Joint USAF/NOAA Report of Solar and Geophysical Activity 20 Apr 2003

SDF Number 110 Issued at 2200Z on 20 Apr 2003

IA. Analysis of Solar Active Regions and Activity from 19/2100Z
to 20/2100Z: Solar activity has been low. Region 339 (N18W45) has
rapidly increased in complexity over the last 24 hours, and was
numbered today.

IB. Solar Activity Forecast: Solar activity is expected to be low.
Regions 337 (S14E55) and 339 (N18W45) harbor the greatest potential
for flare activity.

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field has been at quiet to unsettled levels. The
greater than 2 MeV fluxes at geosynchronous orbit reached high
levels today.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at quiet to unsettled levels for the next 24 hours,
increasing to unsettled to active levels on days 2 and 3 due to a
favorably positioned coronal hole.

III. Event Probabilities 21 Apr-23 Apr

• Class M 25/25/25
• Class X 05/05/05
• Proton 01/01/01
• PCAF green

IV. Penticton 10.7 cm Flux

• Observed 20 Apr 119
• Predicted 21 Apr-23 Apr 125/125/130
• 90 Day Mean 20 Apr 126

V. Geomagnetic A Indices

• Observed Afr/Ap 19 Apr 010/018
• Estimated Afr/Ap 20 Apr 017/014
• Predicted Afr/Ap 21 Apr-23 Apr 012/012-015/015-015/015

VI. Geomagnetic Activity Probabilities 21 Apr-23 Apr

A. Middle Latitudes

• Active 30/35/35
• Minor storm 15/15/15
• Major-severe storm 05/05/05

B. High Latitudes
Active 40/45/45

• Minor storm 20/20/20
• Major-severe storm 05/05/05