Joint USAF/NOAA Report of Solar and Geophysical Activity 11 Apr 2003

SDF Number 101 Issued at 2200Z on 11 Apr 2003

IA. Analysis of Solar Active Regions and Activity from 10/2100Z
to 11/2100Z: Solar activity was low. A C7 x-ray event occurred at
0730 UTC, likely from a site beyond West limb. That was the day’s
largest event. Otherwise, a number of bright regions are appearing
in x-ray imagery along the East limb, possibly heralding the
imminent arrival of some active regions on the disk.

IB. Solar Activity Forecast: Solar activity is expected to be low.

IIA. Geophysical Activity Summary 10/2100Z to 11/2100Z:
The geomagnetic field was at quiet to active levels. The high speed
solar wind has slowed to speeds now near 600 km/s, and the wave
activity in the solar wind has diminished. The greater than 2 MeV
electron flux at geosynchronous orbit was high.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at generally unsettled levels for the next three days.
Remnants of the high speed stream may persist for the next day, but
in general, the geomagnetic field should calm over the interval.

III. Event Probabilities 12 Apr-14 Apr

• Class M 10/10/10
• Class X 01/01/01
• Proton 01/01/01
• PCAF green

IV. Penticton 10.7 cm Flux

• Observed 11 Apr 103
• Predicted 12 Apr-14 Apr 100/100/095
• 90 Day Mean 11 Apr 131

V. Geomagnetic A Indices

• Observed Afr/Ap 10 Apr 017/026
• Estimated Afr/Ap 11 Apr 012/015
• Predicted Afr/Ap 12 Apr-14 Apr 015/015-015/015-015/015

VI. Geomagnetic Activity Probabilities 12 Apr-14 Apr

A. Middle Latitudes

• Active 40/40/40
• Minor storm 20/20/20
• Major-severe storm 10/10/10

B. High Latitudes

• Active 50/50/50
• Minor storm 25/25/25
• Major-severe storm 10/10/10