NOAA/USAF Report of Solar-Geophysical Activity 18 May 2000

Report of Solar-Geophysical Activity
:Issued: 2000 May 18 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 139 ISSUED AT 2200Z ON 18 MAY 2000
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  17/2100Z
TO 18/2100Z:  SOLAR ACTIVITY INCREASED TO MODERATE LEVELS. REGION
9002 (N18E31) PRODUCED AN IMPULSIVE M2/2B FLARE AT 18/1557Z ALONG
WITH OCCASIONAL C-CLASS SUBFLARES. THIS REGION SHOWED LITTLE CHANGE
DURING THE PERIOD AND REMAINED A LARGE REGION WITH A MIXED-POLARITY
STRUCTURE. REGION 8998 (S13E04), A MODERATE-SIZED MIXED-POLARITY
GROUP, PRODUCED ISOLATED C-CLASS SUBFLARES AND SHOWED GRADUAL
DEVELOPMENT. REGION 8996 (S21W09) REMAINED THE LARGEST GROUP ON THE
DISK WITH AN AREA EXCEEDING 1200 MILLIONTHS AND RETAINED A
MIXED-POLARITY STRUCTURE. IT PRODUCED OCCASIONAL C-CLASS SUBFLARES.
NEW REGIONS 9009 (S15E68) AND 9010 (N16E74) WERE NUMBERED TODAY.
IB.  SOLAR ACTIVITY FORECAST:  ACTIVITY IS EXPECTED TO REMAIN AT
MODERATE LEVELS. ISOLATED M-CLASS FLARES ARE LIKELY. THERE IS ALSO A
SLIGHT CHANCE FOR A MAJOR FLARE SOMETIME DURING THE PERIOD.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 17/2100Z TO 18/2100Z:
GEOMAGNETIC FIELD ACTIVITY WAS AT QUIET TO UNSETTLED LEVELS.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  GEOMAGNETIC FIELD ACTIVITY IS
EXPECTED TO REMAIN AT QUIET TO UNSETTLED LEVELS DURING THE FIRST
DAY. ACTIVITY IS EXPECTED TO INCREASE DURING THE LAST TWO DAYS OF
THE PERIOD WITH UNSETTLED TO ACTIVE PERIODS POSSIBLE DUE TO CORONAL
HOLE EFFECTS.
III.  EVENT PROBABILITIES 19 MAY-21 MAY
CLASS M    80/80/80
CLASS X    15/15/15
PROTON     10/10/10
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           18 MAY 253
PREDICTED   19 MAY-21 MAY  260/265/265
90 DAY MEAN        18 MAY 193
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 17 MAY  020/022
ESTIMATED AFR/AP 18 MAY  010/010
PREDICTED AFR/AP 19 MAY-21 MAY  012/012-015/015-015/015
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 19 MAY-21 MAY
A.  MIDDLE LATITUDES
ACTIVE                25/30/30
MINOR STORM           10/15/15
MAJOR-SEVERE STORM    01/01/01
B.  HIGH LATITUDES
ACTIVE                30/35/35
MINOR STORM           15/20/20
MAJOR-SEVERE STORM    01/01/01