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000
FXUS66 KMFR 220521
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1020 PM PDT Sun Apr 21 2024

Updated AVIATION Section

.DISCUSSION...An update is not necessary. Monday will be a warmer
version of today`s weather, with lingering high clouds. It will
likely be the second week of May at the earliest before we once
again reach the level of warmth of Monday and Tuesday afternoons.

The pattern changes for Tuesday and Wednesday with low pressure
bringing an influx of mid-level moisture and instability for a
slight chance to chance of showers and late day thunderstorms on
both days for northern California and south central Oregon,
possibly extending into far southern and far eastern Jackson
County. Also of note in the short term are easterly winds for
downslope warming/Chetco effect for Brookings on Monday with a
high in the upper 70s expected, and a southerly surge of stratus
along the Curry County coast about as far north as Gold Beach on
Monday night into Tuesday with much cooler coastal readings on
Tuesday.

Slight cooling Wednesday is likely to be followed by a relatively
strong cold front with wet, breezy, brisk conditions for Thursday
and Friday. Continued active, very slightly warmer but still
showery weather is likely for Saturday with another front possible
on Sunday.

&&

.AVIATION...22/06Z TAFs...VFR will prevail for the next 24 hours,
albeit with some high cirrus. Gusty north winds will redevelop
Monday afternoon along the coast (up to 30 kt) and in the Umpqua
Basin (up to 20 kt), then gradually subside Monday evening. -Spilde

&&

.MARINE...Updated 830 PM Sunday, April 21, 2024...A thermal
trough will maintain moderate to strong north winds and steep to
very steep wind driven seas tonight into Monday. The strongest winds
and steepest seas are expected south of Cape Blanco. The thermal
trough will weaken Monday night into Tuesday. Weaker north winds
will persist in most areas on Tuesday, but a southerly surge of
stratus could reach up to around Gold Beach. Conditions will improve
with lighter winds and lower seas on Wednesday. The next period of
unsettled weather is expected Wednesday night through Friday.
-Spilde

&&

.PREV DISCUSSION... /Issued 437 PM PDT Sun Apr 21 2024/

DISCUSSION...Aside from some high level cirrus clouds streaming
over the region, skies are clear across the area this afternoon
and temperatures are running about 5 to 10 degrees cooler than
this time yesterday. Overall, it`ll be pleasant spring afternoon
for the area, with high temperatures peaking near seasonal normals
today -- upper 60s/low 70s West Side and low to mid 60s East
Side. Gusty north winds have kicked in along the coast due to a
strengthening thermal trough. This thermal trough will induce east
to northeasterly flow today and Monday, resulting in the Chetco
Effect and warmer temperatures (compared to the rest of the
coastal locations) in the Banana Belt region. Dry conditions are
expected to continue across the region today and through Monday
before a subtle shift in the weather occurs Tuesday and Wednesday,
and a more notable change in the pattern occurs for the latter
half of the week and into next weekend.

Zonal flow is in place today, but a shortwave ridge will pass
through the region Monday. This, along with the thermal trough
pushing inland, will bring a sharp jump in high temperatures on
Monday. Expect afternoon temperatures to be about 5 to 10 degrees
warmer than what is expected today, along with unseasonably low day
time humidities. The Chetco Effect will peak Monday, and locations
along the southern coast (Brookings, Gold Beach) are expected to
reach into the upper 70s before the flow reverses and the cooler air
from the Pacific returns.

Tuesday into Wednesday, the upper level pattern will transition with
low pressure developing out near 130 W west of the California coast
and low pressure pushing toward the British Columbia Coast. This
will put our region in southwest flow and some mid level moisture
will move into the area. This combined with some model indicated
instability (-2 to -4 LIs, 300-500 J/kg CAPE) is boosting confidence
in thunderstorm potential for Tuesday and Wednesday. The focus for
thunderstorm potential will be over northern California and in the
southern half of Klamath and Lake Counties on Tuesday, then a bit
farther east on Wednesday over eastern Siskiyou, Modoc and southern
Lake Counties. For the remainder of the area, conditions will remain
dry though expect an uptick in afternoon winds and cloud cover with
temperatures trending cooler.

Thursday into next weekend, the pattern turns cooler and wetter with
a front expected to push onshore late Thursday morning and move
through the region through the day. The upper level trough will be
reinforced by another trough, deepening and digging in along the
West Coast into the weekend. This will maintain a cool and showery
pattern, with most, if not all, of the area seeing a good chance of
rain at some point before the end of the forecast term. /BR-y

&&

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

PACIFIC COASTAL WATERS...Gale Warning until 11 PM PDT Monday for
     PZZ350-356-370-376.

Small Craft Advisory until 11 PM PDT Monday for PZZ350-370.

&&

$$