Strong Geomagnetic Storm Expected Today (July 27th)

Official Space Weather Advisory issued by NOAA Space Environment Center Boulder, Colorado, USA

SPACE WEATHER ADVISORY BULLETIN #04- 1

2004 July 26 at 01:17 p.m. MDT (2004 July 26 1917 UTC)

**** STRONG GEOMAGNETIC STORM EXPECTED ****

A large and moderately complex sunspot cluster known as NOAA Region 652 was responsible for a significant eruption on 25 July, 2004 at 915 a.m. MDT. A radiation storm, currently at the S2 level, began soon after the eruption was observed on the Sun. An Earth-directed coronal mass ejection (CME) was also observed and is expected to impact the geomagnetic field early on 27 July. This CME will likely produce periods of strong (G3) geomagnetic storming.

Agencies impacted by geomagnetic storms and radiation storms may experience disruptions in the next 48 hours. These include spacecraft operations, electric power systems, HF communications, and navigation systems.

A full halo CME was observed on LASCO imagery following yesterday's long duration M1 flare at 25/1514Z. This CME will likely impact the geomagnetic field early on 27 July. Expect minor to major storm periods at all latitudes and severe storm levels at high latitudes. The storm is expected to end by 28 July. Mostly unsettled to active conditions are expected on 28 July. A return to quiet to unsettled levels is expected on 29 July with isolated high latitude active period possible. The greater than 10 MeV proton event in progress now will likely end on 28 July.

AURORA ALERT: Sky watchers should remain alert for auroras because a geomagnetic storm is underway. It began around 2300 UT (4:00 p.m. PDT) on July 26th when a coronal mass ejection (CME, movie) hit Earth's magnetic field. The impact triggered intense geomagnetic activity, which was sustained through the night by a south-pointing interplanetary magnetic field.

"I just received a call from Bill Murtagh who is the top forecaster for
the Space Weather Center in Boulder, Colorado. He told me the Kp index has gone off the charts and all SWC personnel has been called in. There is a great concern of a second CME heading towards Earth. There is a real and present danger of power grids going down. I am also told Dr. Ernest Hildner, director of the SWC, is on his way to Washington DC at this very moment.
Bill Murtagh has informed me our interview scheduled for tonight may
have to be postponed due to urgent circumstances."

An intense geomagnetic storm that sparked auroras in many US states last night is subsiding. The storm began around 2300 UT (4:00 p.m. PDT) on July 26th when a coronal mass ejection (CME, movie) hit Earth's magnetic field, and it was sustained through the night by a south-pointing IMF