NOAA/USAF Report of Solar-Geophysical Activity 24 May 2000

Report of Solar-Geophysical Activity

:Issued: 2000 May 24 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 145 ISSUED AT 2200Z ON 24 MAY 2000

IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  23/2100Z

TO 24/2100Z:  SOLAR ACTIVITY WAS MODERATE. REGION 8996 (S22W87)

PRODUCED AN M1 X-RAY FLARE AT 24/0546Z. AN OPTICALLY UNCORRELATED M1

FLARE OCCURRED AT 24/1152Z. THE LIKELY SOURCE FOR THIS FLARE WAS NEW

REGION 9017 (S14E76) WHICH HAS EXHIBITED FREQUENT SURGING FOR MOST

OF THE PERIOD. REGIONS 9002 (N19W51) AND 9004 (N12W61) CONTINUE TO

PRODUCE C-CLASS FLARES. NEW REGIONS 9015 (N13W08) AND 9016 (N26E46)

WERE ALSO NUMBERED TODAY.

IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO CONTINUE

AT LOW TO MODERATE LEVELS. ANY ONE OF A NUMBER OF REGIONS ON OR NEAR

THE WEST LIMB ARE CAPABLE OF PRODUCING AN ISOLATED M-CLASS FLARE.

NEW REGION 9017 MAY ALSO PRODUCE AN M FLARE.

IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 23/2100Z TO 24/2100Z:

THE GEOMAGNETIC FIELD WAS AT ACTIVE TO SEVERE STORM LEVELS. THE

TRANSIENT OBSERVED TO PASS ACE AT 23/1625Z HERALDED THE BEGINNING OF

A COMPACT AND COMPLEX MAGNETIC STRUCTURE. A NUMBER OF STRONG

NORTHWARD TO SOUTHWARD VARIATIONS IN BZ OCCURRED THAT REACHED

EXTREMES OF -36 NT TO +30 NT. CONDITIONS IMPROVED BY 24/12Z BUT

SOLAR WIND VELOCITY REMAINS ELEVATED RESULTING IN ACTIVE TO MINOR

STORM CONDITIONS PERSISTING THROUGH LATE IN THE PERIOD. THIS

ACTIVITY IS PRESUMED TO BE ASSOCIATED WITH THE C7/1N FLARE THAT

OCCURRED AT 20/0535Z.

IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD IS

EXPECTED TO BE AT ACTIVE TO MINOR STORM LEVELS THROUGH DAY ONE AS

THE PRESENT STORM SUBSIDES. UNSETTLED CONDITIONS ARE EXPECTED ON

DAYS TWO AND THREE.

III.  EVENT PROBABILITIES 25 MAY-27 MAY

CLASS M    50/50/40

CLASS X    10/10/05

PROTON     05/05/01

PCAF       GREEN

IV.  PENTICTON 10.7 CM FLUX

OBSERVED           24 MAY 189

PREDICTED   25 MAY-27 MAY  180/175/165

90 DAY MEAN        24 MAY 196

V.  GEOMAGNETIC A INDICES

OBSERVED AFR/AP 23 MAY  019/022

ESTIMATED AFR/AP 24 MAY  048/070

PREDICTED AFR/AP 25 MAY-27 MAY  018/030-010/010-010/010

VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 25 MAY-27 MAY

A.  MIDDLE LATITUDES

ACTIVE                40/40/30

MINOR STORM           40/20/10

MAJOR-SEVERE STORM    10/05/01

B.  HIGH LATITUDES

ACTIVE                40/50/40

MINOR STORM           45/30/20

MAJOR-SEVERE STORM    15/10/05