std_oler@HG.ULeth.CA (Cary Oler) (12/13/90)
-- MAJOR SOLAR FLARE ALERT --
DECEMBER 12, 1990
Flare Event Summary
Potential Impact Forecast
Revised Prediction Charts
--> Geomagnetic Storm Warning Update <--
--> High Latitude Auroral Storm Warning Update <--
--------
MAJOR ENERGETIC EVENT SUMMARY
An explosive surge of solar activity occurred today. There were a total
of eight M-class flares today. Two of these were major energetic events. The
largest event was the class M8.9/SF flare which occurred at 14:10 UT on 12
December. This flare originated from Region 6398 at a position of N10W72 and
lasted 71 minutes. This region will disappear beyond the west limb tommorrow.
No significant bursts or sweep frequency events occurred with this flare.
Region 6399 was by far the most active flare-producer today. It was
responsible for five M-class flares today, including the major class M5.1/SF
flare which occurred at 08:03 UT on 12 December. This latter event occurred at
a position of N20W73 and lasted 57 minutes. No significant radio bursts or
sweeps were observed from this event either.
Among one of the M-class events of today was an M1.6/SF flare which also
originated from Region 6399. This flare is worthy of note because it was
accompanied by a Type II sweep. The flare occurred at 11:12 UT and lasted 36
minutes. The shock velocity of the Type II sweep is estimated at 2000 km/sec.
No significant proton enhancements were observed today, despite the amount
of solar activity which has occurred.
A significant drop in the solar flux is anticipated over the next 48 hours
as the very active regions in the northwest solar quadrant rotated out of view
beyond the west limb. The solar flux is expected to drop by as much as 30
points by 15 December.
As the regions in the northeast rotate out of view, all attention will be
shifted to the northeast quadrant where Region 6410 is showing signs of
increased flare output. Over the past 24 hours, Region 6410 (N05E32) has
rapidly increased in size from 1,320 million square kilometers to 1,830 million
square kilometers, an increase of 510 million square kilometers. Area, flare
output and sunspot numbers have also increased within this region over the
past 24 hours.
Regions 6398, 6399, 6410 and 6412 are all capable of spawning M-class
flares. They are also capable of producing isolated major flares. Regions
6398 and 6399 will be out of view on 13 December and will not return to the
eastern limb until near 27 December. Regions 6410 and 6412, however, are still
in the eastern hemisphere of the sun and will remain in view for quite some
time yet.
Region 6412 (old region 6368 which was enormous in size on its last
appearance several weeks ago) has retained a great deal of it's size. Today, a
significant portion of its old trailer spot complex rotated into view. Hence
the size of the region was adjusted accordingly and now stands at 3,870 million
square kilometers. The trailer spot region has definitely decayed since it was
last observed several weeks ago, but this region is still capable of spawning
M-class flares.
The sunspot number has been decreasing steadily over the past 48 hours,
due to the rotation of active regions beyond the west limb. At the present
time, the sunspot number is 208, but will drop further as the major active
centers rotate out of view. Likewise, the x-ray background flux is expected
to begin dropping over the next several days from its present C2.1 level.
GEOMAGNETIC STORM WARNING UPDATE
Geomagnetic activity increased notably between 22:00 UT and 24:00 UT on
12 December due to the effects of the major solar flare of 10 December.
Activity has remained confined to mostly active levels over middle latitudes.
High latitudes have experienced periods of minor storming.
Activity is expected to calm down somewhat on 14 December, but should be
followed by another increase of activity due to the major solar flares which
occurred today. This second increase of activity is expected to occur on
15 December. Levels of activity should be comparable to the activity
experienced today (12/13 December). No significant storming is expected,
although periodic minor storming may again recur over high latitudes.
HIGH LATITUDE AURORAL STORM WARNING UPDATE
The auroral storm which was anticipated for high latitudes never reached
the intensities anticipated. Significant periods of auroral activity has
occurred over the high latitudes, but the activity has been relatively
localized. The auroral storm warning has been cancelled for all regions.
Localized periods of high auroral activity may still be possible, but such
activity will be isolated.
