Viewing archive of Monday, 27 April 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 Apr 27 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 117 Issued at 2200Z on 27 APR 1998IA. Analysis of Solar Active Regions and Activity from 26-2100Z to 27-2100Z SOLAR ACTIVITY BECAME HIGH. REGION 8210 (S17E43)
PRODUCED AN X1/2B AT 27/0920Z WITH A STRONG TYPE IV AND 950 SFU
BURST AT 2695 MHZ. THIS MODERATE DURATION EVENT WAS ACCOMPANIED BY A
CORONAL MORETON WAVE AND HALO CORONAL MASS EJECTION. REGION 8210
REMAINED A SMALL-MODERATE SIZE C-CLASS GROUP. HOWEVER, A MAGNETIC
DELTA CONFIGURATION FORMED IN THE NORTHERN PORTION OF THE REGION AND
LOCALIZED MAGNETIC GRADIENTS WERE HIGH. SMALL REGIONS WERE VISIBLE
NEARING THE NORTHEAST AND SOUTHEAST LIMBS.
IB. Solar Activity Forecast
SOLAR ACTIVITY SHOULD BE LOW TO
OCCASIONALLY MODERATE WITH REGION 8210 THE PROBABLE SOURCE REGION.
OBVIOUSLY, X-CLASS EVENTS ARE POSSIBLE BUT NOT CONSIDERED LIKELY DUE
TO THE SMALL AREAL COVERAGE OF THIS REGION IN WHITE LIGHT. CONTINUED
INCREASES IN MAGNETIC COMPLEXITY COULD MODIFY THIS FORECAST.
IIA. Geophysical Activity Summary 26-2100Z to 27-2100Z
THE GEOMAGNETIC FIELD RANGED FROM UNSETTLED TO MINOR STORM LEVELS.
THE MOST DISTURBED PERIOD WAS FROM 27/0000-0300Z. THIS DISTURBANCE
APPEARS TO BE CAUSED BY AN EXTENSION OF THE SOUTHERN POLAR CORONAL
HOLE. ENERGETIC ELECTRON FLUXES AT GEOSYNCHRONOUS ORBIT WERE
PREDOMINANTLY HIGH.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD SHOULD BE
UNSETTLED TO SLIGHTLY ACTIVE ON 28 APR AS THE END OF THE CORONAL
HOLE STREAM ROTATES PAST THE EARTH DURING THAT PERIOD. UNSETTLED TO
MINOR STORM CONDITIONS ARE PREDICTED FOR 29-30 APR IN RESPONSE TO
THE X1 FLARE AND HALO CME MENTIONED ABOVE. ISOLATED PERIODS OF MAJOR
STORMING ARE POSSIBLE AT HIGH LATITUDES. THE ARRIVAL TIME FOR THIS
DISTURBANCE IS SOMEWHAT ADVANCED FROM PREVIOUS HALO CMES DUE TO A
HIGH LAUNCH SPEED OBSERVED NEAR THE SUN.
III. Event Probabilities 28 APR to 30 APR
| Class M | 20% | 20% | 20% |
| Class X | 15% | 15% | 15% |
| Proton | 10% | 15% | 15% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 27 APR 091 Predicted 28 APR-30 APR 092/094/096 90 Day Mean 27 APR 104
V. Geomagnetic A Indices
OBSERVED AFR/AP 26 APR 021/031 ESTIMATED AFR/AP 27 APR 015/020 PREDICTED AFR/AP 28 APR-30 APR 010/015-020/020-020/020
VI. Geomagnetic Activity Probabilities 28 APR to 30 APR
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 20% | 30% | 35% |
| Minor storm | 10% | 20% | 25% |
| Major-severe storm | 05% | 10% | 10% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 25% | 35% | 35% |
| Minor storm | 15% | 25% | 30% |
| Major-severe storm | 05% | 15% | 15% |
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