Joint USAF/NOAA Report of Solar and Geophysical Activity 18 Jul 2004
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2004 Jul 18 2210 UTC
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 200 Issued at 2200Z on 18 Jul 2004
IA. Analysis of Solar Active Regions and Activity from 17/2100Z
to 18/2100Z: Solar activity remained at high levels today. Region
649 (S10E00) produced five M-class events, all of which occurred in
a constricted area around the delta structure in the trailing
portion of the spot group. The M-class flares chronologically
occurred with an M2/1f at 17/2131Z, an M1 x-ray at 17/2308Z, an
M2/1f at 18/0035Z, an M1/Sf at 18/0257Z, and an M1/1f at 18/1713Z.
Weak radio bursts accompanied many of today’s events while LASCO
imagery depicted only faint CME signatures in association with the
flare activity observed during the period. Magnetically, Region 649
remains a beta-gamma-delta spot group. Region 652 (N05E58) has
fully rotated into view today and is currently measured in white
light at over 1300 millionths of spot area coverage. Several
C-class flares were observed during the period and a strong delta
structure is evident in the intermediate cluster of spots. No new
regions were numbered today.
IB. Solar Activity Forecast: Solar activity is expected to be at
moderate to high levels. Region 649 and 652 are both capable of
producing major flare level activity.
IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z:
The geomagnetic field was at quiet to unsettled levels.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at predominantly unsettled levels throughout the
period. Isolated active to minor storm conditions are possible on
19 and 20 July mostly at higher latitudes due to the potential for
transient passages from the major flare activity seen from Region
649 during the past several days.
III. Event Probabilities 19 Jul-21 Jul
- Class M 80/80/80
- Class X 40/40/40
- Proton 20/20/20
- PCAF Green
IV. Penticton 10.7 cm Flux
- Observed 18 Jul 155
- Predicted 19 Jul-21 Jul 150/150/145
- 90 Day Mean 18 Jul 098
V. Geomagnetic A Indices
- Observed Afr/Ap 17 Jul 013/024
- Estimated Afr/Ap 18 Jul 008/010
- Predicted Afr/Ap 19 Jul-21 Jul 010/015-010/015-008/012
VI. Geomagnetic Activity Probabilities 19 Jul-21 Jul
A. Middle Latitudes
- Active 15/15/15
- Minor storm 10/10/05
- Major-severe storm 05/05/01
B. High Latitudes
- Active 30/30/25
- Minor storm 15/15/10
- Major-severe storm 10/10/05
