Status Report

Joint USAF/NOAA Report of Solar and Geophysical Activity 20 Sep 2004

By SpaceRef Editor

September 20, 2004

Filed under Space Weather Prediction Center (NOAA), Space Weather Solar-Geophysical Activity, US

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2004 Sep 20 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 264 Issued at 2200Z on 20 Sep 2004

IA. Analysis of Solar Active Regions and Activity from 19/2100Z
to 20/2100Z: Solar Activity was low. Region 672 (N05W71) produced
two C-class flares. The first was a C1.7 at 20/0310Z. The second
was a C2.1 at 20/0721Z. Region 672 has shown little change over the
past 24 hours as it approaches the west limb. Region 673 (S13E09)
decayed some this period and exhibited no significant activity. New
Region 674 (S10W23) was numbered.

IB. Solar Activity Forecast: Solar Activity is expected to be very
low to low with a slight chance for an isolated M-class flare from
Region 672 as it rotates around the west limb.

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field ranged from quiet to unsettled levels with an
isolated active period from 0600-0900Z. The active level followed a
period of southward IMF Bz. The greater than 10 MeV proton event
that began yesterday, has ended. The start time was 19/1925Z and the
maximum of 57 pfu occurred at 20/0100Z. The event ended at 20/1205Z.
The greater than 2 MeV electron flux at geosynchronous orbit
briefly reached high levels.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be quiet to unsettled with isolated high latitude active
periods on 21 September. Unsettled to minor storm levels are
expected on 22 and 23 September due to a CME associated with the
M1.9 flare on 19 September.

III. Event Probabilities 21 Sep-23 Sep