:Product: 19981219RSGA.txt
:Issued: 1998 Dec 19 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 353 ISSUED AT 2200Z ON 19 DEC 1998
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  18/2100Z
TO 19/2100Z:  SOLAR ACTIVITY WAS LOW. REGION 8415 (N20E50) PRODUCED A
C4/SF AT 19/1436Z AND REGION 8406 (S26W85) PRODUCED A C1/SF AT
19/0949Z. REGION 8415 EXHIBITED MIXED POLARITIES IN RECENT
MAGNETOGRAMS. SMALL SPOTS RE-EMERGED IN REGION 8414 (N27E14) DURING
THE PERIOD. MORE DATA BECAME AVAILABLE REGARDING THE M8/2N FLARE
FROM REGION 8415 AT 18/1722Z. THIS FLARE WAS COINCIDENT WITH A LONG
DURATION X-RAY EVENT (ESTIMATED AT M2) FROM A FILAMENT DISRUPTION
AND PARALLEL RIBBON FLARE FROM AN AREA VERY NEAR REGION 8414. THE
PARTIAL HALO CORONAL MASS EJECTION MENTIONED YESTERDAY APPEARS AT
THIS TIME TO BE NEARLY A FULL HALO. IT IS NOT POSSIBLE TO ACCURATELY
DETERMINE THE DENSITY EACH EVENT CONTRIBUTED TO THE HALO CME BUT THE
MAJORITY OF MATERIAL SHOULD BE RELATED TO THE DISAPPEARING FILAMENT
AND LDE.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY SHOULD BE LOW TO
MODERATE. REGIONS 8415 AND 8409 ARE CAPABLE OF PRODUCING OCCASIONAL
M-CLASS EVENTS. THE FILAMENT IN REGION 8414 REFORMED AND MAY ERUPT
AGAIN WITH ANOTHER LARGE LDE/CME PRIOR TO WEST LIMB TRANSIT.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 18/2100Z TO 19/2100Z:
THE GEOMAGNETIC FIELD WAS QUIET. SOLAR WIND PARAMETERS WERE VARIABLE
(TOTAL FIELD AND DENSITY INCREASES AND PERIODS OF BZ SOUTHWARD) AT
THE END OF THE PERIOD BUT HAD LITTLE EFFECT ON THE FIELD.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD SHOULD BE
QUIET TO UNSETTLED THROUGH MIDDAY ON 21 DEC. THEN, GENERALLY
UNSETTLED TO ACTIVE CONDITIONS ARE FORECAST TO BEGIN BASED UPON THE
HALO CME MENTIONED ABOVE. THIS DISTURBANCE SHOULD CONTINUE THROUGH
22 DEC. OCCASIONAL MINOR STORM CONDITIONS ARE POSSIBLE DURING THE
DISTURBANCE AND HIGH LATITUDES COULD EXPERIENCE BRIEF PERIODS OF
MAJOR STORMING.
III.  EVENT PROBABILITIES 20 DEC-22 DEC
CLASS M    50/50/40
CLASS X    10/10/05
PROTON     05/05/05
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           19 DEC 138
PREDICTED   20 DEC-22 DEC  135/130/128
90 DAY MEAN        19 DEC 133
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 18 DEC  001/003
ESTIMATED AFR/AP 19 DEC  003/009
PREDICTED AFR/AP 20 DEC-22 DEC  008/012-018/018-025/025
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 20 DEC-22 DEC
A.  MIDDLE LATITUDES
ACTIVE                15/30/30
MINOR STORM           10/20/20
MAJOR-SEVERE STORM    01/20/20
B.  HIGH LATITUDES
ACTIVE                20/25/25
MINOR STORM           10/25/25
MAJOR-SEVERE STORM    01/30/30