241
FXUS66 KMFR 141120
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
420 AM PDT Mon Apr 14 2025

.DISCUSSION...Updated Aviation Discussion...

&&

.AVIATION...14/12Z TAFs...VFR conditions will prevail through the
TAF period as high pressure remains in control and very dry air
persists in the boundary layer. Breezy north winds will be present
at the coast, especially in Coos County, this afternoon.

-Smith/Hermansen

&&

.PREV DISCUSSION... /Issued 323 AM PDT Mon Apr 14 2025/

DISCUSSION...It is a clear, cool night in southern Oregon and
far northern California. High pressure aloft and a thermal trough
at the surface will keep area skies clear today, and push
afternoon temperatures even warmer compared to yesterday, reaching
highs more typical of early June than mid April.

Tuesday, the upper ridge and surface thermal trough will shift
east resulting in slight cooling west of the Cascades. At the same
time, we`ll be sandwiched in between a weak approaching upper
trough from the west and a cut off upper low off the California
coast. Mid level moisture will move up from the south ahead of the
upper low, providing enough fuel for convective showers in
northern California mid to late Tuesday afternoon and evening. An
isolated thunderstorm or two is not out of the question, and due
to an east to northeast steering flow, a few may even sneak into
southern Klamath and Lake counties in the evening.

On Wednesday, the pattern will shift slightly, this time placing
the area between the cutoff upper low slowly creeping towards the
California coast, and an approaching and stronger upper trough
digging south from Canada. The upper trough from the north could
put a squeeze play on the incoming moisture from the south, basically
pushing the moisture and instability to the south and east. This
will keep the bulk of the shower and thunderstorm chances out of
the forecast area, but a few locations in southern Siskiyou and
Modoc County, and maybe even along the Warners in Lake County,
could still see an isolated storm or two Wednesday afternoon into
Wednesday evening.

The aforementioned stronger upper trough will drop south into our
area Wednesday night into Thursday, a feature we like to call an
"inside slider." The trajectory of this upper trough is one that
does not typically result in precipitation, but models continue to
produce some showers across the East Side, likely due to residual
moisture funneling north from the low to the south, although the
latest runs have pushed these showers more to the east, now only
covering portions of Lake County with slight chance. Other than
these low precipitation chances, we do expect a cooler and drier
air mass to arrive with the trough, with moderate to occasionally
strong north winds east of the Cascades Thursday afternoon into
Thursday evening, and then again, but to a lesser extent, Friday
afternoon.

Warm and dry conditions then return Friday and Saturday as
ridging builds in overhead, allowing for another few days of warm
daytime highs and mostly clear skies. A weak impulse could pass
over the area Saturday, but little will mark its passage other
than some increased cloudiness and breezy afternoon winds.
Precipitation chances will hold off until a more robust shortwave
arrives Sunday, but even then the bulk of rain chances will stay
relegated to the coast and the Umpqua Basin. -BPN

MARINE...Updated 230 AM Monday, April 14th...The thermal trough
will shift inland and result in some weaker northerly winds today.
Seas still remain steep and hazardous to smaller crafts today.

Data suggests the thermal trough will rebuild off the Oregon coast
Tuesday afternoon or evening with some stronger northerly winds. For
now, guidance supports hazardous seas south of Cape Blanco Tuesday
until the conditions spread to all waters Tuesday afternoon. There
is the potential for a brief period of gale force winds south of
Gold Beach on Tuesday evening.

-Smith/Hermansen

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PDT Tuesday
     for PZZ350-356-370-376.

Hazardous Seas Warning from 5 AM Tuesday to 5 AM PDT Wednesday
     for PZZ350-356-370-376.

&&

$$