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

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 May 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 138 Issued at 2200Z on 18 May 2011
IA. Analysis of Solar Active Regions and Activity from 17/2100Z
to 18/2100Z: Solar activity has been low for the last 24 hours. New
Region 1218 (S16E66) was numbered today and produced a C1 event at
18/1259Z. Region 1208 (N09W90) produced a long duration C2 event at
18/1830Z just as it was rotating around the west limb. All other
regions on the disk remained relatively quiet and stable.
IB. Solar Activity Forecast: Solar activity is expected to remain
very low with a chance for C-class activity for the next three days
(19-21 May) as new Region 1218 continues to develop.
IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z:
The geomagnetic field has been mostly quiet for the last 24 hours.
Solar wind at ACE showed a decrease from approximately 550 km/s to
450 km/s during the period as effects from the coronal hole high
speed stream subside.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be quiet for the next three days (19-21 May) as the
solar wind returns to background levels.
III. Event Probabilities 19 May-21 May
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 18 May 091
Predicted 19 May-21 May 095/095/095
90 Day Mean 18 May 109
V. Geomagnetic A Indices
Observed Afr/Ap 17 May 008/010
Estimated Afr/Ap 18 May 004/005
Predicted Afr/Ap 19 May-21 May 005/005-005/005-005/005
VI. Geomagnetic Activity Probabilities 19 May-21 May
A. Middle Latitudes
Active 05/05/05
Minor storm 01/01/01
Major-severe storm 01/01/01
B. High Latitudes
Active 05/05/05
Minor storm 01/01/01
Major-severe storm 01/01/01