Joint USAF/NOAA Report of Solar and Geophysical Activity 26 Apr 2005
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2005 Apr 26 2210 UTC
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 116 Issued at 2200Z on 26 Apr 2005
IA. Analysis of Solar Active Regions and Activity from 25/2100Z
to 26/2100Z: Solar activity increased to low levels today. Region
756 (S06E55) appears to be a magnetically complex beta-delta sunspot
group. There were several C-class flares produced from this region
during the period, the largest was an impulsive C5 x-ray event that
occurred at 26/0441Z. A disappearing filament was observed starting
late yesterday and continued into the early part of the interval.
This event resulted in a partial halo CME which was first observed
in SOHO/LASCO C2 imagery beginning at 24/2306Z. There is a chance
this CME may become geoeffective and produce a weak glancing blow as
it passes the Earth. No new regions were numbered today.
IB. Solar Activity Forecast: Solar activity is expected to be at
low levels. There is a slight chance for an isolated M-class flare
from Region 756.
IIA. Geophysical Activity Summary 25/2100Z to 26/2100Z:
The geomagnetic field was at quiet levels today.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at predominantly quiet to unsettled levels. The
partial halo CME seen today on the southwest limb may result in
isolated periods of active conditions on 29 April.
III. Event Probabilities 27 Apr-29 Apr
- Class M 20/20/20
- Class X 01/01/01
- Proton 01/01/01
- PCAF green
IV. Penticton 10.7 cm Flux
- Observed 26 Apr 091
- Predicted 27 Apr-29 Apr 090/090/090
- 90 Day Mean 26 Apr 090
V. Geomagnetic A Indices
- Observed Afr/Ap 25 Apr 009/011
- Estimated Afr/Ap 26 Apr 003/005
- Predicted Afr/Ap 27 Apr-29 Apr 005/008-005/005-012/012
VI. Geomagnetic Activity Probabilities 27 Apr-29 Apr
A. Middle Latitudes
- Active 15/15/25
- Minor storm 01/01/10
- Major-severe storm 01/01/05
B. High Latitudes
- Active 20/15/25
- Minor storm 05/01/10
- Major-severe storm 01/01/05
