Press Release

NOAA/USAF Report of Solar-Geophysical Activity 30 Apr 2000

By SpaceRef Editor
April 30, 2000
Filed under

Report of Solar-Geophysical Activity
:Issued: 2000 Apr 30 2210 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 121 ISSUED AT 2200Z ON 30 APR 2000
IA. ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM 29/2100Z
TO 30/2100Z: SOLAR ACTIVITY WAS LOW. REGION 8976 (S11W25) PRODUCED
THE LARGEST EVENT OF THE PERIOD, A C7/1N FLARE WITH AN ACCOMPANYING
TYPE II RADIO SWEEP (VELOCITY = 700 KM/S) AT 30/0808UT. IMAGES FROM
THE LASCO SPACECRAFT INDICATE THAT A POSSIBLY EARTH-DIRECTED CORONAL
MASS EJECTION (CME) ALSO OCCURRED IN CONJUNCTION WITH THIS EVENT.
THE TWO LARGEST REGIONS ON THE DISK, 8970 (S17E44) AND 8971
(N21W48), SHOWED SIGNS OF DECAY BUT STILL PRODUCED OCCASIONAL
OPTICAL SUBFLARES. OLD REGION 8948 SHOULD ROTATE ONTO THE DISK
TOMORROW. EIT IMAGERY HAS SHOWN CONSIDERABLE ACTIVITY FROM THIS
RETURNING REGION.
IB. SOLAR ACTIVITY FORECAST: SOLAR ACTIVITY IS EXPECTED TO BE LOW.
THE RETURNING REGION 8948 COULD PRODUCE ISOLATED M-CLASS EVENTS.
IIA. GEOPHYSICAL ACTIVITY SUMMARY FROM 29/2100Z TO 30/2100Z:
THE GEOMAGNETIC FIELD WAS QUIET TO UNSETTLED.
IIB. GEOPHYSICAL ACTIVITY FORECAST: THE GEOMAGNETIC FIELD IS
EXPECTED TO BE QUIET TO UNSETTLED. THE CME DESCRIBED IN SECTION IA
COULD CAUSE ACTIVE CONDITIONS ON THE THIRD DAY OF THE PERIOD,
DEPENDING ON HOW CLOSE IT COMES TO EARTH.
III. EVENT PROBABILITIES 01 MAY-03 MAY
CLASS M 30/30/30
CLASS X 01/01/01
PROTON 01/01/01
PCAF GREEN
IV. PENTICTON 10.7 CM FLUX
OBSERVED 30 APR 170
PREDICTED 01 MAY-03 MAY 175/180/180
90 DAY MEAN 30 APR 189
V. GEOMAGNETIC A INDICES
OBSERVED AFR/AP 29 APR 012/012
ESTIMATED AFR/AP 30 APR 010/012
PREDICTED AFR/AP 01 MAY-03 MAY 010/010-010/010-015/020
VI. GEOMAGNETIC ACTIVITY PROBABILITIES 01 MAY-03 MAY
A. MIDDLE LATITUDES
ACTIVE 20/20/30
MINOR STORM 05/05/05
MAJOR-SEVERE STORM 01/01/01
B. HIGH LATITUDES
ACTIVE 30/30/40
MINOR STORM 05/05/10
MAJOR-SEVERE STORM 01/01/01

SpaceRef staff editor.