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000
FXUS66 KMFR 111725
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1025 AM PDT Thu Apr 11 2024

Updated AVIATION Section

.DISCUSSION...There is stratus at the coast and in the Coquille
Basin this morning. This will lift through the morning, although
mid and high level clouds will continue moving in from the Pacific
through the day. The rain chances for the coast are still on
track, although changes have been made inland for tonight`s
forecast. Later this afternoon and into this evening a 25-45%
chance of rain has been added to areas east in eastern Siskiyou
County and Modoc County that tracks northeastward. This has been
added with more short-term models showing this area that has
enough energy and moisture to see rain. Today`s updates will
focus on the thunderstorm chances and potential for gusty winds on
the east side.
-Hermansen

&&

.AVIATION...11/18Z TAFs...VFR prevails in all areas through early
this evening. Westerly breezes are expected this afternoon/evening
in Medford and Klamath Falls with gusts of 20-25kt. Strongest winds
will be near higher terrain and east of the Cascades. Isolated
showers/stray thunderstorm could pop up in southeastern Siskiyou and
Modoc counties up to around Lakeview in the 03-15z time frame.

Meanwhile, a cold front will approach the coast with MVFR ceilings
moving into North Bend around or just after 06z along with areas of
light rain/drizzle. These lower ceiliings/light rain will spread
into the coast ranges/Umpqua Basin through the overnight, but
probably stop short of the Rogue Valley/Medford. Conditions will
remain VFR elsewhere through 18z.

The character of precipitation changes Friday afternoon as the
atmosphere becomes more convective. Scattered showers are most
likely near and west of the Cascades, but also over portions of the
east side (especially from the Warner Mtns in eastern Modoc County
northward into Lake County). There is also a slight chance (~20%) of
thunderstorms. In between those areas, there will be a relative
minimum in shower potential (though not zero). -Spilde

&&

.MARINE...Updated 845 AM Thursday, April 11, 2024...Improving
conditions this morning continue through Friday, though low pressure
moving south is likely to bring rain late tonight into Friday.
Meanwhile, stronger, gusty northerly winds are likely in the
offshore waters, beyond 60 nm from shore.

As this low moves inland into central California, these stronger
north winds are likely to move into the coastal waters Friday night
and persist through the weekend. Hazardous conditions are likely to
return Friday night as gusty north winds build steep to very steep
wind driven seas through the weekend. /BR-y/Hermansen

&&

.PREV DISCUSSION... /Issued 307 AM PDT Thu Apr 11 2024/

DISCUSSION...Satellite image shows varying amounts of high clouds
moving into the northwest part of the forecast area. Marine stratus
up to this point is mainly confined to the coast and coastal valleys
in Curry county. The marine stratus will push farther inland into
the Coquille Basin around daybreak and could sneak into northwest
Douglas County, but were not expecting it to make it into the Umpqua
Basin.

Today will be the last dry day with mild afternoon temperatures for
most interior locations. Gusty breezes are expected east of the
Cascades this afternoon and evening. We`ll see high and mid level
clouds increase during the day as an upper low digs south and a
surface front moves closer to the coast.

There`s good agreement an upper trough will dig south off the Oregon
coast tonight and remain off the Oregon coast Friday. Meanwhile a
surface front will approach the coast bringing slight chance of
showers along the coast, north of Cape Blanco late this evening,
then overnight Thursday along the coast and coastal counties.
There`s some evidence pointing towards a few showers popping up
inland near the Mount Shasta Area with enough instability to warrant
a slight chance of thunderstorms in that area, but this will be the
exception not the rule in terms of showers and storms. It `s mainly
a heads up that we could not be surprised if something should pop up
late in the afternoon and early evening hours.

The upper low remains off the Oregon coast Friday with a southerly
flow ahead of the upper low. This will result in a net increase in
showers during the day Friday and instability could be sufficient
enough for isolated thunderstorms along and east of the Cascades
Friday afternoon into early Friday evening.

The upper low will continue to move south Friday night into Saturday
and set up just west of the Bay area Saturday afternoon. There are
still indications showers will move up from the south to southeast
into our forecast area, especially in the afternoon due to daytime
heating and increasing instability. Saturday could end up being the
wettest day of the forecast period with some guidance showing the
potential for locally moderate to heavy rain. This will be due in
combination of unstable conditions and wraparound moisture that will
move from east to west over the Cascades and west side to include
Jackson, Josephine and Curry County.

There were some question`s surrounding thunderstorm potential west
ofthe Cascades and while it will be marginally unstable, there will
be plenty of cloud cover and moisture moving in which should be
enough to inhibit thunderstorms, so we`ll keep them out of the
westside for now, but this will need to be reevaluated.

Isolated thunderstorms however are still possible Saturday afternoon
along and east of the Cascades.

The upper low will slowly move inland south of the Bay Area Sunday,
but we`ll still feel the effects with isolated to scattered showers
Sunday morning, with the best chance for showers shifting east of
the Cascades Sunday afternoon. There is still a slight chance of
thunderstorms in eastern Lake County Sunday afternoon into early
Sunday evening.

An approaching upstream upper trough will kick the low in California
east on Monday. Pattern recognition regarding the track of the upper
trough typically does not result in much, if any precipitation.
However, some of the individual ECMWF ensembles members show limited
precipitation amounts north of the Umpqua Divide and northern
Cascades. Therefore, we`ll keep a slight chance of showers in the
forecast.

The upstream upper trough will settle into our area Tuesday and
Wednesday, bringing cooler temperatures and a continued chance of
showers. -Petrucelli

AVIATION...11/12Z TAFs...VFR conditions will prevail for most areas
today, with high level clouds (cirrus) continuing to stream in well
ahead of a front. The exception being in the Coquille Basin where
MVFR cigs will continue and south of Cape Blanco where IFR
conditions are expected through this morning. Patchy MVFR may also
develop in the Umpqua Valley, though should be less in coverage
compared to Wednesday morning. Also, westerly afternoon breezes will
develop again this afternoon, with strongest winds over higher
terrain and east of the Cascades.

MVFR cloud cover thickens and precipitation chances increase at the
coast this evening as a front approaches. Lower ceilings are likely
to spread inland late tonight. -DW/BR-y

&&

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

CA...None.

PACIFIC COASTAL WATERS...None.

&&

$$