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000
FXUS66 KMFR 271339
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
639 AM PDT Sat Apr 27 2024

.Updated Aviation Discussion.

.AVIATION...27/06Z TAFs...Along the coast and just offshore, VFR
conditions are expected start, except near Brookings where MVFR
ceilings are being observed. An approaching front will result in
ceilings lowering later this morning and lasting into the afternoon
with MVFR conditions being the predominate condition. However could
not rule out brief periods of IFR late this afternoon and early this
evening.

Elsewhere, VFR ceilings are expected through the TAF period. The
exception will be at Roseburg where there is sufficient evidence
showing ceilings could lower to MVFR between 22-23z, but confidence
is low on the duration of lower conditions. Winds will increase are
east of the Cascades late in the afternoon, including Klamath Falls,
but strong winds are not expected. -Petrucelli

&&

.DISCUSSION...Satellite imagery this morning shows plenty of cloud
cover along and west of the Cascades. Clouds east of the Cascades
are more scattered and focused along the higher terrain. Radar is
fairly quiet this morning, though a few showers can be noted
along the Cascades and into the Douglas County Foothills. Latest
observations indicate the showers are fairly light with reports
only showing a hundredth or two in these locations over the last
hour or so. While isolated showers are likely to continue in these
locations through the early morning hours, most locations will
remain dry through the morning.

After this brief lull in shower activity this morning, a shortwave
arrives late this morning and afternoon, bringing another round of
light precipitation. This will be a quick moving and weakening wave,
but it will be the leading edge of sustained zonal onshore flow that
will persist into early next week. This pattern is known to produce
ongoing light showers with most precipitation remaining confined to
areas along and west of the Cascades and the best chances for
accumulating precipitation expected along the coast, Cascades and
north of the Rogue-Umpqua Divide.

On Sunday, onshore flow will contribute to a 30-60% chance of
showers north and west of the Umpqua Divide with PoPs diminishing
quickly south and east of there. It looks like a mainly dry, at
least partly sunny day elsewhere (including here in the Rogue
Valley) with gusty breezes (25-35 mph) developing in the afternoon.
The next upper air disturbance will move through Sunday night into
Monday. Once again, the main forcing for precipitation will be to
our north, but there`s a high probability of showers (50-70%) along
the coast and over to the Cascades. Again, precip chances drop off
quickly to the south and east of the mountains. We can`t rule out a
shower or two around the Rogue Valley/Medford area during that time
period, but most of the time will be rain free. Snow levels Sunday
night could dip to around 3500 feet or so, but any light snow
accumulations (2-4") should be confined to the Cascade mountains
from around Crater Lake northward. This system exits to the east
Monday evening, followed by another upper disturbance that will
swing through northern Oregon on Tuesday. Again, we`ll be on the
southern fringes of this system, so PoPs remain highest across the
north and west, lowest across the south and east.

Overall, temperatures during this period will be near to below
normal. Widespread frost/freezing conditions west of the Cascades
appear unlikely at the moment, but a colder night or two is
possible, especially if skies clear and remain clear all night. Best
chance right now for frost is Monday night/Tue morning with the
usual suspects (Illinois/Applegate Valley/Grants Pass areas) having
the highest probability (30-60%). Recent guidance even shows a
slight chance (15-25%) for Freeze conditions in these areas.

There remains quite a bit of uncertainty regarding mid-late next
week. Recent deterministic guidance wants to dry things out across
the area Tuesday night into Wednesday with a return of higher
heights by Thu/Fri. Some multi-model members have also gone in this
direction, which would potentially bring a substantial warm up late
in the week. This is being reflected in recent blended guidance as
well with some lowering of PoPs in the Wed-Fri time frame. However,
there are still several members that fall into a cluster of
solutions (~30%) that bring another upper trough into the area
maintaining a cooler, wetter regime, similar to what is expected
this weekend into early this week. At this point, confidence in any
of these solutions is low, so we prefer to keep the official
forecast closer to the NBM, which results in modest PoPs (generally
20-40%) area wide during the period with temperatures trending
higher as well. -Spilde/BR-y


&&

.MARINE...Updated 245 AM Saturday, April 27, 2024...A weak front
will approach the waters this morning with increasing south winds.
The front will move inland this afternoon and winds will shift to
the west and diminish. However, seas will remain elevated into late
this evening. The combination of south winds and seas will result in
Small craft conditions this morning into late this evening for most
of the waters. Thus, a Small Craft Advisory has been issued.

Calmer conditions are likely overnight tonight into Sunday, then
another front will move into the waters Monday. The pattern will
remain active next week, but were not anticipating any headlines
into at least the middle of next week. -Petrucelli

&&

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

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory from 9 AM this morning
     to 11 PM PDT this evening for PZZ350-356-370-376.

&&

$$

MNF/MAP/MAS