:Product: 19980421RSGA.txt
:Issued: 1998 Apr 21 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 111 ISSUED AT 2200Z ON 21 APR 1998
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  20/2100Z
TO 21/2100Z:  SOLAR ACTIVITY WAS VERY LOW. THE ONLY ACTIVITY OF NOTE
WAS AN ERUPTIVE PROMINENCE THAT OCCURRED ON THE WEST LIMB NEAR N30.
NO OTHER ACTIVITY WAS NOTED WITH THIS ERUPTION. REGION 8205
(N21W53) DECAYED SLIGHTLY IN WHITE LIGHT AREA BUT IS STILL
EXHIBITING OCCASIONAL PLAGE FLUCTUATIONS AND SURGING. THE REMAINING
REGIONS HAVE BEEN QUIET.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE VERY
LOW TO LOW. REGION 8205 HAS POTENTIAL TO PRODUCE AN ISOLATED C-CLASS
FLARE. STILL A SLIGHT CHANCE FOR FURTHER ACTIVITY NEAR THE SW LIMB -
THE SOURCE OF YESTERDAY'S M1 X-RAY FLARE; HOWEVER, THE LIKELY SOURCE
REGION HAS PROBABLY ROTATED ENOUGH TO ELIMINATE CONCERN.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 20/2100Z TO 21/2100Z:
THE GEOMAGNETIC FIELD WAS QUIET TO UNSETTLED. THE GREATER THAN 10 MEV
PROTON EVENT THAT BEGAN AT 20/1130Z IS STILL IN PROGRESS. A MAXIMUM
VALUE OF 1700 PFU WAS REACHED AT 21/1205. THE EVENT APPEARS TO BE
IN DECLINE NOW WITH A CURRENT VALUE OF 640 PFU. THE GREATER THAN 100
MEV EVENT PEAKED AT 7.4 PFU AT 21/1255Z AND IS CURRENTLY AT 2.5 PFU.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO CONTINUE AT QUIET TO UNSETTLED LEVELS. AN EXTENSION OF
THE SOUTHERN CORONAL HOLE WILL MOVE INTO FAVORABLE POSITION FOR
GEOEFFECTIVNESS ON DAY TWO AND THREE. EXPECT OCCASIONAL ACTIVE
PERIODS DURING THIS PERIOD. THE PROTON EVENT IN PROGRESS IS EXPECTED
TO LAST THROUGH TOMORROW.
III.  EVENT PROBABILITIES 22 APR-24 APR
CLASS M    05/05/05
CLASS X    01/01/01
PROTON     05/05/01
PCAF       IN PROGRESS
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           21 APR 92
PREDICTED   22 APR-24 APR  092/090/090
90 DAY MEAN        21 APR 104
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 20 APR  009/010
ESTIMATED AFR/AP 21 APR  007/010
PREDICTED AFR/AP 22 APR-24 APR  012/010-012/015-012/020
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 22 APR-24 APR
A.  MIDDLE LATITUDES
ACTIVE                15/30/30
MINOR STORM           05/05/05
MAJOR-SEVERE STORM    01/01/01
B.  HIGH LATITUDES
ACTIVE                20/40/45
MINOR STORM           10/10/10
MAJOR-SEVERE STORM    01/06/06