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 UTC
Prepared 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 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 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 M50%40%30%
Class X20%20%15%
Proton15%15%10%
PCAFGREEN
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
Active30%25%20%
Minor storm15%10%10%
Major-severe storm05%05%05%
B. High Latitudes
Active30%30%25%
Minor storm15%15%10%
Major-severe storm05%05%05%

All times in UTC

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