943 FXUS66 KMFR 260322 AFDMFR Area Forecast Discussion National Weather Service Medford OR 822 PM PDT Fri Jul 25 2025 .DISCUSSION...Tonight`s radar was still active with thunderstorms mainly in Northern California. There have been reports of small hail in a couple of these storms so far, although more of the storms fell onto more secluded areas. There are a few cells to still track tonight, namely near Weed and Tennant. These could still bring gusty winds, small hail and lightning. Outflows will also need to be monitored as they have been forming new cells behind. Tomorrow`s rain chances will focus on central to eastern Siskiyou and Modoc counties, as well as eastern Lake County. -Hermansen && .MARINE...Updated 800 PM PDT Friday, July 25, 2025...Sub-advisory north winds and low seas of 5 ft or less, will persist through the weekend into early next week. Of note, winds will briefly approach small craft advisory levels through this evening, between Port Orford and Gold Beach, 2 to 20 nm from shore. Winds then lower overnight. Areas of fog and low stratus will also persist through this time. Winds and seas may trend slightly higher around Tuesday of next week. && .PREV DISCUSSION... /Issued 521 PM PDT Fri Jul 25 2025/ UPDATE...Updated Aviation Discussion. AVIATION...26/11Z TAFs...IFR along the coast will become widespread this evening and persist through Saturday morning. Areas of MVFR may spread into the northwest Umpqua Basin early Saturday morning, mainly near and north of Roseburg. Then expect clearing to VFR in the Umpqua and along the coast late Saturday morning and early Saturday afternoon. However, local MVFR may persist into the afternoon along the coast. Elsewhere over inland areas, VFR prevails but scattered thunderstorms are developing again this afternoon/evening, mainly impacting Siskiyou, MOdoc, Lake and southeast Klamath counties. These could locally and temporarily reduce visibility/ceilings to IFR/MVFR. Any thunderstorms will have the ability to produce cloud to ground lightning, strong, gusty outflow wind gusts of 40-60 mph, brief, heavy rain and small hail. PREV DISCUSSION... /Issued 145 PM PDT Fri Jul 25 2025/ DISCUSSION...The first cells of the day are showing up on radar/satellite early this afternoon. One formed directly atop Mt. Shasta with others developing in the Trinity Alps, Medicine Lake region and also parts of Lassen/northern Washoe counties. The expectation for the rest of this afternoon and evening is another round of widespread lightning across NorCal and into portions of south-central Oregon (east of the Cascades). Activity will be in the same general areas that it occurred yesterday, with a slight shift in the main focus area off to the south and east. Generally if you draw a line from Happy Camp to Klamath Falls to Summer Lake, locations north and west of there should miss out on the thunderstorms all together. Hi-res models are showing the bullseye of highest lightning probability (>80%) across portions of southeastern Siskiyou and into Modoc County. Storms today will be slow-movers, with mid-level steering flow of only around 5-15kt (very similar to yesterday). So, they should have the ability to produce brief, heavy rainfall. WPC shows marginal risk for excessive rainfall, which, if cells train over a spot for more than an hour, could lead to urban and small stream flooding with a low chance (5-14%) of flash flooding. This seems most likely for storms in southern Siskiyou County, but also western Modoc where PWATs are in some cases greater than 1.00". Farther east, inverted-V profiles over the far east side indicate higher-based storms (bases of 10-12K ft) with model DCAPE (downdraft CAPE) of more than 1000 J/KG. This is a good indicator of strong, gusty outflow winds. Notably, the SPC has beefed up the severe thunderstorm risk to marginal for this afternoon/evening in SE portions of the area (Modoc), where isolated severe wind gusts (5-14% chance) are possible. Of course, gusty winds really can occur with any storm. Much like yesterday, storms that build and maintain their cores should also be able to produce at least pea to marble size hail. Strongest cells could bring hail stones up to 1.00" in diameter. Activity will once again wane after sunset and probably end sometime between 10 and 11 pm. Marine layer stratus has broken up and is mostly offshore north of Cape Blanco early this afternoon, but it persists south of Pistol River. A coastal eddy can be seen in visible satellite imagery off Crescent City. Expect mainly sunny skies west of the Cascades through very early this evening, then stratus/fog will push back onshore. Models are showing a bit deeper marine layer tonight, so stratus should push a bit farther into the Umpqua Basin and could end up closer to or even to Roseburg for a few hours Saturday morning. The rest of the area inland from the coast and west of the Cascades will remain clear tonight. While Saturday won`t be quite as active as it was yesterday and will be today, the area won`t be devoid of thunderstorms. Models show a bit more of a drier WSW flow aloft as an upper trough approaches the PacNW coast. This will, once again, shift the axis of activity a bit farther to the south and east. But, there still can be isolated thunderstorms from around the Trinity Alps ENE across eastern Siskiyou into Modoc and southern Lake counties Saturday afternoon/evening. High temperatures will be fairly typical for late July, mostly in the 80s and low 90s for west side valleys, and generally 80-85F over the East Side. Model guidance indicates a relative drop in thunderstorm potential on Sunday/Monday (at least compared to today/yesterday). But, chances don`t go away completely. It appears there`s just enough moisture, instability and upper forcing for isolated storms. We`ve actually added slight chances (15-24%) into the forecast for both afternoons/evenings. While confidence in exactly where storms will be is on the low side, areas that stand the best chance continue to be in the mountains of western Siskiyou County, but also from the Warner Mtns of Modoc County up into south- central Oregon from around Crater Lake eastward. A more potent upper trough/disturbance is then forecast to approach the central CA coast again by Tuesday taking on a negative tilt as it heads toward the Great Basin at midweek. Model probabilities of showers and thunderstorms increase across a larger portion of the area then along with some potential for west side storms. Tuesday/Wednesday looks like the best chance for that to happen. We`ll continue to hone in on this as we get closer. There`s still plenty of uncertainty with how quickly this trough arrives. -Spilde FIRE WEATHER...Updated 100 PM PDT Friday, July 25, 2025...The main fire weather concern for the next week will be thunderstorms. Temperatures, humidities, and breezy afternoon winds will all remain near seasonable levels. Scattered to numerous thunderstorms this afternoon/evening are expected to resemble those of yesterday in strength, and in where they occur. Abundant lightning with some strong to severe storms is expected, especially in northern California. These will be wet, slow moving storms with the region of scattered storms extending into southeast Klamath and southern Lake counties. