NOAA/USAF Report of Solar-Geophysical Activity 26 November 2000

:Product: Report of Solar-Geophysical Activity
:Issued: 2000 Nov 26 2200 UT
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
#Space Environment Center and the U.S. Air Force.
#
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 331 Issued at 2200Z on 26 Nov 2000
IA.  Analysis of Solar Active Regions and Activity from  25/2100Z
to 26/2100Z:  Solar activity remained high. Region 9236 (N24W38)
produced an X4/2b at 26/1648 UTC. This flare included a Type II
radio sweep (1000 km/s estimated drift speed) and a 700 sfu radio
burst at 2695 MHz. This region also generated an M2/1f flare at
26/0308 UTC and several C-class subflares. The sunspot group remains
large and magnetically complex. Other disk regions were relatively
quiet.
IB.  Solar Activity Forecast:  Solar activity is expected to be high.
Region 9236 is capable of producing another major flare.
IIA.  Geophysical Activity Summary 25/2100Z to 26/2100Z:
The geomagnetic field ranged from quiet to minor storm levels. The
first of the expected CME's arrived at ACE at 26/0500 UTC. The
greater than 10 MeV proton event remains in progress. A new maximum
of 923 pfu was observed at 26/1955 UTC. The greater than 100 MeV
protons exceeded the event threshold at 26/1640 UTC and reached a
peak of 1.2 pfu at 26/1650 UTC. These particles have since dropped
below event level.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be at minor to major storm levels during the next 48
hours in response to the flare/CME activity of the last few days.
The greater than 10 MeV event is expected to remain in progress for
at least the next 24 hours. Another 100 MeV event is possible if
Region 9236 produces another significant flare.
III.  Event Probabilities 27 Nov-29 Nov
Class M    80/70/60
Class X    60/50/40
Proton     99/75/50
PCAF       in progress
IV.  Penticton 10.7 cm Flux
Observed           26 Nov 202
Predicted   27 Nov-29 Nov  205/205/200
90 Day Mean        26 Nov 175
V.  Geomagnetic A Indices
Observed Afr/Ap 25 Nov  004/007
Estimated Afr/Ap 26 Nov  020/025
Predicted Afr/Ap 27 Nov-29 Nov  050/060-030/045-020/025
VI.  Geomagnetic Activity Probabilities 27 Nov-29 Nov
A.  Middle Latitudes
Active                05/20/40
Minor storm           40/20/10
Major-severe storm    50/30/05
B.  High Latitudes
Active                10/20/50
Minor storm           30/40/10
Major-severe storm    60/35/05