:Product: Report of Solar-Geophysical Activity
:Issued: 2000 Apr 16 2200 UT
# 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 107 ISSUED AT 2200Z ON 16 APR 2000
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  15/2100Z
TO 16/2100Z:  SOLAR ACTIVITY WAS LOW. REGION 8955 (S21E07) ENDURES AS
THE MOST COMPLEX AND ACTIVE REGION ON THE SUN. THIS REGION PRODUCED
A C6/SF AT 15/2143UT AND A C6/1N AT 16/0015UT.  BOTH EVENTS WERE
ACCOMPANIED BY MINOR CENTIMETRIC BURSTS. NO SIGNIFICANT CHANGES WERE
OBSERVED IN THE OVERALL SIZE OF THIS REGION, BUT SOME DECREASE IN
COMPLEXITY WAS NOTED. REGIONS 8957 (S12W90) AND 8959 (S17W25) ALSO
PRODUCED MINOR C-CLASS X-RAY FLARES. NEW REGION 8964 (N34E21) WAS
NUMBERED TODAY.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE. ISOLATED M-CLASS EVENTS ARE STILL POSSIBLE FROM REGION
8955.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 15/2100Z TO 16/2100Z:
THE GEOMAGNETIC FIELD WAS AT UNSETTLED TO MINOR STORM LEVELS. MINOR
STORMING BEGAN AFTER A WEAK SHOCK WAS OBSERVED PASSING THE ACE
SPACECRAFT AT 16/0951UT.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD SHOULD
REMAIN PREDOMINANTLY UNSETTLED TO ACTIVE WITH OCCASIONAL MINOR
STORMING AT HIGH LATITUDES. ACTIVE CONDITIONS MAY BE PROLONGED
THROUGH DAYS TWO AND THREE BY THE ARRIVAL OF A DISTURBANCE FROM THE
M4/CME EVENT ON 15/1018UT.
III.  EVENT PROBABILITIES 17 APR-19 APR
CLASS M    50/50/50
CLASS X    10/10/10
PROTON     05/05/05
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           16 APR 159
PREDICTED   17 APR-19 APR  160/160/165
90 DAY MEAN        16 APR 184
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 15 APR  007/007
ESTIMATED AFR/AP 16 APR  022/024
PREDICTED AFR/AP 17 APR-19 APR  015/015-015/018-012/012
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 17 APR-19 APR
A.  MIDDLE LATITUDES
ACTIVE                40/40/30
MINOR STORM           20/20/15
MAJOR-SEVERE STORM    05/05/01
B.  HIGH LATITUDES
ACTIVE                50/50/35
MINOR STORM           30/30/20
MAJOR-SEVERE STORM    15/15/05