717
FXUS66 KMFR 041506
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
706 AM PST Tue Nov 4 2025

.DISCUSSION...Compared to yesterday`s data, there is a high
degree of consistency for such an active, lengthy period of wet,
windy weather. Probably, the most notable change is a general
trend to weaken the depiction of Friday`s front, which was already
anticipated to weaken as it moves inland, and also slow and weaken
a subsequent frontal system early next week. In that regard, the
Friday afternoon and night period looks to have a high probability
of being dry, and the probability of dry weather for all of the
weekend has increased.

An active pattern will continue through the next several days,
with only a few breaks here and there all the way through Friday.
There will be several systems impacting the area between now and
next weekend: a very robust system today 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.

The most impactful system in the forecast is set to arrive late
Today into Wednesday, with a intense front and a substantial
moisture plume bringing strong winds and heavy precipitation to
southern Oregon and far northern California. First, a warm front
will push north through the area this morning into this afternoon,
producing some breezy winds and light rain. Then tonight 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 the 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. Confidence has nudged higher that a
weak front will weaken as it reaches our area late Sunday night or
Monday. -DW/BPN

&&

.AVIATION...04/12Z TAFs...There is a mix of conditions early this
morning, with a lingering front producing light rain and mainly MVFR
ceilings from southern Siskiyou County, including Mount Shasta,
across Modoc and southern Lake counties. Meantime, there is a brief
break for most of our area with VFR. But, moist onshore flow is also
creating areas of IFR and light showers along and near the coast.

The front will strengthen and lift north as a warm front today,
while the stronger cold frontal portion moves toward the coast. This
will allow additional rain, and increased gusty winds late in the
day to become strong. Low clouds with areas of MVFR/IFR are expected
at the coast. Inland, conditions will remain mainly VFR, but
ceilings will thicken and lower. This will result in obscuration of
higher terrain.

As the cold front approaches this afternoon, the gusty
winds will develop across the area. Winds will be particularly
strong for some areas this evening into Wednesday morning, including
along the coast, in the Shasta Valley, in the Rogue Valley (from
Medford to Ashland) and east of the Cascades. Wind gusts of 35-45kt
will be common in those areas with local gusts to 70 kt. Low level
wind shear is likely from late afternoon into early evening leading
up to the strong winds.

&&

.MARINE...Updated 200 AM PDT Tuesday, November 4, 2025...The main
update today was to issue a Gale Warning for Wednesday, immediately
following the Storm Warning that is in effect this afternoon into
early Wednesday morning.

First, conditions briefly improve through mid-morning before a
significant, strong front approaches. Models show strong 925 mb flow
(80-85kt) and the likelihood of a coastal jet developing. As such,
the storm warning remains in effect. South winds are expected to
reach peak strength late tonight into early Wednesday morning.
Widespread gusts of 50-55 kt are expected and may approach 60 kt in
the outer waters. Additionally, isolated to scattered marine
thunderstorms are expected late tonight into Wednesday evening,
especially Wednesday afternoon north of Cape Blanco.

Southerly winds ease Wednesday night into Thursday morning, but very
steep and hazardous long-period west swell will persist. 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 is likely to bring additional gales and very
high seas late Thursday morning through Thursday evening. High
pressure brings improving weather Friday into the weekend. But,
lingering swell is likely to support high, steep to very steep and
hazardous seas at least into Saturday morning. Active weather may
return early next week. -DW/Spilde

&&

.BEACH HAZARDS/HIGH SURF...Updated 200 AM PDT Tuesday, November 4,
2025...Tonight into Wednesday, storm force winds will build very
steep seas to high surf advisory criteria (20-25 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. 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 this afternoon to 4 AM PST Wednesday
     for ORZ021-022-030-031.

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

     High Surf Advisory from 7 PM this evening to 10 PM PST Thursday
     for ORZ021-022.

     Coastal Flood Watch from late Wednesday night through Thursday
     evening for ORZ021.

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

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

PACIFIC COASTAL WATERS...Storm Warning from 1 PM this afternoon to 7
     AM PST Wednesday for PZZ350-356-370-376.

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

&&

$$