Viewing archive of Thursday, 18 February 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 Feb 18 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 049 Issued at 2200Z on 18 FEB 1999

IA. Analysis of Solar Active Regions and Activity from 17-2100Z to 18-2100Z

SOLAR ACTIVITY WAS LOW. THE DAY'S LARGEST EVENT WAS A C5 XRAY BURST AT 0329Z. THERE WAS NO ASSOCIATED OPTICAL FLARE. REGION 8462 (N20W40) PRODUCED MOST OF THE C-CLASS EVENTS OBSERVED, AND REGIONS 8458 (S23W36) AND 8459 (S29W80) SPLIT THE REMAINDER. IN GENERAL, ALL SPOTTED REGIONS WERE STABLE OR DECAYING AND THE 10.7 CM RADIO FLUX DROPPED SUBSTANTIALLY FROM YESTERDAY. THE LIMBS WERE QUIET.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW TO MODERATE. REGIONS 8458 AND 8462 ARE POTENTIAL SITES FOR M-CLASS ACTIVITY, SHOULD AN INSTABILITY DEVELOP.
IIA. Geophysical Activity Summary 17-2100Z to 18-2100Z
THE GEOMAGNETIC FIELD WAS AT ACTIVE TO SEVERE STORM LEVELS THROUGHOUT THE PERIOD. A SUDDEN STORM COMMENCEMENT MEASURING 43 NANOTESLAS AT BOULDER, OCCURRED AT 0250Z. THE ACE SPACECRAFT MEASURED SOLAR WIND VELOCITIES NEAR 700 KM/S, AND SOUTHWARD IMF OF APPROXIMATELY 20 NT, FOR HOURS FOLLOWING THE PASSAGE OF THE SHOCK. THE SOLAR ORIGIN OF THIS ACTIVITY IS THOUGHT TO BE THE LONG-DURATION M-CLASS EVENT FROM NEAR CENTER DISK, EARLY ON FEBRUARY 16. A FORBUSH DECREASE BEGAN EARLY IN THE DAY, AS SEEN IN NEUTRON MONITOR DATA.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS EXPECTED TO BE AT ACTIVE TO MINOR STORM LEVELS FOR THE NEXT 24 HOURS. THE CURRENT STORM SHOULD GRADUALLY WEAKEN, ALTHOUGH EPISODES OF MAJOR STORM MAY OCCUR DURING LOCAL NIGHTTIMES. THE SOLAR WIND SPEED AT ACE IS STILL ABOVE 600 KM/S, BUT THE SOUTHWARD COMPONENT OF THE IMF IS NOW NEAR ZERO. THE RETURN TO MORE BENIGN CONDITIONS SHOULD BRING QUIET TO UNSETTLED LEVELS BY FEBRUARY 21.
III. Event Probabilities 19 FEB to 21 FEB
Class M50%50%50%
Class X05%05%05%
Proton05%05%05%
PCAFGREEN
IV. Penticton 10.7 cm Flux
  Observed       18 FEB 168
  Predicted   19 FEB-21 FEB  160/155/150
  90 Day Mean        18 FEB 146
V. Geomagnetic A Indices
OBSERVED AFR/AP 17 FEB  015/016
ESTIMATED AFR/AP 18 FEB  060/050
PREDICTED AFR/AP 19 FEB-21 FEB  030/030-015/015-005/010
VI. Geomagnetic Activity Probabilities 19 FEB to 21 FEB
A. Middle Latitudes
Active10%40%10%
Minor storm60%20%05%
Major-severe storm25%05%01%
B. High Latitudes
Active10%50%20%
Minor storm60%30%10%
Major-severe storm30%10%01%

All times in UTC

<< Go to daily overview page

Latest news

Support SpaceWeatherLive.com!

A lot of people come to SpaceWeatherLive to follow the Sun's activity or if there is aurora to be seen, but with more traffic comes higher server costs. Consider a donation if you enjoy SpaceWeatherLive so we can keep the website online!

SpaceWeatherLive Pro
Support SpaceWeatherLive with our merchandise
Check out our merchandise

Latest alerts

Get instant alerts!

Space weather facts

Last X-flare2024/12/08X2.2
Last M-flare2024/12/24M4.1
Last geomagnetic storm2024/12/17Kp5+ (G1)
Spotless days
Last spotless day2022/06/08
Monthly mean Sunspot Number
November 2024152.5 -13.9
December 2024110.7 -41.8
Last 30 days117.3 -41.4

This day in history*

Solar flares
12001M5
22024M4.7
32024M4.1
42023M2.9
52023M2.6
DstG
11995-65G1
22014-57
32001-55G1
42002-49G1
51990-47
*since 1994

Social networks