Broadbent, Oregon Weather Forecast Discussion

447
FXUS66 KMFR 061906
AFDMFR
Area Forecast Discussion
National Weather Service Medford OR
1206 PM PDT Sat Sep 6 2025
...Updated AVIATION discussion for 18Z TAFs...
.DISCUSSION...Radar is rather quiet this early morning, especially
compared to 24 hours ago. Earlier there was a few cells that
popped up in far northern Douglas County, but that activity
quickly moved north out of the forecast area, and most of the
thunderstorm activity has been northward in the Willamette Valley.
There are some isolated showers moving northward into portions of
Modoc/Lake/Klamath Counties, with a handful of lightning strikes
observed so far. Based on latest satellite trends and model
guidance, early morning thunderstorm activity, is likely to be
over Modoc/eastern Siskiyou/southern Klamath and Lake Counties.
Meanwhile, areas of degraded air quality persist in southwest
Oregon/northern California, currently worst in the
Rogue/Applegate/Klamath River Valleys and portions of the Umpqua
Basin. Smoke from the Kelsey Peak/Backbone fires northeast of
Agness is largely what`s responsible for the smoke in the
Rogue/Applegate Valleys. Smoke models show improvement/lessening
smoke concentrations this afternoon for most areas except the
Klamath River Valley.
Looking at the rest of the day today, afternoon temperatures will be
continue trending downward and be more noticeable compared to
Friday`s "cooler" temperatures. Our persistent daily thunderstorm
chances will continue again today, focused along and east of the I-5
corridor, and guidance maintains the best chances being in the area
between I-5/US-199 and the Cascade crest as the most likely location
for development, which includes Medford, Roseburg, and Grants Pass.
Storms are expected to fire up over the Siskiyous and western
Siskiyou County around 2-4 pm this afternoon, then move northward
through the West Side Valleys through the evening. The bullseye for
activity looks to be over the Applegate/Rogue Valleys northward into
eastern Douglas County and over to the Cascades, but storms are
possible as far west as the Illinois Valley (including Grants Pass)
and northward to Roseburg. Main threat with storms today will be
gusty winds and brief downpours. Nocturnal potential tonight looks
limited with moisture present, but lacking the instability and
trigger. Though if any storm outflows linger in the region after
sunset, there could be a stray storm across the northern portions of
Klamath/Lake/Douglas Counties.
After today, storm chances diminish in coverage and shift farther
north with the activity focused over the Cascades north of Lake of
the Woods. The parent trough that has drifted around over the
eastern Pacific, firing shortwaves at us this past week will nudge
closer to the coast on Sunday. Sunday will be more of a transition
day as we move away from this persistent thunderstorm pattern toward
a much cooler and wetter one. Afternoon temperatures trend cooler by
another 5 degrees, resulting in near to just below normal values for
early September. Late Sunday into early Monday, this low pressure
finally move onshore and stick around through early next week. This
pattern change will result in below normal temperatures and several
days (roughly Sunday night through Wednesday) of light, but
beneficial, showery precipitation (with some embedded thunderstorms
possible Monday) which will make the area feel more like early-mid
October than early September. We are confident that healthy
measurable rainfall will occur across the area over the first half
of next week, which would definitely be helpful with local
firefighting efforts, and would put a large dent in fire weather
concerns.
Guidance is in good agreement on this trough lingering over the West
Coast states through much of next week. A brief period of shortwave
ridging is possible around the end of the week, bringing a warming
trend back to more seasonal values. While guidance shows another
frontal system approaching the West Coast next weekend, confidence
is low on whether this system will deliver any precipitation. Stay
tuned for updates as details unfold.
&&
.AVIATION...06/18Z TAFs...MVFR levels continue along the Oregon
coast and into the Umpqua Valley under a persisting marine stratus
layer. MVFR levels look to rebuild along the Oregon coast this
evening, while possible thunderstorm activity over the Umpqua Valley
this afternoon and evening brings some uncertainty to overnight
flight levels. VFR conditions are expected, but MVFR ceilings may
rebuild in the Umpqua Valley.
Inland ares look to remain under generally VFR levels. Smoke has
brought MVFR visibilities to the Medford terminal, but conditions
should clear early this afternoon. Thunderstorm chances are also
present over Medford as well as along the Cascades and other west
side areas this afternoon and evening. Isolated thunderstorms may
continue into the night, but activity should be absent by Sunday
morning. -TAD
&&
MARINE...Updated 200 AM PDT Saturday, September 6, 2025...Sub-
advisory conditions are expected to persist through the forecast
period. Light south winds and low seas with marine fog/drizzle and
low clouds will persist today as weak low pressure passes through
the area. Despite an uptick in southerly winds Sunday into Monday,
expect generally calm conditions with no significant swell and
widespread showers Monday and Tuesday as a stronger low pressure
moves inland. Winds turn northerly Tuesday into Wednesday, but look
to remain below advisory criteria at this time.
&&
.FIRE WEATHER...Updated 330 AM PDT Saturday, September 6, 2025...The
primary fire weather concern through Sunday will be isolated to
scattered thunderstorms primarily in the afternoons/evenings.
Isolated showers and thunderstorms are moving northward into
Modoc/eastern Siskiyou/southern Klamath and Lake Counties this
morning, but lightning activity has been fairly minimal so far with
this area of instability. See the "DISCUSSION" above for details on
locations for where we expect the focus of thunderstorm activity
today. We may need to consider a Red Flag Warning for abundant
lightning this afternoon/evening in those areas (FWZs
617/623/622/621). Stay tuned for potential updates this morning.
Otherwise, another day of breezy afternoon winds and generally
cooler temperatures is expected today.
The pattern will start to transition on Sunday as low pressure
approaches the region, then moves inland late Sunday into Monday.
Temperatures will trend cooler by another 5 degrees or so on Sunday
and again on Monday while daytime RHs trend higher. Temperatures
will feel more like October for the first half of the week, and we
are confident that healthy measurable rainfall will occur across the
area over the first half of next week, which would definitely be
helpful with local firefighting efforts, and would put a large dent
in fire weather concerns. There is the possibility of embedded
thunderstorms with this incoming precipitation on Monday, but given
the ample moisture and moderated fire environment, likely won`t be
needing any headlines for Monday`s lightning activity.
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.
CA...None.
PACIFIC COASTAL WATERS...None.
&&
$$

NWS MFR Office Area Forecast Discussion