MIDDLE LATITUDE AURORAL ACTIVITY WARNING

[Ulrich Rieth]

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MIDDLE LATITUDE AURORAL ACTIVITY WARNING

ISSUED: 15:05 UTC, 17 APRIL 2002

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*** POTENTIAL FOR MODERATE TO HIGH ACTIVITY EXISTS ***

VALID BEGINNING AT: EFFECTIVE IMMEDIATELY (11:05 am EDT on 17 April)
VALID UNTIL: 19:00 UTC ON 18 APRIL

HIGH RISK PERIOD: 17 - 18 APRIL (UTC DAYS)
MODERATE RISK PERIOD: 17 - 18 APRIL

PREDICTED ACTIVITY INDICES: 40, 20, 40, 30 (17 APRIL - 19 APRIL)

POTENTIAL MAGNITUDE OF MIDDLE LATITUDE AURORAL ACTIVITY: MODERATE TO HIGH

POTENTIAL DURATION OF THIS ACTIVITY: MAIN BELT = 12 TO 18 HOURS

MINOR BELT = 18 TO 24 HOURS

ESTIMATED OPTIMUM OBSERVING CONDITIONS: NEAR LOCAL MIDNIGHT

EXPECTED LUNAR INTERFERENCE: LOW TO NIL

OVERALL OPPORTUNITY FOR OBSERVATIONS FROM MIDDLE LATITUDES: FAIR TO GOOD

AURORAL ACTIVITY *MAY* BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...

(IF ACTIVITY HOLDS OUT)... NORTHERN OREGON TO IDAHO TO WYOMING TO EXTREME

NORTHERN NEBRASKA TO IOWA TO NORTHERN ILLINOIS TO NORTHERN INDIANA TO OHIO

TO PENNSYLVANIA TO NORTHERN NEW JERSEY.

ACTIVITY *MAY* ALSO BE OBSERVED APPROXIMATELY NORTH OF A LINE FROM...

EXTREME NORTHERN FRANCE TO NORTHERN BELGIUM TO NORTHERN GERMANY TO POLAND

TO NORTHERN BELARUS TO NORTH-CENTRAL RUSSIA. NEW ZEALAND AND EXTREME

SOUTHERN REGIONS OF AUSTRALIA MAY ALSO SPOT PERIODS OF ACTIVITY.

SYNOPSIS...

The impact of the coronal mass ejection observed on 15 April occurred
near 11:07 UTC on 17 April, roughly 9 hours earlier than most preferred
predictions but within the expected error-bar window. The faster than
expected disturbance has produced periods of moderate to strong auroral
storming over the high and upper-middle latitude regions. Periods of
intensified auroral storming is expected to continue through the next 12 to
18 hours. Activity may at times become visible over fairly widespread middle
latitude regions, particularly given the fact that the moon will not play
interference during the optimally dark hours near local midnight.

This warning will remain in effect until 19:00 UTC on 18 April. It
will then be updated or allowed to expire. Another Earthward-directed CME was
observed a few hours ago. This latest CME appears to have a higher velocity
than the one we are currently observing. Analysis is underway, although it
appears probable that auroral activity watch conditions will be extended
for another few days to cover the anticipated impact of this latest CME.

PLEASE REPORT OBSERVATIONS OF AURORAL ACTIVITY TO:

http://solar.spacew.com/www/auroras.html

Other Tools:

o A new and advanced space weather monitoring tool is available at:
http://www.spacew.com/swim

o Real-time notification of events via Digital SMS (cell phone/pager):
using the SWIM software.

o Monitor real-time conditions and report sightings using software at:
http://www.spacew.com/aurora

o On-line global discussion forum:
http://www.spacew.com/aurora/forum.html

o Chat in real-time with others using IRC at:
http://www.spacew.com/irc
and join the #aurora channel (type /join #aurora in the IRC software).

** End of Warning **