Wedderburn, Oregon Weather Forecast Discussion

017
FXUS66 KMFR 171140
AFDMFR
Area Forecast Discussion
National Weather Service Medford OR
440 AM PDT Wed Sep 17 2025
...New Aviation Section...
.AVIATION (12Z TAFs)...
A marine layer is still evident over the coast which is resulting
in IFR conditions at North Bend. These conditions will stick
around through the morning hours and transition to MVFR by this
afternoon. Uncertainty does exist for tonight along the coast, but
there is about a 70% chance for MVFR ceilings to linger through
the overnight period. Otherwise, inland sites will be under
mostly clear skies and VFR conditions with increased diurnal
breezes.
-Guerrero
&&
.PREV DISCUSSION... /Issued 414 AM PDT Wed Sep 17 2025/
DISCUSSION (Today through Tuesday)...
Overview:
Overall, expecting minimal impacts through this forecast. Today
will be our last well above normal temperature day under mostly
clear skies for inland areas. Thursday onward temperatures will be
near normal. The next few days will also be accompanied by a
drying trend which could lead to more receptive fuels across the
area. Lastly, we will keep an eye on potential for showers and
thunderstorms that could start as early as tomorrow
afternoon/evening. At this time, the signal is not the greatest
for our area, but we will continue to monitor this threat as
thunderstorms could pose a risk for fire weather.
Further Details:
Current water vapor imagery depicts a fairly dry airmass as high
pressure continues over the region. The ridge axis has shifted
slightly east compared to yesterday but we are still expecting
another warm day compared to normal temperatures for mid
September. Thereafter an upper level trough will help break this
ridge down, and the result will be a cooler airmass Thursday
onward with temperatures closer to normal. That said, we may not
have seen the last 90+ degree day for westside areas as some
indication points to Monday of next week potentially well above
normal again.
At the same time, we will see remnants of Post-Tropical Storm
Mario influencing the upper levels Thursday as it gets absorbed
into the mean flow. There is some question to how far north
moisture advection will occur, and the trajectory is somewhat in
question as well. Overall, deterministic models are more in phase
with one another as compared to yesterday which helps increase
confidence. HiRes guidance indicates our northern California
counties have a small chance (15-20%) for showers and perhaps an
isolated thunderstorms late tomorrow afternoon/early evening.
However, instability is weak which may result in more of a shower
environment. The biggest question is how far north the PVA spreads
from the remnants of Mario. A broader area of cyclonic rotation
over the Gulf of Alaska may block energy spreading north. Can`t
rule out isolated activity late tomorrow afternoon and early
evening and again Friday afternoon/evening. Overall, not expecting
much activity as these will likely be isolated and low
precipitation producers. Probability of thunder is currently low,
and will need to be evaluated further for fire weather concerns,
but at this time energy release component values are low from
recent rainfall and cooler weather. Another day of drying will be
telling for fire weather concerns.
Looking ahead, ensemble members are somewhat split with regards
to precipitation through the end of this month. There is a signal
for the upper levels to bring a trough into the region which could
result in more widepsread chances for rainfall to end the month
which could start as early as Tuesday of next week. The Climate
Prediction Center is calling for above normal precipitation
chances to end the month.
-Guerrero
AVIATION (06Z TAFs)...
Marine stratus is bringing IFR to LIFR conditions along the
Oregon coast. This layer could clear out late on Wednesday morning
as gusty northerly winds develop. IFR to LIFR levels return to
the coast on Wednesday afternoon and remain into the night.
Inland areas are forecast to remain at VFR levels with normal
diurnal breezes.
-TAD
MARINE...Updated 300 AM PDT Wednesday, September 17, 2025...Below
advisory seas continue through this afternoon. By tonight, gusty
northerly winds build across area waters. Steep to very steep seas
are expected north of Cape Blanco, with possible gale gusts south of
Cape Blanco. These conditions continue through at least Friday
morning but could linger into the evening hours.
FIRE WEATHER...Updated 300 AM PDT Wednesday, September 17,
2025...With an upper level ridge in place, hot temperatures and low
daytime humidities are expected again this afternoon. With onshore
flow returning today, daytime RHs will trend somewhat higher and
temperatures somewhat lower west of the Cascades. There will be
another round of northeasterly winds tonight into Thursday morning,
but recoveries will continue the improving trend compared to early
in the week.
Confidence remains low in the forecast for the latter half of the
week. Another upper level trough will approach the region today and
this may result in some enhanced afternoon breezes for inland areas.
The approaching trough looks to stall offshore in response to Post-
Tropical Storm Mario moving northward along the California coast,
then getting swept into the main flow over the weekend. This pattern
will likely bring a thunderstorm threat to the region Thursday
through Friday, though there`s some uncertainty in how far north and
west this moisture gets. As the moisture moves northward,
thunderstorms could return to portions of northern California as
early as Thursday afternoon, then potentially into portions of the
eastside on Friday. At this point it doesn`t look like a big
lightning event, and in coordination with local fire agencies, will
just go with a headline for this potential in the FWF unless the
coverage of lightning trends higher over the upcoming days.
Beyond Friday, another trough approaches the region over the weekend
and sweeps these tropical remnants east of the area. There will
likely be periods of enhanced breezes with this trough, but we don`t
expect any meaningful precipitation out of it. 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...Small Craft Advisory from 5 PM this
     afternoon to 11 AM PDT Friday for PZZ350-356-370-376.
Gale Watch from this evening through Friday morning for PZZ356-
     376.
Hazardous Seas Watch from this evening through Friday morning
     for PZZ370.
&&
$$

NWS mfr Office Area Forecast Discussion