Joint USAF/NOAA Report of Solar and Geophysical Activity 29 April 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Apr 29 2200 UTC
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
# Space Weather Prediction Center and the U.S. Air Force.
#
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 119 Issued at 2200Z on 29 Apr 2011
IA. Analysis of Solar Active Regions and Activity from 28/2100Z
to 29/2100Z: Solar activity has been at low levels for the past 24
hours. Region 1203 (N18E64) produced the largest event of the
period, a C3 flare at 29/0026Z. Region 1200 (S17E05) regained spots
and has developed into a beta group.
IB. Solar Activity Forecast: Solar activity is expected to be at
low levels for the next two days (30 April – 01 May). Very low to
low levels are expected on day three (02 May) as Regions 1199
(N18W62) and 1195 (S15W65) rotate off the west limb.
IIA. Geophysical Activity Summary 28/2100Z to 29/2100Z:
The geomagnetic field has been at predominantly quiet levels for the
past 24 hours. However, late in the summary period, unsettled
conditions were observed. Measurements by the ACE spacecraft showed
an increase in solar wind speed from around 350 – 450 km/s. The total
interplanetary magnetic field increased from 5 – 18 nT over the
period with the negative component peaking at -10 nT. These changes
in solar wind indicate the arrival of a coronal hole high-speed
stream (CH HSS).
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be unsettled to active with isolated periods at minor
storm levels for the next three days (30 April – 02 May) as a CH HSS
becomes geoeffective.
III. Event Probabilities 30 Apr-02 May
Class M 05/05/05
Class X 01/01/01
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 29 Apr 110
Predicted 30 Apr-02 May 110/105/105
90 Day Mean 29 Apr 107
V. Geomagnetic A Indices
Observed Afr/Ap 28 Apr 001/003
Estimated Afr/Ap 29 Apr 007/008
Predicted Afr/Ap 30 Apr-02 May 010/010-012/012-010/010
VI. Geomagnetic Activity Probabilities 30 Apr-02 May
A. Middle Latitudes
Active 35/40/35
Minor storm 10/10/10
Major-severe storm 01/01/01
B. High Latitudes
Active 40/45/40
Minor storm 10/15/15
Major-severe storm 01/05/05