[Aurorawatch] MID-LATITUDE AURORA WATCH EFFECTIVE IMMEDIATELY - 13 Sept

[aurorawatch at spacew.com]

MIDDLE LATITUDE AURORAL ACTIVITY WATCH
Issued: 20:25 UTC, 13 September 2004
Solar Terrestrial Dispatch
www.spacew.com


VALID BEGINNING AT: EFFECTIVE IMMEDIATELY
VALID UNTIL: 18:00 UTC (7 pm EDT) ON 16 SEPTEMBER

PREDICTED IMPACT TIME OF DISTURBANCE: IN-PROGRESS !

HIGH RISK PERIOD: 14-15 SEPTEMBER
MODERATE RISK PERIOD: 14 - 16 SEPTEMBER

PREDICTED ACTIVITY INDICES: 35, 17, 15, 15 (13 - 16 SEPTEMBER)

POTENTIAL MAGNITUDE OF MIDDLE LATITUDE AURORAL ACTIVITY: MODERATE

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: NONE

OVERALL OPPORTUNITY FOR OBSERVATIONS FROM MIDDLE LATITUDES: FAIR TO GOOD

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

     NORTHERN OREGON TO SOUTHERN IDAHO TO WYOMING TO SOUTH DAKOTA TO ILLINOIS
TO OHIO TO NORTHERN VIRGINIA TO MARYLAND.

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

     ENGLAND TO NORTHERN BELGIUM TO NORTHERN GERMANY TO NORTHERN POLAND TO
NORTHERN BELARUS TO NORTH-CENTRAL RUSSIA.

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

     NEW ZEALAND TO EXTREME SOUTHERN AUSTRALIA.


SYNOPSIS...

     The aforementioned coronal mass ejection has arrived much earlier than
predictions suggested. This is due to an unexpectedly high transit velocity.
The velocity of the disturbance is almost twice what solar radio observations
hinted at. The lack of SOHO data until just prior to the arrival of the
disturbance did not impart sufficient time to adjust predictions prior to its
arrival.

     The CME impacted the Earth's magnetosphere near 20:01 UTC on 13
September, increasing the solar wind velocity from a quiet value near 350
km/sec to values in excess of 550 km/sec. At the present time, the
interplanetary magnetic field (IMF) is oriented in a near-neutral
configuration and might not contribute to significant intensification of
auroral storm activity unless it rotates into a more favorable southward
(negative) direction.

     The middle latitude auroral activity watch has been activated, effective
immediately. The next 12 to 24 hours will be the most volatile period.

     This watch will remain valid through 18:00 UTC (2 pm EDT) on 16
September. It will then be allowed to expire. For updated information, visit:
http://www.spacew.com/aurora/forum.html. For real-time plots of current
activity, visit: http://www.spacew.com/plots.html or www.sec.noaa.gov.

              PLEASE REPORT OBSERVATIONS OF AURORAL ACTIVITY TO:
                  http://www.spacew.com/submitsighting.html


**  End of Watch  **