NOAA SEC Report of Solar-Geophysical Activity 26 Apr 2002

:Product: Report of Solar-Geophysical Activity

:Issued: 2002 Apr 26 2210 UTC

# 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 116 Issued at 2200Z on 26 Apr 2002

IA.  Analysis of Solar Active Regions and Activity from  25/2100Z

to 26/2100Z:  Solar activity was low with very isolated low C-class

activity observed. Region 9912 (N11W78) continues to slowly decay as

it approaches the west limb. Regions 9914 (N04W25), 9915 (N11W12),

and 9919 (N12E33), exhibited minor growth. The remaining regions on

the visible disk were stable or in decay. A significant segment of

the large E-W filament centered near S32W12 disappeared late in the

period. It is too early to confirm if a CME accompanied this

filament eruption.

IB.  Solar Activity Forecast:  Solar activity is expected to continue

at low levels. Isolated low c-class flares are expected.

IIA.  Geophysical Activity Summary 25/2100Z to 26/2100Z:

The geomagnetic field was quiet. The greater than 10 MeV proton event

that began on 21/0225Z, and peaked on 21/2320Z at 2520 pfu, ended

today at 26/0715Z. The 10 MeV proton flux remains elevated at near 5

pfu, but continues to slowly decline.

IIB.  Geophysical Activity Forecast:  The geomagnetic field is

expected to become unsettled with isolated active periods. A

recurrent coronal hole is moving into a geoeffectively favorable

position; expect disturbed conditions to develop this period.

III.  Event Probabilities 27 Apr-29 Apr

Class M    25/25/25

Class X    05/05/05

Proton     01/01/01

PCAF       in progress

IV.  Penticton 10.7 cm Flux

Observed           26 Apr 163

Predicted   27 Apr-29 Apr  165/165/170

90 Day Mean        26 Apr 196

V.  Geomagnetic A Indices

Observed Afr/Ap 25 Apr  002/005

Estimated Afr/Ap 26 Apr  005/007

Predicted Afr/Ap 27 Apr-29 Apr  012/015-012/012-010/010

VI.  Geomagnetic Activity Probabilities 27 Apr-29 Apr

A.  Middle Latitudes

Active                35/35/30

Minor storm           15/15/10

Major-severe storm    05/05/01

B.  High Latitudes

Active                40/40/35

Minor storm           20/20/15

Major-severe storm    05/05/01