A slight southward expansion of the auroral zone was noted on 13 December,
but the expansion was not enough to permit observations from low latitudes. It
is expected to return to its normal position over the next 24 hours. However,
it may again migrate southward slightly when the effects of today's major
flare's reach the earth on 15 December. No significant migration is expected.
The prediction charts have been revised yet again to compensate for the major
flare activity which occurred today. The previously revised charts are still
valid, but will not be quite as accurate as the following revised charts.
PLANETARY 10-DAY GEOMAGNETIC ACTIVITY OUTLOOK (09 DECEMBER - 18 DECEMBER)
________________________________________________________________________
| EXTREMELY SEVERE | | | | | | | | | | | VERY HIGH! |
| VERY SEVERE STORM | | | | | | | | | | | HIGH |
| SEVERE STORM | | | | | | | | | | | MODERATE |
| MAJOR STORM | | | | | | | | | | | MODERATE |
| MINOR STORM | | | | | | | | | | | LOW |
| VERY ACTIVE | | | | |** | | * | | | | NONE - LOW |
| ACTIVE | | | | *|***| |***|* | | | NONE |
| UNSETTLED | | | | **|***|***|***|***|* *|***| NONE |
| QUIET |***|***|***|***|***|***|***|***|***|***| NONE |
| VERY QUIET |***|***|***|***|***|***|***|***|***|***| NONE |
|-------------------|---|---|---|---|---|---|---|---|---|---|------------|
| Geomagnetic Field |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| Anomaly |
| Conditions | Given in 8-hour intervals | Intensity |
|________________________________________________________________________|
HF RADIO SIGNAL PROPAGATION PREDICTIONS (09 DECEMBER - 18 DECEMBER)
High Latitude Paths
________________________________________________________
| EXTREMELY GOOD | | | | | | | | | | |
| VERY GOOD | | | | | | | | | | |
| GOOD | *| *|* | | | | | | | |
| FAIR |** |** | **|* | | *| | *|* *|* *|
| POOR | | | | * | *|** |* *|** | * | * |
| VERY POOR | | | | *|** | | * | | | |
| EXTREMELY POOR | | | | | | | | | | |
|----------------|---|---|---|---|---|---|---|---|---|---|
| PROPAGATION |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue|
| QUALITY | Given in 8-Hour UT Intervals |
--------------------------------------------------------
Middle Latitude Paths
________________________________________________________
| EXTREMELY GOOD | | | | | | | | | | |
| VERY GOOD |***|***|***| | | | | | | |
| GOOD | | | |* | | *| | *|***|* *|
| FAIR | | | | **| *|** |* *|** | | * |
| POOR | | | | |** | | * | | | |
| VERY POOR | | | | | | | | | | |
| EXTREMELY POOR | | | | | | | | | | |
|----------------|---|---|---|---|---|---|---|---|---|---|
| PROPAGATION |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue|
| QUALITY | Given in 8-Hour UT Intervals |
--------------------------------------------------------
Low Latitude Paths
________________________________________________________
| EXTREMELY GOOD | | | | | | | | | | |
| VERY GOOD |***|***|***| | | | | | | |
| GOOD | | | |** | *|* *| *|* *|***|***|
| FAIR | | | | *|** | * |** | * | | |
| POOR | | | | | | | | | | |
| VERY POOR | | | | | | | | | | |
| EXTREMELY POOR | | | | | | | | | | |
|----------------|---|---|---|---|---|---|---|---|---|---|
| PROPAGATION |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue|
| QUALITY | Given in 8-Hour UT Intervals |
--------------------------------------------------------
NOTES:
High latitudes >= 55 degree's north latitude
Middle latitudes >= 40 < 55 degree's north latitude
