331
FXUS66 KMFR 032330
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
330 PM PST Mon Nov 3 2025

.UPDATE...Aviation Discussion updated.


&&

.AVIATION...04/00Z TAFs...Low pressure is bringing IFR/LIFR in low
clouds with  and rain to the coast this afternoon. This will persist
into tonight.  Rain and low ceilings will spread inland this
afternoon and evening. Expect areas of MVFR with higher terrain
obscuration and also increasing southerly winds. The gusty south to
southwest winds will be the most widespread impact, which includes
areas of low level wind shear across southern Oregon and northern
California through this evening, but lingering over Lake and Modoc
counties into early Tuesday morning. Both wind speeds and areal
coverage of low level wind shear will reach a peak this evening.

Late tonight into early Tuesday morning, things should dry out for
most of southwest Oregon with rain continuing over northern
California  and post-frontal showers along the coast. Along the
coast expect a mix of IFR/MVFR through the morning. Inland, areas of
LIFR/IFR in fog/low stratus are expected to develop west side
valleys around or just before sunrise. A warm front will lift north
across the area Tuesday with light rain, areas of MVFR and mountain
obscuration. This will initially affect northern California then
spread north across southwest Oregon in the late morning and
afternoon. Stronger south winds will develop again during Tuesday
afternoon, especially along the coast, in the Shasta Valley and over
the East side.

A period of strong S-SE winds is expected Tuesday night into
Wednesday morning, affecting North Bend, Medford and Klamath Falls
and to a lesser extent, Roseburg. Wind gusts of 35-40kt will be
possible and wind shear will again be likely leading up to the
strong winds.


&&

.PREV DISCUSSION... /Issued 215 PM PST Mon Nov 3 2025/

DISCUSSION...An active pattern will continue through the next
several days, with only a few breaks here and there all the way
into next weekend. There will be several systems impacting the
area between now and next weekend: the first a compact surface
low passing just offshore today, followed by a very robust system
Tuesday into early Wednesday, followed by yet another front
around Thursday, then finally another system arrives late next
weekend. Wet and windy weather will accompany nearly all of these
systems, but winter weather will not be too much of a concern
given the expected higher snow levels.

A compact surface low has developed offshore and is approaching
the southern ORegon coastline this afternoon. These smaller scale
lows have a tendency to spin up quickly and are known to produce
a burst of strong winds as they move onshore, as this one will do
later this evening and tonight near or just north of Florence.
Rain bands are moving onshore already, and winds have already
intensified along the coast. As this low sweeps up the coast, high
winds are almost guaranteed for the capes and headlands, as well
as some of our more exposed coastline. Have issued a High Wind
Warning for those portions of the coast, with the idea that strong
winds could spread to other areas as well depending on the exact
track and strength of the low. Breezy winds are expected across
the area with this low, but outside of the coast, are not expected
to be impactful at this time. Also, the system will bring a burst
of rain, again concentrated along and west of the coastal
mountains. Winds die down and most areas should see precipitation
come to an end tonight, but the break will be brief.

The most impactful system in the forecast is then set to arrive
late Tuesday into Wednesday, with a intense front and a
substantial moisture plume bringing strong winds and heavy
precipitation to southern Oregon and far northern California.
Today`s surface low has altered the pattern sightly with some of
the downstream systems, with some minor changes in timing and
intensity, but only slightly. First, a warm front will push north
through the area Tuesday morning, producing some breezy winds and
light rain. Then Tuesday night into Wednesday morning, the cold
front will push onshore with strong winds and significant rain.
With surface pressure gradients ranging roughly between -6 and -8
mb across the area, and with 700mb winds of 50 to 70 kts (or even
up to 80 kt), all of southern Oregon and far northern California
will see at least gusty winds, with strong winds along the coast,
in the Shasta Valley, and across the East Side. The negative tilt
in the upper level trough also suggests that that stronger winds
could impact portions of the West Side as well, including the I-5
corridor from Ashland to Medford, and in some of the other roughly
south/north oriented valleys. Numerous wind headlines have been
issued, covering most of the region. More information and detail
on these can be found at PDXNPWMFR.

Meanwhile, moisture transport values for this front, as measured
by IVT, a function of wind and humidity, are expected to reach
values of 1000 to 1250 (a typical front would average about 500).
This would be considered a strong atmospheric river, or a rather
classic "Pineapple Express," as the moisture plume originates
from the tropics near Hawai`i. A substantial amount of rain is
possible for much of the area, especially along the coast and in
Siskiyou County. However, the front is a fast mover, and some
locations, such as the Rogue Valley near Medford and much of the
East Side, will see lesser amounts due to significant downsloping
winds off the Siskiyous and Cascades. While widespread flooding is
not expected at this time, we will likely see nuisance type
flooding with ponding on roadways and blocked drains due to
recently fallen leaves. Additionally, King Tides are expected Nov
5-7 (Wednesday through Friday) which could bring additional
impacts to the coast as this storm and the following system
enters the region, especially with heavy rains putting additional
water into area rivers and estuaries.

