NOAA/USAF Report of Solar-Geophysical Activity 28 July 2000

:Product: Report of Solar-Geophysical Activity
:Issued: 2000 Jul 28 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 210 ISSUED AT 2200Z ON 28 JUL 2000
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  27/2100Z
TO 28/2100Z:  SOLAR ACTIVITY HAS BEEN MODERATE. REGION 9090 (N15W83)
PRODUCED TODAY'S ONLY M-CLASS FLARE, AN M1/SF AT 27/2342Z. THE
REGION WAS QUIET FOR THE REMAINDER OF THE DAY AS IT ROTATED AROUND
THE WEST LIMB. REGION 9103 (N10E03) SHOWED GROWTH DURING THE PAST 24
HOURS BUT COULD ONLY PRODUCE A SUBFLARE. REGION 9097 (N09W55),
CURRENTLY THE LARGEST REGION ON THE DISK, CONTINUED TO DECAY
QUIETLY. CLOSER ANALYSIS OF YESTERDAY'S HALO CME USING AVAILABLE EIT
AND H-ALPHA DATA INDICATE THAT THE TRANSIENT ORIGINATED FROM THE
BACKSIDE OF THE SUN.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE LOW
FOR THE NEXT THREE DAYS, BUT THERE IS A CHANCE FOR AN ISOLATED
M-CLASS EVENT, WITH REGIONS 9097 AND 9103 AS THE MOST LIKELY
SOURCES.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY 27/2100Z TO 28/2100Z:
THE GEOMAGNETIC FIELD HAS RANGED FROM QUIET TO MINOR STORM LEVELS
DURING THE PAST 24 HOURS. AN INITIALLY QUIET TO UNSETTLED FIELD
BECAME DISTURBED WITH THE ARRIVAL OF THE TRANSIENT MATERIAL FROM THE
CME OF 25 JULY. THE FIRST INDICATION OF THE TRANSIENT WAS A SHOCK AT
ACE AT 0543Z, SHORTLY FOLLOWED BY A SUDDEN IMPULSE AT 0635Z
(MEASURING 41 NT ON THE BOULDER MAGNETOMETER). THE SHOCK WAS
FOLLOWED BY STRONG TO MODERATELY SOUTHWARD BZ FIELDS (-5 TO -15 NT)
UNTIL 1318Z WHEN BZ INTENSIFIED TO STRONGLY NEGATIVE VALUES FOR
ABOUT 3 HOURS (-15 TO -20 NT). MINOR STORM LEVELS (ESTIMATED KP'S OF
5) WERE SUSTAINED FOR 12 HOURS FROM 0600-1800Z. A GREATER THAN 10
PFU PROTON EVENT AT GREATER THAN 10 MEV WAS OBSERVED: PARTICLE
FLUXES BEGAN TO RISE SLOWLY AFTER 0200Z AND ATTAINED THRESHOLD AT
1050Z. THE PEAK OF THE EVENT WAS 18 PFU AT 1130Z AND THE EVENT FELL
BELOW THRESHOLD AT 1310Z.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE ACTIVE FOR THE NEXT 24 HOURS, WITH A POSSIBILITY FOR
SOME ISOLATED MINOR STORM PERIODS. NIGHTTIME SECTORS IN PARTICULAR
MAY EXPERIENCE EFFECTS OF LOCAL SUBSTORM ACTIVITY AS THE CURRENT
DISTURBANCE SUBSIDES. PREDOMINANTLY UNSETTLED CONDITIONS ARE 
EXPECTED FOR THE SECOND AND THIRD DAYS.
III.  EVENT PROBABILITIES 29 JUL-31 JUL
CLASS M    30/30/30
CLASS X    05/05/05
PROTON     05/05/05
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           28 JUL 158
PREDICTED   29 JUL-31 JUL  155/155/150
90 DAY MEAN        28 JUL 189
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 27 JUL  006/009
ESTIMATED AFR/AP 28 JUL  030/030
PREDICTED AFR/AP 29 JUL-31 JUL  020/020-010/015-010/012
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 29 JUL-31 JUL
A.  MIDDLE LATITUDES
ACTIVE                35/30/30
MINOR STORM           30/15/15
MAJOR-SEVERE STORM    25/05/05
B.  HIGH LATITUDES
ACTIVE                30/30/30
MINOR STORM           30/15/10
MAJOR-SEVERE STORM    25/05/05