248
FXUS66 KMFR 180520
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1020 PM PDT Mon Jun 17 2024

...New Aviation Section...


.AVIATION (06Z TAFs)...

Expecting VFR conditions to persist through this TAF cycle with
Roseburg (KRBG) being the only terminal forecast to see
deteriorating conditions. Given recent rainfall and moisture in
the Umpqua Valley, there is a reasonable chance (~20%) for low
ceilings and/or visibility restrictions which could lead to MVFR
conditions. Only went with a TEMPO group for this because
confidence wasn`t high enough for persistent conditions.
Otherwise, VFR high clouds are expecting tomorrow afternoon.

-Guerrero

&&

.PREV DISCUSSION... /Issued 432 PM PDT Mon Jun 17 2024/

SHORT TERM...A trough is swinging across the Pacific Northwest
today. More locations west of the Cascades in the valleys and at
the coast will see a warm up this afternoon, although temperatures
will still be 10 to 15 degrees cooler than normal. A thermal
trough has been building today, and this has brought breezy
conditions to the coast with gusts near 25 mph possible this
afternoon, especially on the Curry County coast.

The next area of concern will be tonight with colder overnight
temperatures. Tonight there is a 68% probability to reach 32 degrees
at Klamath Falls. There is a 65% probability for Chemult to reach 26
degrees or lower tonight. A Freeze Watch was out for tonight with
the concern of sub-freezing temperates as low as 24 degrees. This
has been upgraded to a Freeze Warning which will be in effect
from 1 AM through 8 AM Tuesday. This includes most of Klamath and
Lake counties and portions of Siskiyou and Modoc counties near
Macdoel and Alturas. Please see the NPWMFR for more information.
There was a concern for a Frost Advisory in parts of Siskiyou
County, but the probabilities are too low and isolated to bring
about another product, so the Freeze Warning will be the only land
product tonight.

As the trough moves off to the east, higher heights will be
present in Oregon on Tuesday, and this will be enough to bring a
return to near normal temperatures. Tuesday night into Wednesday
morning, temperatures east of the Cascades will be in the mid-
/upper 30s, putting an end to the freeze risk in most spots. WEst
side valleys will have lows in the mid-/upper 40s. Dry conditions
will be favored in the coming days as well.

-Hermansen

LONG TERM...Wednesday through next Monday (June 19-24, 2024)...

Things will start to warm up more Wednesday with a return to
temperatures near 90F for the Rogue Valley. The Rogue Valley and
western Siskiyou valleys will be under a moderate HeatRisk
Wednesday/Thursday afternoons. In addition to the Rogue Valley,
moderate HeatRisk will spread into more of the Umpqua Basin and
Illinois Valley in the later part of the work week (Thu/Fri). The
warmest day of the week will be Friday for west side valleys and
Saturday for east side locations. High temperatures will peak in
the low/mid 90s for the west side valleys and in the upper 80s to
low 90s over the east side. The official forecast for Medford is
for 96/95F for both Fri/Sat, respectively, with a low chance
(~20%) of 100F. Best chance for >=100F (40-60%) will be in the
lower Klamath and Salmon river valleys (Happy Camp/Somes Bar), and
the Shasta and Scott valleys of western Siskiyou County. Breezy,
but fairly typical, afternoon W-NW winds will be present each day,
but will pick up into the weekend, especially east of the
Cascades. These areas will have wind speeds of 15-25 mph and
occasional gusts to 30 mph both Fri/Sat.

A mostly dry front/marine push appears likely over the weekend.
As mentioned, Saturday should be another very warm day over inland
areas. The front will push onshore Saturday night into Sunday.
This could deepen the marine layer just enough for some light rain
or drizzle at the coast, especially north of Cape Blanco and
perhaps into lower portions of the Umpqua Basin, but right now
PoPs are less than 15% in these areas. This trough/front should
at least drop temps back by a few degrees both Sun/Mon. Otherwise,
dry conditions will prevail through the long term.

-Hermansen/Spilde

AVIATION...18/00Z TAFs...

Overall, we are looking at a mainly VFR forecast for the
terminals; however, there will be a time period overnight where
Roseburg (KRBG) could get down to MVFR/IFR. The thought behind
this is the recent rainfall/moisture sticking around KRBG and the
valley which may lead to low ceilings and/or visibilities. Will
have to watch this potential (20%), but confidence was high enough
to place a TEMPO group for this MVFR potential. If confidence
increase, we will place a "from group" for more persistent
conditions.

-Guerrero

MARINE...Updated 800 PM Monday, June 17, 2024...A thermal trough
will remain in place along/near the coast through at least next
weekend. This will result in persistent northerly winds and wind-
driven seas through this period. Conditions will be worse south of
Cape Blanco where winds and seas hazardous to small craft will
persist. The thermal trough strengthens and expands northward on
Tuesday, which will result in small craft advisory conditions across
the waters north of Cape Blanco Tuesday afternoon into Wednesday
morning.

The thermal trough will strengthen further later this week into the
weekend, and this may bring northerly gales to the waters south of
Cape Blanco. Consequently, it is recommended mariners to stay tuned
to updates as we move through the week.

-Guerrero

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Freeze Warning until 8 AM PDT Tuesday for ORZ029>031.

CA...Freeze Warning until 8 AM PDT Tuesday for CAZ084-085.

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

     Small Craft Advisory from 2 PM Tuesday to 5 AM PDT Wednesday for
     PZZ350-370.

&&

$$