Marine Weather and Tide Forecast for Lakeview, OR

FXUS66 KMFR 181035 AFDMFR

Area Forecast Discussion National Weather Service Medford OR 335 AM PDT Thu Jun 18 2026

DISCUSSION
High pressure responsible for the recent heat has moved east of the region, and in it's place, an open/weak trough has developed offshore over the eastern Pacific and will be the main weather influencer through Saturday. The two main impacts from this trough will be high temperatures lowering closer to seasonal normals (though still above normal) and a thunderstorm pattern today through Saturday (more below). 500 mb heights will lower today, which typically indicates somewhat cooler temperatures. At the surface, however, the thermal trough will push inland this morning, resulting in a slight uptick in temperatures (mid-upper 90s West/upper 80s-low 90s East) compared to yesterday's readings. Temperatures trend cooler for Friday and Saturday the weak trough passes through the region. Afternoon highs will still be above normal, but instead of being 15-25 degrees above normal like earlier this week, it'll "cool" to only 5-10 degrees above normal. Saturday will be the "coolest" day of the forecast period as high temperatures start trending upward on Sunday, and even more so early next week.

The upper level trough offshore will bring a few days of thunderstorms to the region, starting today and peaking in terms of activity on Friday. Upper level moisture and instability is evident on satellite imagery this morning with an area of cloud cover lingering over southern OR/northern CA. Satellite derived lightning detection shows some in cloud lightning activity out beyond 130 W.
Guidance indicates moisture and instability will be in the region today, focused mainly along the Sierras and into Siskiyou/Modoc counties, and this is where we expected shower/thunderstorm activity today. There could be some cumulus buildups north of the OR/CA border today, but model guidance maintains the best chances (20-30%)
for thunderstorms is across southern areas.

The upper trough moves closer to the coast Thursday night into Friday (a somewhat faster timing trend in the model guidance), bringing increasing moisture and instability to the region for Friday. Current guidance maintains the best chances (40-60%) in the typical areas, across northern California and east of the Cascades, but there is the potential for as far west as Jackson County (10- 30%, highest for SE areas). With the faster arrival, shower/thunderstorm activity could get going by early afternoon across northern California, with storms moving into south-central OR as the afternoon progresses. Storm motion is more southwesterly, shifting to westerly as the afternoon progresses and mid-level moisture sharply drops off farther west and north. While, this should limit storm activity west of the Cascades and north of the Siskiyous, guidance is showing the potential for shower/thunderstorm activity to move into portions of Jackson/Josephine Counties, highest chances for SE half of Jackson County (10-30% chance).
Adjustments may be needed to the forecast if model trends continue this. 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.

The trough axis moves through the region Friday night, taking the moisture and instability father east for Saturday. It's possible that shower and isolated thunderstorm activity continues across Lake/Modoc Counties Friday night, which could hinder instability for Saturday. Current guidance, however, maintains enough instability to overcome this and shows some lingering thunderstorm chances across Siskiyou County northeastward into northern Modoc/southern Lake Counties. The coolest temperatures of the forecast period are expected Saturday as this trough passes through.

For Sunday through the first half of next week, lingering weak troughing on Sunday transitions to shortwave ridging on Monday, then to southwesterly flow on Tuesday as a weak trough swings through to the north. Temperatures tick upward on Sunday by a few degrees with a more notable warm up on Monday under building heights.
Temperatures could flirt with the triple digit mark (25% chance)
again on Monday and Tuesday for the Rogue Valley. We'll need to monitor model guidance for that trough passing through to the north in the Tuesday/Wednesday timeframe. Some guidance is hinting at the potential for thunderstorms across far eastern areas Tuesday afternoon, but we'll also need to monitor for any potential gust winds/low RH resulting in fire weather concerns that typically accompany a dry frontal/upper level trough passage. Stay tuned for updates.
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