:Product: 19980731RSGA.txt
:Issued: 1998 Jul 31 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 212 ISSUED AT 2200Z ON 31 JUL 1998
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  30/2100Z
TO 31/2100Z:  SOLAR ACTIVITY WAS LOW. THREE NOTABLE FLARES OCCURRED.
THE FIRST WAS A C1 PEAKING AT 31/0345Z AND WAS ASSOCIATED WITH
MODERATE INTENSITY TYPE II/IV SWEEP EVENTS. ALTHOUGH NO OPTICAL
FLARE REPORTS WERE RECEIVED, ENHANCED PLAGE OBSERVED IN REGION 8280
(S24W54) SHORTLY AFTER THIS FLARE MAY SUGGEST ITS ORIGIN. THE SECOND
FLARE OF NOTE WAS A LONG-DURATION C2/2F AT 31/0538Z IN REGION 8283
(N27E16). THIS FLARE WAS ASSOCIATED WITH A 12 DEGREE DSF AND STRONG
TYPE II SWEEP. THE THIRD FLARE WAS A B7 AT 31/1540Z ASSOCIATED WITH
FILAMENT ACTIVATION AND PARTIAL ERUPTION IN REGION 8282 (N30W48).
NEW REGIONS 8289 (N22W63), 8290 (N17E63), AND 8291 (S23E09) WERE
NUMBERED. REGION 8290 PRODUCED THE ONLY OTHER OPTICAL FLARE
REPORTED, A SF (NO X-RAY OUTPUT) AT 31/1605Z.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE VERY
LOW TO LOW. FLARES ARE POSSIBLE IN REGIONS 8280, 8282, AND 8290.
REGION 8282 MAY PRODUCE AN ISOLATED M-CLASS FLARE BEFORE ITS DISK
DEPARTURE.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 30/2100Z TO 31/2100Z:
THE GEOMAGNETIC FIELD RANGED FROM QUIET TO STORM LEVELS. ACE RTSW
DATA SUGGESTS THAT THE EARTH'S MAGNETOSPHERE IS REACTING TO SEVERAL
HOURS OF SOLAR WIND CHARACTERIZED BY HIGH DENSITY (20-70 P/CC),
SLIGHTLY ENHANCED SPEED (420 KM/S), AND VARIABLE BZ (+/- 12 NT). THE
NATURE OF THIS STRUCTURE (TRANSIENT OR NOT) IS NOT CLEAR FROM THE
AVAILABLE DATA.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE UNSETTLED TO ACTIVE FOR THE NEXT 24 HOURS, BECOMING
QUIET TO UNSETTLED BY THE END OF THE FORECAST PERIOD. THE SOLAR
EVENTS WHICH WERE OBSERVED TODAY (DSFS AND TYPE II/IV SWEEPS) MAY
INDICATE THE OCCURRENCE OF CMES WHICH COULD AFFECT ACTIVITY LEVELS
AT THE END, OR JUST OUTSIDE, OF THE 3-DAY FORECAST PERIOD.
III.  EVENT PROBABILITIES 01 AUG-03 AUG
CLASS M    15/10/05
CLASS X    01/01/01
PROTON     01/01/01
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           31 JUL 114
PREDICTED   01 AUG-03 AUG  112/110/108
90 DAY MEAN        31 JUL 110
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 30 JUL  011/012
ESTIMATED AFR/AP 31 JUL  024/025
PREDICTED AFR/AP 01 AUG-03 AUG  015/015-010/012-010/015
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 01 AUG-03 AUG
A.  MIDDLE LATITUDES
ACTIVE                20/15/15
MINOR STORM           10/01/01
MAJOR-SEVERE STORM    05/05/05
B.  HIGH LATITUDES
ACTIVE                25/15/15
MINOR STORM           15/05/05
MAJOR-SEVERE STORM    10/05/05