:Product: 19981218RSGA.txt
:Issued: 1998 Dec 18 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 352 ISSUED AT 2200Z ON 18 DEC 1998
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  17/2100Z
TO 18/2100Z:  SOLAR ACTIVITY WAS HIGH.  REGION 8415 (N19E61) PRODUCED
A M8/2N EVENT AT 18/1722Z WITH AN ASSOCIATED TYPE II SWEEP.  THE
TYPE II SPEED WAS ESTIMATED AT 1200 KM/S.  AN 880 SFU TENFLARE WAS
ALSO DETECTED DURING THE M8 X-RAY EVENT.  REGION 8415 ALSO PRODUCED
NUMEROUS C-CLASS X-RAY EVENTS DURING THE PERIOD.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE WITH CONTINUED C-CLASS EVENTS AND THE LIKELIHOOD OF MORE
M-CLASS X-RAY EVENTS FROM REGION 8415 OR REGION 8409 (S27W63).
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 17/2100Z TO 18/2100Z:
THE GEOMAGNETIC FIELD WAS QUIET. A CME WAS OBSERVED FROM SOHO LASCO
IMAGERY AT 18/1834Z IN ASSOCIATION WITH THE M8 X-RAY EVENT IN REGION
8415 EARLIER TODAY.  LASCO AND EIT REPORTED A PARTIAL HALO.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE QUIET, BECOMING QUIET TO UNSETTLED DURING THE THREE
DAY PERIOD.  NO SIGNIFICANT GEOMAGNETIC EFFECTS ARE EXPECTED FROM
THE X-RAY EVENT AT 18/1722Z UNTIL THE END OF THE PERIOD.
III.  EVENT PROBABILITIES 19 DEC-21 DEC
CLASS M    50/50/50
CLASS X    05/05/05
PROTON     01/01/01
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           18 DEC 155
PREDICTED   19 DEC-21 DEC  150/145/140
90 DAY MEAN        18 DEC 133
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 17 DEC  000/002
ESTIMATED AFR/AP 18 DEC  002/003
PREDICTED AFR/AP 19 DEC-21 DEC  005/009-008/009-008/009
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 19 DEC-21 DEC
A.  MIDDLE LATITUDES
ACTIVE                15/15/15
MINOR STORM           01/01/01
MAJOR-SEVERE STORM    01/01/01
B.  HIGH LATITUDES
ACTIVE                15/20/20
MINOR STORM           01/05/05
MAJOR-SEVERE STORM    01/01/01