Status Report

Joint USAF/NOAA Report of Solar and Geophysical Activity 26 Apr 2004

By SpaceRef Editor
April 26, 2004
Filed under , ,

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.

Updated 2004 Apr 26 2200 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 117 Issued at 2200Z on 26 Apr 2004

IA. Analysis of Solar Active Regions and Activity from 25/2100Z
to 26/2100Z: Solar activity was low. There was only one C-class
event during the past 24 hours, a C2/Sf from Region 599 (N16E15) at
0242 UTC. Although this region emerged rapidly yesterday, the past
24 hours have see a noticeable decrease in spot area, flare
production, and overall brightness of the region. New Region 600
(N18W06) emerged on the disk today as a small beta-type sunspot

IB. Solar Activity Forecast: Solar activity is expected to be
predominantly low for the next three days. There is a slight chance
for an isolated M-class event.

IIA. Geophysical Activity Summary 25/2100Z to 26/2100Z:
The geomagnetic field was quiet to unsettled. Mostly quiet conditions
prevailed early in the day as solar wind signatures showed a gradual
declining trend in solar wind velocity with very weak interplanetary
magnetic field, up until around 1520 UTC. Beginning around 1520 UTC
a compression wave followed by some transient flow was observed:
density, velocity, temperature and magnetic field all increased over
a few minutes, and Bz showed a rotation over 2-3 hours from +5 to
around -7 nT. The geomagnetic field responded by an increase to
unsettled levels.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be predominantly unsettled for the next 24 hours (27
April). Quiet to unsettled levels are expected to prevail for the
second and third days (28-29 April).

III. Event Probabilities 27 Apr-29 Apr

  • Class M 15/15/15
  • Class X 01/01/01
  • Proton 01/01/01
  • PCAF green

IV. Penticton 10.7 cm Flux

  • Observed 26 Apr 100
  • Predicted 27 Apr-29 Apr 100/095/090
  • 90 Day Mean 26 Apr 107

V. Geomagnetic A Indices

  • Observed Afr/Ap 25 Apr 007/012
  • Estimated Afr/Ap 26 Apr 007/007
  • Predicted Afr/Ap 27 Apr-29 Apr 010/010-005/008-005/008

VI. Geomagnetic Activity Probabilities 27 Apr-29 Apr

A. Middle Latitudes

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

B. High Latitudes

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

SpaceRef staff editor.