:Product: 19990917RSGA.txt
:Issued: 1999 Sep 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 260 ISSUED AT 2200Z ON 17 SEP 1999
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  16/2100Z
TO 17/2100Z:  SOLAR ACTIVITY INCREASED TO MODERATE LEVELS. REGION
8690 (N16W74) SHOWED GRADUAL DECAY AS IT APPROACHED THE WEST LIMB.
IT PRODUCED AN M2/SF AT 17/0120Z. REGION 8700 (N13E20) SHOWED SOME
MIXED POLARITIES AS IT GRADUALLY DECAYED AND PRODUCED ISOLATED
C-CLASS SUBFLARES. A PARTIAL-HALO CME WAS OBSERVED FOLLOWING
YESTERDAY'S (16/1508 - 1615Z) 50-DEGREE DSF. NEW REGIONS 8702
(N22E15), 8703 (N21W92), AND 8704 (S21E63) WERE NUMBERED. REGION
8704 APPEARED TO BE THE RETURN OF OLD REGION 8674, WHICH PRODUCED
MAJOR FLARES DURING ITS PREVIOUS ROTATIONS. THUS FAR, IT HAS BEEN A
STABLE H-TYPE GROUP.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE LOW
WITH A SLIGHT CHANCE FOR AN M-CLASS FLARE FROM REGIONS 8690 AND
8700.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 16/2100Z TO 17/2100Z:
THE GEOMAGNETIC FIELD WAS AT QUIET TO ACTIVE LEVELS WITH PERIODS OF
MINOR TO MAJOR STORMING DETECTED AT HIGH LATITUDES. THE GREATER THAN
2 MEV ELECTRON FLUX REACHED HIGH LEVELS DURING THE PERIOD.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  GEOMAGNETIC FIELD ACTIVITY IS
EXPECTED TO BE AT MOSTLY QUIET TO UNSETTLED LEVELS DURING THE FIRST
DAY. ACTIVITY IS EXPECTED TO INCREASE TO ACTIVE TO MINOR STORM
LEVELS LATE ON 19 SEPTEMBER DUE TO YESTERDAY'S DSF/CME. STORM LEVELS
ARE EXPECTED TO CONTINUE THROUGH THE END OF THE PERIOD. THE GREATER
THAN 2 MEV ELECTRON FLUX IS EXPECTED TO BE AT MODERATE TO HIGH
LEVELS DURING THE PERIOD.
III.  EVENT PROBABILITIES 18 SEP-20 SEP
CLASS M    15/15/15
CLASS X    01/01/01
PROTON     01/01/01
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           17 SEP 158
PREDICTED   18 SEP-20 SEP  160/165/170
90 DAY MEAN        17 SEP 164
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 16 SEP  018/032
ESTIMATED AFR/AP 17 SEP  012/020
PREDICTED AFR/AP 18 SEP-20 SEP  015/015-015/015-030/030
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 18 SEP-20 SEP
A.  MIDDLE LATITUDES
ACTIVE                30/50/50
MINOR STORM           10/30/30
MAJOR-SEVERE STORM    05/10/10
B.  HIGH LATITUDES
ACTIVE                40/50/50
MINOR STORM           15/30/30
MAJOR-SEVERE STORM    05/10/10