Low latitudes < 40 degree's north latitude
POTENTIAL VHF DX PROPAGATION PREDICTIONS (09 DECEMBER - 18 DECEMBER)
INCLUDES SID AND AURORAL BACKSCATTER ENHANCEMENT PREDICTIONS
HIGH LATITUDES
__________________________________________________ ___________________
| SIGNAL | Given in 8 hour local time intervals | | SID ENHANCEMENT |
| QUALITY |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| |S|M|T|W|T|F|S|S|M|T|
|__________|___|___|___|___|___|___|___|___|___|___| |-|-|-|-|-|-|-|-|-|-|
| VERY GOOD| | | | | | | | | | | 0%|*|*|*|*|*|*|*|*|*|*|
|ABOVE NORM| | | | | | | | | | | 20%|*|*|*|*|*|*|*|*|*|*|
| NORMAL|***|***|***|** | **|** | * |***|***|* *| 40%| | | | | | | | | | |
|BELOW NORM| | | | *|* | *|* *| | | * | 60%| | | | | | | | | | |
| VERY POOR| | | | | | | | | | | 80%| | | | | | | | | | |
| BLACKOUT| | | | | | | | | | |100%| | | | | | | | | | |
|==========|===|===|===|===|===|===|===|===|===|===| |-------------------|
| 100% | | | | | | | | | | |100%| | | | | | | | | | |
| 80% | | | | | | | | | | | 80%| | | | | | | | | | |
| 60% | | | | *|* | | | | | | 60%| | | |*| | | | | | |
| 40% | | | | **|* *| *|* *| |* *|* *| 40%| | | |*|*| |*|*| |*|
| 20% | **| **| **|***|***|***|***|***|***|***| 20%| | |*|*|*|*|*|*|*|*|
| 0% |***|***|***|***|***|***|***|***|***|***| 0%|*|*|*|*|*|*|*|*|*|*|
|----------+---|---|---|---|---|---|---|---|---|---| |-|-|-|-|-|-|-|-|-|-|
|CHANCE OF |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| |S|M|T|W|T|F|S|S|M|T|
| VHF DX | Given in 8 hour local time intervals | |AURORAL BACKSCATTER|
|__________|_______________________________________| |___________________|
MIDDLE LATITUDES
__________________________________________________ ___________________
| SIGNAL | Given in 8 hour local time intervals | | SID ENHANCEMENT |
| QUALITY |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| |S|M|T|W|T|F|S|S|M|T|
|__________|___|___|___|___|___|___|___|___|___|___| |-|-|-|-|-|-|-|-|-|-|
| VERY GOOD| | | | | | | | | | | 0%|*|*|*|*|*|*|*|*|*|*|
|ABOVE NORM| * | * | * | | | | | | | | 20%|*|*|*|*|*|*|*|*|*|*|
| NORMAL|* *|* *|* *|** | **|** | **|***|* *|* *| 40%|*|*|*|*|*|*|*|*|*|*|
|BELOW NORM| | | | *|* | *|* | | * | * | 60%|*|*|*|*|*|*| | | | |
| VERY POOR| | | | | | | | | | | 80%| | | | | | | | | | |
| BLACKOUT| | | | | | | | | | |100%| | | | | | | | | | |
|==========|===|===|===|===|===|===|===|===|===|===| |-------------------|
| 100% | | | | | | | | | | |100%| | | | | | | | | | |
| 80% | | | | | | | | | | | 80%| | | | | | | | | | |
| 60% | | | | | | | | | | | 60%| | | | | | | | | | |
| 40% | * | * | **| **|***| **|* | | | | 40%| | | |*|*| |*| | | |
| 20% | **| **| **|***|***|***|***|***|***|***| 20%| | |*|*|*|*|*|*|*|*|
| 0% |***|***|***|***|***|***|***|***|***|***| 0%|*|*|*|*|*|*|*|*|*|*|
|----------+---|---|---|---|---|---|---|---|---|---| |-|-|-|-|-|-|-|-|-|-|
|CHANCE OF |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| |S|M|T|W|T|F|S|S|M|T|
| VHF DX | Given in 8 hour local time intervals | |AURORAL BACKSCATTER|
|__________|_______________________________________| |___________________|
LOW LATITUDES
__________________________________________________ ___________________
| SIGNAL | Given in 8 hour local time intervals | | SID ENHANCEMENT |
| QUALITY |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| |S|M|T|W|T|F|S|S|M|T|
|__________|___|___|___|___|___|___|___|___|___|___| |-|-|-|-|-|-|-|-|-|-|
