132
FXUS66 KMFR 151209
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
509 AM PDT Sat Jun 15 2024

.DISCUSSION...Radar is showing a few weak showers entering into
southern Oregon along the coast and into Douglas County. Satellite
imagery is showing some clouds across more portions of southern
Oregon and northern California. This is part of a broad low
pressure system that will be pushing through the Pacific Northwest
this weekend. These showers will largely be confined to the coast
and to areas north of the Jackson/Douglas County border. The main
story regarding this low is that it will lead to generally colder
temperatures and expected freezing conditions for Saturday night
into Sunday morning for Father`s Day. Have upgraded the freeze
watch to a freeze warning. Please see the NPWMFR for more details.
Otherwise, we will experience cool, breezy afternoon today.

This low and associated fronts are producing a little more uncertainty
in the forecast Sunday afternoon into Monday afternoon than
usual. A stronger front is rotating around the slow-moving low in
the Pacific Northwest and is expected to weaken as it tracks
inland. The strength and positioning of this wave have a wide
range of solutions among the ECMWF and GEFS ensemble members. The
forecast leans slightly wetter than the NBM solution, with a
widespread slight chance to chance probability of light rain in
order to highlight the risk of an honest to goodness rainfall,
especially west of the Cascades, with the highest probability
during late Sunday evening into early Monday morning. The
operational version of the GFS leans toward the wetter side of the
solutions, a little wetter than our forecast, while the weaker
ECMWF is more representative of the NBM. We will be watching this
closely for potential adjustments as data updates.

The upper low is expected to gradually move eastward Monday
night. Then, Tuesday through Friday, models indicate weak trough
to near zonal flow over the region with a high pressure ridge
offshore.

With this pattern expect daytime temperatures to trend warmer
(becoming slightly above normal) and generally dry conditions.
Overnight low temperatures will be cool to mild Monday night/Tuesday
morning, with a potential for areas of frost conditions in valleys
east of the Cascades. For Monday night/Tuesday morning, National
Blend of Models indicates a 50-60% chance for low temperatures in
the mid 30s in valleys east of the Cascades (Klamath Falls, Lakeview
and Alturas) with a 20-25% chance for low temperatures down to 32.
Areas in northern Klamath County, near Chemult, have a higher chance
(60-80%) for freezing conditions (32 deg and below) during this
period. Overnight/morning low temperatures will trend warmer Tuesday
night through late in the week.  Northerly winds maybe gusty during
the afternoons/evenings for areas along the coast as a surface
thermal trough builds beginning Monday night into Tuesday.
Otherwise, expect typical diurnal breezes across the area.
-Schaaf/Clarstrom

&&

.AVIATION...15/12Z TAFs...There are some ceilings around 5000 to
6000 feet west of the Cascades this morning with some showers
closer to the coast under this unstable airmass. Models suggest
some cumulus building over the region this afternoon as the depth
of mixing increases. The chance of rain showers is roughly 5
percent later this afternoon under these clouds with higher
probabilities the farther one travels north. Overall, active
weather across the region as this upper level wave passes through
with VFR ceilings and visibilities near terminals through the TAF
period.

-Smith

&&

.MARINE...Updated 230 AM Saturday, June 15, 2024...Winds will
increase late this afternoon and evening south of Port Orford with
steeper seas developing near the California border. The steeper seas
and gustier winds will continue in this area into Sunday.

The active weather will persist into next week, but the timing and
sea state forecast will both benefit from extra guidance. Another
upper level disturbance is expected to move over the area, bring
more slight precipitation chances (10-20%) and wind gusts of 15 to
20 kts over all waters Sunday into Monday morning. A wider thermal
trough is forecast to build on Monday evening and remain into
midweek, bringing wind-built steep seas to most if not all waters
and gusts of near 30 kts south of Gold Beach. Long-term
probabilistic guidance currently has low (10-30%) chances of waves
over 9 feet limited to Brookings and farther south through next
week, so anything more than steep seas is not currently expected.

-TAD

&&

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

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

PACIFIC COASTAL WATERS...Small Craft Advisory from 5 PM this
     afternoon to 11 PM PDT Sunday for PZZ356-376.

&&

$$