Joint USAF/NOAA Report of Solar and Geophysical Activity 21 Jul 2004

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2004 Jul 21 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 203 Issued at 2200Z on 21 Jul 2004

IA. Analysis of Solar Active Regions and Activity from 20/2100Z
to 21/2100Z: Solar activity has been low. Region 649 (S10W41)
produced a C6.6/1f at 21/0034 UTC. Region 652 produced several
C-class flares, including a C8.9/1f at 21/0521 UTC. Region 649 was
stable in size and decreased in magnetic complexity to a beta-gamma
configuration. Region 652 increased signficantly in size over the
period, to 2010 millionths in white light, although most of the
growth was observed in the trailing penumbral field. The region’s
magnetic class continues to be beta-gamma-delta, but all of the
magnetic complexity is in the northern part of the leader spots. No
new regions were numbered on the visible disk.

IB. Solar Activity Forecast: Solar activity is expected to be
predominantly moderate. However, there is still a possibility for
major flare activity from Region 652.

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z:
The geomagnetic field has been quiet to unsettled.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be quiet to unsettled tomorrow (22 July), with active to
minor storm conditions expected on day two (23 July) from the
possible effects of a CME observed on LASCO imagery on 20 July.
Geomagnetic activity should return to quiet to unsettled conditions
on 24 July.

III. Event Probabilities 22 Jul-24 Jul
Class M 65/65/65
Class X 20/20/20
Proton 10/10/15
PCAF green

IV. Penticton 10.7 cm Flux
Observed 21 Jul 172
Predicted 22 Jul-24 Jul 175/170/160
90 Day Mean 21 Jul 101

V. Geomagnetic A Indices
Observed Afr/Ap 20 Jul 008/009
Estimated Afr/Ap 21 Jul 005/007
Predicted Afr/Ap 22 Jul-24 Jul 010/010-025/025-010/015

VI. Geomagnetic Activity Probabilities 22 Jul-24 Jul
A. Middle Latitudes
Active 20/40/20
Minor storm 10/25/15
Major-severe storm 05/15/05
B. High Latitudes
Active 25/40/30
Minor storm 15/30/20
Major-severe storm 10/20/10