Viewing archive of Wednesday, 17 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 17 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 048 Issued at 2200Z on 17 FEB 1999IA. Analysis of Solar Active Regions and Activity from 16-2100Z to 17-2100Z SOLAR ACTIVITY WAS LOW. OCCASIONAL C-CLASS FLARES MADE
UP THE DAY'S ACTIVITY, THE LARGEST BEING AN UNOBSERVED C6 AT
2029Z.REGION 8462 (N20W27) HAD THE VAST MAJORITY OF THE ASSOCIATED
FLARE ACTIVITY, WITH ITS LARGEST A C5/1N WITH TYPE II SWEEP AT
16/2121Z. REGION 8458 (S23W36) HAD ONLY A FEW C-CLASS FLARES. REGION
8457 (N15W42), ALTHOUGH QUIET, REMAINS BRIGHT IN H-ALPHA. THE
REMAINDER OF THE DISK AND LIMBS WERE QUIET.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE. REGIONS 8457, 8458 AND 8462 RETAIN THE POTENTIAL FOR
ISOLATED M-CLASS FLARES.
IIA. Geophysical Activity Summary 16-2100Z to 17-2100Z
THE GEOMAGNETIC FIELD WAS AT QUIET TO MINOR STORM LEVELS. A TRANSIENT
STRUCTURE WAS SEEN TO PASS ACE AROUND 0500Z, WITH ELEVATED SPEED AND
PROLONGED SOUTHWARD BZ. CONDITIONS HAVE SINCE STABILIZED WITH
NOMINAL CONDITIONS NOW OCCURRING. THIS TRANSIENT MAY BE AN EFFECT OF
SOLAR ACTIVITY ON FEBRUARY 12.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE GENERALLY UNSETTLED FOR THE NEXT THREE DAYS. THERE IS
A CHANCE FOR EPISODES OF ELEVATED ACTIVITY IN THE FIRST TWO DAYS,
DUE TO SOLAR ACTIVITY FROM REGION 8458 EARLY ON FEBRUARY 16.
III. Event Probabilities 18 FEB to 20 FEB
| Class M | 50% | 50% | 50% |
| Class X | 10% | 10% | 10% |
| Proton | 10% | 10% | 10% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 17 FEB 190 Predicted 18 FEB-20 FEB 185/175/165 90 Day Mean 17 FEB 146
V. Geomagnetic A Indices
OBSERVED AFR/AP 16 FEB 003/004 ESTIMATED AFR/AP 17 FEB 015/015 PREDICTED AFR/AP 18 FEB-20 FEB 015/010-015/010-010/008
VI. Geomagnetic Activity Probabilities 18 FEB to 20 FEB
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 40% | 40% | 30% |
| Minor storm | 20% | 20% | 10% |
| Major-severe storm | 05% | 05% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 50% | 50% | 40% |
| Minor storm | 25% | 25% | 20% |
| Major-severe storm | 10% | 10% | 05% |
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