:Product: 19990417RSGA.txt
:Issued: 1999 Apr 17 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 107 ISSUED AT 2200Z ON 17 APR 1999
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  16/2100Z
TO 17/2100Z:  SOLAR ACTIVITY WAS VERY LOW. TWO NEW REGIONS WERE
ASSIGNED TODAY: REGION 8518 NEAR S16E66 AND REGION 8519 NEAR N17W33.
TWO FILAMENTS ERUPTED DURING THE PERIOD: AN 8 DEGREE FILAMENT NEAR
S19W08 BETWEEN 16/2144UT AND 17/1116UT AND A 20 DEGREE FILAMENT NEAR
S32W15 BETWEEN 17/1640-1830UT.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE LOW
FOR THE NEXT THREE DAYS.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 16/2100Z TO 17/2100Z:
THE GEOMAGNETIC FIELD RANGED FROM UNSETTLED TO MAJOR STORM LEVELS. A
GEOMAGNETIC DISTURBANCE THAT BEGAN WITH A SUDDEN IMPULSE YESTERDAY
AT 16/1126Z INTENSIFIED INTO A GEOMAGNETIC STORM. MID-LATITUDES WERE
AT MINOR TO MAJOR STORM LEVELS ON THE 17TH FROM 00-09UT AND HIGH
LATITUDES WERE AT MAJOR TO SEVERE STORM LEVELS DURING THE SAME TIME
INTERVAL. THE DISTURBANCE SUBSIDED AFTER 0900Z WITH PREDOMINANTLY
UNSETTLED CONDITIONS PREVAILING FROM 1200 TO THE END OF THE DAY.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE MOSTLY UNSETTLED FOR THE NEXT 24 HOURS, AND IS
EXPECTED TO BE QUIET TO UNSETTLED FOR THE SECOND AND THIRD DAYS.
III.  EVENT PROBABILITIES 18 APR-20 APR
CLASS M    15/15/15
CLASS X    01/01/01
PROTON     01/01/01
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           17 APR 116
PREDICTED   18 APR-20 APR  114/112/110
90 DAY MEAN        17 APR 134
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 16 APR  013/014
ESTIMATED AFR/AP 17 APR  035/045
PREDICTED AFR/AP 18 APR-20 APR  010/010-005/010-010/012
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 18 APR-20 APR
A.  MIDDLE LATITUDES
ACTIVE                20/15/15
MINOR STORM           10/10/10
MAJOR-SEVERE STORM    05/01/01
B.  HIGH LATITUDES
ACTIVE                35/25/20
MINOR STORM           15/10/10
MAJOR-SEVERE STORM    10/05/05