NOAA/USAF Report of Solar-Geophysical Activity 20 May 2000

Report of Solar-Geophysical Activity

:Issued: 2000 May 20 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 141 ISSUED AT 2200Z ON 20 MAY 2000

IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  19/2100Z

TO 20/2100Z:  SOLAR ACTIVITY DECREASED TO LOW LEVELS. THE HIGHLIGHT

OF THE PERIOD WAS A C7/1N FLARE AT 20/0535Z WITH ASSOCIATED TYPE II

AND IV RADIO SWEEPS FROM REGION 8998 (S12W22). THIS REGION SHOWED NO

SIGNIFICANT CHANGES IN SIZE OR STRUCTURE AND REMAINED A LARGE GROUP

WITH A MODERATE DEGREE OF MAGNETIC COMPLEXITY. REGION 9004 (N12W06)

SHOWED SIGNIFICANT GROWTH DURING THE PERIOD AND PRODUCED ISOLATED

SUBFLARES. REGION 8996 (S21W35) GRADUALLY DECREASED IN SIZE AND

MAGNETIC COMPLEXITY AND PRODUCED ISOLATED SUBFLARES. REGION 9002

(N19E04) GAINED A FEW SPOTS, BUT WAS LARGELY UNCHANGED AS IT

REMAINED A LARGE GROUP OF MODERATE MAGNETIC COMPLEXITY. NEW REGIONS

9012 (S29W36), 9013 (S06W61), AND 9014 (S43E21) WERE NUMBERED.

IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY IS EXPECTED TO BE AT

MODERATE LEVELS. ISOLATED M-CLASS FLARES ARE LIKELY. THERE IS A

SLIGHT CHANCE FOR A MAJOR FLARE AS WELL.

IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 19/2100Z TO 20/2100Z:

GEOMAGNETIC FIELD ACTIVITY WAS AT QUIET LEVELS.

IIB.  GEOPHYSICAL ACTIVITY FORECAST:  GEOMAGNETIC FIELD ACTIVITY IS

EXPECTED TO BE AT QUIET TO UNSETTLED LEVELS WITH ACTIVE LEVELS

POSSIBLE DURING 23 MAY.

III.  EVENT PROBABILITIES 21 MAY-23 MAY

CLASS M    70/70/70

CLASS X    10/10/10

PROTON     05/05/05

PCAF       GREEN

IV.  PENTICTON 10.7 CM FLUX

OBSERVED           20 MAY 246

PREDICTED   21 MAY-23 MAY  240/240/235

90 DAY MEAN        20 MAY 195

V.  GEOMAGNETIC A INDICES

OBSERVED AFR/AP 19 MAY  007/009

ESTIMATED AFR/AP 20 MAY  007/008

PREDICTED AFR/AP 21 MAY-23 MAY  008/008-008/008-015/010

VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 21 MAY-23 MAY

A.  MIDDLE LATITUDES

ACTIVE                25/25/30

MINOR STORM           10/10/15

MAJOR-SEVERE STORM    01/01/01

B.  HIGH LATITUDES

ACTIVE                30/30/35

MINOR STORM           15/15/20

MAJOR-SEVERE STORM    01/01/01