Joint USAF/NOAA Report of Solar and Geophysical Activity 27 April 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Apr 27 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 117 Issued at 2200Z on 27 Apr 2011
IA. Analysis of Solar Active Regions and Activity from 26/2100Z
to 27/2100Z: Solar activity has been at low levels for the past 24
hours. New Region 1201 (N16E40), grew rapidly early in the period,
producing a C2 flare at 27/0301Z with a non-Earth directed CME. A
Type II radio sweep, with a shock velocity of 845 km/s, was also
associated with this event. Region 1201 has since decayed and is
now spotless plage. A second, back-sided CME, first visible in
LASCO C2 imagery at 27/0800Z, was also observed during the period.
Neither CME is expected to become geoeffective. Region 1199 (N21W34)
continues to grow and evolve.
IB. Solar Activity Forecast: Solar activity is expected to be at
very low to low levels for the next three days (28-30 April).
IIA. Geophysical Activity Summary 26/2100Z to 27/2100Z:
The geomagnetic field has been at quiet levels for the past 24 hours.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at predominantly quiet levels for the next 2 days
(28-29 April). Unsettled to active levels are expected on day three
(30 April) as a recurrent coronal hole high-speed stream becomes
geoeffective.
III. Event Probabilities 28 Apr-30 Apr
Class M 05/05/05
Class X 01/01/01
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 27 Apr 108
Predicted 28 Apr-30 Apr 105/105/105
90 Day Mean 27 Apr 107
V. Geomagnetic A Indices
Observed Afr/Ap 26 Apr 001/003
Estimated Afr/Ap 27 Apr 001/003
Predicted Afr/Ap 28 Apr-30 Apr 005/005-005/005-010/010
VI. Geomagnetic Activity Probabilities 28 Apr-30 Apr
A. Middle Latitudes
Active 05/10/35
Minor storm 01/01/05
Major-severe storm 01/01/01
B. High Latitudes
Active 05/10/35
Minor storm 01/01/05
Major-severe storm 01/01/01