:Product: 19990817RSGA.txt
:Issued: 1999 Aug 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 229 ISSUED AT 2200Z ON 17 AUG 1999
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  16/2100Z
TO 17/2100Z:  SOLAR ACTIVITY WAS LOW. REGION 8668 (N21E28), THE MOST
PROMINENT ON THE DISK, HAD TWO LONG-DURATION C-CLASS FLARES. THE
FIRST, A C2/SF AT 1323Z, LASTED NEARLY 90 MINUTES. THIS EVENT WAS
FOLLOWED SOON AFTER BY A C5/SF AT 1602Z THAT ENDURED FOR NEARLY
THREE AND ONE HALF HOURS. BOTH OF THESE EVENTS WERE RICH IN DISCRETE
RADIO BURSTS ACROSS THE SPECTRUM. REGION 8662 (S16W90) IS SURGING AS
IT TRANSITS THE LIMB.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE LOW.
REGION 8668 SHOULD CONTINUE TO PRODUCE C-CLASS FLARES. IF ADDITIONAL
GROWTH OCCURS THERE, M-CLASS EVENTS MAY EVENTUATE.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 16/2100Z TO 17/2100Z:
THE GEOMAGNETIC FIELD WAS AT ACTIVE TO MINOR STORM LEVELS THROUGHOUT
THE PERIOD. A HIGH SPEED SOLAR WIND STREAM, REGISTERING BETWEEN 500
AND 700 KM/S, CONTINUES TO BUFFET THE MAGNETOPAUSE. THE FLUX OF
GREATER THAN 2 MEV ELECTRONS AT GEOSYNCHRONOUS ORBIT REACHED HIGH
LEVELS FROM APPROXIMATELY 1500 TO 1800Z.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE UNSETTLED TO ACTIVE DURING THE NEXT 24 HOURS AS THE
EFFECT OF THE HIGH SPEED STREAM ABATES. CONDITIONS SHOULD CALM EVEN
FURTHER THEREAFTER, WITH STRICTLY UNSETTLED CONDITIONS PREVALENT BY
THE END OF THE INTERVAL.
III.  EVENT PROBABILITIES 18 AUG-20 AUG
CLASS M    15/15/15
CLASS X    01/01/01
PROTON     01/01/01
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           17 AUG 141
PREDICTED   18 AUG-20 AUG  150/155/165
90 DAY MEAN        17 AUG 163
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 16 AUG  025/029
ESTIMATED AFR/AP 17 AUG  025/035
PREDICTED AFR/AP 18 AUG-20 AUG  015/017-010/012-010/008
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 18 AUG-20 AUG
A.  MIDDLE LATITUDES
ACTIVE                35/25/20
MINOR STORM           10/05/05
MAJOR-SEVERE STORM    01/01/01
B.  HIGH LATITUDES
ACTIVE                45/30/25
MINOR STORM           10/10/10
MAJOR-SEVERE STORM    01/01/01