Viewing archive of Tuesday, 18 August 1998
Solar activity report
Any mentioned solar flare in this report has a scaling factor applied by the Space Weather Prediction Center (SWPC). Because of the SWPC scaling factor, solar flares are reported as 42% smaller than for the science quality data. The scaling factor has been removed from our archived solar flare data to reflect the true physical units.
Report of Solar-Geophysical Activity 1998 Aug 18 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 230 Issued at 2200Z on 18 AUG 1998IA. 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 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 to 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 to 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% |
All times in UTC
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