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FXXX12 KWNP 311231

:Product: Forecast Discussion
:Issued: 2015 Jul 31 1230 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
#             Forecast Discussion
Solar Activity

.24 hr Summary...
Solar activity remained at very low levels with a few B-class flares
observed. Region 2390 (S15W60, Dai/beta) continued to decay,
particularly in the intermediate portion of the region. Region 2393
(N17E40, Dao/beta) exhibited slight intermediate spot growth as it
rotated further onto the visible disk. The remaining numbered regions
remained stable and inactive. No Earth-directed coronal mass ejections
(CME) were observed in available coronagraph imagery.

Solar activity is expected to remain very low with a chance for C-class
activity for the next three days (31 Jul-02 Aug).

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux was at normal to moderate levels
with a peak flux of 825 pfu observed at 30/1440 UTC. The greater than 10
MeV proton flux remained at background levels through the period.

The greater than 2 MeV electron flux is expected to be at normal to
moderate levels on days one and two (31 Jul-01 Aug) with moderate to
high levels expected on day three (02 Aug) due to high speed winds
associated with a negative polarity coronal hole. The greater than 10
MeV proton flux is expected to remain at background levels (below

Solar Wind

.24 hr Summary...
Solar wind parameters, measured at the ACE satellite, indicated a
near-ambient solar wind environment early in the period. Wind speeds
averaged 340 km/s, IMF total field (Bt) measured 3-5 nT, the Bz
component was mostly negative to -5 nT and the phi angle was in a
positive (away) sector. Shortly after 30/1300 UTC, the phi angle rotated
to a negative (towards) sector. Coincident with this sector change were
increases in density, temperature, Bt and a gradual increase in wind

Bt increased to a maximum of 14 nT by about 30/2120 UTC while the Bz
component turned further southward to -10 nT through about 31/0230 UTC
when it rotated northward to +13 nT through 31/1000 UTC. Bz was then
variable between +2 nT to -8 nT through periods end. Wind speed
increased to about 425 km/s through about 31/0320 UTC when a further
increase to about 475 km/s was observed. The period ended with wind
speeds approaching 525 km/s. This solar wind enhancement was consistent
with a co-rotating interaction region (CIR) in advance of an anticipated
negative polarity coronal hole high speed stream (CH HSS).

A further increase in solar wind speed is expected late on day one (31
Jul) due to CIR effects in advance of an anticipated negative polarity
CH HSS. Solar wind speed parameters are expected to remain enhanced
through day three (02 Aug) due to continued CH HSS influences.


.24 hr Summary...
The geomagnetic field was at quiet to active levels due to CIR effects
in advance of an anticipated negative polarity CH HSS.

Mostly unsettled to active conditions, with a late period of G1 (minor)
storm conditions, are expected for the remainder of day one (31 Jul).
Day two (01 Aug) will see similar conditions with unsettled to active
levels, with isolated G1 (minor) storm periods, as CH HSS influences
continue. Mostly unsettled conditions are expected on day three (02 Aug)
as CH HSS effects begin to wane. is the U.S. government's official web portal to all federal, state and local government web resources and services.