035
FXUS66 KMFR 090543
AFDMFR
Area Forecast Discussion
National Weather Service Medford OR
1043 PM PDT Tue Jul 8 2025
.Updated AVIATION Discussion...
&&
.AVIATION...09/06Z TAFs...LIFR conditions have returned to the coast
and over the coastal waters and will persist into Wednesday morning.
As low pressure moves inland late tonight into early Wednesday, the
marine layer will deepen and push into portions of the Umpqua Basin.
Stratus looks more likely to reach Roseburg tonight, with MVFR
conditions likely. These lower conditions will improve later
Wednesday morning with LIFR/IFR conditions along the coast improving
to IFR/MVFR, and VFR returning to the Umpqua Basin. Ceilings will
likely persist into the afternoon hours and beyond for the coast.
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 Wednesday afternoon
and another round of thunderstorms is expected across central
Klamath/Lake Counties. /BR-y
&&
.PREV DISCUSSION... /Issued 851 PM PDT Tue Jul 8 2025/
DISCUSSION...An update was sent earlier this evening to cancel
this evening's Red Flag Warning over the East Side. Thunderstorms
that materialized across northern Klamath and Lake counties pushed
north and out of the area. No further thunderstorms are expected
there. Made some adjustments to the marine layer and added fog to
coastal waters and some interior coastal zones. Also, added smoke
to the forecast due to the numerous wildfires burning in the
area. -Spilde
From this afternoon's discussion, tonight, there will be a 5-10%
chance for another isolated storm in portions of western Siskiyou
and southern Jackson and Josephine counties. Surface CAPEs are
forecast to remain at 100-250 J/kg, so this would be enough to
keep the potential going later into the night. However, forecast
soundings in the area are showing drier air in the lower
atmosphere, so these would be dry thunderstorms overnight.
Tomorrow an upper low near San Francisco will be moving towards
Southern Oregon, and this will bring breezier conditions in the
afternoon, especially east side. With this upper low there will also
be near normal temperatures the next two days.
The last thunderstorm chance of this string comes tomorrow and will
be concentrated in central and southern Lake County and eastern
Klamath County. Forecast CAPE values in this region will be near 250-
350 J/kg.
In the long term, ridging will start to build into the weekend,
and this will bring a return of heat to the area. There is
currently a 50-70% probability to see 100 degrees in Medford from
Friday through early next week. For now, dry conditions are
forecast during that time frame. -Hermansen
MARINE...Updated 830 PM PDT Tuesday, July 8, 2025...The thermal
trough pattern will be disrupted through Wednesday as an upper
level trough passes through the region. This will result in
relatively calm conditions through then, along with areas of
reduced visibilities due to marine layer fog/stratus. The thermal
trough redevelops Wednesday night into Thursday, and is likely to
persist through the weekend. Gusty north winds will strengthen on
Thursday, resulting in the return of steep seas south of Cape
Blanco by Thursday morning. Steep seas will likely expand north of
Cape Blanco late Thursday into Friday, with very steep seas and
possible gales south of Cape Blanco over the weekend. /BR-y
FIRE WEATHER...Cancelled the Red Flag Warning for this evening
since thunderstorms earlier across northern Klamath and Lake
counties have weakened and moved to the north.
Overnight, as the upper low moves into northwest California,
models are indicating an elevated unstable layer with marginal
moisture for thunderstorms to develop. This will bring a low
chance (5-10%) for overnight/early morning thunderstorms into
western Siskiyou County and the Siskiyou mountains. Given the weak
moisture signal, confidence is low in storms developing. We will
continue to monitor this.
By Wednesday, the low will move inland across northern California.
This will maintain a slight chance to chance of thunderstorms across
eastern portions of the forecast area, including eastern Klamath,
Lake and northern Modoc counties. Models are continuing to highlight
eastern Klamath and Lake counties as well as areas to the east as
having the best chance (15-20%) for thunderstorms. Additionally,
with elevated bases and relatively low precipitable water values,
these storms may be on the dry side. We have upgraded the Fire
Weather Watch to a Red Flag Warning for eastern portion of FWZ 624
and FWZ 625 (2-9 pm PDT) for abundant lightning on dry fuels. The
trough axis pushes east of the area fairly quickly Wednesday evening
and convection is expected to diminish after 9pm.
Following the trough passage, drier westerly flow aloft moves in
Wednesday night and the thunder risk ends. Expect slight cooling
Wed/Thu over inland areas, but northeast winds provide warmer
weather to the south coast by Thursday. A return of hotter weather
is expected Friday into the weekend with fairly typical late-day
summertime breezes, but also dry afternoon humidity. Offshore
northeast flow over the coastal mountains and Siskiyou mountains may
result in moderate to locally poor RH recovery at night.
-CC/Spilde
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning from 2 PM to 9 PM PDT Wednesday for ORZ624-625.
CA...None.
PACIFIC COASTAL WATERS...Small Craft Advisory from 5 AM to 5 PM PDT
Thursday for PZZ356-376.
&&
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