textproduct: Medford

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.