:Product: 19980502RSGA.txt
:Issued: 1998 May 02 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 122 ISSUED AT 2200Z ON 02 MAY 1998
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  01/2100Z
TO 02/2100Z:  SOLAR ACTIVITY HAS BEEN HIGH FOR THE PAST 24 HOURS.
REGION 8210 (S17W21) PRODUCED AN  X1/3B TENFLARE (1300 FLUX UNITS)
THAT REACHED MAXIMUM AT 02/1342 UT. IT WAS ACCOMPANIED BY A
PARTIAL-HALO CORONAL MASS EJECTION (REPORTED BY SOHO/LASCO
OPERATIONS), SIGNIFICANT RADIO BURSTS ACROSS THE SPECTRUM AND A TYPE
IV SWEEP.  THE CME WAS CONCENTRATED OFF THE NW LIMB AND THE MEASURED
SPEED WAS APPROXIMATELY 750 KM/S. REGION 8210 ALSO PARTICIPATED IN
AN M1 X-RAY EVENT ON 01/2254 UT SHARED WITH REGION 8214 (N27E19).
THIS EARLIER EVENT MAY ALSO BE ASSOCIATED WITH A PARTIAL-HALO CME
CONCENTRATED OFF THE NE LIMB. REGION 8210 IS EXTREMELY MAGNETICALLY
COMPLEX, AND REGIONS 8210 AND 8214 ARE BOTH CONTINUING TO GROW IN
SIZE AND SPOT COUNT. NEW REGION 8217 (S17E77), A SIMPLE A-TYPE
GROUP, WAS NUMBERED TODAY. THERE ARE CONTINUING INDICATIONS OF
ACTIVE REGIONS BEYOND THE EAST LIMB THAT WILL BE ROTATING ONTO THE
DISK IN THE NEXT FEW DAYS.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO PERSIST
AT MODERATE TO HIGH LEVELS. REGION 8210 RETAINS THE EXTREME MAGNETIC
COMPLEXITY ASSOCIATED WITH MAJOR X-RAY EVENTS, AND THE PROBABILITY
OF SIGNIFICANT ACTIVITY FROM REGION 8214 IS INCREASING AS IT
CONTINUES TO DEVELOP.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 01/2100Z TO 02/2100Z:
GEOMAGNETIC ACTIVITY REACHED PERIODS AT MAJOR STORM LEVELS DURING THE
PAST 24 HOURS. THE STORM SUDDEN COMMENCEMENT OCCURRED AT 01/2158 UT.
IT IS PRESUMED TO HAVE ORIGINATED WITH A MAJOR SOLAR EVENT ON 29
APRIL. PRECEDING THE SSC, THE PASSAGE OF AN INTERPLANETARY SHOCK WAS
OBSERVED IN ACE SOLAR WIND DATA AT APPROXIMATELY 01/2124 UT. A
GREATER THAN 100 MEV SATELLITE PROTON EVENT BEGAN 02/1405 AND
REACHED 7.6 PFU AT 1540 UT. A GREATER THAN 10 MEV SATELLITE PROTON
EVENT  BEGAN AT 02/1420UT AND REACHED 150 PFU AT 1650 UT.  BOTH
EVENTS ARE STILL IN PROGRESS AT REPORT ISSUE TIME. A POLAR CAP
ABSORPTION EVENT IS IN PROGRESS, AS WELL AS A FORBUSH DECREASE OF
APPROXIMATELY 5 PERCENT.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  GEOMAGNETIC ACTIVITY IS
EXPECTED TO DECLINE TOWARD GENERALLY UNSETTLED TO ACTIVE CONDITIONS
TOMORROW, BUT A NEW STORM COMMENCEMENT IS EXPECTED AFTER MIDDAY ON
04 MAY FROM THE X-CLASS SOLAR ACTIVITY ON 02 MAY. MAJOR STORM
CONDITIONS ARE PROBABLE ON 05 MAY. THE SATELLITE PROTON EVENT AT
GREATER THAN 10 MEV ENERGIES IS EXPECTED TO PERSIST THROUGH 04 MAY,
AND COULD CONTINUE LONGER IF NEW SOLAR ACTIVITY OCCURS.
III.  EVENT PROBABILITIES 03 MAY-05 MAY
CLASS M    50/50/50
CLASS X    30/30/30
PROTON     30/30/30
PCAF       IN PROGRESS
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           02 MAY 117
PREDICTED   03 MAY-05 MAY  130/140/150
90 DAY MEAN        02 MAY 104
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 01 MAY  008/008
ESTIMATED AFR/AP 02 MAY  045/060
PREDICTED AFR/AP 03 MAY-05 MAY  020/035-020/020-050/050
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 03 MAY-05 MAY
A.  MIDDLE LATITUDES
ACTIVE                30/25/10
MINOR STORM           25/15/20
MAJOR-SEVERE STORM    11/21/60
B.  HIGH LATITUDES
ACTIVE                25/35/10
MINOR STORM           30/20/20
MAJOR-SEVERE STORM    16/11/60