:Product: 19991227RSGA.txt
:Issued: 1999 Dec 27 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 361 ISSUED AT 2200Z ON 27 DEC 1999
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  26/2100Z
TO 27/2100Z:  SOLAR ACTIVITY WAS MODERATE.  REGION 8806 (N20W53)
PRODUCED TWO SMALL M FLARES, AN M1/SF AT 27/0146UT AND AN M2/SN AT
27/1154UT.  THIS MAGNETICALLY COMPLEX REGION IS SLOWLY DECLINING AS
IT APPROACHES WEST LIMB.  ONLY MINOR ACTIVITY WAS OBSERVED FROM THE
REMAINING THREE SPOTTED REGIONS.  THE PROMINENCE ON THE EAST LIMB
NEAR N40 IS IN THE PROCESS OF ERUPTING.  SOLAR X-RAY AND RADIO
BACKGROUND FLUX ARE DROPPING.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE.  THERE IS A CHANCE FOR MAJOR FLARES UNTIL AFTER REGION
8806 ROTATES OFF THE DISK ON 31 DEC.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 26/2100Z TO 27/2100Z:
THE GEOMAGNETIC FIELD HAS BEEN QUIET TO UNSETTLED.  A SHOCK WAS
OBSERVED AT THE ACE SPACECRAFT AT 26/2126UT RESULTING IN A MINOR
INCREASE IN ACTIVITY AT THE EARTH AFTER 26/2230UT.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE MOSTLY QUIET.
III.  EVENT PROBABILITIES 28 DEC-30 DEC
CLASS M    50/50/50
CLASS X    10/10/10
PROTON     10/10/10
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           27 DEC 162
PREDICTED   28 DEC-30 DEC  160/155/150
90 DAY MEAN        27 DEC 176
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 26 DEC  002/002
ESTIMATED AFR/AP 27 DEC  005/006
PREDICTED AFR/AP 28 DEC-30 DEC  005/005-005/005-008/010
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 28 DEC-30 DEC
A.  MIDDLE LATITUDES
ACTIVE                10/10/15
MINOR STORM           05/05/05
MAJOR-SEVERE STORM    01/01/01
B.  HIGH LATITUDES
ACTIVE                15/15/20
MINOR STORM           10/10/10
MAJOR-SEVERE STORM    01/01/01