mercoledì 29 aprile 2015

Propagation outlook from Boulder

:Product: Weekly Highlights and Forecasts
:Issued: 2015 Apr 27 0348 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# http://www.swpc.noaa.gov/weekly.html
#
#                Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity 20 - 26 April 2015

Solar activity was at low to high levels throughout the period.
Region 2322 (N11, L=116, class/area=Dac/60 on 21 April) grew and
intensified as it rotated to the western limb; producing numerous
low level C-class flares and five moderate level M-class flares on
21 April. Region 2322 also produced the largest flare of the period,
an impulsive M4/Sf at 22/1545 UTC. Region 2322 continued to produce
C-class and M-class flares until it rotated beyond the western limb
by 24 April, including a long-duration M1 flare at 23/1007 UTC with
an associated Type-II radio sweep and coronal mass ejection (CME)
from the western limb as observed in SOHO/LASCO C2 imagery. The CME
was not Earth-directed.

Regions 2325 (N05, L=050, class/area=Cai/220 on 19 April) and 2326
(N20, L=086, class/area=Cao/80 on 23 April) were the other most
prolific flare producers during the period. Region 2325 produced an
M1 flare at 21/2201 UTC and Region 2326 produced numerous C-class
X-ray flares with the most notable being a C7 flare at 23/1203 UTC.
Both flares were very impulsive and did not have any observed
optical flares nor notable radio signatures.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at
moderate to high levels during the week; reaching high levels on
20-21 April and 24 April with a peak flux of 2,620 pfu on 20 April.

Geomagnetic field activity was at quiet to unsettled levels on 20
April as Earth was in a background ambient solar wind environment.
On 21 April, Earth came under the influence of an isolated positive
coronal hole high speed stream (CH HSS) and solar wind speeds
increased to over 600 km/s as measured at the ACE satellite. This CH
HSS produced occasional periods of active levels of geomagnetic
activity from 21-24 April. The CH HSS rotated out of a geo-effective
alignment by midday on 24 April and the winds decreased to mainly
nominal solar wind conditions of about 375 km/s, returning Earth to
quiet to unsettled geomagnetic conditions.

During the week, ACE solar wind parameters measured a high wind
speed of 628 km/s on 21/0632 UTC and a low wind speed of 291 km/s on
26/1123 UTC. Total field (Bt) ranged from about 1 to 14 nT, while
the Bz component varied between +12 to -7 nT. The phi angle was
generally in a positive (away from the Sun) orientation with a short
period of negative (towards the Sun) sector to begin the week.

FORECAST OF SOLAR AND GEOMAGNETIC ACTIVITY 27 APRIL - 23 MAY 2015

Solar activity is expected to be at very low to low levels through 03 May due to the low number of complex active regions. Solar activity levels are expected to increase to low levels; with a slight chance for moderate (R1-R2/minor-moderate) levels beginning 04 May with the return of Region 2322 (N11, L=116) and remain at low levels, but increase to a chance for moderate (R1-R2/minor-moderate) levels beginning 07 May as Region 2326 (N20, L=086) also rotates back onto the disc. Solar activity level is expected to decrease back to very low to low levels with the departure of Regions 2322 and 2326 beginning 17 May. 

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at normal to moderate levels from 27 April-06 May, normal levels from 07-12 May, moderate to high levels from 13-14 May, high levels from 15-18 May, moderate levels from 19-20 May, and moderate to high levels from 21-23 May. 

Geomagnetic field activity is expected to be at quiet levels from 27-28 April and increase to quiet to unsettled levels beginning 29 April due to CH HSS effects. Field activity is expected to begin decreasing by 02 May, with overall quiet levels likely from 03-10 May. Field activity is expected to increase to unsettled to active levels beginning late on 11 May and likely reaching active levels on 12-13 May due to CH HSS effects. Field activity is expected to decrease to unsettled to active levels by 14 May as CH HSS effects begin to wane; and return to quiet to unsettled conditions from 15-17 May. Field conditions are expected to increase to unsettled to active levels on 18 May due to a CH HSS and return to quiet to unsettled conditions as the CH HSS rotates out of a geo-effective position by 21 May, and remain at quiet levels for the remainder of  the outlook period.

:Product: 27-day Space Weather Outlook Table 27DO.txt
:Issued: 2015 Apr 27 0348 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# http://www.swpc.noaa.gov/wwire.html
#
#      27-day Space Weather Outlook Table
#                Issued 2015-04-27
#
#   UTC      Radio Flux   Planetary   Largest
#  Date       10.7 cm      A Index    Kp Index
2015 Apr 27     120           5          2
2015 Apr 28     120           5          2
2015 Apr 29     115           8          3
2015 Apr 30     110          10          3
2015 May 01     110          10          3
2015 May 02     110           8          3
2015 May 03     115           5          2
2015 May 04     120           5          2
2015 May 05     125           5          2
2015 May 06     130           5          2
2015 May 07     135           5          2
2015 May 08     135           5          2
2015 May 09     135           5          2
2015 May 10     130           5          2
2015 May 11     125           5          2
2015 May 12     130          25          5
2015 May 13     130          20          5
2015 May 14     130          20          4
2015 May 15     125          12          4
2015 May 16     130           8          3
2015 May 17     125          12          3
2015 May 18     120          20          4
2015 May 19     120          12          3
2015 May 20     115           8          3
2015 May 21     115           5          2
2015 May 22     115           5          2
2015 May 23     115           5          2
(SWPC via DXLD)