NOAA/USAF Report of Solar-Geophysical Activity 18 September 2000

:Product: Report of Solar-Geophysical Activity
:Issued: 2000 Sep 18 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 262 ISSUED AT 2200Z ON 18 SEP 2000
IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  17/2100Z
TO 18/2100Z:  SOLAR ACTIVITY WAS LOW. A NUMBER OF C-CLASS SUBFLARES
OCCURRED IN REGIONS 9165 (N14W40), 9166 (S14E24), AND 9167 (N12E57).
DECAY IN REGION 9165 HAS SLOWED AND THE AREA RETAINS SOME MAGNETIC
COMPLEXITY. REGION 9166 CONTINUES TO GROW SLOWLY AND IS PRESENTLY AN
E-TYPE SUNSPOT GROUP WITH SOME MIXED POLARITIES. NEW REGION 9169
(N08E70) IS A LARGE SUNSPOT GROUP ROTATING AROUND THE EAST LIMB, AND
IS ABUTTED TO THE SOUTHEAST OF REGION 9167. SO FAR IT HAS NOT
PRODUCED SIGNIFICANT FLARES BUT IT APPEARS TO BE A CAPABLE REGION;
HOWEVER, ITS LIMB PROXIMITY MAKES ANALYSIS DIFFICULT.
IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE LOW
TO MODERATE. FLARE ACTIVITY IS EXPECTED FROM REGIONS 9165, 9166,
9167, AND 9169.
IIA.  GEOPHYSICAL ACTIVITY SUMMARY 17/2100Z TO 18/2100Z:
THE GEOMAGNETIC FIELD RANGED FROM ACTIVE TO MAJOR STORM LEVELS AT
MIDDLE LATITUDES AND ACTIVE TO SEVERE STORM LEVELS AT HIGH
LATITUDES. THE MOST DISTURBED PERIOD OCCURRED FROM 17/2100 UTC TO
18/0300 UTC. THE GEOMAGNETIC FIELD APPEARS TO BE UNDER THE INFLUENCE
OF A HIGH-SPEED CORONAL HOLE STREAM, PUNCTUATED WITH  THE PASSAGE OF
CME MATERIAL. THE MOST DISTURBED PERIOD WAS ASSOCIATED WITH A CME.
IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS
EXPECTED TO BE AT ACTIVE  TO STORM LEVELS. THE HIGH-SPEED STREAM IS
EXPECTED TO PERSIST AND ANOTHER CME IS EXPECTED TO ARRIVE EITHER
LATE ON SEP 18 OR EARLY ON SEP 19.
III.  EVENT PROBABILITIES 19 SEP-21 SEP
CLASS M    50/50/50
CLASS X    05/05/05
PROTON     05/05/05
PCAF       GREEN
IV.  PENTICTON 10.7 CM FLUX
OBSERVED           18 SEP 204
PREDICTED   19 SEP-21 SEP  210/215/220
90 DAY MEAN        18 SEP 177
V.  GEOMAGNETIC A INDICES
OBSERVED AFR/AP 17 SEP  032/040
ESTIMATED AFR/AP 18 SEP  035/045
PREDICTED AFR/AP 19 SEP-21 SEP  040/055-030/040-020/020
VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 19 SEP-21 SEP
A.  MIDDLE LATITUDES
ACTIVE                10/15/30
MINOR STORM           30/30/15
MAJOR-SEVERE STORM    60/50/35
B.  HIGH LATITUDES
ACTIVE                10/15/30
MINOR STORM           30/30/15
MAJOR-SEVERE STORM    60/50/35
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 WEB SITE AT
SEC.NOAA.GOV/MIXEDCASE.HTML