:Product: 19990916RSGA.txt
:Issued: 1999 Sep 16 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 259 ISSUED AT 2200Z ON 16 SEP 1999
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  15/2100Z
TO 16/2100Z:  SOLAR ACTIVITY WAS LOW. THE LARGEST EVENT THIS PERIOD
WAS A C7/SF FROM REGION 8700 (N14E31). OCCASIONAL MINOR C-CLASS
SUBFLARES WERE ALSO OBSERVED IN REGIONS 8699 (N22W39) AND 8692
(S26W41). AN IMPRESSIVE DARK, 50 DEGREE FILAMENT ERUPTED FROM
NORTH-CENTER DISK. THIS FILAMENT WAS ACTIVE FOR MOST OF THE PAST 24
HOURS. ELEVATION WAS FIRST DETECTED AT AROUND 16/1230UT WITH THE
TOTAL ERUPTION OF THIS TWO-PART FILAMENT OCCURRING AT 16/1620UT. THE
EVENT WAS OBSERVED ON BOTH GROUND AND SPACE-BASED INSTRUMENTS WITH A
LARGE CME OBSERVED BY LASCO.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO REMAIN
LOW. SEVERAL EXISTING SUNSPOT REGIONS ARE CAPABLE OF PRODUCING
C-CLASS ACTIVITY WITH AN ISOLATED CHANCE FOR A LOW M-CLASS.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 15/2100Z TO 16/2100Z:
THE GEOMAGNETIC FIELD WAS AT QUIET TO MINOR STORM LEVELS WITH
ISOLATED MAJOR STORMING PERIODS AT HIGH LATITUDES. A SUSTAINED
PERIOD OF SOUTHWARD BZ AND A 600KM/S SOLAR WIND SPEED FOLLOWED A
SUDDEN IMPULSE (SI) OBSERVED AT 15/2019UT.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE QUIET TO ACTIVE WITH OCCASIONAL MINOR STORMING MOSTLY
AT HIGH LATITUDES. DAY TWO SHOULD BE LESS ACTIVE AS THE HIGH SPEED
STREAM SUBSIDES, EXPECT QUIET TO OCCASIONAL ACTIVE. WE MAY SEE THE
EFFECTS OF TODAY'S LARGE DSF ON DAY 3, LOOK FOR ACTIVE TO MINOR
STORM CONDITIONS POSSIBLE BY LATE DAY 3.
III.  EVENT PROBABILITIES 17 SEP-19 SEP
CLASS M    15/15/15
CLASS X    05/05/05
PROTON     05/05/05
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           16 SEP 158
PREDICTED   17 SEP-19 SEP  160/165/170
90 DAY MEAN        16 SEP 164
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 15 SEP  021/032
ESTIMATED AFR/AP 16 SEP  025/030
PREDICTED AFR/AP 17 SEP-19 SEP  020/025-015/020-012/012
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 17 SEP-19 SEP
A.  MIDDLE LATITUDES
ACTIVE                50/40/50
MINOR STORM           30/20/30
MAJOR-SEVERE STORM    10/05/10
B.  HIGH LATITUDES
ACTIVE                40/40/50
MINOR STORM           50/25/30
MAJOR-SEVERE STORM    10/05/10