Viewing archive of Thursday, 21 October 1999

Solar activity report

Report of Solar-Geophysical Activity 1999 Oct 21 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 294 Issued at 2200Z on 21 OCT 1999

IA. Analysis of Solar Active Regions and Activity from 20-2100Z to 21-2100Z

SOLAR ACTIVITY WAS LOW. THERE WERE SEVERAL C-CLASS SUBFLARES DURING THE DAY. MOST OF THESE WERE FROM REGIONS 8732 (N21W76) AND 8739 (S12E58). REGIONS 8739 AND 8737 (S15W12) BOTH SHOWED GROWTH DURING THE PAST 24 HOURS. REGION 8731 (N12W68) CONTINUES TO BE THE LARGEST REGION ON THE DISK BUT WAS RELATIVELY QUIET AND STABLE.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW TO MODERATE. REGIONS 8731 AND 8732 CONTINUE TO BE THE MOST LIKELY SOURCES FOR ENERGETIC FLARES. IIA. GEOPHYSICAL ACTIVITY SUMMARY FROM 20/2100Z TO 21/2100Z: THE GEOMAGNETIC FIELD WAS QUIET TO ACTIVE. A SUDDEN IMPULSE WAS OBSERVED AT 0226Z, WHICH WAS PRECEDED BY A SHOCK OBSERVED AT THE ACE SPACECRAFT AT 0138Z. THE SHOCK WAS FOLLOWED BY AN INTERPLANETARY TRANSIENT, BUT THE TRANSIENT WAS NOT VERY GEOEFFECTIVE: ONLY ONE ACTIVE PERIOD OCCURRED FROM 0300-0600Z. THE REMAINDER OF THE DAY WAS QUIET TO UNSETTLED. THE GREATER THAN 2 MEV ELECTRON FLUXES EXCEEDED HIGH LEVELS.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO BE UNSETTLED TO ACTIVE FOR THE NEXT 24 HOURS. THERE IS A GOOD CHANCE FOR SOME ENHANCED ACTIVITY DURING LOCAL NIGHTTIME HOURS. CONDITIONS SHOULD SUBSIDE A BIT ON THE SECOND DAY, BUT ANOTHER INCREASE IS ANTICIPATED ON THE THIRD DAY IN RESPONSE TO A FAVORABLY POSITIONED CORONAL HOLE.
III. Event Probabilities 22 OCT to 24 OCT
Class M 40%35%30%
Class X 10%05%05%
Proton10%05%05%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       21 OCT 159
  Predicted    22 OCT-24 OCT  150/145/140
  90 Day Mean        21 OCT 158
V. Geomagnetic A Indices
OBSERVED AFR/AP 20 OCT  004/004
ESTIMATED AFR/AP 21 OCT  012/012
PREDICTED AFR/AP 22 OCT-24 OCT  015/020-015/010-020/015
VI. Geomagnetic Activity Probabilities 22 OCT to 24 OCT
A. Middle Latitudes
Active40%40%50%
Minor storm 20%20%30%
Major-severe storm 05%05%10%
B. High Latitudes
Active50%50%40%
Minor storm 25%25%35%
Major-severe storm 15%15%20%

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