246
FXUS66 KMFR 270403
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
903 PM PDT Sun May 26 2024

.DISCUSSION...We`re expecting rather uneventful, unimpactful weather
tonight into Monday morning. Evening satellite imagery reveals what
remaining cumulus clouds were out there over inland areas are
dissipating, with a mainly clear sky for most. Some moisture is
moving onshore into Coos and northern Curry counties, where we
expect a marine push of stratus/stratocumulus tonight that will last
into Monday morning. Some models are also showing enough moisture in
the Umpqua Basin for patchy low clouds to form. However, not
everyone there will get the clouds. They`re most likely to occur
closer to the Camas Valley and in the lower Umpqua Valley as opposed
to the rest interior Douglas County. In addition, we expect some
coastal stratus to develop in Del Norte County in norCal which
should also sneak into southern Curry County near Brookings
overnight.

The morning clouds close to the coast will break for some
sunshine Monday. Inland, expect sunny conditions with a warmer
afternoon. Some mid-level moisture arriving from the south will
allow for convective initiation over the east side and in portions
of NorCal near the Trinity/southern Siskiyou Mtns west of Mt
Shasta mid-afternoon Monday. Expect some cumulus build-ups, but
instability and forcing are fairly weak. Still, there could be a
pop-up shower or thunderstorm here or there (10-20% chance) in
those areas during late Monday pm/eve. Best chance is in eastern
Lake and Modoc counties. Once the sun goes down though, the risk
diminishes.

The next upper trough will swing through Tuesday with a slightly
cooler air mass and isolated showers/tstorms. Best chances for
precip will be over NW sections. Best chance for thunder will be
over the east side/NE California again.

The cooler air mass persists Wednesday, then modest warming
Thursday is followed by a more significant warm-up Friday and
Saturday. -Spilde

&&

.AVIATION...27/00Z TAFs...VFR will prevail across northern
California and southern Oregon through the TAF period. Marine
stratus will develop tonight along the Oregon coast, with MVFR
ceilings expected early Monday morning and clearing out late
Monday morning or early Monday afternoon. -TAD


&&

.MARINE...Updated 800 PM Sunday, May 26, 2024...Relatively calm
conditions will continue through Tuesday. Expect some locally gusty
north winds (15 to 20 kt) south of Cape Blanco within 20 nm from
shore tonight into Monday. Otherwise, relatively light winds and
seas are expected, and a weak upper trough will bring some slight
(10-20%) chances for showers north of Cape Blanco on Tuesday.

An upper ridge will build on Wednesday and remain in place through
the rest of the week with a strong thermal trough developing. This
will bring increasing north winds, with conditions hazardous to
small craft likely for all areas by Thursday. Strong north winds may
reach gales (50-90% chance) south of Cape Blanco, with the highest
chance for locations south of Gold Beach. Gusty winds and steep to
very steep and hazardous seas are likely through the end of the
week. Conditions may improve over the weekend. /BR-y

&&

.PREV DISCUSSION... /Issued 420 PM PDT Sun May 26 2024/

..Updated AVIATION Discussion...

DISCUSSION...Satellite image shows clear skies over most of the
forecast area. Some fair weather cumulus exist in portions of
northern California, northern Klamath and northwest Lake County.

Any clouds in these areas will dissipate towards sunset with clear
skies and continued dry weather tonight.

Monday, weak upper ridging will move east and a southwest flow will
set up. Instability will increase some east of the Cascades Monday
afternoon, and this in combination with a slightly stronger trigger
could be enough to warrant a slight chance of thunderstorms and this
has been added to the forecast. Afternoon temperatures will trend
higher for the interior.

Any isolated storms will end early Monday evening with it will
remain dry Monday night with milder overnight low temperatures due
to increasing clouds ahead of the next upper trough and front.

An upper trough will approach from the west Tuesday and could bring
a few showers north of Cape Blanco, north of the Umpqua Divide and
northern Cascades. Additionally, instability will be on the increase
along with ample low level moisture and trigger east of the
Cascades resulting in another round of Isolated storms. Several
ofthe models show convection breaking out and orientated from
southwest to northeast from Mount Shasta northeast to southeast
Klamath and central Lake County. Afternoon temperatures for the
interior will be cooler and winds will be stronger east of the
Cascades Tuesday afternoon and evening, but not strong enough to
warrant any headlines.

Isolated storms will once again diminish and end early Tuesday
evening with not much more than a few showers in northern Coos and
Douglas County Tuesday night. -Petrucelli

LONG TERM DISCUSSION...Models and ensembles continue to indicate
the upper trough will remain over the area on Wednesday, with
continued mild temperatures, breezy/gusty afternoon winds and a
slight chance for showers, mainly far northeast Douglas County.
There is moderate agreement (90% of the GFS ensembles and over 50%
of the EC ensembles) that the upper trough will begin to move
eastward Wednesday night, with a high pressure ridge building into
the area Thursday. This ridge is expected to remain in place through
Friday.  This would result in a warming trend and dry weather across
the area. Additionally, models indicate a surface thermal trough
developing along the coast late Wednesday, then peaking Thursday
into Friday, with gusty north to northeast winds along the coast and
over the coastal mountains. This pattern may also bring a warming
and drying trend to the Brookings area along the southern Curry
coast late in the week. Guidance the National Blend of Models (NBM)
supports temperatures in the mid 70s at Brookings Thursday and
Friday. -CC

AVIATION...27/00Z TAFs...VFR levels continue across northern
California and southern Oregon this afternoon, and look to continue
for most areas through the TAF period. Marine stratus will develop
tonight along the Oregon coast, with MVFR ceilings expected early
Monday morning and clearing out late Monday morning or early Monday
afternoon. -TAD

MARINE...Updated 200 PM Sunday, May 26, 2024...Stable atmospheric
conditions are continuing to bring generally calm seas in all
waters. Elevated northerly winds will develop south of Cape Blanco
this afternoon, with sustained speeds up to 20 kts. Gusts of up to
25 kts are possible near Brookings. These winds will decrease
overnight before returning Monday morning. While local areas of
steep seas are possible, guidance suggests that constant steep seas
are not expected.

A weak upper trough will bring some slight (10-20%) chances for
showers north of Cape Blanco on Tuesday. An upper ridge will build
on Wednesday and remain in place through the rest of the week. Model
guidance suggests a strong thermal trough will develop, with gusty
northerly winds in all waters and near gale gusts south of Cape
Blanco. While the exact conditions and hazards need further time to
develop, some amount of chaotic seas will build from midweek to the
weekend. -TAD

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.

CA...None.

PACIFIC COASTAL WATERS...None.

&&

$$

MAS/MAS/MAS