Helm, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

112
FXUS66 KMFR 170512
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
912 PM PST Tue Dec 16 2025

.DISCUSSION...Light to moderate rain associated with the passage
of a seasonably strong cold front will continue overnight with
around a half inch to more than an inch of new precipitation for
most of our area, less for Modoc County. Snow levels will drop as
west-slope favored, post-frontal showers taper off during
Wednesday morning. 1 to 3 inches of snow is forecast during the
morning for the Cascades north of Highway 140 at elevations above
4000 to 4500 feet.

With a partial arrival of the new suite of 00Z model data, there
is a continued shift toward both a farther northward arrival
onshore of the next, stronger atmospheric river system on
Thursday, and a faster progression of the system southward through
our area Thursday night through Friday. Curry County still looks
to receive the highest amounts in our area, and storm totals of 3
to 6 inches still look to be an appropriate forecast for Coos,
Douglas, and Curry counties. But, the day-time hours of Thursday
look to be signifcantly less impactful with little or even no
rainfall for much of our area. The highest probability will be for
northern portions of Coos, Douglas, and Klamath counties. This
also would result in a slight diminishment of wind speeds and
slight reduction in the risk of flooding. Any good news is good,
but I do want to emphasize that these changes are slight, as both
the Flood Potential Outlook for the coast into Douglas and western
Josephine, and High Wind Watch for the coast and portions of the
east side from Winter Rim eastward remain in effect Thursday into
Friday.

The pattern looks to remain active during the weekend into early
next week with frequent rain chances, but with a new long-
duration storm most likely aimed south of our area into the
Sierra Nevada.

Please see the previous discussion below for further details.

&&

.AVIATION...17/06Z TAFs...The main hazard overnight will be low
level wind shear and moderate to strong winds that are projected to
surface at the North Bend terminal, and east of the Cascades,
including the Klamath Falls terminal.

A strong cold front will move across the area tonight, and result in
strong winds aloft. Winds shift and gradually diminish early
Wednesday morning. Low level wind speed shear will be a concern
across the area, mainly between 04Z and 12Z overnight. Meantime,
southwest wind gusts of 20 to 40 kt are also expected into Wednesday
morning, strongest east of the Cascades.

This strong system will also bring moderate to heavy precipitation
into Wednesday morning, which will keep ceilings and visibilities
mainly in a mix of IFR and MVFR conditions, with terrain at least
partly obscured.

After 12Z, winds and precipitation intensity will diminish. Post-
frontal showers will linger longest on west facing slopes during
Wednesday morning into the early afternoon, with some slight
improvement in conditions expected for the afternoon.

A break between systems is likely to result in mainly west side
valley LIFR developing during Wednesday evening, with a brief
episode of VFR elsewhere.

&&

.MARINE...Updated 830 PM PST Tuesday, December 16, 2025...Active
weather will continue through most of the rest of this week.

Moderate to strong south winds and steep wind driven seas are
expected tonight with gale gusts likely north of Cape Blanco.
Warning level hazardous seas are expected in the south, despite
slightly lower winds. A front will move through overnight and winds
will shift to the west and gradually diminish into Wednesday.
However, seas will remain very steep with a Hazardous Seas Warning
continuing through at least Wednesday afternoon. Right now, there
are no headlines for Wednesday night, but it`s possible seas could
be high enough for Small Craft Conditions to continue.

The next storms will be stronger and there`s good agreement for a
coastal jet for form along the coast, mainly from about Port Orford
north and out to 30 nm or so from shore early Thursday morning and
lasting into Thursday evening. Models show 925 mb winds pushing
towards 70 kts which could early translate to storm force winds in
the area mentioned above. Given the above mentioned reasoning, a
Storm Watch has been issued. Where storm force winds are not
expected there will be solid gales for the remainder of the waters
from early Thursday morning into Thursday evening and a Gale Watch
has been issued.

The front will move southeast into the marine waters Thursday night
with winds shifting from south to northwest and diminishing, first
over the northern waters, then towards Friday morning in the
southern waters.

In a relative sense, winds will be lighter later Friday morning into
the weekend. Seas are expected to remain elevated Friday morning,
then they will also gradually diminish later Friday afternoon into
the weekend.

It`s also worth noting, moderate to heavy rain will accompany both
fronts resulting in limited visibility. -Petrucelli/Spilde

&&

.PREV DISCUSSION... /Issued 308 PM PST Tue Dec 16 2025/

DISCUSSION...After a brief period of fog and calmer conditions this
morning, active weather continues this afternoon and evening. Rain
showers are present over Siskiyou and southernmost Curry and
Josephine counties, where Somes Bar and Sawyers Bar have already had
amounts exceed one quarter of an inch. Rainfall is expected across
northern California and southern Oregon this evening into Wednesday
morning. The highest amounts are forecast over western Siskiyou
County, southern Curry County, and along the Cascades. In these
areas, 2 to 4 inches of rainfall are possible in this timeframe.
Moderate to heavy rainfall is also possible over other elevated
terrain. There are slight chances (10-15%) for embedded
thunderstorms over Curry, Coos, and western Douglas counties, but
thunderstorms are not widely expected. Initial snow levels of 8000
to 9000 feet will limit snowfall to the highest peaks into early
Wednesday morning. Snow levels drop to 3000-4000 feet later in the
morning, but by this point most areas will see precipitation
trailing off. Cascades passes may see 1 to 3 inches of snowfall,
with Highway 140 being at the lower end of that range. Residual
surface warmth and liquid water will work to prevent accumulation,
but locally slick conditions are possible.

