:Product: 19990913RSGA.txt
:Issued: 1999 Sep 13 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 256 ISSUED AT 2200Z ON 13 SEP 1999
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  12/2100Z
TO 13/2100Z:  SOLAR ACTIVITY WAS LOW. THE LARGEST EVENT THIS PERIOD
WAS A C4/SF FROM REGION 8699 (N21E01), WHICH OCCURRED AT 13/0846UT.
THE RAPID GROWTH NOTED IN THIS REGION OVER THE PAST 48 HOURS
SUBSIDED DURING THE LATTER HALF OF THIS PERIOD. THE REGION RETAINS A
MODERATELY COMPLEX MAGNETIC STRUCTURE BUT HAS RELATIVELY SMALL WHITE
LIGHT AERIAL COVERAGE. REGION 8690 (N14W06) EXHIBITED GROWTH,
PRODUCED OCCASIONAL SUBFLARES LATE IN THE PERIOD AND WAS THE LIKELY
SOURCE FOR A TYPE II SWEEP AT 13/1622UT. NEW REGION 8701 (N18E13),
WAS NUMBERED TODAY.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE LOW.
SEVERAL EXISTING REGIONS HAVE C-CLASS FLARE POTENTIAL WITH A SMALL
CHANCE OF AN ISOLATED M-CLASS EVENT.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 12/2100Z TO 13/2100Z:
THE GEOMAGNETIC FIELD WAS AT UNSETTLED TO MINOR STORM CONDITIONS WITH
AN ISOLATED MAJOR STORM PERIOD OBSERVED BETWEEN 13/0000 - 0300Z.
THIS DISTURBANCE IS LIKELY ASSOCIATED WITH A HIGH-SPEED CORONAL HOLE
WIND STREAM.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO  CONTINUE AT UNSETTLED TO MINOR STORM LEVELS WITH THE
MOST DISTURBED CONDITIONS EXPECTED DURING LOCAL NIGHTTIME HOURS.
III.  EVENT PROBABILITIES 14 SEP-16 SEP
CLASS M    20/20/20
CLASS X    05/05/05
PROTON     05/05/05
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           13 SEP 155
PREDICTED   14 SEP-16 SEP  160/165/170
90 DAY MEAN        13 SEP 164
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 12 SEP  020/026
ESTIMATED AFR/AP 13 SEP  032/040
PREDICTED AFR/AP 14 SEP-16 SEP  025/025-018/015-018/015
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 14 SEP-16 SEP
A.  MIDDLE LATITUDES
ACTIVE                50/50/40
MINOR STORM           20/20/15
MAJOR-SEVERE STORM    10/10/05
B.  HIGH LATITUDES
ACTIVE                60/60/50
MINOR STORM           30/30/25
MAJOR-SEVERE STORM    10/10/05