Viewing archive of Wednesday, 26 August 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 Aug 26 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 238 Issued at 2200Z on 26 AUG 1998

IA. Analysis of Solar Active Regions and Activity from 25-2100Z to 26-2100Z

.SOLAR ACTIVITY HAS BEEN VERY LOW. X-RAY LEVELS ARE LOW AND NO ENHANCEMENTS TO CLASS C LEVELS HAVE OCCURRED IN THE PAST 24 HOURS. ACTIVE REGION 8307 (N31 W15) CONTINUES TO CHANGE VERY SLOWLY. THE AREA HAS DECREASED AND THE NUMBER OF SPOTS APPEAR TO BE DECLINING AS WELL. IT IS CLASSED AS A DKO REGION WITH A BASIC BETA STRUCTURE AND A REMAINING HINT OF MAGNETIC COMPLEXITY. AN ACTIVE FILAMENT CURLS AROUND THE CENTER OF THE REGION AND EXTENDS SOUTHWARD INTO AN OPEN AREA. A NEW REGION (8319, N21 E09) WITH AN ACTIVE ARCH-FILAMENT SYSTEM HAS EMERGED WITHIN THE SCATTERED, REMNANT PLAGE EAST OF REGION 8307. BETWEEN THESE TWO REGIONS, OLD, SPOTLESS REGION 8310 (N24 E11) HAS A SMALL ARCH-FILAMENT SYSTEM. TWO OTHER SMALL NEW SUNSPOT GROUPS HAVE EMERGED AT S21 E03 (# 8318) AND N36 W 57 (# 8319).
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW TO MODERATE. REGION 8307 APPEARS LIKELY TO PRODUCE SPORADIC EVENTS. IT APPEARS TO RETAIN THE POTENTIAL TO PRODUCE CLASS M FLARES EVERY 2-3 DAYS AND ANOTHER CLASS X OR TWO BEFORE IT REACHES THE WEST LIMB OF THE SUN. THE EMERGENCE OF NEW ARCH-FILAMENT SYSTEMS IN THE SCATTERED PLAGE COVERING NEARLY 50 DEGREES IN LONGITUDE FROM 8307 INDICES THIS AREA MAY BE A SOURCE OF NEW SIGNIFICANT ACTIVE REGIONS IN FUTURE WEEKS.
IIA. Geophysical Activity Summary 25-2100Z to 26-2100Z
THE GEOMAGNETIC FIELD HAS BEEN AT ACTIVE TO MINOR STORM CONDITIONS. A SUDDEN IMPULSE WAS OBSERVED AT 26/0651 UT. AFTER THE IMPULSE, MID-LATITUDE K-INDICES UP TO 5 WERE OBSERVED. ENERGETIC PARTICLE FLUXES INCREASED IN ASSOCIATION WITH THE SUDDEN IMPULSE, WITH THE GREATER THAN 10 MEV PROTON FLUX REACHING APPROXIMATELY 600 PFU AT 26/0330 UT. A FORBUSH DECREASE BEGAN AT ABOUT THE TIME OF THE SUDDEN IMPULSE AND REACHED APPROXIMATELY 10 PERCENT DECREASE BY 26/1200 UT. THE SOLAR WIND DATA FROM THE ADVANCED COMPOSITION EXPLORER (ACE) INDICATED A PROBABLE SHOCK PASSED THE SATELLITE SHORTLY BEFORE THE SUDDEN IMPULSE AT EARTH. SINCE THAT TIME, THE SOLAR WIND VELOCITY FROM ACE HAS INCREASED TO 900 KM/S, THE DENSITY HAS REMAINED LOWER THAN PREVIOUSLY, AND THE INTERPLANETARY MAGNETIC FIELD DOES NOT HAVE A CLEAR PATTERN, ALTHOUGH THERE IS INDICATION THAT THE FIELD HAS ROTATED FROM NORTH TO SOUTH TO ABOUT 10 TO 15 NANOTESLA AND THEN BACK TO VALUES THAT LEAVE IT IN THE ECLIPTIC PLANE.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO BE AT ACTIVE TO MAJOR STORM CONDITIONS. THE PRESENT DISTURBANCE IS EXPECTED TO CONTINUE INTO TONIGHT AND BECOME MORE INTENSE AS CONDITIONS CHANGE IN THE SOLAR WIND AND LOCAL NIGHT-TIME EFFECTS WORK TOGETHER TO ENHANCE K-INDICES. VALUES AS HIGH AS 7 ARE PROBABLE WITH A CHANCE OF HIGHER VALUES AS WELL.
III. Event Probabilities 27 AUG to 29 AUG
Class M35%35%35%
Class X15%15%15%
Proton25%25%25%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       26 AUG 127
  Predicted   27 AUG-29 AUG  125/125/125
  90 Day Mean        26 AUG 117
V. Geomagnetic A Indices
OBSERVED AFR/AP 25 AUG  008/011
ESTIMATED AFR/AP 26 AUG  026/032
PREDICTED AFR/AP 27 AUG-29 AUG  060/065-025/030-010/015
VI. Geomagnetic Activity Probabilities 27 AUG to 29 AUG
A. Middle Latitudes
Active20%40%30%
Minor storm30%30%20%
Major-severe storm40%15%05%
B. High Latitudes
Active10%20%40%
Minor storm50%40%30%
Major-severe storm35%25%16%

All times in UTC

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