:Product: 19990420RSGA.txt
:Issued: 1999 Apr 20 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 110 ISSUED AT 2200Z ON 20 APR 1999
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  19/2100Z
TO 20/2100Z:  SOLAR ACTIVITY REMAINED AT VERY LOW LEVELS. REGIONS
8517 (N22W77) AND 8518 (S15E29) PRODUCED ISOLATED B-CLASS SUBFLARES,
BUT SHOWED NO SIGNIFICANT CHANGES IN SIZE OR STRUCTURE. THE
REMAINING SPOT GROUPS WERE SMALL, STRUCTURALLY SIMPLE, AND STABLE.
NO NEW REGIONS WERE ASSIGNED.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE VERY
LOW TO LOW. REGION 8518 APPEARS CAPABLE OF ISOLATED C-CLASS FLARE
PRODUCTION.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 19/2100Z TO 20/2100Z:
THE GEOMAGNETIC FIELD WAS AT UNSETTLED TO MINOR STORM LEVELS AT ALL
LATITUDES.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO REMAIN AT UNSETTLED TO MINOR STORM LEVELS DURING THE
FIRST DAY, THEN DECLINE TO QUIET TO UNSETTLED LEVELS FOR THE
REMAINDER OF THE PERIOD.
III.  EVENT PROBABILITIES 21 APR-23 APR
CLASS M    10/10/10
CLASS X    01/01/01
PROTON     01/01/01
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           20 APR 105
PREDICTED   21 APR-23 APR  105/105/105
90 DAY MEAN        20 APR 132
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 19 APR  010/013
ESTIMATED AFR/AP 20 APR  022/022
PREDICTED AFR/AP 21 APR-23 APR  020/030-010/010-007/005
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 21 APR-23 APR
A.  MIDDLE LATITUDES
ACTIVE                40/20/10
MINOR STORM           30/10/05
MAJOR-SEVERE STORM    05/01/01
B.  HIGH LATITUDES
ACTIVE                40/25/10
MINOR STORM           40/15/10
MAJOR-SEVERE STORM    05/01/01