:Product: 19991225RSGA.txt
:Issued: 1999 Dec 25 2200 UTC
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
# Space Environment Center and the U.S. Air Force.
#
JOINT USAF/NOAA REPORT OF SOLAR AND GEOPHYSICAL ACTIVITY
SDF NUMBER 359 ISSUED AT 2200Z ON 25 DEC 1999
IA.  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 FROM 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-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-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