Grants Pass, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

195
FXUS66 KMFR 250707
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1107 PM PST Wed Dec 24 2025

...Updated the Aviation and Marine Sections...

.AVIATION...25/06Z TAFs...A strengthening front will approach
tonight and sweep across the area on Thursday. LIFR has developed in
the Umpqua Valley and should persist until low level winds increase
toward sunrise. Elsewhere, patches of MVFR and southerly winds
increase overnight.

Conditions will deteriorate overnight into Thursday. Expect rain and
mountain snow to first spread into northern California and rain to
spread along the coast, with a mix of MVFR/IFR and widespread
mountain obscurations. Elsewhere, expect areas of rain and mountain
snow to develop late tonight and continue through Thursday with
strong southerly winds, widespread low level wind shear, areas of
MVFR, including at Klamath Falls. There is also an expectation of
isolated thunderstorms near the coast late tonight through Thursday
into the early evening. Snow may develop at Mount Shasta City,
around 3500 feet on Thursday morning, with snow levels lowering
further in southern Siskiyou County, to around 3000 feet for
Thursday evening.

&&

.MARINE...Updated 830 PM PST Wednesday, December 24, 2025...Steep
seas continue through tonight. South to southeast winds have begun
to increase.

Another strong system arrives late tonight and Christmas day,
bringing widespread and strong gales (30-40 kt with gusts to 50
kt) along with very steep seas between 13 to 23 ft. Locally storm
force gusts are possible late Thursday morning and Thursday
afternoon. Guidance indicates a 30-40% chance for storm force
gusts for the waters with in 20 nm of shore between Gold Beach and
Cape Blanco and a 20% chance for storm force gusts for other
areas. With this frontal system, there is also a 20% chance for
thunderstorms over the waters on Thursday with the chance for
thunderstorms continuing across the waters from Cape Blanco south
Thursday night and Friday morning.

As the low pressure moves over the waters from west to east on
Thursday night and Friday morning, expect continued areas of gales
for the waters from Cape Blanco south. Winds will shift from south
to northwest as this low moves through Friday afternoon. Very steep
seas will persist across all the waters through at least Friday
morning. Gusty north winds (20-30 mph with gusts up to 35 mph) are
expected to develop Friday afternoon and evening.

Once the low exits the region Friday night, the overall weather
pattern looks to settle down over the weekend, possibly into next
week, and conditions will improve overall with light to moderate
north winds. Areas of gusty north winds and steep seas are possible
south of Cape Blanco.

&&

.PREV DISCUSSION... /Issued 751 PM PST Wed Dec 24 2025/

DISCUSSION...An update was issued early this evening to expand
coverage of isolated thunderstorms over the coastal waters and
coast late tonight through Thursday into early Thursday evening.

Weather conditions are mostly quiet in our area early this
evening, but the leading edge of a band of heavy precipitation has
reached the Cape Mendocino area and will continue to spread
northeastward. Heavy snow is expected to begin in southern
Siskiyou County in a few hours, around 10 PM PST at elevations
above around 5000 to 5500 feet. Meantime, southerly winds will
continue to increase. High Wind Warnings and Wind Advisories are
in effect for most of the area late tonight into early Thursday
afternoon. Winds speeds are likely to reach peak strength around
3 to 4 am pst for both Weed (gusts around 65 mph), and Ashland
(gusts around 35 to 45 mph), 6 to 8 am for the Klamath Falls
area (gusts around 45 mph), and remaining near peak strength (with
gusts of 30 to 50 mph) through the morning for Lake and Modoc
counties.

