Harbor, Oregon Weather Forecast Discussion

763
FXUS66 KMFR 072054
AFDMFR
Area Forecast Discussion
National Weather Service Medford OR
154 PM PDT Sun Sep 7 2025
.DISCUSSION...
Overview:
Still expecting thunderstorms today, but less coverage than
yesterday with focus around Crater Lake, Eastern Douglas, and
northern portions of both Klamath and Lake counties. Then a much
cooler air mass will settle in starting tomorrow which will feel
much more like October. Monday has the potential for wetting rains
across mainly westside areas with widespread showers anticipated.
Isolated thunder cannot be ruled out next week, but we are not
expecting widespread severe weather. Rain chances continue through
Friday, with each subsequent day after Monday posing less chances
for both rain and rainfall amounts. An Air Quality Alert remains in
effect for eastern portions of Douglas County until this evening due
to smoke/haze from nearby wildfires.
Further Details:
A broad area of cyclonic rotation is noted over the Pacific. This H5
low is progged to kick out small areas of PVA over the forecast area
today through peak heating. This will result in convection this
afternoon and early evening. Today will be far more isolated than
yesterday and mainly across areas near Crater Lake like eastern
Douglas County, and northern parts of both Klamath and Lake
counties. A storm or two could be strong with lightning and gusty
winds as the main threats. Not expecting much--if any--activity past
8pm.
For Monday, the aforementioned low pressure system will start to
move inland, bringing widespread rainfall chances to the forecast
area. This cool weather pattern will likely resemble stratiform rain
with isolated embedded thunder versus more convective type of storm
mode. Forecast soundings show very tropical like profiles with very
weak lapse rates which is resulting in very "skinny" CAPE through
the profile. This means skies will be mostly cloudy and more like
stratus versus cumulonimbus. To further illustrate this, LCL heights
are going to be atypical/very low given the tropical soundings.
Updrafts will struggle in this environment, but given the dynamics
we cannot rule out some thunder. Perhaps an isolated updraft could
poke out through the cloud layers but this will not be common
tomorrow as the wind field is nearly uniform and lacking overall
shear. In fact, satellite already shows this cloud shield over the
Pacific, and this area will move onshore tomorrow bring our
widespread rainfall. Every single member from both the GFS and
European ensemble suite is showing rainfall for Medford/Rogue
Valley. In fact, this is the case for many westside areas where 24hr
rainfall amounts (Monday morning through Tuesday morning) could be
around 0.25-0.75 for most areas, but some areas could be closer to
1.00". This type of rainfall is more typical for October, but should
be a welcoming experience, especially those areas dealing with
wildfire suppression. Areas like the Emigrant Fire could see these
higher rainfall amounts.
After Monday, rainfall chances continue but generally decrease each
subsequent day as the low pressure system meanders over the forecast
area. Temperatures will remain very mild for this time of year, and
its not until Thursday until we start seeing more widespread highs
back in the 80s. Through this stretch, isolated areas of thunder are
expected with showers that develop. Not seeing any days that could
experience widespread severe weather, but a couple storms could be
strong with lightning and gusty outflows as the main threats.
-Guerrero
&&
.AVIATION (18Z TAFs)...
Marine stratus has cleared out over the Oregon coast, with MVFR
levels remaining in the Umpqua Valley. Satellite imagery is
showing that layer starting to break up, with VFR levels expected
across the area for this afternoon and evening. Slight chances for
isolated thunderstorms are in the forecast along the Cascades
into western Siskiyou County for this afternoon and evening, with
the highest chances for activity over eastern Douglas and northern
Klamath counties. Lightning strikes, locally heavy rainfall, and
gusty and erratic winds are possible around developed
thunderstorms. Activity decreases into the evening.
Guidance is split on marine stratus rebuilding tonight ahead of
an approaching low pressure system. Possible timing for IFR
conditions are included for North Bend, but at slight to moderate
confidence of developing. Rain showers arrive on Monday morning,
possibly lowering ceilings and visibilities as well as obscuring
terrain for areas west of the Cascades.
-TAD
&&
.MARINE...Updated 200 PM PDT Sunday, September 8, 2025...Sub-
advisory conditions will likely persist through next week. Low
pressure will maintain light south winds, low seas and marine fog.
Additionally, drizzle may start late tonight before more
widespread rainfall starts tomorrow morning. Widespread showers
are expected Monday with isolated thunder as the low pressure
moves inland. Far less shower activity is expected on Tuesday as
this activity moves inland. Winds turn northerly Tuesday through
Thursday.
&&
.FIRE WEATHER...Updated 200 PM PDT Sunday, September 7, 2025...
Thunderstorm chances return again today. The highest chances are
over eastern Douglas and northern Klamath counties, with chances
decreasing into northern Lake County. Rain showers are expected as
parts of any activity. While periods of scattered coverage may be
possible over those northernmost areas, limited timing and areal
coverage do not support any warning products. Activity decreases
into the evening hours.
On Monday, a pattern change will bring cool temperatures and
widespread rain showers. Embedded thunderstorms are possible
through the day Monday. Cool temperatures and shower chances
continue into midweek, with shower chances decreasing day by day.
Seasonal conditions are forecast to end the week, with another
round of showers possible for next weekend.
-TAD
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.
CA...None.
PACIFIC COASTAL WATERS...None.
&&
$$

NWS MFR Office Area Forecast Discussion