104
FXUS66 KMFR 210954
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
254 AM PDT Tue Jul 21 2026

.KEY MESSAGES...

* Today and Wednesday will be the hottest of the next several days
  with highs generally 5 to 10 degrees above normal (mid 80s to
  mid 90s on the east side and lower 90s to 103 for west side
  valleys). Near or slightly below normal temperatures at the
  coast will reach the 60s.

* Isolated light showers this morning, especially in Modoc/Lake
  counties will give way to isolated thunderstorms this
  afternoon/evening. Highest risk is in the Cascades north of
  Crater Lake, but can occur anywhere from the mountains of
  western Siskiyou County up the Cascades, over to Winter Rim and
  the Warner mountains.

* The highest risk of thunderstorms for the area will be on
  Wednesday (could reach scattered coverage Cascades/Foothills
  eastward), including lesser chances for areas west of the
  Cascades. Some storms will be strong with gusty winds and
  possible hail. Best chance for this is up the Cascades into the
  Douglas County foothills and over to NW Klamath County.

* A drier pattern takes hold late week, but probably with an
  increase in afternoon/evening breezes, especially east of the
  Cascades.

&&

.DISCUSSION...The forecast area remains wedged in between a strong
ridge over the nation`s mid section/Rockies and low pressure off
the California coast (including tropical remnants). Monsoonal
moisture continues to stream northward into the area and is
generating a few light showers from Modoc into Lake County this
morning. This flow pattern hasn`t allowed things to cool off as
readily at night, as evidenced by the daily record highest
minimum set here at Medford yesterday morning (71F). The record
was 68F set in 2023. It`s a little cooler than it was at this time
yesterday morning, but still warmer than usual (70F). We`re still
expecting some high-mid level clouds today. Even so, we should
see at least a thinning of the high cloud cover, so some
instability could generate isolated thunderstorms, mainly near or
just north of Crater Lake in the Cascades and southeastward down
to around the Warners during the afternoon/evening.

Wednesday, stronger southerly flow aloft is expected between the
trough offshore tracking northward (including the remnants of
Tropical Storm Elida) and the persistent ridge over the Great
Basin/Rockies. There is still a modest amount of uncertainty in
the convective forecast (especially with areal extent), but there
is a decent chance of scattered thunderstorm coverage over a
broad portion of our area, to include areas from the Cascades
eastward and also portions of the west side (most likely Douglas
County east of Roseburg, but also the Siskiyous and western
foothills of the Cascades south and east of the Rogue Valley).
Farther south and west, coverage should be more isolated or non-
existent (coast). Storms do look to trend wetter over time with
highest precipitable water values at around 200% of normal
(perhaps near or above 1.50 inches). While a widespread severe
weather outbreak is not likely, a stronger cell or two could
produce strong, gusty winds and hail. This appears most likely
over the Cascades near/north of Crater Lake, the eastern Douglas
Foothills and also NW Klamath County. Generally, any storms that
develop Wednesday will move to the north to northeast, contain
frequent lightning, small hail, and gusty winds, and could produce
periods of heavy rainfall.

The region of greatest instability looks to shift northeastward
out of the area Thursday with a shift to an onshore flow pattern
Friday into this weekend. The result will be a more stable, dry
air mass, but along with enhanced afternoon and evening winds.
This will be the case here in the Rogue Valley, but also
especially for areas east of the Cascade. -Spilde/BPN


&&

.AVIATION...21/12Z TAFs...LIFR will persist at the coast this
morning. Patchy LIFR will then linger north of Cape Blanco through
late afternoon before widespread LIFR returns this evening.

Areas of mid-level and mostly high-level clouds will continue to
produce VFR ceilings over portions of northern California and
southern Oregon today. These clouds could produce a few light
showers or virga, mainly over Modoc and Lake counties, including
Lakeview. By this afternoon and evening, cumulus buildups are
expected with a slight chance of thunderstorms in western and
central Siskiyou County, also north and northeastward along the
Cascades and across much of south central Oregon. There is a slight
chance of wildfire smoke affecting the Medford and Klamath Falls
terminals. -Spilde

&&

.MARINE...Updated 200 AM PDT Tuesday, July 21, 2026...Winds and seas
are expected to remain below advisory levels through at least this
weekend. North winds today switch to southerly Wednesday as the
remnants of Elida move northward offshore. Isolated showers and even
a couple of thunderstorms are possible. Mixed seas with fresh short
period northwest swell and low longer period south swell are
expected through Friday. South winds switch back to northerly this
weekend, but wind wave dominated seas probably hold off until early
next week. -Spilde

&&

.FIRE WEATHER...Updated 230 AM PDT Tuesday, July 21, 2026...A large
upper ridge remains centered over the Great Basin/Rockies and into
the southern Plains, while low pressure is off the California coast.
Southerly flow aloft continues to bring a broad moist plume
northward across much of the West and this is resulting a swaths of
mid-high level clouds across NW Nevada, northern California and into
south-central/SW Oregon. We are seeing another thicker area of
clouds this morning across NE California, and this is bringing some
scattered light showers from Modoc into Lake County at this time.
Isolated showers are also moving up from Trinity County into western
Siskiyou County. Most of these are aloft, but some could reach the
surface, especially over the higher terrain. The cloud cover won`t
be quite as thick (or persistent) as it was yesterday and this
should allow temps today to be near or several degrees higher than
yesterday. As such, the atmosphere should destabilize a bit better
today. By this afternoon and evening, cumulus buildups are expected
with a slight chance of thunderstorms in western and central
Siskiyou County, also north and northeastward along the Cascades and
across much of south central Oregon and also Modoc County in NE Cal.
Coverage of lightning doesn`t appear to be very high (mainly
isolated), so despite the lightning risk, we aren`t planning any red
flag warnings for today.

On Wednesday, there is a greater concern for increased afternoon and
evening thunderstorm coverage. This is due to better instability
expected in advance of moisture arriving in southerly flow aloft at
peak heating along with the potential for better forcing as the
remnants of Elida push northward offshore. We think the greatest
activity in terms of coverage will occur from the Siskiyous and
western slopes of the Cascades (FWZ 621, and eastern 622/617) east
across the Cascades (FWZ623), and then also east of the Cascades in
the typical arc (FWZs 624/625). Isolated storms are also possible
elsewhere across the area, including in northern California and
across the valleys west of the Cascades, though a surge of drier air
aloft does appear to be pushing into NorCal later in the
afternoon/evening (this should keep best activity confined to areas
north of the OR/CA border). Storms that do develop should be moving
at a pretty good clip - in the 20-30 mph range, so while they are
likely to be wetter storms with higher PWs, the faster storm motions
should still raise the risk of lightning-induced fire ignitions. We
have maintained the fire weather watch for this shift, but since
guidance hasn`t changed much, there`s a good chance this will be
upgraded later today.

Later this week (Thursday/Friday), eastward movement in the upper
level pattern is likely, which is likely to shift the region of
instability east of our area with drier SW flow aloft winning out.
As such, lightning risk will diminish to almost nil, but at the
expense of enhanced westerly winds during the afternoons and
evenings east of the Cascades, which could overlap with low
humidity. Any new fire starts would then have the ability to
spread/grow quickly. We`ll continue to monitor this potential and
consider potential wind/low RH headlines.

The dry, diurnally breezy pattern looks to last this weekend and
into early next week. But, temperatures should also lower some
compared to earlier this week. -Spilde/BPN


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Fire Weather Watch from Wednesday morning through Wednesday
     evening for ORZ617-621>625.

CA...PACIFIC COASTAL WATERS...None.

&&

$$

MAS