:Product: 19980503RSGA.txt
:Issued: 1998 May 03 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 123 ISSUED AT 2200Z ON 03 MAY 1998
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  02/2100Z
TO 03/2100Z:  SOLAR ACTIVITY HAS BEEN LOW FOR THE PAST 24 HOURS.
REGIONS 8210 (S17W34) AND 8214 (N27E07) HAVE EACH PRODUCED C-CLASS
X-RAY EVENTS. NUMEROUS TYPE III RADIO BURSTS HAVE BEEN REPORTED.
REGION 8210 HAS STABILIZED IN GROWTH AND HAS LESSENED IN MAGNETIC
COMPLEXITY TO A BETA GAMMA CONFIGURATION. REGION 8214 HAS INCREASED
IN AREA AND DOUBLED IN SPOT COUNT SINCE YESTERDAY BUT STILL HAS A
SIMPLE (BETA) MAGNETIC CONFIGURATION.  THE REMAINDER OF THE DISK AND
LIMBS WERE QUIET. SOHO EIT IMAGES INDICATE NEW ACTIVITY OVER THE
EAST LIMB THAT WILL SOON ROTATE INTO VIEW.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE
MODERATE BASED ON THE COMBINED FLARE POTENTIAL IN REGIONS 8210 AND
8214.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 02/2100Z TO 03/2100Z:
GEOMAGNETIC ACTIVITY HAS BEEN AT UNSETTLED TO SEVERE STORM LEVELS
DURING THE PAST 24 HOURS. THIS DISTURBANCE BEGAN ON 01 MAY AND IS
ATTRIBUTED TO A SIGNIFICANT SOLAR EVENT ON 29 APRIL. SOLAR WIND DATA
FROM THE NASA/ACE SPACECRAFT SHOWED THAT THE SOLAR MASS EJECTION
PLASMA HAS NOW PASSED EARTH. A SMALL DISCONTINUITY IN THE SOLAR WIND
PASSED ACE AT APPROXIMATELY 1700 UT. THIS DISCONTINUITY WAS SEEN AS
A SUDDEN IMPULSE IN EARTH'S MAGNETIC FIELD AT ABOUT 1744 UT.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  GEOMAGNETIC ACTIVITY IS
EXPECTED TO BE UNSETTLED TO ACTIVE UNTIL THE ARRIVAL OF A NEW BLAST
OF SOLAR MATERIAL FROM THE MAJOR EVENT (X1 PROTON FLARE AND
PARTIAL-HALO CORONAL MASS EJECTION) OF 2 MAY. SHOCK ARRIVAL IS
EXPECTED NEAR MID-DAY ON 04 MAY, AND MAJOR GEOMAGNETIC STORM
CONDITIONS SHOULD ENSUE ON 5 MAY. THE DISTURBANCE IS EXPECTED TO
SUBSIDE BY THE END OF THE FORECAST PERIOD. THE ENERGETIC PROTON
EVENT IS EXPECTED TO END ON 04 MAY, BUT NEW SOLAR ACTIVITY FROM
REGION 8210 WOULD LIKELY PRODUCE ANOTHER PROTON EVENT BECAUSE OF ITS
FAVORABLE LONGITUDE ON THE SUN.
III.  EVENT PROBABILITIES 04 MAY-06 MAY
CLASS M    70/70/50
CLASS X    20/20/20
PROTON     20/20/20
PCAF       YELLOW
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           03 MAY 117
PREDICTED   04 MAY-06 MAY  130/140/150
90 DAY MEAN        03 MAY 105
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 02 MAY  041/056
ESTIMATED AFR/AP 03 MAY  045/055
PREDICTED AFR/AP 04 MAY-06 MAY  020/043-050/055-025/030
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 04 MAY-06 MAY
A.  MIDDLE LATITUDES
ACTIVE                25/10/30
MINOR STORM           15/20/25
MAJOR-SEVERE STORM    15/60/20
B.  HIGH LATITUDES
ACTIVE                25/10/30
MINOR STORM           20/25/30
MAJOR-SEVERE STORM    15/65/20