Joint USAF/NOAA Report of Solar and Geophysical Activity 18 August 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Aug 18 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 230 Issued at 2200Z on 18 Aug 2011
IA. Analysis of Solar Active Regions and Activity from 17/2100Z
to 18/2100Z: Solar activity was low. Both Regions 1271 (N15E38) and
1272 (S22E41) produced C1/Sf flares during the past 24 hours.
Region 1271 became more consolidated during the period, but remained
a large Ehc type spot group with beta magnetic characteristics.
IB. Solar Activity Forecast: Solar activity is expected to be low
with a chance for moderate activity. The continued persistence of
Region 1271, as well as the return of old Region 1261 on Day 2 (20
Aug), make moderate activity more probable. During the last
rotation, old Region 1261 produced five M-class events including an
M9 and CME on 04 August.
IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z:
The geomagnetic field was quiet and the ambient solar wind
unremarkable. The greater than 2 MeV electron flux at geosynchronous
orbit reached high levels during the period.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be predominantly quiet for the first two days of the
forecast period (19-20 Aug). A recurrent coronal hole high speed
stream is expected to become geoeffective on Day 3 (21 Aug) leading
to unsettled conditions with a chance for active periods at high
latitudes.
III. Event Probabilities 19 Aug-21 Aug
Class M 45/45/45
Class X 10/10/10
Proton 01/01/01
PCAF Green
IV. Penticton 10.7 cm Flux
Observed 18 Aug 098
Predicted 19 Aug-21 Aug 098/100/100
90 Day Mean 18 Aug 096
V. Geomagnetic A Indices
Observed Afr/Ap 17 Aug 006/006
Estimated Afr/Ap 18 Aug 005/005
Predicted Afr/Ap 19 Aug-21 Aug 005/005-005/005-010/012
VI. Geomagnetic Activity Probabilities 19 Aug-21 Aug
A. Middle Latitudes
Active 05/10/20
Minor storm 01/05/05
Major-severe storm 01/05/05
B. High Latitudes
Active 05/10/50
Minor storm 05/05/15
Major-severe storm 01/01/10