Message:21055 In: SPACWX.USA
From: N4SDDate: Sat, 18 Apr 26 12:32:00 Z
Newsgroups: SPACWX.USA
Subject: Space Weather Forecast Discussion
Message-ID: <11415_N4SD>
Path: N2MH4|WB4WPF|KA3VSP|N4SD
R:260418/1856Z 30375@N2MH4.#SENC.NC.USA.NOAM LinBPQ6.0.24
R:260418/1856Z 10507@WB4WPF.#SFL.FL.USA.NOAM LinBPQ6.0.25
R:260418/1854Z 935@KA3VSP.DE.USA.NOAM BPQ6.0.25
R:260418/1232Z 11415@N4SD.#TIDE.VA.USA.NOAM BPQ6.0.24
FXXX12 KWNP 181231
DAYDIS
:Product: Forecast Discussion
:Issued: 2026 Apr 18 1230 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
#
# Forecast Discussion
#
Solar Activity
.24 hr Summary...
Solar activity was at low levels. Region 4416 (N22W85, Cso/beta)
produced the largest event of the period, a C1.6 flare at 18/0704 UTC,
as it rotated around the western limb. Region 4419 (N13E8,
Eki/beta-gamma) displayed slight decay and consolidation in its trailing
spots, with the leader spots separating yet decaying as well. Region
4415 (S18W68, Hsx/alpha) remained unchanged and was unremarkable.
From around 18/0730-0823 UTC, an approximately 30 degree long eruptive
filament was observed in GONG H-alpha and GOES-19 SUVI imagery lifting
off the solar disk. The associated CME will be modeled when coronagraph
imagery becomes available.
No other Earth directed CMEs were observed in coronagraph imagery.
.Forecast...
Solar activity is expected to be low with a chance for M-class (R1-R2,
Minor-Moderate) flares on 18-20 Apr, primarily due to the flare
potential of Region 4419.
Energetic Particle
.24 hr Summary...
The greater than 2 MeV electron flux at geosynchronous orbit reached
high levels with a peak of 2,441 pfu observed at 17/1650 UTC. The
greater than 10 MeV proton flux was at background levels.
.Forecast...
The greater than 2 MeV electron flux is expected to briefly drop to
normal to moderate levels on 18 Apr with the arrival of a negative
polarity CH HSS. Flux levels are expected to increase back to high
levels on 19-20 Apr. The greater than 10 MeV proton flux is expected to
continue at background levels on 18-20 Apr.
Solar Wind
.24 hr Summary...
Solar wind parameters were at nominal levels the first half of the
reporting period. At around 17/2300 UTC, enhancements were noted as the
anticipated CH HSS moved into a geoeffective position. Total field
increased to a peak of 17 nT, while the Bz component was mostly
negative, seeing a maximum southward deflection to -14 nT. Solar wind
speeds varied between approximately 280-360 km/s before gradually
increasing to a maximum velocity of ~540 km/s. Phi rotated into a
negative orientation just after 18/2300 UTC.
.Forecast...
Solar wind parameters are expected to remain enhanced on 18 Apr as
negative polarity CH HSS influence persists. Solar wind speeds ranging
from 600-700 km/s are likely based on recurrent values. Enhanced
conditions are expected to continue through 20 Apr.
Geospace
.24 hr Summary...
The geomagnetic field reached G1 (Minor) levels before increasing to G2
(Moderate) levels after 18/0825 UTC.
.Forecast...
G1-G2 (Minor-Moderate) geomagnetic storming levels are expected on 18
Apr as negative polarity CH HSS geomagnetic conditions persist. Active
to G1 (Minor) levels are expected to continue through 19 Apr, followed
by unsettled to active conditions on 20 Apr, as HSS effects linger.
------
73 de Sperry N4SD
N4SD@N4SD.#TIDE.VA.USA.NOAM
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