Joint USAF/NOAA Report of Solar and Geophysical Activity 21 Apr 2008

Product: Report of Solar-Geophysical Activity
Issued: 2008 Apr 21 2200 UTC
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Weather Prediction Center and the U.S. Air Force.

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 112 Issued at 2200Z on 21 Apr 2008

IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity was very low. No flares occurred during the past 24 hours. The solar disk is void of spots.

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

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field was mostly quiet during the past 24 hours.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected be quiet for most of the first day (22 April). However, an increase to unsettled with a chance for isolated active periods is expected late on the first day (22 April) or early on the second day (23 April) with the onset of a high speed solar wind stream. Unsettled levels with occasional active periods are expected to persist for the second and third days (23-24 April).

III. Event Probabilities 22 Apr-24 Apr

• Class M 01/01/01
• Class X 01/01/01
• Proton 01/01/01
• PCAF Green

IV. Penticton 10.7 cm Flux

• Observed 21 Apr 071
• Predicted 22 Apr-24 Apr 075/075/075
• 90 Day Mean 21 Apr 072

V. Geomagnetic A Indices

• Observed Afr/Ap 20 Apr 001/004
• Estimated Afr/Ap 21 Apr 005/005
• Predicted Afr/Ap 22 Apr-24 Apr 008/008-015/015-012/012

VI. Geomagnetic Activity Probabilities 22 Apr-24 Apr

A. Middle Latitudes

• Active 25/40/35
• Minor storm 10/15/15
• Major-severe storm 05/05/05

B. High Latitudes

• Active 25/45/40
• Minor storm 15/20/20
• Major-severe storm 05/10/10