197
FXUS66 KMFR 171753
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1053 AM PDT Mon Jun 17 2024

Updated aviation discussion.

.AVIATION...17/18Z TAFs...A large shield of cumulus is sliding down
the coast and into the Umpqua Basin this morning. Ceilings within
this cumulus are largely VFR, but occasional dips into MVFR are
possible. This is especially true along the coast where low-topped
showers not seen by radar may be embedded. These clouds should stay
bottled up west of the Cascades and north of the Umpqua Divide
today, with only pop-up fair weather cumulus elsewhere.

Residual moisture may result in the return of stratus and fog in the
Umpqua Basin (including KRBG) tonight, similar to this morning. But
with the probability remaining relatively low (30% at most), have
opted to exclude from their TAF for now. VFR conditions should
prevail elsewhere tonight. -Wright

&&

.PREV DISCUSSION... /Issued 524 AM PDT Mon Jun 17 2024/

DISCUSSION...Satellite imagery is showing some patchy cloud cover
across portions of southern Oregon and northern California.
While the weather is unsettled, our RADAR is indicating no
precipitation early this morning. The overall pattern remains part
of a broad low pressure system that will move away from our area
later today. Another weak trough will continue to keep
temperatures much cooler than normal, but we should remain mainly
dry. It is worth noting that the GFS seemed to handle the
precipitation chances pretty well today, and have continued to
blend toward the GFS for tomorrow`s precipitation chances, mainly
centered along the Douglas County coast, the Cascades and for
portions of northeast Lake County. Any showers will be light and
wetting rains are generally not expected.

In addition, this trough will continue to keep temperatures colder
than average. We have a freeze warning in effect until 8 AM this
morning. Ensembles have lowered temperatures east of the Cascades
once again for tonight, and a freeze watch has been issued for
Monday night into Tuesday morning for most of the same areas as
the Freeze Warning. Please see the NPWMFR for more details.

In addition to the freezing temperatures east of the Cascades,
temperatures will be relatively chilly west of the Cascades--
especially for the Scott Valley in Siskiyou County. Some patchy
frost could form early Tuesday morning, but confidence was not
high enough in widespread frost potential to warrant a frost
advisory. However, will recommend the next shifts to continue to
evaluate the frost potential.

After that, conditions are expected to dry out and warm up with
temperatures approaching normal and then above normal by the end
of the week. Some ensemble members show continued troughiness
which could limit our temperatures and introduce showers into the
forecast, but have favored the National Blend of Models as it
factors in the difference ensemble solutions. That being said, it
is patterns like this in which the NBM could be underdispersive in
its solutions. An ensemble being underdispersive means that the
range of solutions of the ensemble is too narrow and does not
accurately capture the full extent of possibility set up by the
weather pattern. Regardless, the weather should continue to be
monitored for updates to the weather pattern. -Schaaf

MARINE...Updated 330 AM Monday, June 17, 2024...Steep seas will
persist south of Cape Blanco this morning and into the remainder
of the day as a thermal trough builds into the coast. Conditions
will worsen this afternoon and evening with wind gusts up to 35
knots south of Brookings. Winds weaken slightly on Tuesday before
they potentially restrengthen again on Wednesday if a thermal
trough builds into the coast again. Models suggest a west swell
will arrive in the waters around Saturday or Sunday. Overall,
conditions will likely remain hazardous to smaller craft for most
of the week south of Cape Blanco with wind waves around 6 to 7
feet with periods around 7 to 8 seconds.

-Smith

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Freeze Warning from 1 AM to 8 AM PDT Tuesday for ORZ029>031.

CA...Freeze Warning from 1 AM to 8 AM PDT Tuesday for CAZ084-085.

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

&&

$$