Viewing archive of Friday, 31 July 1998

Solar activity report

Report of Solar-Geophysical Activity 1998 Jul 31 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 212 Issued at 2200Z on 31 JUL 1998

IA. Analysis of Solar Active Regions and Activity from 30-2100Z to 31-2100Z

SOLAR ACTIVITY WAS LOW. THREE NOTABLE FLARES OCCURRED. THE FIRST WAS A C1 PEAKING AT 31/0345Z AND WAS ASSOCIATED WITH MODERATE INTENSITY TYPE II/IV SWEEP EVENTS. ALTHOUGH NO OPTICAL FLARE REPORTS WERE RECEIVED, ENHANCED PLAGE OBSERVED IN REGION 8280 (S24W54) SHORTLY AFTER THIS FLARE MAY SUGGEST ITS ORIGIN. THE SECOND FLARE OF NOTE WAS A LONG-DURATION C2/2F AT 31/0538Z IN REGION 8283 (N27E16). THIS FLARE WAS ASSOCIATED WITH A 12 DEGREE DSF AND STRONG TYPE II SWEEP. THE THIRD FLARE WAS A B7 AT 31/1540Z ASSOCIATED WITH FILAMENT ACTIVATION AND PARTIAL ERUPTION IN REGION 8282 (N30W48). NEW REGIONS 8289 (N22W63), 8290 (N17E63), AND 8291 (S23E09) WERE NUMBERED. REGION 8290 PRODUCED THE ONLY OTHER OPTICAL FLARE REPORTED, A SF (NO X-RAY OUTPUT) AT 31/1605Z.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE VERY LOW TO LOW. FLARES ARE POSSIBLE IN REGIONS 8280, 8282, AND 8290. REGION 8282 MAY PRODUCE AN ISOLATED M-CLASS FLARE BEFORE ITS DISK DEPARTURE. IIA. GEOPHYSICAL ACTIVITY SUMMARY FROM 30/2100Z TO 31/2100Z: THE GEOMAGNETIC FIELD RANGED FROM QUIET TO STORM LEVELS. ACE RTSW DATA SUGGESTS THAT THE EARTH'S MAGNETOSPHERE IS REACTING TO SEVERAL HOURS OF SOLAR WIND CHARACTERIZED BY HIGH DENSITY (20-70 P/CC), SLIGHTLY ENHANCED SPEED (420 KM/S), AND VARIABLE BZ (+/- 12 NT). THE NATURE OF THIS STRUCTURE (TRANSIENT OR NOT) IS NOT CLEAR FROM THE AVAILABLE DATA.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO BE UNSETTLED TO ACTIVE FOR THE NEXT 24 HOURS, BECOMING QUIET TO UNSETTLED BY THE END OF THE FORECAST PERIOD. THE SOLAR EVENTS WHICH WERE OBSERVED TODAY (DSFS AND TYPE II/IV SWEEPS) MAY INDICATE THE OCCURRENCE OF CMES WHICH COULD AFFECT ACTIVITY LEVELS AT THE END, OR JUST OUTSIDE, OF THE 3-DAY FORECAST PERIOD.
III. Event Probabilities 01 AUG to 03 AUG
Class M15%10%05%
Class X01%01%01%
Proton01%01%01%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       31 JUL 114
  Predicted   01 AUG-03 AUG  112/110/108
  90 Day Mean        31 JUL 110
V. Geomagnetic A Indices
OBSERVED AFR/AP 30 JUL  011/012
ESTIMATED AFR/AP 31 JUL  024/025
PREDICTED AFR/AP 01 AUG-03 AUG  015/015-010/012-010/015
VI. Geomagnetic Activity Probabilities 01 AUG to 03 AUG
A. Middle Latitudes
Active20%15%15%
Minor storm10%01%01%
Major-severe storm05%05%05%
B. High Latitudes
Active25%15%15%
Minor storm15%05%05%
Major-severe storm10%05%05%

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