textproduct: Medford

Updated AVIATION Discussion

AVIATION...17/12Z TAFs

Patchy areas of LIFR conditions are impacting the Coquille Basin as well as along the coast from Brookings southward. Expect improving conditions along the coast later this morning as gusty north winds (strongest north of Cape Blanco -- 25-35 kt) return. Otherwise, VFR conditions will prevail through the TAF period with typical afternoon winds and increasing high level cloud cover

PREV DISCUSSION

/Issued 302 AM PDT Wed Jun 17 2026/

KEY POINTS...

* Temperatures trend somewhat cooler today with a more noticeable cool down Friday into the weekend.

* Elevated fire weather concerns Thursday -- dry and unstable conditions.

* Thunderstorms pattern Thursday - Saturday, with best chances (40- 60%) on Friday. Focus for activity expected over northern California and east of the Cascades.

DISCUSSION...Another quiet morning today. Satellite imagery shows some marine stratus along the coast from Brookings southward and in the Coquille Basin, with clear skies across the rest of the area. Another day of above normal temperatures is expected today, but will be slightly cooler compared to recent days. High pressure responsible for the recent heat will expand eastward today, and settle into the Great Basin region by Thursday. Meanwhile, weak energy will linger off the coast of California which will come into play Thursday through Saturday. After another uptick in temperatures (mid-upper 90s West/upper 80s-low 90s East) on Thursday with the thermal trough shifting inland, temperatures trend cooler for Friday into the weekend as an upper level trough passes through the region. Afternoon highs will still be above normal, but instead of being 15- 25 degrees above normal like recent days, it'll "cool" to only 5-10 degrees above normal.

The upper level pattern shifts on Thursday. That meandering weak energy combines with a few other weak shortwaves passing through in the westerlies and carves out a weak open trough over the eastern Pacific by Thursday afternoon. Temperatures tick upward a few degrees on Thursday under southerly flow, and it's possible we see another triple degree day here in Medford on Thursday. The larger concern however, is the thunderstorm potential that comes with this pattern transition. It's almost a guarantee that heat waves conclude with a thunder threat, and it seems this event is no different. Moisture and instability increase on Thursday, and there are some weak shortwaves passing through, but moisture is pretty marginal on Thursday. It's more likely that there will be some cumulus buildups with a stray shower across northern California.

As the upper level low moves closer to the coast on Friday, the chance of showers and thunderstorms increases. 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). Storm motion is more southwesterly, shifting to westerly as the afternoon progresses and mid-level moisture sharply drops off farther west and north, so this should limit storm activity west of the Cascades and north of the Siskiyous. Storms are likely to be a mix of wet/dry with strong outflows. The trough axis moves through the region Friday night, taking the moisture and instability east of our region for Saturday. It's possible some isolated activity lingers across far eastern Lake/Modoc counties early Saturday afternoon. 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 flat 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 (10% 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.

MARINE...Updated 100 AM PDT Wednesday, June 17, 2026...The thermal trough pattern peaks today, then gradually eases through Friday. North gales will continue south of Cape Blanco today with very steep seas expected as far north as Cape Arago. Winds ease below gales on Thursday as the thermal trough weakens, but steep to very steep seas are likely into Friday. Conditions improve moreso Friday, but steep seas and moderate north winds are likely to persist through the weekend.

FIRE WEATHER...Updated 100 AM PDT Wednesday, June 17, 2026...A weak marine push will bring improving recoveries this morning compared to recent days, but this improvement will be shortlived. The thermal trough will remain along the coast through Wednesday, then push inland on Thursday. This will maintain broad north through east flow across the midslopes/ridges, and poor recoveries are expected again tonight. As the thermal trough shifts inland Thursday, expect another uptick in temperatures across the region. Additionally, this pattern will bring dry and unstable conditions across northern California and east of the Cascades.

Meanwhile, an open trough develops offshore over the eastern Pacific on Thursday, moving inland late Friday 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 on Friday, but could begin as early as Thursday for southern Siskiyou and Modoc counties. Moisture remains fairly marginal for Thursday, but instability is present. Could just be some cumulus buildups with a stray shower or even an isolated thunderstorm in the afternoon.

As the upper level low moves closer to the coast on Friday, the chance of showers and thunderstorms increases. 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). Storm motion is more southwesterly, shifting to westerly as the afternoon progresses and mid-level moisture sharply drops off farther west and north, so this should limit storm activity west of the Cascades and north of the Siskiyous. Storms are likely to be a mix of wet/dry with strong outflows. By Saturday, the best moisture/instability shifts east, leaving some lingering chances along/east of the Warners/Winter Ridge.

MFR WATCHES/WARNINGS/ADVISORIES

OR...CA...None.

PACIFIC COASTAL WATERS...Gale Warning until 8 PM PDT Thursday for PZZ356-376.

Small Craft Advisory until 8 PM PDT Thursday for PZZ350-370.

Hazardous Seas Warning until 8 PM PDT Thursday for PZZ350-370.