396
FXUS66 KMFR 051355 CCA
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
655 AM PDT Sat Jul 5 2025

.DISCUSSION...A stable air mass will be in place for the rest of
the weekend, while a warming trend begins. Above normal inland
temperatures and seasonably breezy winds are expected through the
week. Afternoon and evening thunderstorms return to the area
Monday through Wednesday with isolated coverage most likely
during at least the first two of those days.

Coastal stratus is already beginning to erode, and night and
morning coverage will be a bit more sparse tonight through
Tuesday. The next marine push for the coast and coastal valleys
looksto be Tuesday night into Thursday morning, possibly deep
enough for stratus to briefly reach Roseburg during early Thursday
morning.

Near normal temperatures today will then rise to several degrees
above normal for Sunday, with a peak of this warming trend to
follow on Monday with readings from the lower 90s to lower 100s
expected in valleys.

Yesterday`s trough is tracking toward the Rockies, with ridging
today into Sunday as the next trough moves southward. It will make
it to around offshore of San Francisco this weekend and close off,
before meandering back northward toward Cape Mendocino Monday and
Tuesday. Agreement has improved that it will then track across far
northern California on Wednesday. As a result, coverage of showers
and thunderstorms looks to trend a little greater each of the
three days, particularly for Wednesday. Slight differences in the
track will affect the location of storms. The forecast reflects a
consensus of the 00Z data with a slight chance mention included
for the southern Oregon Cascades of eastern Jackson and western
Klamath counties. Meantime, the recently arrived 06Z GFS and 09Z
SREF shift the focus to Siskiyou County, possibly tracking into
Jackson County later Monday evening, with a secondary lobe of
energy from Klamath into northern Lake counties. Meantime, a more
consistent picture is developing for isolated thunderstorms to
occur in the Chemult to Fort Rock area of northeastern Klamath and
northwestern Lake counties on Tuesday afternoon/evening.

A higher probability over a broader area of the northern portion
of south central Oregon is forecast for Wednesday
afternoon/evening with shortwaves rotating around the inland
moving trough. The 06Z data has slowed the speed of the trough
passage just enough to suggest Siskiyou County and southeast
Klamath County may need to be added to the region with at least a
slight chance of storms. The approach of the trough on Tuesday and
passage of the trough on Wednesday should bring a few degrees of
cooling of high temperatures for each day.

Model differences increase beyond Wednesday, but there is general
agreement that we will be in a post-trough, stable environment on
Thursday. The shift to a northwest or north flow aloft should
bring another degree or two of cooling for Thursday.

High temperatures are likely to rebound at least somewhat higher on
Friday, though models do not yet agree on whether that is due to
stronger ridging or the introduction of southerly flow and weak
instability from the next Pacific trough.

The strength and track of this trough has wide disparity between
the models but is likely to have at least some effect on our
weather next weekend, even if it hasn`t already begun to
influence things on Friday. Simply too soon to be too definitive
about day 7.

&&

.AVIATION...05/12Z TAFs...A stable air mass for the remainder of the
weekend will result in VFR inland, and puts the main focus back on
coastal stratus.

Aside from clear skies from Port Orford to Gold Beach, the coast and
the Coquille and lower Umpqua valleys are a mix of IFR/LIFR early
this morning. The marine stratus will gradually erode this morning,
with mainly VFR expected for the afternoon into the early evening. A
shallower marine layer tonight into Sunday morning along with a
slight veering of the winds to northeast will result in a lesser
coverage of stratus, but LIFR where it does form. -DW

&&


.MARINE...Updated 200 AM PDT Saturday, July 5, 2025...The hazards
were updated to reflect gradually deteriorating conditions this
weekend with gales likely developing south of Port Orford late
Sunday morning and persisting into Monday morning. The thermal
trough pattern returns today, bringing gusty north winds and
building seas into Monday. Steep seas will develop south of Cape
Blanco this morning then expand northward with steep seas across the
waters by Sunday evening. Except, gales are likely to produce very
steep and hazardous seas south of Port Orford Sunday afternoon
through early Monday. Briefly improving conditions are expected
Tuesday into Wednesday, with the thermal trough strengthening again
and likely persisting Wednesday afternoon into Saturday. -DW

&&

.FIRE WEATHER...Updated 200 PM PDT Friday, July 4, 2025...
For the remainder of the holiday weekend, more typical summer
conditions will return in terms of temperatures and humidities.
The persistent thunderstorm pattern finally shifts eastward, and
thunderstorms drop out of the forecast for the rest of the
weekend. Temperatures will trend warmer Saturday into early next
week, and daytime humidities will trend lower. Temperatures look
to peak on Monday and Tuesday when high temperatures reach into
the mid to upper 90s and maybe even the triple digit mark for some
West Side and NorCal valleys. Temperatures trend slightly cooler
from mid-week onward, but still remain above normal through the
end of the week.

Meanwhile, confidence is increasing in yet another low pressure
redeveloping offshore of California on Sunday and persisting through
around mid-week. There have differences in exact location and
trajectory of this low, which leads to low confidence in details
regarding timing and location of thunderstorm chances. However,
considering models have been consistent in at least showing the
presence of this feature, confidence is growing in thunderstorm
chances returning to the region for the early part of next week. The
deep southerly moisture flow will be cut off during our break this
weekend, so it`s possible that this next pattern would have less
thunderstorm coverage compared to what we have seen over the past
week. We`ve introduced a 10-15% chance of thunderstorms for parts of
the East Side and Siskiyou County, but we anticipate changes to this
forecast over the next day or so as models become more consistent in
resolving this feature. At this time, it looks like thunderstorms
could arrive as early as Monday and linger into Wednesday. Stay
tuned for updates.

Otherwise, the forecast will be for continued near to slightly above
normal temperatures, seasonal humidities, and the typical diurnal
wind patterns, although general east flow late this weekend into
early next week could lead to drying, especially across the
ridgelines, where poor to moderate recoveries are possible. /BR-y

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory from 11 PM this evening
     to 8 AM PDT Monday for PZZ350-370.
     Small Craft Advisory until 8 AM PDT Monday for PZZ356-376.
     Gale Watch from Sunday morning through Monday morning for
     PZZ356-376.

&&

$$