Status Report

Joint USAF/NOAA Report of Solar and Geophysical Activity 21 Apr 2005

By SpaceRef Editor
April 21, 2005
Filed under , ,

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2005 Apr 21 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 111 Issued at 2200Z on 21 Apr 2005

IA. Analysis of Solar Active Regions and Activity from 20/2100Z
to 21/2100Z: Solar activity was very low. Regions 752 (N03W55) and
755 (S12E21) continue to decay. X-ray flux background is down to
approximately A2 level. No new regions were numbered today.

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

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z:
The geomagnetic field was quiet to unsettled.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be quiet to unsettled early on 22 April. A geoeffective
coronal hole high speed stream is expected to increase conditions
later in the day. Unsettled to active with minor storm periods are
possible late on 22 April continuing into early 23 April.
Conditions are expected to settle down on 24 April to mostly quiet
to unsettled.

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 077
  • Predicted 22 Apr-24 Apr 080/080/080
  • 90 Day Mean 21 Apr 091

V. Geomagnetic A Indices

  • Observed Afr/Ap 20 Apr 012/021
  • Estimated Afr/Ap 21 Apr 005/010
  • Predicted Afr/Ap 22 Apr-24 Apr 015/020-012/020-008/015

VI. Geomagnetic Activity Probabilities 22 Apr-24 Apr

A. Middle Latitudes

  • Active 30/30/20
  • Minor storm 15/15/10
  • Major-severe storm 05/05/01

B. High Latitudes

  • Active 40/40/30
  • Minor storm 15/15/15
  • Major-severe storm 10/10/05

SpaceRef staff editor.