Joint USAF/NOAA Report of Solar and Geophysical Activity 17 Aug 2002

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 229 Issued at 2200Z on 17 Aug 2002

IA.  Analysis of Solar Active Regions and Activity from  16/2100Z
to 17/2100Z:  Solar activity was at moderate levels.  Region 69
(S07W03) has produced three M-class events, the largest an M3.4/Sf
at 17/2051 UTC.  Other activity from this region has been a number
of C-class events and numerous sub-flares.  Region 69 continues to
grow in area and spot count at 1950 millionths and 58 spots, and is
exhibiting multiple magnetic delta configurations within the same
penumbra.  Region 79 (S21E18) has shown growth particularly in spot
count.  Two new regions were numbered today:  Region 82 (N21E06) and
Region 83 (S18E67).

IB.  Solar Activity Forecast:  Solar activity is expected to be
moderate to high.  Region 69 has the potential to produce a major
event.

IIA.  Geophysical Activity Summary 16/2100Z to 17/2100Z:
The geomagnetic field was at quiet to unsettled condition with one
three-hour period of isolated active levels at 17/0900 UTC.  Greater
than 2 MeV electron flux at geosynchronous orbit exceeded event
threshold at 17/1405 UTC, reached a peak value of 1350 pfu at
17/1710 UTC and decreased below threshold levels at 17/1845 UTC. 
NASA/ACE data indicates that the solar wind velocities decreased
throughout the day from a peak velocity of 600 km/s to around 450
km/s due to waning coronal hole effects.

IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be at minor to major storm levels on day one of the
forecast period.  A shock arrival from the M5/full halo CME event on
16 August is expected early on day one.  The geomagnetic field for
day two and three of the forecast period is expected to be at quiet
to unsettled levels.

III.  Event Probabilities 18 Aug-20 Aug
Class M    75/75/75
Class X    20/20/20
Proton     15/15/15
PCAF       yellow

IV.  Penticton 10.7 cm Flux
Observed           17 Aug 227
Predicted   18 Aug-20 Aug  230/235/235
90 Day Mean        17 Aug 167

V.  Geomagnetic A Indices
Observed Afr/Ap 16 Aug  008/017
Estimated Afr/Ap 17 Aug  012/012
Predicted Afr/Ap 18 Aug-20 Aug  050/070-018/020-012/015

VI.  Geomagnetic Activity Probabilities 18 Aug-20 Aug
A.  Middle Latitudes
Active                40/30/25
Minor storm           30/15/10
Major-severe storm    20/05/05
B.  High Latitudes
Active                40/30/25
Minor storm           30/15/10
Major-severe storm    20/10/05