:Product: 19990831RSGA.txt
:Issued: 1999 Aug 31 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 243 ISSUED AT 2200Z ON 31 AUG 1999
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  30/2100Z
TO 31/2100Z:  SOLAR ACTIVITY RETURNED TO LOW LEVELS. REGION 8681
(N22W30) PRODUCED FOUR MID TO HIGH LEVEL C-CLASS EVENTS. THE LARGEST
WAS A C8/SF AT 31/0554Z. THIS REGION BEGAN TO DECAY BUT RETAINED ITS
ANOMALOUS MAGNETIC STRUCTURE. IN PARTICULAR, THE CENTER NEGATIVE
FIELDS HAVE BECOME PINCHED. REGION 8674 (S23W60) CONTINUED TO DECAY
AND PRODUCED ONLY A FEW MINOR SUBFLARES. THIS REGION RETAINED SOME
MIXED POLARITIES BUT THE DELTA CONFIGURATION APPEARED TO FADE. THE
M3/2B FROM REGION 8681 AT 30/1805Z DID IN FACT PRODUCE A CORONAL
MASS EJECTION. HOWEVER, THE CME WAS FAIRLY NARROW IN LONGITUDINAL
EXTENT AND APPEARED TO PROPAGATE NORTHWARD OUT OF THE ECLIPTIC
PLANE.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY SHOULD BE LOW TO
MODERATE FOR THE NEXT THREE DAYS. REGIONS 8681 AND 8674 REMAIN
CAPABLE OF PRODUCING ISOLATED M-CLASS EVENTS BUT THAT CAPABILITY IS
EXPECTED TO DECREASE AS DECAY IN THESE REGIONS CONTINUES. THE
POSSIBILITY OF A DECAY PHASE MAJOR FLARE FROM REGION 8674 REMAINS.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 30/2100Z TO 31/2100Z:
THE GEOMAGNETIC FIELD WAS PRIMARILY UNSETTLED TO ACTIVE. THE MOST
DISTURBED PERIOD WAS FROM 31/0600-1200Z.  SOLAR WIND VELOCITY
INCREASED SLOWLY DURING THE PERIOD TO NEAR 600 KM/S BUT NO SHOCKS
WERE OBSERVED. ENERGETIC ELECTRON FLUXES AT GEOSYNCHRONOUS ORBIT
REACHED HIGH LEVELS DURING THE PERIOD.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD SHOULD BE
PREDOMINANTLY QUIET TO UNSETTLED FOR THE NEXT THREE DAYS. ISOLATED
ACTIVE CONDITIONS ARE POSSIBLE DURING THAT TIME DUE TO OBLIQUE
IMPACTS FROM RECENT CMES THAT WERE NOT DIRECTLY AIMED AT THE EARTH.
THERE IS A SLIGHT POSSIBILITY OF A SOLAR PROTON EVENT FROM REGION
8674 DURING THE PERIOD.
III.  EVENT PROBABILITIES 01 SEP-03 SEP
CLASS M    50/40/30
CLASS X    20/20/15
PROTON     15/15/10
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           31 AUG 183
PREDICTED   01 SEP-03 SEP  175/160/148
90 DAY MEAN        31 AUG 169
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 30 AUG  013/020
ESTIMATED AFR/AP 31 AUG  014/015
PREDICTED AFR/AP 01 SEP-03 SEP  012/012-010/012-010/012
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 01 SEP-03 SEP
A.  MIDDLE LATITUDES
ACTIVE                30/25/20
MINOR STORM           15/10/10
MAJOR-SEVERE STORM    05/05/05
B.  HIGH LATITUDES
ACTIVE                30/30/25
MINOR STORM           15/15/10
MAJOR-SEVERE STORM    05/05/05