:Product: 20020418RSGA.txt
:Issued: 2002 Apr 18 2200 UTC
# 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 108 Issued at 2200Z on 18 Apr 2002
IA.  Analysis of Solar Active Regions and Activity from  17/2100Z
to 18/2100Z:  Solar activity was low. Only C-class flares occurred
over the past 24 hours. Some of these flares did not have an obvious
source on the visible disk and may have originated from beyond the
limb. Region 9906 (S14W55) remains large and complex but has shown
some sunspot decay and magnetic simplification. New Regions 9911
(S13E23) and 9912 (N11E28) were numbered.
IB.  Solar Activity Forecast:  Solar activity is expected to be
moderate. M-class activity is expected in Region 9906. A major flare
in this region remains a possibility.
IIA.  Geophysical Activity Summary 17/2100Z to 18/2100Z:
The geomagnetic field ranged from quiet to severe storm levels in
response to the CME that impacted the Earth early yesterday. ACE
solar wind information suggests that this CME has passed. The
geomagnetic field is currently at active levels. Yesterday's greater
than 10 MeV proton event has ended: start 17/1530 UTC, maximum flux
(24 pfu) 17/1540 UTC, and end 18/0035 UTC.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be at unsettled to active levels through the end of 18
April UTC. Another CME is expected to impact the Earth early on 19
April UTC from an LDE/CME that occurred on 17 April. Minor to major
storm conditions are possible for the 24-48 hours following this
CME's arrival. Geomagnetic activity is expected to decline to
unsettled to active levels by the end of the 3-day forecast period.
Another greater than 10 MeV proton event is possible if Region 9906
generates a major flare.
III.  Event Probabilities 19 Apr-21 Apr
Class M    75/50/40
Class X    10/05/01
Proton     10/05/01
PCAF       yellow
IV.  Penticton 10.7 cm Flux
Observed           18 Apr 188
Predicted   19 Apr-21 Apr  180/175/170
90 Day Mean        18 Apr 201
V.  Geomagnetic A Indices
Observed Afr/Ap 17 Apr  027/041
Estimated Afr/Ap 18 Apr  045/050
Predicted Afr/Ap 19 Apr-21 Apr  040/040-030/050-012/020
VI.  Geomagnetic Activity Probabilities 19 Apr-21 Apr
A.  Middle Latitudes
Active                50/50/30
Minor storm           30/20/10
Major-severe storm    20/10/05
B.  High Latitudes
Active                35/50/30
Minor storm           40/30/20
Major-severe storm    25/15/05