textproduct: Medford

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.