Report of Solar-Geophysical Activity

Issued: 2006 May 18 2200 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 138 Issued at 2200Z on 18 May 2006 IA. Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity was very low.

IB. Solar Activity Forecast: Solar activity is expected to be very low.

IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z:

The geomagnetic field was at quiet to minor storm levels. Solar wind speed at ACE showed an increase beginning around 18/0500 UTC as a coronal hole high speed stream moved into geoeffective position.

Solar wind speed increased to around 600 km/s. An isolated minor storm period occurred between 18/1500 and 18/1800 UTC.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be quiet to active with minor storm periods possible on

19 May due to continued coronal hole activity. On 20 and 21 May, mostly quiet to unsettled conditions are expected.

III. Event Probabilities 19 May-21 May

Class M 01/01/01

Class X 01/01/01

Proton 01/01/01

PCAF green

IV. Penticton 10.7 cm Flux

Observed 18 May 073

Predicted 19 May-21 May 075/075/075

90 Day Mean 18 May 081

V. Geomagnetic A Indices

Observed Afr/Ap 17 May 004/005

Estimated Afr/Ap 18 May 012/014

Predicted Afr/Ap 19 May-21 May 010/020-008/010-005/008 VI. Geomagnetic Activity Probabilities 19 May-21 May A. Middle Latitudes

Active 25/20/15

Minor storm 10/10/05

Major-severe storm 01/01/01

B. High Latitudes

Active 35/25/20

Minor storm 20/10/10

Major-severe storm 10/01/01