NOAA/USAF Report of Solar-Geophysical Activity 26 September 2000
:Product: Report of Solar-Geophysical Activity :Issued: 2000 Sep 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 270 ISSUED AT 2200Z ON 26 SEP 2000 IA. ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM 25/2100Z TO 26/2100Z: SOLAR ACTIVITY WAS LOW. THE LARGEST EVENT THIS PERIOD WAS A C-8 X-RAY BURST AT 26/2000Z. NO SIGNIFICANT ACTIVITY WAS OBSERVED IN ANY NUMBERED REGIONS BUT SURGING NOTED ON THE SE LIMB BECAME PARTICULARLY BRIGHT AND ENHANCED DURING THIS X-RAY EVENT. LARGE REGION 9169 (N12W34) CONTINUES TO DECAY AND APPEARS TO NO LONGER CONTAIN A MAGNETIC DELTA CONFIGURATION. ONLY LOW C-CLASS FLARES WERE OBSERVED FROM THIS REGION. REGION 9173 (S13E51) UNDERWENT SOME GROWTH AND PRODUCED A C4/SF FLARE AT 26/1231Z. NEW REGIONS 9174 (S30W60) AND 9175 (N21E67) WERE NUMBERED TODAY. IB. SOLAR ACTIVITY FORECAST: SOLAR ACTIVITY IS EXPECTED TO BE LOW TO MODERATE. REGION 9169, THOUGH DECAYING, IS STILL CAPABLE OF AN ISOLATED M-CLASS FLARE. SEVERAL OTHER REGIONS ON THE VISIBLE DISK MAY PRODUCE C-CLASS FLARES. IIA. GEOPHYSICAL ACTIVITY SUMMARY 25/2100Z TO 26/2100Z: THE GEOMAGNETIC FIELD WAS UNSETTLED TO ACTIVE. THIS DISTURBANCE APPEARS TO BE ASSOCIATED WITH A HIGH-SPEED CORONAL HOLE STREAM. SOLAR WIND SPEED WAS AVERAGING NEAR 600 KM/S. THE GREATER THAN 2 MEV ELECTRONS AT GEOSYNCHRONOUS ORBIT WERE AT MODERATE TO HIGH LEVELS. IIB. GEOPHYSICAL ACTIVITY FORECAST: THE GEOMAGNETIC FIELD IS EXPECTED TO CONTINUE AT UNSETTLED TO ACTIVE LEVELS WITH PERIODS OF MINOR STORMING POSSIBLE ON DAYS ONE AND TWO. A CME ASSOCIATED WITH THE M-1 FLARE ON 25/0215Z MAY ENHANCE THE CURRENT DISTURBANCE THROUGH DAY TWO. MOSTLY QUIET TO UNSETTLED CONDITIONS ARE EXPECTED ON DAY THREE. III. EVENT PROBABILITIES 27 SEP-29 SEP CLASS M 50/50/50 CLASS X 10/10/10 PROTON 05/05/05 PCAF YELLOW IV. PENTICTON 10.7 CM FLUX OBSERVED 26 SEP 224 PREDICTED 27 SEP-29 SEP 210/200/190 90 DAY MEAN 26 SEP 181 V. GEOMAGNETIC A INDICES OBSERVED AFR/AP 25 SEP 013/016 ESTIMATED AFR/AP 26 SEP 020/021 PREDICTED AFR/AP 27 SEP-29 SEP 020/020-012/010-012/010 VI. GEOMAGNETIC ACTIVITY PROBABILITIES 27 SEP-29 SEP A. MIDDLE LATITUDES ACTIVE 50/50/40 MINOR STORM 20/20/40 MAJOR-SEVERE STORM 05/05/01 B. HIGH LATITUDES ACTIVE 50/50/40 MINOR STORM 30/30/20 MAJOR-SEVERE STORM 10/10/05 VII. COMMENTS EFFECTIVE 2 OCT 2000, SEC WILL ISSUE ITS TEXT PRODUCTS IN MIXED CASE VS. ALL UPPER CASE. THIS CHANGE WILL BE VISIBLE ON ALL SEC PRODUCT DELIVERY SYSTEMS EXCEPT FOR TELETYPE CIRCUITS. ONLY THE CASE OF THE TEXT IN EACH PRODUCT WILL CHANGE, NOT THE FORMAT OR SPACING WITHIN THE PRODUCT. FOR DETAILS SEE OUR WEBSITE AT SEC.NOAA.GOV/MIXEDCASE.HTML
