Joint USAF/NOAA Report of Solar and Geophysical Activity 18 Aug 2002

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 230 Issued at 2200Z on 18 Aug 2002

IA.  Analysis of Solar Active Regions and Activity from  17/2100Z
to 18/2100Z:  Solar activity was at moderate levels.  Region 69
(S08W39) produced three M-class events, the largest an M2.3 at
18/1005 UTC (optically correlated via SOHO/LASCO EIT195 imagery). 
Region 69 has remained unchanged in area coverage and multiple
magnetic delta configurations.  Spot count has increased to 74 spots
due to the slight dissolution to the large central penumbra region. 
Region 79 (S22E04) has grown rapidly in area and spot count to 310
millionths and 38 spots.  New Region 84 (S16E64) was numbered today.

IB.  Solar Activity Forecast:  Solar activity is expected to be
moderate to high.  Region 69 has the potential for major flare
activity.

IIA.  Geophysical Activity Summary 17/2100Z to 18/2100Z:
The geomagnetic field was at quiet to unsettled  levels.  The
expected interplanetary shock from the M5/CME event on 16 Aug was
observed at the L1 position by the NASA/ACE spacecraft at 18/1810
UTC.  A corresponding sudden impulse of 27 nT was recorded on the
Boulder magnetometer at 18/1848 UTC.  Greater than 2 MeV electron
flux at geosynchronous orbit exceeded event threshold at 18/1420
UTC, reached a maximum value of 1590 pfu at 18/1655 UTC, and fell
below threshold value at 18/1905 UTC.

IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be quiet to active levels with a chance of isolated
minor storming.  Active levels are expected on day one of the
forecast period.  Quiet to unsettled conditions are expected for day
two and three of the period.

III.  Event Probabilities 19 Aug-21 Aug
Class M    80/80/80
Class X    20/20/20
Proton     15/15/15
PCAF       yellow

IV.  Penticton 10.7 cm Flux
Observed           18 Aug 241
Predicted   19 Aug-21 Aug  245/245/230
90 Day Mean        18 Aug 168

V.  Geomagnetic A Indices
Observed Afr/Ap 17 Aug  008/013
Estimated Afr/Ap 18 Aug  015/020
Predicted Afr/Ap 19 Aug-21 Aug  025/025-012/012-010/010

VI.  Geomagnetic Activity Probabilities 19 Aug-21 Aug
A.  Middle Latitudes
Active                50/30/25
Minor storm           30/15/10
Major-severe storm    20/05/01
B.  High Latitudes
Active                40/30/25
Minor storm           30/15/10
Major-severe storm    20/10/01