NOAA/USAF Report of Solar-Geophysical Activity 26 June 2000

Report of Solar-Geophysical Activity

:Issued: 2000 Jun 26 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 178 ISSUED AT 2200Z ON 26 JUN 2000

IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  25/2100Z

TO 26/2100Z:  SOLAR ACTIVITY DECREASED TO LOW LEVELS. OCCASIONAL,

MOSTLY LOW-LEVEL C-CLASS SUBFLARES OCCURRED, MOST OF WHICH WERE

PRODUCED BY REGION 9054 (N12W18). THIS REGION IS A MEDIUM-SIZED,

MIXED-POLARITY (BETA-GAMMA) GROUP THAT HAS GRADUALLY DEVELOPED

DURING THE LAST FEW DAYS. IT WAS THE LIKELY SOURCE (BASED ON

SOHO/EIT IMAGES) FOR A C4 X-RAY FLARE AT 26/0157Z ASSOCIATED WITH A

WEAK TYPE II RADIO SWEEP (EST. SHOCK VELOCITY 800 KM/SEC) AND A

POSSIBLE PARTIAL-HALO CME. REGIONS 9046 (N20W75) AND 9049 (N16W09)

DECAYED SLIGHTLY, WHILE THE REMAINING REGIONS WERE STABLE. NEW

REGION 9063 (N24E41) WAS NUMBERED.

IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE AT

LOW TO MODERATE LEVELS. OCCASIONAL C-CLASS SUBFLARES ARE EXPECTED.

REGION 9054 APPEARS CAPABLE OF PRODUCING AN ISOLATED M-CLASS FLARE.

IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 25/2100Z TO 26/2100Z:

GEOMAGNETIC FIELD ACTIVITY INCREASED TO UNSETTLED TO ACTIVE LEVELS

WITH BRIEF MINOR TO MAJOR STORM PERIODS AT HIGH LATITUDES.

IIB.  GEOPHYSICAL ACTIVITY FORECAST:  GEOMAGNETIC FIELD ACTIVITY IS

EXPECTED TO REMAIN AT UNSETTLED TO ACTIVE LEVELS DURING 27 – 28 JUNE

WITH BRIEF STORM LEVELS POSSIBLE AT HIGH LATITUDES. FIELD ACTIVITY

IS EXPECTED TO DECLINE TO QUIET TO UNSETTLED LEVELS DURING THE LAST

DAY OF THE PERIOD. THE GREATER THAN 2 MEV ELECTRON FLUX AT

GEOSYNCHRONOUS ORBIT IS EXPECTED TO INCREASE TO MODERATE TO HIGH

LEVELS DURING THE PERIOD.

III.  EVENT PROBABILITIES 27 JUN-29 JUN

CLASS M    30/30/30

CLASS X    05/05/05

PROTON     01/01/01

PCAF       GREEN

IV.  PENTICTON 10.7 CM FLUX

OBSERVED           26 JUN 177

PREDICTED   27 JUN-29 JUN  170/165/165

90 DAY MEAN        26 JUN 185

V.  GEOMAGNETIC A INDICES

OBSERVED AFR/AP 25 JUN  011/008

ESTIMATED AFR/AP 26 JUN  020/030

PREDICTED AFR/AP 27 JUN-29 JUN  015/020-015/017-012/012

VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 27 JUN-29 JUN

A.  MIDDLE LATITUDES

ACTIVE                35/35/20

MINOR STORM           20/20/10

MAJOR-SEVERE STORM    05/05/01

B.  HIGH LATITUDES

ACTIVE                40/40/25

MINOR STORM           25/25/15

MAJOR-SEVERE STORM    10/10/01