Joint USAF/NOAA Report of Solar and Geophysical Activity 01 April 2012

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Weather Prediction Center and the U.S. Air Force.
Updated 2012 Apr 01 2200 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 092 Issued at 2200Z on 01 Apr 2012

IA. Analysis of Solar Active Regions and Activity from 31/2100Z
to 01/2100Z: Solar activity was very low. Only minor B-class/Sf
flares were observed, one from Region 1444 (N21W86) at 31/2107 and
from 1450 (N17E22) at 01/1454Z. The event from Region 1444 was
associated with a narrow eruption visible in SDO/AIA 304 imagery.
The ejecta is not expected to be geoeffective. The remaining
regions were quiet and magnetically simple.

IB. Solar Activity Forecast: Solar activity is expected to be very
low to low with a slight chance for a C-class flare for the first
two days of the period (02-03 April). The probability of a C class
event increases on Day 3 (04 April) with the anticipated return of
Old Region 1434 (S22 L=207).

IIA. Geophysical Activity Summary 31/2100Z to 01/2100Z:
The geomagneic field was quiet. Solar wind speed measured at the ACE
spacecraft gradually declined from around 380 km/s at the beginning
of the period to about 320 km/s by the end. At approximately
01/0800Z, ACE indicated a solar sector boundary crossing to a
negative orientation accompanied by increased density and slight (-5
nT) southward Bz.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to begin the period at quiet levels. On Day 3 (04 April),
it will become unsettled with the possiblity of an isolated active
period as a coronal hole high speed stream becomes geoeffective.

III. Event Probabilities 02 Apr-04 Apr
Class M 05/05/10
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 01 Apr 107
Predicted 02 Apr-04 Apr 110/115/125
90 Day Mean 01 Apr 118

V. Geomagnetic A Indices
Observed Afr/Ap 31 Mar 004/004
Estimated Afr/Ap 01 Apr 006/006
Predicted Afr/Ap 02 Apr-04 Apr 006/005-006/005-007/008

VI. Geomagnetic Activity Probabilities 02 Apr-04 Apr
A. Middle Latitudes
Active 05/05/10
Minor storm 01/01/01
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/20
Minor storm 15/15/25
Major-severe storm 05/05/15