:Product: Weekly Highlights and Forecasts
:Issued: 1999 Jun 29 2112 UT
HIGHLIGHTS OF SOLAR AND GEOMAGNETIC ACTIVITY
21 - 27 JUNE 1999

SOLAR ACTIVITY RANGED FROM LOW TO MODERATE LEVELS DURING THE WEEK.
REGION 8598 (N23, L=328, CLASS/AREA FKI/650 ON 25 JUNE), THE WEEK'S
DOMINANT FLARE PRODUCER, PROVIDED ISOLATED M-CLASS FLARES INCLUDING
AN M1/2N PARALLEL-RIBBON FLARE AT 23/0709UT WITH A TYPE IV RADIO
SWEEP AND MODERATE CENTIMETRIC RADIO BURSTS. THIS REGION ALSO
PRODUCED AN M2/2N AT 26/0512UT WITH MINOR RADIO EMISSION. REGION
8598 WAS POSITIONED WITHIN A CLUSTER OF FIVE REGIONS THAT ALSO
INCLUDED REGION 8592 (N22, L=352, CLASS/AREA FAO/200 ON 20 JUNE)
WHICH PRODUCED AN M1/1N FLARE AT 22/1829UT WITH AN ASSOCIATED 760
SFU TENFLARE, AND TYPE II AND IV RADIO SWEEPS. THIS REGION ALSO
PRODUCED AN M1/2N PARALLEL-RIBBON FLARE WITH AN ASSOCIATED TYPE IV
RADIO SWEEP AND A 240 SFU TENFLARE. ANOTHER EVENT OF NOTE WAS A
LONG-DURATION C4 X-RAY FLARE AT 24/1412UT ASSOCIATED WITH A
15-DEGREE FILAMENT DISAPPEARANCE, A HYDER FLARE, AND A PARTIAL-HALO
CME. THE PRESENCE OF NUMEROUS SMALL- TO MEDIUM-SIZED GROUPS PROVIDED
THE HIGHEST DAILY SUNSPOT NUMBERS OBSERVED SO FAR THIS CYCLE. THE
DAILY 10.7 CM SOLAR RADIO FLUX ALSO EXCEEDED 200 SFU FOR THE SECOND
TIME THIS CYCLE.

REAL-TIME SOLAR WIND DATA WERE AVAILABLE FROM THE ADVANCED
COMPOSITION EXPLORER (ACE) SPACECRAFT FOR MOST OF THE PERIOD. PHI
DATA INDICATED A SHIFT TO A TOWARD (NEGATIVE POLARITY) SOLAR SECTOR
DURING 23 - 24 JUNE. OTHERWISE, NO SIGNIFICANT CHANGES WERE NOTED IN
THE SOLAR WIND FLOW THROUGH 25 JUNE. TWO SHOCKS WERE DETECTED ON 26
JUNE. THE FIRST OCCURRED AT APPROXIMATELY 26/0215UT AND WAS FOLLOWED
BY A MINOR VELOCITY INCREASE, A BRIEF DENSITY INCREASE TO 34 P/CC,
AND PERIODS OF SOUTHWARD IMF BZ WITH DEFLECTIONS TO MINUS 12 NT
(GSM).THE SECOND SHOCK WAS DETECTED AT APPROXIMATELY 26/1925UT AND
WAS ACCOMPANIED BY A VELOCITY INCREASE FROM 340 TO 430 KM/SEC AND
ENHANCED PARTICLE DENSITIES, BUT IMF BZ REMAINED MOSTLY NORTHWARD
FOLLOWING THE SHOCK. IMF BZ EVENTUALLY TURNED MOSTLY SOUTHWARD
DURING THE LATTER HALF OF 27 JUNE WITH MAXIMUM DEFLECTIONS TO MINUS
13 NT (GSM). BOTH SHOCKS WERE FOLLOWED BY SUDDEN IMPULSES AT EARTH
(SEE THE GEOMAGNETIC ACTIVITY DISCUSSION BELOW).

THERE WERE NO PROTON ENHANCEMENTS AT GEO-SYNCHRONOUS ORBIT DURING THE
PERIOD.

THE GREATER THAN 2 MEV ELECTRON FLUX AT GEO-SYNCHRONOUS ORBIT WAS AT
NORMAL LEVELS.

THE GEOMAGNETIC FIELD WAS MOSTLY QUIET THROUGH 25 JUNE, THEN
INCREASED TO UNSETTLED TO MINOR STORM LEVELS DURING 26 - 27 JUNE
WITH THE MINOR STORM LEVELS LIMITED TO HIGH LATITUDES. TWO SUDDEN
IMPULSES WERE DETECTED ON 26 JUNE. THE FIRST OCCURRED AT 26/0326UT
(16 NT) AND THE OTHER AT 26/2020UT (38 NT).

FORECAST OF SOLAR AND GEOMAGNETIC ACTIVITY
30 JUNE - 26 JULY 1999

SOLAR ACTIVITY IS EXPECTED TO RANGE FROM LOW TO MODERATE LEVELS.
ISOLATED M-CLASS FLARES MAY OCCUR AT ANY TIME DURING THE PERIOD.
THERE WILL ALSO BE A SLIGHT CHANCE FOR A MAJOR FLARE SOMETIME DURING
THE PERIOD.

THERE WILL BE A SLIGHT CHANCE FOR A PROTON EVENT AT GEO-SYNCHRONOUS
ALTITUDE.

THE GREATER THAN 2 MEV ELECTRON FLUX AT GEO-SYNCHRONOUS ALTITUDE IS
EXPECTED TO BE AT  NORMAL TO MODERATE LEVELS DURING MOST OF THE
PERIOD.

GEOMAGNETIC FIELD ACTIVITY IS EXPECTED TO BE QUIET TO UNSETTLED
DURING MOST OF THE PERIOD. HOWEVER, ACTIVE LEVELS MAY OCCUR DURING
30 JUNE - 01 JULY.


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