:Product: 19990424RSGA.txt
:Issued: 1999 Apr 24 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 114 ISSUED AT 2200Z ON 24 APR 1999
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  23/2100Z
TO 24/2100Z:  SOLAR ACTIVITY WAS VERY LOW. THE MOST IMPRESSIVE EVENT
OF THE PERIOD WAS A LARGE CORONAL MASS EJECTION FROM BEHIND THE NW
LIMB THAT PRODUCED A PROTON EVENT. EJECTA WAS FIRST OBSERVED AT
AROUND 24/1230Z AND THE LIKELY SOURCE WAS OLD REGION 8517 WHICH
ROTATED FROM VIEW EARLY ON 22 APRIL NEAR NORTH 20. THE REGION WAS
DEVELOPING AS IT ROTATED THE LIMB. REGION 8522 (N16E50) THOUGH
SMALL, PRODUCED THREE SUBFLARES WITH MINOR B-CLASS X-RAY BURSTS. NEW
REGIONS 8523 (N32E42) AND 8524 (N22E53) WERE NUMBERED TODAY.
REMAINING REGIONS WERE QUIET.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE VERY
LOW TO LOW.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 23/2100Z TO 24/2100Z:
THE GEOMAGNETIC FIELD WAS QUIET WITH ISOLATED UNSETTLED PERIODS AT
HIGH LATITUDES. A GREATER THAN 10 MEV PROTON EVENT BEGAN AT 24/1610Z
AND IS CURRENTLY IN PROGRESS. THE 10 PFU THRESHOLD WAS CROSSED AT
24/1840Z AND CONTINUES TO INCREASE SLOWLY, REACHING A MAXIMUM OF 22
PFU LATE IN THE PERIOD. NO ENHANCEMENTS WERE OBSERVED YET ON THE
GREATER THAN 100 MEV FLUX AND POLAR CAP ABSORPTION WAS JUST UNDER 1
DB AT ISSUE TIME.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD SHOULD
REMAIN AT MOSTLY QUIET LEVELS. MATERIAL FROM THIS MORNING'S CME IS
NOT EXPECTED TO IMPACT THE GEOMAGNETIC FIELD.
III.  EVENT PROBABILITIES 25 APR-27 APR
CLASS M    01/05/05
CLASS X    01/01/01
PROTON     01/01/01
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           24 APR 101
PREDICTED   25 APR-27 APR  105/110/115
90 DAY MEAN        24 APR 129
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 23 APR  004/005
ESTIMATED AFR/AP 24 APR  007/007
PREDICTED AFR/AP 25 APR-27 APR  010/010-010/010-010/010
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 25 APR-27 APR
A.  MIDDLE LATITUDES
ACTIVE                15/20/20
MINOR STORM           05/05/05
MAJOR-SEVERE STORM    01/01/01
B.  HIGH LATITUDES
ACTIVE                20/25/25
MINOR STORM           05/05/05
MAJOR-SEVERE STORM    01/01/01