Viewing archive of Friday, 23 July 1999

Solar activity report

Any mentioned solar flare in this report has a scaling factor applied by the Space Weather Prediction Center (SWPC). Because of the SWPC scaling factor, solar flares are reported as 42% smaller than for the science quality data. The scaling factor has been removed from our archived solar flare data to reflect the true physical units.
Report of Solar-Geophysical Activity 1999 Jul 23 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.com

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 204 Issued at 2200Z on 23 JUL 1999

IA. Analysis of Solar Active Regions and Activity from 22-2100Z to 23-2100Z

SOLAR ACTIVITY BECAME MODERATE. NEW REGION 8644 (S24E69) PRODUCED AN M1 AT 23/1601Z. THE BIG BEAR OBSERVATORY REPORTED A FLARE BRIGHT KNOT OF MATERIAL AT THE SOUTHEAST LIMB AT THE TIME OF THE X-RAY BURST. THERE MAY BE A REGION BEHIND 8644 THAT WAS THE PRIMARY SOURCE OF THE X-RAY BURST. THIS WOULD BE NEAR THE LOCATION OF THE RETURN OF OLD REGION 8611 THAT PRODUCED 5 M-CLASS EVENTS LAST ROTATION. REGION 8636 (N21W02) GREW SLOWLY DURING THE PERIOD AND SIMPLIFIED. THE WEAK DELTA CONFIGURATION VISIBLE IN THIS REGION ON 22 JUL FADED. REGION 8636 PRODUCED A VERY LONG DURATION M1/2F THAT BEGAN AT 23/1832Z AND REACHED MAXIMUM AT 23/2005Z. SEVERAL MID TO HIGH LEVEL C-CLASS FLARES WERE PRODUCED BY THIS REGION. REGION 8639 (N38W60) GREW AT A MODERATE PACE AND EXHIBITED A STRAIGHT BIPOLAR, BUT REVERSE POLARITY, CONFIGURATION.
IB. Solar Activity Forecast
AT A MINIMUM, SOLAR ACTIVITY SHOULD CONTINUE AT MODERATE LEVELS FOR THE NEXT THREE DAYS. REGIONS 8636, 8639, AND 8644 (OR THE REGION BEHIND IT) ARE CAPABLE OF PRODUCING M-CLASS EVENTS. REGION 8636 COULD PRODUCE AN X-CLASS EVENT DURING THE PERIOD.
IIA. Geophysical Activity Summary 22-2100Z to 23-2100Z
THE GEOMAGNETIC FIELD WAS PREDOMINANTLY UNSETTLED WITH BRIEF QUIET PERIODS. SOLAR WIND VELOCITY BEGAN TO DECREASE DURING THE PERIOD BUT REMAINED ABOVE NORMAL.
IIB. Geophysical Activity Forecast
THE GEOMAGNETIC FIELD SHOULD BE QUIET TO UNSETTLED FOR THE NEXT THREE DAYS. ISOLATED ACTIVE CONDITIONS ARE POSSIBLE ON 24-25 JUL. SHOULD REGION 8636 PRODUCE A LARGE FLARE, IT WOULD LIKELY HAVE THE CHARACTERISTICS (LARGE AREA, LONG DURATION, AND CME CREATION) TO PRODUCE A SOLAR PROTON EVENT AT THE EARTH.
III. Event Probabilities 24 JUL to 26 JUL
Class M90%90%90%
Class X20%20%20%
Proton20%20%20%
PCAFYELLOW
IV. Penticton 10.7 cm Flux
  Observed       23 JUL 194
  Predicted   24 JUL-26 JUL  175/178/180
  90 Day Mean        23 JUL 155
V. Geomagnetic A Indices
OBSERVED AFR/AP 22 JUL  023/024
ESTIMATED AFR/AP 23 JUL  010/012
PREDICTED AFR/AP 24 JUL-26 JUL  012/012-012/012-008/008
VI. Geomagnetic Activity Probabilities 24 JUL to 26 JUL
A. Middle Latitudes
Active30%20%20%
Minor storm05%05%05%
Major-severe storm01%05%01%
B. High Latitudes
Active40%35%30%
Minor storm05%05%05%
Major-severe storm01%05%01%

All times in UTC

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