:Product: 19980428RSGA.txt
:Issued: 1998 Apr 28 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 118 ISSUED AT 2200Z ON 28 APR 1998
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  27/2100Z
TO 28/2100Z:  SOLAR ACTIVITY DROPPED PRECIPITOUSLY TO A VERY LOW
LEVEL. ONLY B-CLASS ENHANCEMENTS WERE OBSERVED. REGION 8210 (S17E31)
RETAINED ITS DELTA CONFIGURATION, DEVELOPED ADDITIONAL MIXED
POLARITIES, AND EXHIBITED MINOR GROWTH. H-ALPHA FIBRIL AND VECTOR
MAGNETOGRAPH DATA INDICATE STRONG SHEAR IN THIS REGION WHERE THE
DELTA IS LOCATED. A FILAMENT IN THIS REGION FADED RAPIDLY BETWEEN
28/1851-1914Z. TWO SMALL REGIONS EMERGED ON THE DISK NEAR S30W64 AND
S25E55 AND WERE NUMBERED AS REGIONS 8212 AND 8213 RESPECTIVELY.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY SHOULD BECOME LOW TO
MODERATE DURING THE NEXT THREE DAYS. REGION 8210 RETAINS THE
CAPABILITY OF PRODUCING ANOTHER SMALL X-CLASS EVENT. OLD REGION 8194
WILL BE RETURNING TO THE EAST LIMB NEAR S18 AROUND 01 MAY. THIS
REGION PRODUCED A LONG DURATION M1 FLARE ON 20 APR FROM SEVERAL DAYS
BEYOND THE WEST LIMB THAT RESULTED IN A LARGE SOLAR PROTON EVENT AT
EARTH. ACTIVITY LEVELS MAY INCREASE UPON THE RETURN OF THIS REGION.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 27/2100Z TO 28/2100Z:
THE GEOMAGNETIC FIELD WAS QUIET TO UNSETTLED. SOLAR WIND VELOCITIES
DECREASED DURING THE PERIOD TO BELOW 400 KM/S INDICATING AN END OF
THE CORONAL HOLE RELATED DISTURBANCE OF THE LAST SEVERAL DAYS.
ENERGETIC ELECTRON FLUXES AT GEOSYNCHRONOUS ORBIT WERE PREDOMINANTLY
HIGH.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD SHOULD BE
QUIET TO UNSETTLED UNTIL NEAR MIDDAY ON 29 APR WHEN A HALO CME
RELATED DISTURBANCE IS EXPECTED TO BEGIN. UNSETTLED TO MINOR STORM
CONDITIONS SHOULD BE EXPERIENCED FROM THAT TIME AND THROUGH 30 APR.
ISOLATED PERIODS OF MAJOR STORMING ARE POSSIBLE. PREDOMINANTLY
UNSETTLED TO ACTIVE CONDITIONS ARE EXPECTED ON 01 MAY AS THE
DISTURBANCE PASSES THE EARTH.
III.  EVENT PROBABILITIES 29 APR-01 MAY
CLASS M    20/20/25
CLASS X    15/15/15
PROTON     15/15/15
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           28 APR 098
PREDICTED   29 APR-01 MAY  099/100/103
90 DAY MEAN        28 APR 104
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 27 APR  012/014
ESTIMATED AFR/AP 28 APR  010/015
PREDICTED AFR/AP 29 APR-01 MAY  020/020-020/020-015/015
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 29 APR-01 MAY
A.  MIDDLE LATITUDES
ACTIVE                30/30/25
MINOR STORM           30/30/15
MAJOR-SEVERE STORM    10/10/05
B.  HIGH LATITUDES
ACTIVE                30/30/25
MINOR STORM           35/40/15
MAJOR-SEVERE STORM    15/15/05