Joint USAF/NOAA Report of Solar and Geophysical Activity 20 Sep 2002

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 263 Issued at 2200Z on 20 Sep 2002

IA.  Analysis of Solar Active Regions and Activity from  19/2100Z
to 20/2100Z:  Solar activity was moderate. New Region 126 (S24E62)
produced two M-class flares this period. Both were M1/Sf flares, at
20/0512Z and 0928Z, and both were accompanied by minor centimetric
bursts. Limb proximity makes it too difficult to accurately assess
Region 126's complexity, but initial measurements indicate a D type
group with 200 millionths of white light areal coverage. Region 119
(S14W24) continues to grow and the delta configuration is now more
pronounced. Despite this region's moderate complexity, flare output
has been nothing more than occasional minor C-class flares. Early in
the period, a large CME was observed, originating along a filament
channel near S30E12. The ejecta does not appear earthward directed.
New Regions 127 (S14E19) and 128 (N11E63) were numbered today.
Region 127 is in close proximity to Region 122 (S18E21), but the
consensus is that these are separate regions.

IB.  Solar Activity Forecast:  Solar activity is expected to continue
at low to moderate levels. Low M-class flares are possible from
Regions 119 and 126.

IIA.  Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field was quiet to unsettled. Solar wind speed began
the period near 700 km/s following the arrival of a CME earlier
yesterday. However, a weak IMF with sustained northward Bz offset
any significant impact on the geomagnetic field.

IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to remain at quiet to unsettled levels for the next three
days.

III.  Event Probabilities 21 Sep-23 Sep
Class M    50/50/50
Class X    05/05/05
Proton     05/05/05
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           20 Sep 164
Predicted   21 Sep-23 Sep  165/160/160
90 Day Mean        20 Sep 178

V.  Geomagnetic A Indices
Observed Afr/Ap 19 Sep  011/013
Estimated Afr/Ap 20 Sep  006/010
Predicted Afr/Ap 21 Sep-23 Sep  008/012-008/010-008/010

VI.  Geomagnetic Activity Probabilities 21 Sep-23 Sep
A.  Middle Latitudes
Active                20/15/15
Minor storm           05/05/05
Major-severe storm    01/01/01
B.  High Latitudes
Active                25/20/20
Minor storm           05/05/05
Major-severe storm    01/01/01