13 days.  The next week or two could see some considerable
solar radiation storms, auroral storm activity, ionospheric
storming, and significant geomagnetic storming.  Similar historic
periods have produced heavy Auroral events, radio blackouts, and so
on.  These Auroral event have been visible throughout the
continental United States and Canada, even into parts of Mexico. 
New Zealand, Australia, Southern Africa, and South America have
witnessed the "Southern Lights" during such events.  This type of
Aurora might happen as early as July 24.  Storms of this magnitude
("superstorms") occur on average once every six years or so.  It
has now been about 12 years since the Earth was hit by a
superstorm.

Shortwave (High Frequency) propagation will experience fadeouts,
with possible R1 to R2 radio blackouts from July 23 through July
25.  Long distance medium wave (AM) band propagation along
east-west paths over high and upper middle latitudes is poor to
very poor.  If we get the Aurora, look for Auroral-mode
propagation.

73 de Tomas, NW7US // AAR0JA
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