Gusty southwest winds will develop late tonight into late Wednesday
morning, with some winds reaching hazardous speeds over area
terrain. To help highlight these conditions, a Wind Advisory is in
place over terrain in Curry, Josephine, and western Douglas County.
Even though these are remote areas, anyone spending the night in
this terrain will want to be aware of these conditions. A High Wind
Warning is in place for terrain across Lake County and for the
Warner Mountains in Modoc County, with Wind Advisories covering
lower elevation areas across Lake, Klamath, and southern Klamath
counties for late tonight into late Wednesday afternoon. Please see
PDXNPWMFR for more details on these products.

Wednesday afternoon and evening will offer a brief pause before an
atmospheric river looks to bring moderate to heavy precipitation
across most of the area from early Thursday morning into Late Friday
night. Rainfall on Thursday morning will be focused to the north of
the area, although coastal counties, Douglas County, and the
Cascades may still see periods of moderate precipitation. By the
afternoon and evening, rainfall rates look to start increasing along
the coast north of Cape Blanco and northern Douglas County. The
Oregon coast, the Cascades, and western Siskiyou County will see the
most activity, with the NBM indicating a a 60-90% chance to see at
least 3 inches of precipitation in these areas. West side valleys
look to be in the 1 inch (Rogue, Shasta, Scott) to 2 inch (Douglas,
Illinois) range. Northern Klamath County could see 1 to 2 inches of
rainfall get past the Cascades, while other east side areas look to
stay below an inch of precipitation. Snow levels are back in the 8000-
9000 foot range for most of this event, but could drop to 6000-7000
feet on Friday afternoon. With this outcome, terrain around Crater
Lake and east of Diamond Lake may see 5 to 10 inches of snowfall but
impactful winter conditions are not currently expected.

While the rainfall amounts expected through Thursday and Friday are
significant, river flooding concerns are minimal. Please see the
HYDROLOGY discussion below for more detail about this topic. This
is not to discount the possibility of noticeable river rises,
small stream flooding, or urban ponding in areas with poor
drainage. Please be aware of your surroundings when on foot and
use extra caution while traveling. Wind concerns are also present
in this period. A High Wind Watch is in place to address possible
Warning conditions along the Oregon coast as well as for Lake
County south of Summer Lake and the Warner Mountains in Modoc
County.

Beyond the atmospheric river, westerly flow aloft may support
showers continuing through the weekend and into next week. Wind
concerns are minimal. Snow levels are forecast to hover in the 5000-
7000 foot range, which could bring light snowfall to the Cascades
and northern Klamath and Lake counties. Long-term guidance shows an
upper disturbance may increase activity on Monday afternoon into
Tuesday morning, but ensemble outcomes for that period are far from
unanimous. Both ECMWF and GFS ensembles indicate chances for
activity to continue beyond Monday, but with even less agreement on
timing and amounts. -TAD

HYDROLOGY...Two rounds of moderate to heavy rain will impact the region this
week. The first arrives tonight into early Wednesday, bringing 1 to
2 inches of rain across Douglas, Coos, Curry and Josephine counties,
with up to 3 inches in the coastal mountains of Curry County. An
atmospheric river arrives early Thursday and persists through Friday
afternoon, bringing another round of moderate to heavy rain.
Rainfall amounts of 3 to 6 inches are expected, with the highest
amounts likely in Curry County.

Small streams and creeks are likely to run high and could result in
nuisance flooding along with ponding of water on roadways during
periods of heavy rain. Significant rises on mainstem rivers are
expected, but the overall concern for widespread river flooding is
low at this time due to antecedent dry conditions and minimal
snowpack. We will be monitoring rivers in the Coquille and Umpqua
Basins for flooding potential.

The exact scenario for flooding remains uncertain. Watches and
warnings may be issued if this situation worsens.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning until 4 PM PST Wednesday for ORZ030-031.

     Wind Advisory until 4 PM PST Wednesday for ORZ023-024-029>031.

     High Wind Watch from Thursday morning through Friday morning for
     ORZ021-022-030-031.

CA...High Wind Warning until 4 PM PST Wednesday for CAZ085.

     Wind Advisory until 4 PM PST Wednesday for CAZ085.

     High Wind Watch from Thursday morning through Friday morning for
     CAZ085.

PACIFIC COASTAL WATERS...Hazardous Seas Warning until 4 PM PST
     Wednesday for PZZ350-356-370-376.

     Gale Watch from late Wednesday night through Thursday evening
     for PZZ350-356-370-376.

     Gale Warning until 4 AM PST Wednesday for PZZ350-370.

     Storm Watch from late Wednesday night through Thursday evening
     for PZZ350-356-370-376.

&&

$$