037
FXUS66 KMFR 191750
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1050 AM PDT Fri Jun 19 2026

.DISCUSSION...
Key Points:

* Thunderstorm chances begin in Siskiyou County later this morning
  and move north to Lake and Klamath counties in the afternoon.
* Temperatures will remain near to slightly above normal through the
  weekend.
* Ridging takes control early next week, with 90s/low 100s forecast
  Monday and Tuesday.

Satellite shows marine stratus along Southern Oregon coast this
morning, with clear skies elsewhere. However, it will still be
warmer this morning with lows in the 50s in most locations. This
afternoon will still be warm with 60s at the coast, 90s west of the
Cascades and 80s east. However, some locations will feel more of the
moisture as it comes in from the south today.

An upper low will reach the coast and move inland today, bringing
rain and thunderstorm chances. CAMs forecast the activity to move
north from Shasta and Lassen counties by late this morning. Forecast
soundings show that during peak heating more energy will be found in
southern Siskiyou County this afternoon. Paintball ensembles also
favor cells with >40 dBZ in western Siskiyou County and northern
Lake County today. The activity is forecast to wind down in the
evening, however late night showers and a few thunderstorms are
possible east of the Cascades tonight. Rainfall is forecast to reach
0.05"-0.15" in these areas through tonight. However, if storm
movement is slower, there will be locally heavier amounts.

As the low moves eastward Saturday, a shortwave will bring energy to
the area. Forecast models are supporting a few cells in southern
Lake and Klamath counties and portions of Siskiyou County in the
afternoon. This will be less coverage than today`s activity, and
there will be a drier trend after. For other spots, there will be a
slight cooldown with 80s in west side valleys and mid-70s/low 80s
east.

&&

.LONG TERM...The flow pattern becomes more zonal for the start of
next week as temperatures begin to warm. A thermal trough will
likely develop west of the Cascades by Sunday night into Monday
and persist into Tuesday. High temperatures in Medford will
approach the 100 degree mark on both Monday and Tuesday. Heat risk
becomes elevated/moderate during these days as low temperatures
cool into the lower 60`s. As a reminder, moderate heat risk
affects those who are sensitive to heat, especially those without
cooling.

On a side note, the extreme forecast index(EFI) is showing values
around 0.7-0.85 for maximum temperatures through Thursday west of
the Cascades. These values suggest the ensembles are forecasting
unusually warm temperatures for this time of year, yet by no
means extreme. Conditions will begin to cool down by Thursday and
Friday. -CZS


&&

.AVIATION...19/18Z TAFs...To start the TAF period, a line of
thunderstorms is present from the Trinity Horn area in Sikiyou
County to the northeast into southern Lake County. This line
represents the leading edge of atmospheric instability rather than
any sort of organized activity. Lightning activity has been present
along this line, which is moving northward across eastern Siskiyou
County and areas east of the Cascades. This may bring thunderstorms
into the vicinity of Klamath Falls by this afternoon. While
indications of severe activity are absent, these thunderstorms can
still put out gusty and erratic winds and localized moderate to
heavy rainfall in addition to lightning. Radar indicates rain
showers continuing behind this line, with little to no lightning
observed.

Thunderstorms may continue in northern California as well as east of
the Cascades into the evening. Activity looks unlikely for inland
areas west of the Cascades, where VFR levels are expected to
continue through the TAF period.

Current LIFR levels along the coast may improve to IFR through the
TAF period, which may include improving visibilities as well as
rising ceilings. Stratus may start to break up south of Cape Blanco
early Saturday morning, with areas to the north possibly seeing
clearing just beyond this forecast period. -TAD

&&

.MARINE...Updated 300 AM PDT Friday, June 19, 2026...Winds are
diminishing this morning. Fresh swell dominated seas and weak winds
will result in steep seas in the outer waters through Saturday
afternoon.

On Saturday afternoon, a thermal trough pattern starts to
develop, bringing gusty northerly winds south of Cape Blanco. Steep
seas are likely to move into the inner waters south of Cape Blanco
on Saturday evening. Very steep and hazardous seas may be present
south of Gold Beach by Sunday afternoon. Long-term guidance suggests
the thermal trough will stay in place next week, with an increase
winds for Tuesday into Thursday (including gales possible south of
Gold Beach).

&&

.FIRE WEATHER...Updated 300 AM PDT Friday, June 19, 2026...An open
trough is developing offshore over the eastern Pacific today, moving
inland later today and east of the region on Saturday. This pattern
sets up the potential for thunderstorms during this time frame,
focused across northern California and east of the Cascades.

Chances for thunderstorms are highest today. This activity is
forecast to be focused on southern Siskiyou and northern Lake
counties. There is the potential for as far west as Jackson County
(10-30%, highest for SE areas). Storm motion is more southwesterly,
shifting to westerly as the afternoon progresses and mid-level
moisture sharply drops off farther west and north. Overall, storms
are likely to be a mix of wet/dry with strong outflows (30-40 mph),
lightning and small hail being the main threats. A Fire Weather
Warning is in effect for abundant lightning on dry fuels for this
afternoon/evening, including fire weather zones (FWZs)
280/281/284/285/624/625.

By Saturday, the best moisture/instability shifts east, leaving some
lingering chances along/east of the Warners/Winter Ridge, as well as
portions of Siskiyou County from the Trinity Alps to the Medicine
Lake area. Then, ridging builds and more typical 10-15% minRH values
will be seen in the afternoons east of the Cascades and in west side
valleys. There is a note to make that light northeast/easterly
winds are forecast Monday afternoon for portions of Lake County.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning from 8 AM this morning to 7 PM PDT this evening
     for ORZ621.

     Red Flag Warning from 1 PM this afternoon to 1 AM PDT Saturday
     for ORZ624-625.

CA...Red Flag Warning from 8 AM this morning to 7 PM PDT this evening
     for CAZ280-281-284-285.

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 PM PDT Saturday
     for PZZ370-376.

&&

$$