:Product: 19990430RSGA.txt
:Issued: 1999 Apr 30 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 120 ISSUED AT 2200Z ON 30 APR 1999
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  29/2100Z
TO 30/2100Z:  SOLAR ACTIVITY WAS LOW. CONTINUING DEVELOPMENT IN
REGION 8524 (N21W28) RESULTED IN ITS MERGER WITH NEARBY REGION 8522,
FORMING ONE LARGE BIPOLE. REGION 8524 PRODUCED A NUMBER OF C-CLASS
EVENTS, THE LARGEST BEING A C8/1F FLARE AT 1221Z. ONE NEW REGION,
8527 (N27E68), ROTATED FULLY INTO VIEW NEAR EAST LIMB, WHERE ANOTHER
REGION MAY BE SOON TO APPEAR NEAR S10. REGION 8525 (N16E59),
ALTHOUGH QUIET, HAS PATCHES OF BRIGHT PLAGE.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE. REGION 8524 IS THE MOST PROMISING SITE OF M-CLASS
ACTIVITY. REGION 8525 MAY ALSO CONTRIBUTE SHOULD FURTHER DEVELOPMENT
OCCUR.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 29/2100Z TO 30/2100Z:
THE GEOMAGNETIC FIELD WAS GENERALLY ACTIVE. A HIGH SPEED SOLAR WIND
STREAM, AT TIMES REACHING MORE THAN 650 KM/S AT THE ACE SPACECRAFT,
DROVE THE FIELD TO EPISODES OF MINOR STORM ACTIVITY DURING THE
PERIOD. THE GREATER THAN 2 MEV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT
ATTAINED HIGH LEVELS FROM ABOUT 1300 TO 2100Z.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE AT ACTIVE TO MINOR STORM LEVELS FOR THE NEXT THREE
DAYS. THE HIGH SPEED STREAM SHOULD ABATE BY THE LATTER PART OF THE
PERIOD. A CME, RELATED TO YESTERDAY'S M1 EVENT, MAY IMPACT THE FIELD
AT THE END OF THE FORECAST INTERVAL.
III.  EVENT PROBABILITIES 01 MAY-03 MAY
CLASS M    30/30/30
CLASS X    05/05/05
PROTON     05/05/05
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           30 APR 124
PREDICTED   01 MAY-03 MAY  130/135/140
90 DAY MEAN        30 APR 128
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 29 APR  018/019
ESTIMATED AFR/AP 30 APR  023/025
PREDICTED AFR/AP 01 MAY-03 MAY  015/030-015/030-015/025
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 01 MAY-03 MAY
A.  MIDDLE LATITUDES
ACTIVE                30/30/30
MINOR STORM           10/10/10
MAJOR-SEVERE STORM    01/01/01
B.  HIGH LATITUDES
ACTIVE                40/40/40
MINOR STORM           15/15/15
MAJOR-SEVERE STORM    01/01/01