:Product: 19980818RSGA.txt
:Issued: 1998 Aug 18 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 230 ISSUED AT 2200Z ON 18 AUG 1998
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  17/2100Z
TO 18/2100Z:  SOLAR ACTIVITY HAS BEEN HIGH.  TWO X LEVEL (1.2 AT
17/2120UT AND 2.8 AT 18/0818UT)AND ONE M LEVEL (1.5 AT 18/0414UT)
X-RAY EVENTS HAVE OCCURRED IN THE LAST 24 HOURS.  THEY ARE BEING
ASSOCIATED WITH REGION 8307 (N30E77) WHICH IS IN THE PROCESS OF
CROSSING THE LIMB.  OPTICAL AND X-RAY SENSORS HAVE SHOWN CORONAL
LOOPS AND RAIN AS WELL AS ACTIVE SURGES AND BRIGHTENINGS.  A SINGLE
SPOT HAS COME OVER THE LIMB AT TIME OF ISSUE, BUT OF UNKNOWN TYPE.
SUB-FAINT FLARES HAVE OCCURRED IN REGIONS 8297 (N32W80) AND 8299
(N16W69).  A TYPE IV AND 10CM BURST WERE ASSOCIATED WITH THE X2.8
FLARE WHICH OCCURRED AT 0818UT.  NO PARTICLE, PCA, OR GLE EVENTS
HAVE TAKEN PLACE, AND THEY ARE NOT EXPECTED TO OCCUR.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE
MODERATE TO HIGH.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 17/2100Z TO 18/2100Z:
THE GEOMAGNETIC FIELD HAS BEEN QUIET.  A CORONAL HOLE WHICH EXTENDS
FROM THE NORTHERN POLE TO ALMOST N30 IS BELIEVED TO BE MOVING ACROSS
THE CENTRAL MERIDIAN AND INTO A GEOEFFECTIVE POSITION.  THREE DSFS
OCCURRED IN THE LAST 24 HOURS.  THE SIZES AND LOCATIONS WERE  9 DEG
AT S30E22 ENDING AT 17/2332, 15 DEG AT N44W38 ENDING AT 17/2332, AND
10 DEG AT S51E16 ENDING AT 18/1150.  THESE COMBINED WITH AN EXPECTED
HIGH SPEED STREAM ARE CAUSE FOR EXPECTING HIGHER GEOMAGNETIC
ACTIVITY IN THE NEXT 3 DAYS.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE UNSETTLED TO ACTIVE WITH ISOLATED MINOR STORM
CONDITIONS AT HIGHER LATITUDES NEAR THE END OF THE DAY AND LATER IN
THE PERIOD.
III.  EVENT PROBABILITIES 19 AUG-21 AUG
CLASS M    75/75/75
CLASS X    25/30/30
PROTON     10/10/15
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           18 AUG 133
PREDICTED   19 AUG-21 AUG  140/140/145
90 DAY MEAN        18 AUG 114
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 17 AUG  001/005
ESTIMATED AFR/AP 18 AUG  005/010
PREDICTED AFR/AP 19 AUG-21 AUG  010/015-015/020-020/020
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 19 AUG-21 AUG
A.  MIDDLE LATITUDES
ACTIVE                10/20/20
MINOR STORM           05/10/10
MAJOR-SEVERE STORM    01/05/05
B.  HIGH LATITUDES
ACTIVE                15/25/25
MINOR STORM           05/10/15
MAJOR-SEVERE STORM    01/05/05