| VERY GOOD| | | | | | | | | | | 0%|*|*|*|*|*|*|*|*|*|*|
|ABOVE NORM| * | * | * | | | | | | | | 20%|*|*|*|*|*|*|*|*|*|*|
| NORMAL|* *|* *|* *|***|***|***|***|***|***|***| 40%|*|*|*|*|*|*|*|*|*|*|
|BELOW NORM| | | | | | | | | | | 60%|*|*|*|*|*|*| | | | |
| VERY POOR| | | | | | | | | | | 80%| | | | | | | | | | |
| BLACKOUT| | | | | | | | | | |100%| | | | | | | | | | |
|==========|===|===|===|===|===|===|===|===|===|===| |-------------------|
| 100% | | | | | | | | | | |100%| | | | | | | | | | |
| 80% | | | | | | | | | | | 80%| | | | | | | | | | |
| 60% | | | | | | | | | | | 60%| | | | | | | | | | |
| 40% | * | * | * | **|** | * | * | * | * | * | 40%| | | | | | | | | | |
| 20% | **| **| **|***|***| **|***|***| **| **| 20%| | | | | | |*| | | |
| 0% |***|***|***|***|***|***|***|***|***|***| 0%|*|*|*|*|*|*|*|*|*|*|
|----------+---|---|---|---|---|---|---|---|---|---| |-|-|-|-|-|-|-|-|-|-|
|CHANCE OF |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| |S|M|T|W|T|F|S|S|M|T|
| VHF DX | Given in 8 hour local time intervals | |AURORAL BACKSCATTER|
|__________|_______________________________________| |___________________|
NOTES:
These VHF DX prediction charts are defined for the 50 MHz to 220 MHz
bands. They are based primarily on phenomena which can affect VHF DX
propagation globally. They should be used only as a guide to potential
DX conditions on VHF bands. Latitudinal boundaries are the same as those for
the HF predictions charts. For more information, request the document
"Understanding Solar Terrestrial Reports" from: "std_oler@hg.uleth.ca".
AURORAL ACTIVITY PREDICTIONS (09 DECEMBER - 18 DECEMBER)
High Latitude Locations
________________________________________________________
| EXTREMELY HIGH | | | | | | | | | | |
| VERY HIGH | | | | | | | | | | |
| HIGH | | | | * | | | | | | |
| MODERATE | | | |***| * | |***| * | | * |
| LOW | | |***|***|***|***|***|***|***|***|
| NOT VISIBLE |***|***|***|***|***|***|***|***|***|***|
|----------------|---|---|---|---|---|---|---|---|---|---|
| AURORAL |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue|
| INTENSITY | Eve.Twilight/Midnight/Morn.Twilight |
--------------------------------------------------------
Middle Latitude Locations
________________________________________________________
| EXTREMELY HIGH | | | | | | | | | | |
| VERY HIGH | | | | | | | | | | |
| HIGH | | | | | | | | | | |
| MODERATE | | | | * | | | * | | | |
| LOW | | | |***| * | * |***|***| * |***|
| NOT VISIBLE |***|***|***|***|***|***|***|***|***|***|
|----------------|---|---|---|---|---|---|---|---|---|---|
| AURORAL |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue|
| INTENSITY | Eve.Twilight/Midnight/Morn.Twilight |
--------------------------------------------------------
Low Latitude Locations
________________________________________________________
| EXTREMELY HIGH | | | | | | | | | | |
| VERY HIGH | | | | | | | | | | |
| HIGH | | | | | | | | | | |
| MODERATE | | | | | | | | | | |
| LOW | | | | | | | | | | |
| NOT VISIBLE |***|***|***|***|***|***|***|***|***|***|
|----------------|---|---|---|---|---|---|---|---|---|---|
| AURORAL |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue|
| INTENSITY | Eve.Twilight/Midnight/Morn.Twilight |
--------------------------------------------------------
NOTE:
For more information regarding these charts, send a request for the
document, "Understanding Solar Terrestrial Reports" to: std_oler@hg.uleth.ca.
** End of Report **