Lastly, snow levels will remain high through next week, between
6000 and 8000 feet, so we are not expecting any impactful winter
weather.

Another robust front arrives Thursday, although it looks weaker
than the previous one. Most model guidance suites are depicting
similar but somewhat lesser potential for impactful winds and
rain. This storm, however, will coincide with the highest King
Tides around noon on Thursday. Ocean level models are depicting a
small storm surge with the event, along with high surf conditions
which will push water into local bays and estuaries, which will
make tidal influences even stronger. Some localized coastal
flooding is possible, particularly for low lying areas and roads
around Coos Bay and any roads or low lying beaches and shorelines,
and erosion along area beaches will be a concern. High Surf
Advisories and a Coastal Flood Watch are in effect, with details
and more information at PDXCFWMFR.

Conditions gradually improve through Friday, then an upper level
ridge builds in overhead Saturday into Sunday. This will dry
things out for the weekend, but it will be just a quick break
before the next system arrives late Sunday into Monday. Despite
the overwhelming consensus for dryer conditions across the model
suites, the NBM continues to produce constant rain chances through
the weekend. This has been adjusted drier, but due to the
limitations in the current forecast procedures within the agency,
the forecast keeps some slight chances in place, despite the very
highly likelihood for dry conditions over the entire weekend.
There continues to be some drastic changes and variation in the
models regarding the front early next week, so confidence remains
low regarding rain and wind chances from Sunday on. Confidence
remains high, however, that the active storm pattern will continue
for the foreseeable future. -BPN

MARINE...Updated 200 PM PDT Monday, November 3, 2025...Low
pressure will move through the waters into this evening with brief
gales and steep to very steep seas. The strongest winds will develop
just north of Cape Blanco and within 30 nm of shore under a coastal
jet. Winds in this jet may exceed may exceed 45 kts. Near-gale gusts
are still forecast for most of the remainder of the waters, so a
Gale Warning remains in effect. All areas will have a period of very
steep seas.

Conditions briefly improve early Tuesday morning before a
significant and even stronger front approaches. Models are now
showing strong 925 mb flow (80-85kt) and the potential for a coastal
jet developing. As such, we decided to go with a storm warning
for all waters beginning Tuesday afternoon and peaking early
Wednesday morning. Widespread gusts of 50-55 kt are expected and
may approach 60 kt in the outer waters. Additionally, marine
thunderstorms may develop Tuesday night into Wednesday evening.

Southerly winds ease Wednesday night into Thursday morning, but very
steep and hazardous long-period west swell follows through the day.
Advisory level high surf is forecast, with current guidance building
22-26 ft surf heights. King Tides are expected on Thursday, which
may increase the impact of hazardous conditions. Bar crossings may
become especially dangerous and fishing infrastructure may be
vulnerable.

Another strong front may bring additional gales and very high seas
Thursday. High pressure brings improving weather late Friday into
the weekend. But, lingering swell is likely to support high, steep
to very steep and hazardous seas at least through Saturday. Active
weather may return early next week. -Spilde

BEACH HAZARDS/HIGH SURF...Updated 200 PM PDT Monday, November 3,
2025...Tuesday night into Wednesday, storm force winds could build
very steep seas to levels that come close to meeting high surf
advisory criteria (20 feet). Some south-facing beaches may
experience high surf and bar crossing could be very dangerous. South-
facing ports like Port Orford/Brookings, could have water spill over
onto parking lots. This will then be followed by a long period swell
Wednesday night into Thursday impacting all west-facing
beaches/ports. Surf heights of 20-25 feet are expected and with King
Tides on Thursday, this may increase the impact of hazardous
conditions. Area beaches will become hazardous due to dangerous surf
conditions, bar crossings will become especially dangerous and
fishing infrastructure may be vulnerable. -Spilde

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning from 4 PM Tuesday to 4 AM PST Wednesday for
     ORZ021-022-030-031.

     Wind Advisory from 10 PM Tuesday to 10 AM PST Wednesday for
     ORZ023>026-029.

     High Surf Advisory from 7 PM Tuesday to 4 PM PST Wednesday for
     ORZ021-022.

CA...High Wind Warning from 4 PM Tuesday to 4 AM PST Wednesday for
     CAZ081-085.

     Wind Advisory from 10 PM Tuesday to 10 AM PST Wednesday for
     CAZ084.

PACIFIC COASTAL WATERS...Gale Warning until 10 PM PST this evening
     for PZZ350-356-370-376.

     Small Craft Advisory from 10 PM this evening to 4 AM PST Tuesday
     for PZZ350-356-370-376.

     Storm Warning from 4 PM Tuesday to 7 AM PST Wednesday for PZZ350-
     356-370-376.

&&

$$