:Product: 19981229RSGA.txt
:Issued: 1998 Dec 29 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 363 ISSUED AT 2200Z ON 29 DEC 1998
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  28/2100Z
TO 29/2100Z:  SOLAR ACTIVITY WAS MODERATE. REGION 8419 (N26W52)
PRODUCED AN M2/1F FLARE AT 28/2338Z AND REGION 8421 (N26E00)
PRODUCED AN M1/1F AT 28/2322Z. REGION 8419 WAS ACTIVE AT THE
BEGINNING OF THE REPORTING PERIOD BUT BEGAN TO QUIET DOWN AROUND
29/0300Z. WHITE LIGHT OBSERVATIONS SHOW THE LOSS OF PENUMBRAL AREA
IN THE TRAILING PORTION OF THE REGION. THE MAGNETIC CONFIGURATION
HAS SIMPLIFIED TO A BETA-GAMMA CLASS. IN CONTRAST, REGION 8421 HAS
SHOWN SIGNIFICANT GROWTH OVER THE PAST 24 HOURS AND BEGAN PRODUCING
FREQUENT C-CLASS SUBFLARES DURING THE LAST 12 HOURS OF THE REPORTING
PERIOD. WHITE LIGHT AND MAGNETIC OBSERVATIONS SHOW A LARGE, COMPACT
SUNSPOT GROUP WITH AT LEAST ONE, AND POSSIBLY TWO DELTA
CONFIGURATIONS. THE MAIN INVERSION LINE RUNS FROM EAST-NORTHEAST TO
WEST-SOUTHWEST THROUGH THE REGION.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE
MODERATE, BUT THERE IS A CHANCE FOR A MAJOR EVENT FROM REGION 8421
OVER THE NEXT THREE DAYS. IN PARTICULAR, CONTINUED FLUX EMERGENCE
AND DEVELOPMENT OF SHEAR ALONG THE NEUTRAL LINE OF THIS REGION COULD
LEAD TO SIGNFICANT FLARE ACTIVITY. REGION 8419 SEEMS TO BE MOSTLY
STABLE, BUT POSES SOME THREAT OF PRODUCING AN ISOLATED LOW-LEVEL
M-CLASS EVENT.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 28/2100Z TO 29/2100Z:
THE GEOMAGNETIC FIELD HAS BEEN PREDOMINANTLY QUIET TO ACTIVE OVER THE
PAST 24 HOURS, ALTHOUGH SOME HIGH LATITUDE SITES OBSERVED SHORT
INTERVALS OF STORM LEVEL ACTIVITY. YESTERDAY'S VERY QUIET CONDITIONS
CAME TO AN END AROUND 0730UT AFTER WHICH UNSETTLED TO ACTIVE LEVELS
PREVAILED. A FEW HIGH-LATITUDE STATIONS SAW SUBSTORM EFFECTS BETWEEN
1000-1400Z, BUT THE DISTURBANCE WASN'T STRONG ENOUGH TO PRODUCE
ACTIVE LEVELS AT MID-LATITUDES. THE LATTER PART OF THE DAY (FROM
1500-2100Z) WAS PREDOMINANTLY UNSETTLED WITH OCCASIONAL ACTIVE
PERIODS AT THE HIGHER LATITUDE SITES. REAL-TIME SOLAR WIND
OBSERVATIONS INDICATE SLIGHTLY ENHANCED DENSITY, VELOCITY AND
MAGNETIC FIELDS, AND SOMEWHAT LOW TEMPERATURES, SUGGESTING THAT THE
CURRENT ACTIVITY IS BEING CAUSED BY TRANSIENT MATERIAL IN THE SOLAR
WIND.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE MOSTLY UNSETTLED WITH OCCASIONAL ACTIVE PERIODS OVER
THE NEXT 24 HOURS. GENERALLY UNSETTLED CONDITIONS ARE LIKELY TO
DOMINATE FOR THE SECOND AND THIRD DAYS AS THERE MAY BE SOME
SHORT-LIVED EFFECTS FROM A SMALL, BUT FAVORABLY POSITIONED CORONAL
HOLE.
III.  EVENT PROBABILITIES 30 DEC-01 JAN
CLASS M    70/70/70
CLASS X    20/20/20
PROTON     15/15/20
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           29 DEC 183
PREDICTED   30 DEC-01 JAN  180/175/165
90 DAY MEAN        29 DEC 135
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 28 DEC  003/005
ESTIMATED AFR/AP 29 DEC  012/011
PREDICTED AFR/AP 30 DEC-01 JAN  012/015-012/010-010/010
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 30 DEC-01 JAN
A.  MIDDLE LATITUDES
ACTIVE                20/20/15
MINOR STORM           10/10/05
MAJOR-SEVERE STORM    05/05/01
B.  HIGH LATITUDES
ACTIVE                45/45/35
MINOR STORM           25/25/20
MAJOR-SEVERE STORM    10/10/05