:Product: 19990915RSGA.txt
:Issued: 1999 Sep 15 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 258 ISSUED AT 2200Z ON 15 SEP 1999
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  14/2100Z
TO 15/2100Z:  SOLAR ACTIVITY WAS LOW. A LONG DURATION OPTICALLY
UNCORRELATED C2.9 X-RAY EVENT WAS THE LARGEST EVENT OF THE PERIOD.
INFREQUENT MINOR C-CLASS X-RAY EVENTS WERE OBSERVED, MOSTLY WITHOUT
OPTICAL CORRELATION. REGION 8700 (N14E45) APPEARS AS THE MOST ACTIVE
REGION ON THE VISIBLE DISK, UNDERGOING SEVERAL BRIGHTNESS
FLUCTUATIONS AND SUBFLARES. REGION 8690 (N15W48) CONTINUES TO SLOWLY
GROW AND APPEARS TO HAVE BECOME MORE MAGNETICALLY COMPLEX. REMAINING
REGIONS WERE STABLE OR IN DECAY.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO CONTINUE
AT LOW LEVELS. REGIONS 8690 AND 8700 WILL LIKELY PRODUCE C-CLASS
EVENTS WITH A SMALL CHANCE FOR AN ISOLATED M-CLASS FLARE.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 14/2100Z TO 15/2100Z:
THE GEOMAGNETIC FIELD WAS QUIET TO ACTIVE PRIOR TO A SHOCK ARRIVAL AT
15/0700Z. A SHORT PERIOD OF SUSTAINED SOUTHWARD BZ WITH A 700 KM/S
WINDSPEED FOLLOWED THE SHOCK ARRIVAL AND RESULTED IN MINOR STORM
CONDITIONS AT MID LATITUDES WITH SEVERE STORMING AT HIGH LATITUDES.
QUIET TO ACTIVE CONDITIONS RETURNED TO ALL LATITUDES AFTER
15/1200UT. A SUDDEN IMPULSE OF 8NT WAS OBSERVED AT 15/2019UT.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE AT QUIET TO ACTIVE LEVELS DURING DAYTIME HOURS AND
ACTIVE TO MINOR STORM LEVELS DURING LOCAL NIGHTTIME. THIS
DISTURBANCE WILL BEGIN TO SUBSIDE ON DAY ONE THROUGH DAY TWO. QUIET
TO UNSETTLED CONDITIONS ARE LIKELY ON DAY THREE.
III.  EVENT PROBABILITIES 16 SEP-18 SEP
CLASS M    15/15/15
CLASS X    05/05/05
PROTON     05/05/05
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           15 SEP 155
PREDICTED   16 SEP-18 SEP  160/165/170
90 DAY MEAN        15 SEP 164
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 14 SEP  022/023
ESTIMATED AFR/AP 15 SEP  026/030
PREDICTED AFR/AP 16 SEP-18 SEP  022/020-012/015-008/012
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 16 SEP-18 SEP
A.  MIDDLE LATITUDES
ACTIVE                50/35/25
MINOR STORM           30/15/10
MAJOR-SEVERE STORM    05/05/05
B.  HIGH LATITUDES
ACTIVE                60/40/30
MINOR STORM           30/20/10
MAJOR-SEVERE STORM    10/05/05