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077
FXXX12 KWNP 020031
DAYDIS

:Product: Forecast Discussion
:Issued: 2025 Dec 02 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...
Flare activity reached high levels due to an X1.9 at 01/0249 UTC from
Region 4299 (N22E68, Dai/beta-gamma). Significant field line movement
and shock wave can be seen in GOES SUVI 195 Angstroms. Dimming can be
seen on over much of the northeast quadrant of the disk, indicating
significant loss of material. The associated CME can be seen in Lasco C2
coronagraph imagery starting at 01/0248 UTC. It had both a Type IV and
Type II radio sweep with reported velocities around 1,000 km/s, and a
Tenflare that reached 410 pfu.

Region 4299 continues to come into better view as it moves from the east
limb but its magnetic field is still too distorted by foreshortening to
be accurate. Its current classification of Dai is less complex than when
it was last seen as Region 4274 (N24, Ekc/beta-gamma-delta) - but this
is to be expected given its age and the amount of CME activity it was
likely responsible for while on the far-side.

The other notable area is the large complex in the southeast which
contains three regions. The leading spot is fairly simple, Region 4298
(S16E32, Hsx/alpha) and has been stable and quiet. Behind that however,
is the biggest baddest group on the disk - Region 4294 (S15E43,
Fkc/beta-gamma-delta) but despite its size and complexity it has only
produced C-class flares throughout the period. There is some flux
emergence within its intermediate area but minimal shearing is occurring
making it more stable. Behind that, is Region 4296 (S14E62,
Eki/beta-gamma) whose structure is coming into better view, and has been
upgraded in its classification, but it too has been fairly quiet with
only C-class flares.

.Forecast...
Flare probabilities have increased to 70-80% chance for R1-R2
(Minor-Moderate) and 30% chance R3 (Strong). This is based on the
complexity and assuming persistent activity of Regions 4294 and 4299,
respectively.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux continues at high levels due to the
geoeffective positioning of the now exiting, south pole coronal hole
(CH) high speed stream (HSS). The peak flux was 8,520 pfu observed at
01/1335 UTC.

Modelling of the aforementioned X1.9 confirmed there is about a 30%
chance for the greater than 10 MeV proton flux to reach S1 (Minor)
radiation storming levels in the next 24 hours (roughly). These higher
percentages is based on flare magnitude, previous activity (S3 levels
from this Region on 12 Nov) as well as radio signatures. Since the event
occurred near the east limb it will take time for protons to reach Earth
as we are not in a favorable position for fast arrival.

.Forecast...
The greater than 2 MeV electrons will continue at high levels, slowly
trending down through 04 Dec. It is unlikely that the next CH HSS,
emanating from the CH near the central meridian will be as potent.

There remains a 30% chance for S1 (Minor) radiation storming levels from
the greater than 10 MeV protons 02 Dec with decreasing chances into 04
Dec. Chances will increase if there continues to be significant flare
activity from Region 4299.

Solar Wind

.24 hr Summary...
Solar wind parameters reflected waning influences from the positive
polarity CH HSS mentioned earlier. The interplanetary magnetic field
(Bt) remained around 5 nT with the north-south (Bz) component between
+/-4 nT. Solar wind speeds have decreased from 550 km/s towards 415
km/s. The phi angle has remained in the positive (away from the Sun)
orientation.

.Forecast...
Solar wind parameters will trend towards nominal conditions 02 Dec
before becoming elevated again. Three things will impact the solar wind
03-04 Dec; 1) sector boundary crossing from positive to negative 2)
co-rotating interacting region (CIR) ahead of the CH HSS associated with
the negative CH near the central meridian 3) and a glancing blow from a
powerful CME associated with the X1.9 discussed earlier. All three will
create turbulence, compression, and overall enhancements within the
solar wind 03-04 Dec.

Geospace

.24 hr Summary...
Geomagnetic field had one synoptic period between 00-03 UTC of active
conditions and has been quiet to unsettled since.

.Forecast...
The geomagnetic field will remain at unsettled levels 02 Dec and into 03
Dec. As discussed in the Solar wind forecast section, three space
weather phenomena will be occurring between 03-04 Dec. The CIR will
likely be strong enough on its own to bring G2 (Moderate) geomagnetic
storming levels but the uncertainty of CME arrival time decreases
confidence in magnitude. If they arrive at the same time, G3 (Moderate)
storming levels are likely with conditions waning towards active to G1
levels thereafter. If they are reasonably spaced apart in time, G2
(Moderate) conditions will persist for longer, throughout 04 Dec. G2
Watches have been issued for 03 and 04 Dec.

-Bri