Joint USAF/NOAA Report of Solar and Geophysical Activity 17 Jul 2005

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.

Updated 2005 Jul 17 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 198 Issued at 2200Z on 17 Jul 2005

IA. Analysis of Solar Active Regions and Activity from 16/2100Z
to 17/2100Z: Activity was at low levels today. Region 790 (S10W93)
produced the largest flare during the period, a very impulsive C4
flare which occurred at 17/0629Z. This region also produced
multiple B-class flares as it began rotating beyond the solar west
limb. Spotless Region 789 (N17W86) was responsible for producing
several B-class flares today. A back-sided full halo CME, which is
believed to be from old Region 786 (N12 L=056), was first observed
on LASCO C2 imagery at 17/1130Z. No new regions were numbered
today.

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

IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z:
The geomagnetic field ranged from quiet to minor storm levels. A
weak transient signature (likely from the X1 related CME activity
seen on 14 July) was detected at the ACE spacecraft near 17/0000Z
where the wind speeds increased from near 425 km/sec to 500 km/sec.
Minor storming was later observed between 17/0900 and 1200Z. The
greater than 10 MeV proton event that began on 14/0245Z, had a peak
flux of 134 pfu at 15/0345Z, and underwent an injection of flux at
17/1735Z allowing for the event to remain in-progress at near 17 pfu
at the time of this writing. The source believed responsible for
the increase in proton flux was the back-sided activity relating to
the full halo CME mentioned in 1A.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at predominantly quiet to unsettled levels on 18 and
19 July. A recurrent high speed coronal hole stream is expected to
become geoeffective 20 July with active to minor storming expected
and isolated major storm conditions possible. The greater than 10
proton event is expected to end on 18 July.

III. Event Probabilities 18 Jul-20 Jul

• Class M 15/05/01
• Class X 01/01/01
• Proton 99/15/01
• PCAF yellow

IV. Penticton 10.7 cm Flux

• Observed 17 Jul 074
• Predicted 18 Jul-20 Jul 075/075/075
• 90 Day Mean 17 Jul 097

V. Geomagnetic A Indices

• Observed Afr/Ap 16 Jul 010/009
• Estimated Afr/Ap 17 Jul 010/020
• Predicted Afr/Ap 18 Jul-20 Jul 005/015-008/012-020/025

VI. Geomagnetic Activity Probabilities 18 Jul-20 Jul

A. Middle Latitudes

• Active 15/20/35
• Minor storm 05/05/20
• Major-severe storm 01/01/15

B. High Latitudes

• Active 35/30/40
• Minor storm 20/15/35
• Major-severe storm 05/05/15