Report of Solar Geophysical Activity

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 254 Issued at 2200Z on 11 Sep 2017

Analysis of Solar Active Regions and Activity from 09/2100Z to
10/2100Z: Solar activity has been at high levels for the past 48 hours.
The largest solar event of the period was a X8 event observed at
10/1606Z from old Region 2673 (S09, L=119).

IA.  Analysis of Solar Active Regions and Activity from 10/2100Z to
11/2100Z: Solar activity has been at low levels for the past 24 hours.
There are currently 2 numbered sunspot regions on the disk.
IB.  Solar Activity Forecast: Solar activity is expected to be very low
with a chance for a C-class flares and a slight chance for an M-class
flare on day one (12 Sep) and expected to be very low with a slight
chance for a C-class flare on day two (13 Sep) and expected to be very
low on day three (14 Sep).

IIA.  Geophysical Activity Summary 10/2100Z to 11/2100Z: The geomagnetic
field has been at quiet to active levels for the past 24 hours. Solar
wind speed reached a peak of 668 km/s at 11/0203Z. Total IMF reached 7
nT at 10/2328Z. The maximum southward component of Bz reached -5 nT at
10/2330Z. Protons greater than 10 MeV at geosynchronous orbit reached a
peak level of 1493 pfu at 11/1145Z. Protons greater than 100 MeV at
geosynchronous orbit reached a peak level of 68 pfu at 10/2215Z.
Electrons greater than 2 MeV at geosynchronous orbit reached a peak
level of 5361 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to active levels on day one (12 Sep), unsettled to major
storm levels on day two (13 Sep) and unsettled to minor storm levels on
day three (14 Sep). Protons are expected to cross threshold on day one
(12 Sep), are expected to cross threshold on day two (13 Sep) and are
likely to cross threshold on day three (14 Sep).

III.  Event probabilities 12 Sep-14 Sep
Class M    10/01/01
Class X    01/01/01
Proton     99/80/60
PCAF       red

IV.  Penticton 10.7 cm Flux
Observed           11 Sep 080
Predicted   12 Sep-14 Sep 078/076/076
90 Day Mean        11 Sep 081

V.  Geomagnetic A Indices
Observed Afr/Ap 10 Sep  012/007
Estimated Afr/Ap 11 Sep  012/014
Predicted Afr/Ap 12 Sep-14 Sep  010/012-024/040-025/034

VI.  Geomagnetic Activity Probabilities 12 Sep-14 Sep
A.  Middle Latitudes
Active                25/25/30
Minor Storm           10/35/35
Major-severe storm    01/20/20
B.  High Latitudes
Active                15/05/05
Minor Storm           30/20/15
Major-severe storm    40/75/75

Radio Events Observed 11 Sep 2017
A.  245 MHz Bursts
Start  End   Peak Flux  Time of Peak  Duration
0307   0308    130          0307        0001  
0319   0319    130          0319        0000  
0434   0434    110          0434        0000  
0439   0439    150          0439        0000  
0501   0501    120          0501        0000  
0508   0508    100          0508        0000  
0515   0515    100          0515        0000  
0722   0722    140          0722        0000  
0911   0911    100          0911        0000  
0946   0947    200          0947        0001  
1055   1055    110          1055        0000  
B.  245 MHz Noise Storms
No 245 MHz Noise Storms Observed.

**** SPACE WEATHER OUTLOOK ****

Summary For September 4-10

R1 (Minor) radio blackouts were observed on 04-09 September, R2 (Moderate) radio blackouts were observed on 04, 07, 08 September, and R3 (Strong) radio blackouts were observed on 06, 07, 10 September due to solar flare activity from active sunspot Region 2673.

S1 (Minor) solar radiation storm levels were observed on 05-09 Sep and 10 September, S2 (Moderate) solar radiation storm levels were observed on 05-08 September and 10 September, and S3 (Strong) solar radiation storm levels were observed on 10 September due to significant flare activity from Region 2673.

G1 (Minor) geomagnetic storm levels were observed on 04 September due to coronal hole high speed stream activity.

G4 (Severe) geomagnetic storm levels were observed on 07 September while G1-G4 (Minor-Severe) storm levels were observed on 08 September due to a combination of activity from the arrival of the 04 and 06 September coronal mass ejections.

Outlook For September 11-17

R1-R2 (Minor-Moderate) radio blackouts are expected on 11 September due to the potential for significant flare activity from Region 2673 as it rotates further around the west limb.

S3 (Strong) solar radiation storm levels are expected to continue on 11 September and slowly decrease below S1 (Minor) storm levels by 15 September.

G1 (Minor) geomagnetic storm levels are likely from 13-16 September with G2 (Moderate) levels likely on 13 September due to recurrent coronal hole high speed stream activity.

Data used to provide space weather services are contributed by NOAA,
USAF, NASA, NSF, USGS, the International Space Environment Services
and other observatories, universities, and institutions. More
information is available at SWPC's Web site http://swpc.noaa.gov