:Product: 19990419RSGA.txt
:Issued: 1999 Apr 19 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 109 ISSUED AT 2200Z ON 19 APR 1999
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  18/2100Z
TO 19/2100Z:  SOLAR ACTIVITY REMAINED AT VERY LOW LEVELS. MINOR
GROWTH OCCURRED IN REGIONS 8517 (N22W63) AND 8518 (S14E40), BOTH OF
WHICH PRODUCED ISOLATED SUBFLARES. THE REMAINING REGIONS WERE EITHER
STABLE OR DECLINING. NEW REGIONS 8520 (N20E12) AND 8521 (N34W07)
WERE NUMBERED.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE VERY
LOW TO LOW. REGIONS 8517 AND 8518 MAY PRODUCE C-CLASS FLARES.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 18/2100Z TO 19/2100Z:
GEOMAGNETIC FIELD ACTIVITY RANGED FROM QUIET TO ACTIVE LEVELS DURING
THE PERIOD. ACTIVE LEVELS WERE DETECTED AT ALL LATITUDES DURING
19/0900 - 1000Z. QUIET TO UNSETTLED LEVELS OCCURRED DURING THE
REMAINING HOURS.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE AT UNSETTLED TO MINOR STORM LEVELS DURING THE FIRST
TWO DAYS IN RESPONSE TO A PARTIAL-HALO CME OBSERVED ON 17 APRIL.
FIELD ACTIVITY IS EXPECTED TO DECLINE TO QUIET TO UNSETTLED LEVELS
ON THE FINAL DAY.
III.  EVENT PROBABILITIES 20 APR-22 APR
CLASS M    10/10/10
CLASS X    01/01/01
PROTON     01/01/01
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           19 APR 110
PREDICTED   20 APR-22 APR  110/110/105
90 DAY MEAN        19 APR 133
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 18 APR  005/006
ESTIMATED AFR/AP 19 APR  008/008
PREDICTED AFR/AP 20 APR-22 APR  020/014-020/030-010/015
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 20 APR-22 APR
A.  MIDDLE LATITUDES
ACTIVE                40/40/25
MINOR STORM           20/20/10
MAJOR-SEVERE STORM    05/05/01
B.  HIGH LATITUDES
ACTIVE                45/45/30
MINOR STORM           25/25/15
MAJOR-SEVERE STORM    05/05/01