Langlois, Oregon Weather Forecast Discussion

354
FXUS66 KMFR 181159
AFDMFR
Area Forecast Discussion
National Weather Service Medford OR
459 AM PDT Thu Sep 18 2025
...New Aviation Section...
.AVIATION (12Z TAFs)...
A lingering marine layer may bring brief periods of lower
ceilings, but overall expecting this TAF cycle to be mostly VFR.
However, there is a 40% chance MVFR conditions will return
tonight. While high clouds will infiltrate from the south today,
not expecting categorical changes for inland TAF sites as VFR
should prevail.
-Guerrero
&&
.PREV DISCUSSION... /Issued 345 AM PDT Thu Sep 18 2025/
DISCUSSION (Today through Wednesday)...
Overview:
Overall, weather hazards and impacts are forecast to be minimal, but
isolated thunderstorms each afternoon/evening today through Saturday
could pose some risk for fire weather and people with outdoor plans.
Temperatures will be near normal starting today and will continue
into next week for the most part. The next few days will be
accompanied by a drying trend which could lead to more receptive
fuels across the area.
Further Details:
Current mid-level water vapor imagery depicts an area of increased
moisture from post-tropical storm Mario pushing north. This area
will be the focus for isolated thunderstorms this afternoon and
evening.  While forecast soundings indicate we may reach convective
temperatures today, the better trigger will be the PVA and upper
dynamics associated with the remnants of Mario. Today and tonight
have the most uncertainty as these notable feature move northward
and interact with opposing flow. There are questions about how far
north thunderstorm activity could develop, but its not a zero chance
for our area. Have maintained small chances (15-20%) for isolated
thunderstorm starting as early as this afternoon. Relied more on
HiRes convective allowing models for this forecast as ensembles are
lacking a strong signal for todays rainfall/convection. Forecast
soundings indicate an inverted-v profile, so there will be dry air
to overcome near the surface as this mid-level moisture moves into
the region. Tomorrow and Saturday have a slightly better chance for
isolated thunderstorms but again not a slam dunk by any means as
another incoming trough from the Gulf of Alaska will essentially
block features pushing north. Not ruling out convection for Oregon,
but there is uncertainty to how far north we see these chances. That
said, chances increase slightly for Friday and Saturday to around 25-
35 percent with areas along/near the Cascades and eastside areas
getting into the mix. Again we will be looking at inverted-v
profiles so dry air near the surface will limit rainfall amounts.
Saturday night into Sunday we will see the aforementioned through
over the Gulf of Alaska start to push into the PacNW which will
likely bring more widespread rainfall to the region, but the
southern extent of this rainfall is uncertain which has implications
for our forecast area. We will be on the tail end of this QPF
sheild, but areas like the coast and Umpqua Basin will have decent
chances (20-60%) for showers and isolated thunderstorms. This will
be a progress system quickly exiting to the east Sunday night. The
result thereafter will be a complicated split flow pattern. Ensemble
members are still split on rainfall for our area so its tough to say
with much confidence the finer details, but we are expecting a
wetter pattern with increased chances for above normal precipitation
as we get into later parts of September. Next week could have
multiple rounds of precipitation starting as early as Tuesday night.
However, this split flow pattern has discrepancies between models in
the long term, but relying on ensembles does show better confidence
with more than half the members indicating rainfall through middle
to late next week.
-Guerrero
AVIATION...
IFR/LIFR conditions in low clouds and fog over most areas
offshore are pushing into the coast north of Cape Blanco this
evening, and will persist into Thursday morning. Lower ceilings
may also make it into portions of the Umpqua Basin, including at
KRBG late tonight into early Thursday morning. Lower flight
conditions should retreat back to the immediate coastline by late
morning Wednesday. Meanwhile, gusty north winds will continue
along the coast and over the coastal waters. VFR conditions will
prevail for inland locations with typical diurnal breezes.
MARINE...Updated 300 AM PDT Thursday, September 18, 2025...Gusty
north winds continue to build across area waters today. This will
result in steep to very steep seas north of Cape Blanco, with
possible gale gusts south of Cape Blanco. These conditions
continue through at least Friday morning, but steep seas could
linger into the evening hours. Generally light winds and light to
moderate seas are then expected through the weekend and into early
next week
FIRE WEATHER...Updated 300 AM PDT Thursday, September 18,
2025...Confidence hasn`t really improved much regarding thunder
potential today through Saturday. Another upper level trough will
approach the region today, but will stall offshore in response to
the remnants of Tropical Storm Mario moving northward along the
California coast. There is still uncertainty regarding how far
north and west this moisture makes it, and the high resolution
convection models show quite the spread on where
showers/thunderstorms are possible. They do agree, however, on
moisture not arriving until late this afternoon/tonight. There are
some solutions that bring storms into Jackson/Josephine Counties
and/or southern Klamath/Lake counties while others keep
thunderstorms confined south of the OR/CA border, so there could
continue to be updates to the forecast over the coming shifts. At
this point it doesn`t look like a big lightning event, and in
coordination with local fire agencies, will maintain a headline
for this potential in the FWF unless the coverage of lightning
trends higher over the upcoming days.
Over the weekend, the tropical remnants will get swept into the
westerlies on Saturday as another trough passes through the
region, but thunder chances could linger across eastern Lake/Modoc
Counties Saturday afternoon. We expect periods of enhanced
breezes this weekend as a few dry fronts move through the region,
but we don`t expect any meaningful precipitation this weekend.
Meanwhile a cut off low will linger offshore of California, far
enough west that we aren`t concerned about a thunderstorm pattern.
This will come into play around mid-week next week as it too,
finally gets swept up into the main flow and potentially brings a
more widespread appreciable wetting rainfall in the September
23rd-26th timeframe. Details at this time range of course are
unclear, but numerous members in the ensemble suite of solutions
are pinpointing this timeframe as wetter and cooler. Stay tuned as
the time draws nearer.
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...CA...None.
PACIFIC COASTAL WATERS...Gale Warning until 11 AM PDT Friday for
     PZZ356-376.
Small Craft Advisory until 11 AM PDT Friday for PZZ350-370.
Hazardous Seas Warning until 11 AM PDT Friday for PZZ370.
&&
$$

NWS MFR Office Area Forecast Discussion