The southerly winds will be downslope for the Yreka, Rogue
Valley/Medford, and Roseburg areas. This sinking motion will limit
precipitation amounts in those areas through early Thursday
evening. Meantime, this is an upslope direction for southern
Siskiyou County, which will enhance precipitation rates and lower
snow levels. The focus for heaviest snowfall rates will be overnight
into early Thursday morning (around 10 pm to 7 am pst, above 5000
feet), and again with the next front Thursday evening (around 7 pm
through 1 am pst Friday, above 3500 feet). But, a Winter Storm
Warning remains in effect for Siskiyou County above 3500 to 4500
feet, and also for Modoc County above 5500 feet through 10 am pst
Friday. Also, much lighter snow showers are expected to follow with
a snow level still around 3500 to 4000 feet Friday afternoon into
Friday night. Dry weather looks to follow Saturday through Wednesday
with colder nights and areas of mainly night and morning valley fog
and freezing fog.

PREV DISCUSSION... /Issued 309 PM PST Wed Dec 24 2025/

DISCUSSION...

We are in a lull in the activity as the first storm system is
well out of the way. Radar just shows some lighter showers in
Siskiyou County and east of the Cascades this afternoon.

A low will strengthen to our west around 140W tonight based on
most of the ensemble data and Santa might have a bumpy ride into
some chimneys later tonight. The ECMWF ensemble(ENS) performed
best with the last low taking it farther east, so we based most of
our decisions off that ensemble for this forecast cycle. This low
will likely strengthen down to 980 mb or so around 40N and 140W
overnight.

Strong southerly winds will cover the forecast area again
overnight into Thursday morning with the threat of high winds in
the Shasta Valley and along the coast. The ECMWF wind gust
forecast hinted at wind gusts up to 60 mph along the coastal
headlands in Curry County, so we ended up issuing another high
wind warning there. As for the Shasta Valley, there are more than
a few good indicators there again. The extreme forecast index(EFI)
is showing values near 1 north of Redding for wind gusts.
Therefore, the ensembles are showing forecasting stronger wind
gusts than average compared to climatology, which is already very
windy this time of year. Also the NBM 50th percentile shows wind
gusts around peaking at 60 knots tomorrow with 700 mb flow aligned
with the valley.

Elsewhere, winds should be a bit weaker. If we do get the mixing
tomorrow afternoon, it seems reasonable to see wind gusts around
45mph west of the Cascades. Wind gusts should be stronger farther
to the east given the higher terrain out there and still strong
flow at 700 mb. However, the EFI wasn`t jumping out to us. Perhaps
some wind gusts will approach high wind around Klamath Falls, but
will allow the next shift to decide on upgrade to high wind
instead.

Snow is the other big headline with the major impacts still in
Siskiyou County. Snow levels will start to lower through the night
as this colder air is ushered in behind the first low. Generally,
snow levels start around 4500 feet before lowering to 3500 to 3300
feet later Thursday night around Mt Shasta City. We are
anticipating some accumulating snow there as the SPC HREF is
forecasting around 12 inches of accumulating snow down to Mt
Shasta City with higher totals in the surrounding terrain in
Siskiyou County.

Once we move into Friday, the ENS quickly kicks things out Friday
with plenty of rain and snow showers. Meanwhile the GFS and some
of the GEFS solutions wants to spin up another weaker low off our
coast. High pressure begins to build into the weekend with some
light showers still possible west of the Cascades and morning
valley fog Saturday. The quiet weather continues for the
remainder of 2025.

-Smith

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory until 1 PM PST Thursday for ORZ023>026-029>031.

     High Wind Warning from 7 AM to 1 PM PST Thursday for ORZ022.

     Winter Weather Advisory until 10 PM PST Friday for ORZ027-028.

CA...Winter Storm Warning until 10 AM PST Friday for CAZ080-082>085.

     Wind Advisory until 1 PM PST Thursday for CAZ080-083>085.

     High Wind Warning from 7 AM to 1 PM PST Thursday for CAZ081.

PACIFIC COASTAL WATERS...Small Craft Advisory until 4 AM PST Thursday
     for PZZ350-356-370-376.

     Gale Warning from 4 AM Thursday to 10 AM PST Friday for PZZ350-
     356-370-376.

     Hazardous Seas Warning from 10 PM Thursday to 10 AM PST Friday
     for PZZ350-370.

&&

$$