Viewing archive of Tuesday, 31 August 1999
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 1999 Aug 31 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 243 Issued at 2200Z on 31 AUG 1999IA. 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 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 to 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 to 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% |
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