644
FXUS66 KMFR 192142
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
242 PM PDT Wed Jun 19 2024

.DISCUSSION...Satellite imagery is showing that other than a few
cumulus over the mountains, mostly sunny conditions prevail across
inland SW Oregon and northern California early this afternoon.
Marine layer stratus, however, is affecting the coast north of
Cape Blanco and also along the immediate coast south of Gold
Beach. The sunshine inland is allowing things to warm up nicely in
those areas. Temperatures currently (as of 1 pm) are about where
they were for highs yesterday, so most areas will end up about
5-10F higher compared to yesterday. On the flip side, the clouds
and marine influence along the coast has made things a bit cooler
there compared to just 24 hours ago. Gusty northerly winds (25-30
mph) are expected through this evening. A few more cumulus clouds
will develop over the mountains too through this evening, but
there just isn`t enough moisture/instability to get anything
going. So, it`ll remain dry with fairly typical late
afternoon/early evening breezes.

The marine layer will deepen tonight into early Thursday morning
and this could result in clouds and patchy drizzle for areas over
the coastal waters and also the ports, especially north of Cape
Blanco, but also perhaps near Brookings. The remainder of the area
will remain dry and clear.

The upper pattern will feature a weak upper trough swinging
through the area Thursday afternoon/evening. We don`t think there
is enough moisture/support/instability to initiate convection, but
there is a very low probability (<10%) something occurs over the
mountains. Buildups are the most likely outcome with no
precipitation and/or lightning.

Weak shortwave ridging will traverse the area Friday into
Saturday. These are likely going to be the hottest days of the
stretch; Saturday being the hottest east of the Cascades. Once
again, we aren`t expecting record-breaking heat with this event,
though one or two sites may challenge their record highs (Mt
Shasta City being the most likely to do so due to their shorter
period of record). The official forecast has highs in the low to
mid 90s in the west side valleys, but up around 100F in the
valleys of western Siskiyou County, including near Montague/Yreka.
Northeast California and the east side in Oregon will have highs
in the upper 80s and low 90s, but maybe mid 90s on Saturday. NWS
HeatRisk is once again showing a "moderate" risk (orange category
2) in portions of our area, including the Rogue and Illinois
Valleys, but especially the Siskiyou County valleys. However,
since the daytime heat will be mitigated again by cooling
overnight, we are not planning any heat-related headlines. Folks
sensitive to heat should still: 1) stay hydrated, 2) try to keep
outdoor activities to the coolest parts of the day, and 3) seek
shaded areas or air-conditioned buildings to stay cool during the
hottest part of the day (2-7 pm). -Spilde

A weak front attached to a low pressure system in the Gulf of Alaska
will help to slightly cool temperatures on Sunday and into the
beginning of next week. Generally, daytime highs are forecast to be
in the mid 60s to low 70s along the coast and in the mid to high 80s
inland. Afternoon breezes will increase as the pattern around the
low pressure system will put the area under the leading edge of an
upper trough, but currently nothing approaches advisory levels.
Previous slight precipitation chances over the Oregon coast are
currently absent from deterministic outcomes, and ensemble
meteograms show that only traces of rainfall are possible over North
Bend on Sunday and Monday. This is more likely part of an early
morning marine push than any actual rainfall. Overall, it should
remain above normal through mid next week, but only about 5F or
so. -TAD/Spilde


&&

.AVIATION 19/18Z TAFs...For inland areas, VFR ceilings and
visibilities are anticipated through the TAF period as high pressure
builds. For the coast and coastal waters, IFR/LIFR stratus will
persist just offshore during the daylight hours, but patches of
marine clouds may briefly scrape along the shore and pass over
KOTH in northerly flow. Models bring a marine push into Coos county
after 00Z which will spread into the Coquille and lower Umpqua
valleys overnight into early Thursday morning. This is a very
shallow marine layer so IFR ceilings are expected to last through
the rest of the TAF forecast period for these areas. -Sargeant

&&

.MARINE...Updated 230 PM Wednesday, June 19, 2024...High pressure
offshore and a thermal trough along/near the coast will remain in
place at least through the weekend, and likely through Monday. This
will result in persistent northerly winds and wind-driven seas
through this period. Conditions will be worst south of Cape Blanco
where winds and steep seas hazardous to small craft will persist.

The thermal trough will strengthen further this afternoon into
Friday evening, and this may bring very steep seas and/or northerly
gales to the waters south of Cape Blanco Thursday afternoon into
Friday evening. The latest model solutions keep winds just under
gales at this time. However, the strongest winds will most likely be
1 to 2 nm offshore between Nesika Beach and Brookings out 15 nm.
With this uncertainty, it is recommended mariners to stay tuned to
updates as we move through the week.

-Sargeant/DW

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT Friday
     for PZZ356-376.

&&

$$

MAS/KRS/TAD