NOAA/USAF Report of Solar-Geophysical Activity 15 Apr 2000

:Product: Report of Solar-Geophysical Activity

:Issued: 2000 Apr 15 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 106 ISSUED AT 2200Z ON 15 APR 2000

IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  14/2100Z

TO 15/2100Z:  SOLAR ACTIVITY INCREASED TO MODERATE LEVELS. REGION

8955 (S22E20) SHOWED A GRADUAL INCREASE IN MAGNETIC COMPLEXITY

DURING THE PERIOD AND PRODUCED SEVERAL FLARES, TWO OF WHICH REACHED

M-CLASS. THE FIRST WAS AN M4/SF AT 15/1018Z ASSOCIATED WITH A 570

SFU TENFLARE AND A PARTIAL-HALO CME. THE SECOND WAS AN M2/1N AT

15/1448Z. ANOTHER FLARE OF NOTE FROM REGION 8955 WAS A C7/1N AT

15/1905Z ASSOCIATED WITH A SMALL FILAMENT DISAPPEARANCE. MINOR

GROWTH WAS REPORTED IN REGION 8951 (N12W31). REGION 8948 (S16W76)

PRODUCED ISOLATED LOW-LEVEL C-CLASS FLARES AS IT CONTINUED TO DECAY.

THE REMAINING REGIONS WERE STABLE. NO NEW REGIONS WERE ASSIGNED.

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

LOW TO MODERATE LEVELS. REGION 8955 MAY PRODUCE ADDITIONAL M-CLASS

FLARES.

IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 14/2100Z TO 15/2100Z:

GEOMAGNETIC FIELD ACTIVITY WAS AT QUIET LEVELS. THE GREATER THAN 2

MEV ELECTRON FLUX AT GEOSYNCHROUNOUS ORBIT REMAINED AT MODERATE TO

HIGH LEVELS.

IIB.  GEOPHYSICAL ACTIVITY FORECAST:  GEOMAGNETIC FIELD ACTIVITY IS

EXPECTED TO INCREASE TO UNSETTLED TO ACTIVE LEVELS DURING 16 APRIL

IN RESPONSE TO A PARTIAL-HALO CME OBSERVED LATE ON 13 APRIL. ACTIVE

LEVELS ARE ALSO POSSIBLE ON 18 APRIL DUE TO THE PARTIAL-HALO CME

OBSERVED EARLIER TODAY. THE GREATER THAN 2 MEV ELECTRON FLUX IS

EXPECTED TO RANGE FROM NORMAL TO HIGH LEVELS DURING THE PERIOD.

III.  EVENT PROBABILITIES 16 APR-18 APR

CLASS M    50/50/50

CLASS X    10/10/10

PROTON     05/05/05

PCAF       GREEN

IV.  PENTICTON 10.7 CM FLUX

OBSERVED           15 APR 164

PREDICTED   16 APR-18 APR  165/165/165

90 DAY MEAN        15 APR 184

V.  GEOMAGNETIC A INDICES

OBSERVED AFR/AP 14 APR  002/005

ESTIMATED AFR/AP 15 APR  007/008

PREDICTED AFR/AP 16 APR-18 APR  018/020-010/012-015/018

VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 16 APR-18 APR

A.  MIDDLE LATITUDES

ACTIVE                40/25/30

MINOR STORM           20/10/15

MAJOR-SEVERE STORM    05/01/01

B.  HIGH LATITUDES

ACTIVE                45/30/40

MINOR STORM           25/15/20

MAJOR-SEVERE STORM    10/05/05