228
FXUS66 KMFR 092138
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
238 PM PDT Wed Jul 9 2025

.DISCUSSION...An upper level low pressure system is moving across
southern Oregon and northern California this afternoon. This feature
is helping to keep temperatures at seasonal levels across the area.
Flow around the low is keeping slight thunderstorm chances (10-20%)
over Lake and eastern Klamath counties this afternoon. Precipitable
water vales are moderate at 0.5 to 0.6 inches in these areas, and
expected CAPE values of 200-300 J/Kg are not especially high. Some
cells are popping up and quickly breaking up northwest of Lakeview,
so the potential for activity is out there. Severe activity seems
unlikely this afternoon, and thunderstorm chances decrease quickly
as the low pressure moves eastward out of the area.

The overall message for the rest of the forecast period is a warming
trend across the area. Zonal flow aloft supports slight warming on
Thursday and Friday. On Friday, moderate levels of HeatRisk will
develop in Siskiyou and Modoc counties and could reach as far north
as Medford and Klamath Falls. At moderate levels of HeatRisk,
individuals who are sensitive to heat may experience heat-related
illnesses. Winds mostly stay northerly to end the week, with normal
afternoon breezes. The Klamath River Valley may see some morning
smoke accumulation, and the southern Rogue Valley may see periods of
decreased air quality.

A ridge over the Pacific High will cover the western United States
this weekend. On Saturday, Sunday, and Monday, Moderate HeatRisk is
expected for most if not all low elevation areas on either side of
the Cascades. Areas of Major HeatRisk may be present in Medford and
in the Klamath River Valley. At Major levels of HeatRisk, anyone
without cooling or adequate hydration may experience heat-related
illness. A Heat Watch is in place for Saturday, Sunday, and Monday
to communicate these developing hazardous conditions. In this
timeframe, Medford has a 65-75% chance of seeing daytime highs of
over 100 degrees.

With high pressure over the Pacific growing stronger early next
week, Tuesday looks to be the warmest day of the forecast period.
Current guidance has Major HeatRisk in the Scott, Shasta, and
Klamath River valleys. Major HeatRisk is also in guidance in the
Rogue Valley for areas south of Gold Hill. Other areas are very near
Major levels of heat risk, including Grants Pass and the Illinois
and Applegate valleys. Similar temperatures continue on Wednesday,
with a cooling trend possibly starting next Thursday depending on
how the upper level pattern develops. -TAD


&&

.AVIATION...09/18Z TAFs...LIFR/IFR conditions in marine fog and
stratus will burn back to the immediate coast this afternoon. Some
areas may not fully clear before the marine layer pushes inland
again late this afternoon and  evening, with MVFR/IFr once again
expected overnight along the coast and into the coastal valleys.

Elsewhere, VFR conditions are expected through the TAF period. Areas
of smoke in the vicinity of wildfires could lower visibilities to
MVFR at times. Gusty winds return to the area this afternoon and
another round of thunderstorms is expected across central
Klamath/Lake Counties this afternoon and evening. -BPN/BR-y

&&

.MARINE...Updated 200 PM PDT Wednesday, July 9, 2025...Below
advisory level winds and seas continue across area waters today. A
thermal trough pattern is expected to build tonight, with gusty
northerly winds developing across the area and the strongest winds
south of Cape Blanco. These winds will build steep seas south of
Cape Blanco on Thursday morning and afternoon. On Thursday evening,
steep seas build north of Cape Blanco. South of Cape Blanco, gale
gusts are expected south of Port Orford. Wind-built very steep and
hazardous seas are forecast for other southern waters, with periodic
gale gusts possible. This general pattern could stay in place as
late as Monday night, with some improvement possible on Tuesday and
Wednesday. -TAD

&&

.FIRE WEATHER...Updated 200 PM PDT Wednesday, July 9, 2025...
Isolated to  scattered thunderstorms (15 to 30% chance) are expected
to develop this afternoon/evening east of the Cascades, mainly across
Lake and eastern Klamath counties. Strong, gusty outflows are
possible under and in the vicinity of thunderstorms today (generally
30 to 40 mph but up to 55 mph near strong storm). Models show that
any storms will push off to the east or northeast and out of the
forecast area by roughly 9 PM. A Red Flag Warning remains in effect
for fire weather zones 624 and 625 this afternoon and evening due to
abundant lightning potential.

The upper level trough responsible for this latest round of
convection will push off to the east tonight, and high pressure will
build in overhead this weekend. After warm, slightly above normal
temperatures today and Thursday, heat will then return to the region
this weekend into early next week. Meanwhile, expect fairly typical
late-day summertime breezes, but also dry afternoon humidity. Also,
a general easterly/offshore flow is forecast to develop over the
coastal mountains and Siskiyou mountains each night, which may
result in moderate to locally poor RH recoveries, especially over
the ridgetops. This will not be a strong east wind pattern, but will
be sustained for several days.

Looking ahead, some models are suggesting that thunderstorms could
return to the area late next week. -BPN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Extreme Heat Watch from Saturday afternoon through Monday
     evening for ORZ024-026.

     Red Flag Warning until 9 PM PDT this evening for ORZ624-625.

CA...Extreme Heat Watch from Saturday afternoon through Monday
     evening for CAZ080-081.

PACIFIC COASTAL WATERS...Small Craft Advisory from 5 AM to 5 PM PDT
     Thursday for PZZ350-356-370-376.

     Gale Warning from 5 PM Thursday to 11 PM PDT Friday for PZZ356-
     376.

&&

$$

TAD/BPN