NOAA/USAF Report of Solar-Geophysical Activity 12 September 2000

:Product: Report of Solar-Geophysical Activity
:Issued: 2000 Sep 12 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 256 ISSUED AT 2200Z ON 12 SEP 2000
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  11/2100Z
TO 12/2100Z:  SOLAR ACTIVITY BECAME MODERATE. A CLASSIC HYDER FLARE
WAS OBSERVED NEAR S17W09 BETWEEN APPROXIMATELY 12/1130 - 1330Z. THE
M1/2N LONG DURATION, TWO RIBBON FLARE BEGAN FOLLOWING THE ERUPTION
OF A 23 DEGREE FILAMENT THAT EXTENDED FROM S12W18 TO S28E01. A TYPE
II RADIO SWEEP (SHOCK SPEED NEAR 1000 KM/S) AND MINOR, GRADUAL
RISE-FALL CENTIMETRIC BURSTS ACCOMPANIED THE EVENT. A FULL HALO CME
WAS ALSO OBSERVED ON LASCO IMAGERY BEGINNING AT 12/1331Z. THIS
SIGNIFICANT EVENT OCCURRED ON AN OTHERWISE REMARKABLY DORMANT SUN.
NEW REGIONS 9162 (S32W36) AND 9163 (S19W10) WERE NUMBERED TODAY, AND
JOIN REGION 9161 (N05E38) AS THE ONLY SUNSPOT GROUPS ON THE VISIBLE
DISK.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE LOW.
VERY ISOLATED LOW C-CLASS ACTIVITY IS EXPECTED.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY 11/2100Z TO 12/2100Z:
THE GEOMAGNETIC FIELD WAS MOSTLY QUIET TO ACTIVE WITH PERIODS OF
MINOR STORMING OBSERVED AT HIGH LATITUDES BETWEEN 12/09 - 15Z.
POSSIBLE TRANSIENT EFFECTS INITIALLY INDUCED THIS DISTURBANCE, BUT
WE TRANSITIONED INTO A HIGH SPEED STREAM BY THE END OF THE PERIOD.
THE M1/2N FLARE THAT OCCURRED AT 12/1213Z PRODUCED A PROTON EVENT AT
GREATER THAN 10 MEV WHICH REMAINS IN PROGRESS AT THIS TIME. THE >10
MEV - 10 PFU THRESHOLD WAS CROSSED AT 12/1555Z AND REACHED 100 PFU
AT ISSUE TIME. A >100 MEV PROTON ENHANCEMENT IS ALSO IN PROGRESS,
BUT HAS YET TO REACH EVENT THRESHOLD. A PCA BEGAN NEAR 12/1830Z AND
IS CURRENTLY IN PROGRESS. CURRENT (12/2100Z) PCA ABSORPTION AT
THULE, GREENLAND IS ESTIMATED TO BE 2.5 DB.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE QUIET TO ACTIVE THROUGH DAY ONE WITH ISOLATED MINOR
STORM PERIODS AT HIGH LATITUDES. EFFECTS FROM TODAY'S M1/2N FLARE
AND HALO CME ARE EXPECTED BY DAY TWO - EXPECT MINOR TO MAJOR
STORMING TO DEVELOP ON DAY TWO AND LAST THROUGH DAY THREE BEFORE
TAPERING OFF TO UNSETTLED TO ACTIVE LATE ON DAY THREE. THE >10 MEV
PROTON EVENT CURRENTLY IN PROGRESS IS EXPECTED TO LAST THROUGH MOST
OF DAY ONE BEFORE SLOWLY RETURNING TO BACKGROUND LEVELS.
III.  EVENT PROBABILITIES 13 SEP-15 SEP
CLASS M    05/05/05
CLASS X    01/01/01
PROTON     99/20/05
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           12 SEP 133
PREDICTED   13 SEP-15 SEP  125/125/130
90 DAY MEAN        12 SEP 178
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 11 SEP  003/005
ESTIMATED AFR/AP 12 SEP  015/020
PREDICTED AFR/AP 13 SEP-15 SEP  012/012-040/045-040/040
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 13 SEP-15 SEP
A.  MIDDLE LATITUDES
ACTIVE                40/20/40
MINOR STORM           25/50/40
MAJOR-SEVERE STORM    10/30/20
B.  HIGH LATITUDES
ACTIVE                50/10/15
MINOR STORM           30/50/45
MAJOR-SEVERE STORM    20/40/35