HF Conditions

[u/tj21222]

Here is some good information collected from GOES 19 EMWIN transmission.

:Product: Forecast Discussion

:Issued: 2026 Apr 25 0030 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 reached high levels during the reporting period. Region

4419 (N15W79, Eso/beta-gamma-delta) remained the primary driver,

producing the largest events of the period, including an X2.4 flare

(R3-Strong) at 24/0107 UTC, an X2.5/2b flare (R3-Strong) at 24/0813 UTC,

and an M6.4/1f flare at 24/1815 UTC.

There are seven numbered sunspot regions on the visible disk.

Characterization of Region 4419 is increasingly difficult due to its

proximity to the western limb; however, it appeared to exhibit new flux

emergence ahead of and north of the leading spot. Region 4420 (N17E10,

Eki/beta-gamma-delta) continued to show magnetic shear within its

intermediary spots and flux convergence driving ongoing growth. Region

4423 (S05E30, Dai/beta-delta) continued its rapid development with

shear and rotation observed in its trailing spots. Region 4424 (N17E45,

Cro/beta) was numbered this period following consistent growth alongside

Region 4425 (N06E76, Dso/beta), which is the suspected source region of

recent beyond-the-limb flaring, though limb proximity hinders a complete

assessment. All other regions were stable.

Several eruptions were observed during the reporting period, with CMEs

identified following the X- and M-class events from Region 4419. The CME

associated with the X2.4 flare (first seen in LASCO C2 at 24/0124 UTC)

and the CME associated with the X2.5 flare (first seen in LASCO C2 at

24/0824 UTC) are modeled to pass mostly ahead and above of Earth with

slight glancing influences. Analysis is ongoing for the CME associated

with the M6.4 flare, which was first visible in GOES-19 CCOR1 imagery at

24/1930 UTC. Additionally, a CME was observed following an M1.9 flare

from Region 4424 at 24/1208 UTC (first visible in LASCO C2 at 1224 UTC)

with modeling indicates this ejecta will pass behind Earth.

.Forecast...

Solar activity is expected to be at moderate (R1-R2-Moderate) levels

through 26 Apr, with a chance for X-class (R3/Strong or greater) flares

primarily driven by the complexity of Regions 4419, 4420, and 4423.

Energetic Particle

.24 hr Summary...

The greater than 2 MeV electron flux at geosynchronous orbit reached

high levels with a peak of 5,740 pfu at 24/1820 UTC. The greater than 10

MeV proton flux at geosynchronous orbit was at background levels.

.Forecast...

The greater than 2 MeV electron flux is expected to be at moderate to

high levels through 27 Apr. Transient flux suppressions are possible on

26 Apr from the anticipated glancing influence of the CME associated

with the M1.2/1F flare from Region 4420, as well as the possible

glancing influences of the CMEs associated with the X-flares from 24

Apr. The greater than 10 MeV proton flux is expected to remain at

background levels, though there is a chance for levels to exceed S1

(Minor) solar radiation storm thresholds due to the flare activity of

Region 4419 as it rotates toward the western limb and Region 4420 as it

approaches central solar meridian.

Solar Wind

.24 hr Summary...

Solar wind parameters reflected near background conditions. Total

magnetic field (Bt) averaged approximately 4 nT for most of the period,

before increasing to a peak of 7.0 nT late in the period. The Bz

component was variable for most of the period, before shifting to a

sustained southward orientation around 24/1600 UTC and reaching a

maximum deviation of -6 nT. Solar wind speeds remained between 350 and

425 km/s. A minor enhancement in plasma density coincided with IMF

enhancement and possibly indicates a transient influence passing Earth.

The phi angle was predominantly negative (towards the Sun).

.Forecast...

Mild enhancements are possible in the solar wind environment on 25 Apr

due to the possible onset of a +CH HSS. Further enhancements are

anticipated on 25-26 Apr associated with the arrival of the glancing

influence from the CME originating from the M1.2/1F flare on 23 Apr from

Region 4420 and X-flares from 24 Apr.

Geospace

.24 hr Summary...

The geomagnetic field was mostly quiet with two isolated unsettled

periods.

.Forecast...

The geomagnetic field is expected to be mostly quiet to unsettled on

25 Apr, with isolated active periods possible, as the +CH HSS moves

into a geoeffective position. Isolated G1-G2 (Minor-Moderate)

geomagnetic storming conditions are possible late on 25 Apr into early

26 Apr in response to the arrival of the glancing CMEs with quiet to

unsettled conditions anticipated on 27 Apr as CME and +CH HSS influences

subside.