Viewing archive of Saturday, 25 December 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 Dec 25 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 359 Issued at 2200Z on 25 DEC 1999IA. Analysis of Solar Active Regions and Activity from 24-2100Z to 25-2100Z SOLAR ACTIVITY WAS LOW. TODAY'S ACTIVITY CONSISTED OF
OCCASIONAL C-CLASS FLARES, MOST OF WHICH WERE FROM REGIONS 8806
(N20W23) AND NEW REGION 8810 (N36E64). TODAY'S LARGEST EVENT WAS A
C6 X-RAY FLARE AT 1129Z THAT WAS NOT OBSERVED OPTICALLY. REGION 8806
HAS NOT SHOWN MUCH CHANGE FROM YESTERDAY: THE GROUP STILL HAS A
DELTA CONFIGURATION IN THE PRESENCE OF STRONG MAGNETIC FIELDS, BUT
IS NONETHELESS REMARKABLY STABLE. NEW REGION 8810 IS AN E-TYPE GROUP
(MORE THAN 11 DEGREES WITH PENUMBRA ON LEADER AND TRAILERS) AND
SHOWS OCCASIONAL FLUCTUATIONS AND SUBFLARES.
IB. Solar Activity Forecast
SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE. THERE CONTINUES TO BE A FAIR CHANCE FOR AN ISOLATED
M-CLASS EVENT FROM REGION 8806, AND A SLIGHT CHANCE FOR A MAJOR
FLARE OR PROTON PRODUCING FLARE.
IIA. Geophysical Activity Summary 24-2100Z to 25-2100Z
THE GEOMAGNETIC FIELD RANGED FROM QUIET TO ACTIVE LEVELS. THE ACTIVE
PERIODS WERE ISOLATED SUBSTORMS BETWEEN 0600-0900Z AND 1200-1500Z.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE MOSTLY UNSETTLED TOMORROW BUT THERE IS A CHANCE FOR
ACTIVE LEVELS. A SMALL GEOMAGNETIC RESPONSE IS POSSIBLE FROM A CME
THAT OCCURRED ON 22 DECEMBER. CONDITIONS SHOULD DECLINE TO QUIET TO
UNSETTLED BY THE 27TH AND 28TH.
III. Event Probabilities 26 DEC to 28 DEC
| Class M | 60% | 60% | 60% |
| Class X | 15% | 15% | 15% |
| Proton | 15% | 15% | 15% |
| PCAF | GREEN | ||
IV. Penticton 10.7 cm Flux
Observed 25 DEC 178 Predicted 26 DEC-28 DEC 175/175/170 90 Day Mean 25 DEC 175
V. Geomagnetic A Indices
OBSERVED AFR/AP 24 DEC 011/010 ESTIMATED AFR/AP 25 DEC 013/015 PREDICTED AFR/AP 26 DEC-28 DEC 012/020-007/010-005/007
VI. Geomagnetic Activity Probabilities 26 DEC to 28 DEC
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 30% | 10% | 10% |
| Minor storm | 15% | 05% | 05% |
| Major-severe storm | 05% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 35% | 10% | 10% |
| Minor storm | 15% | 05% | 05% |
| Major-severe storm | 10% | 01% | 01% |
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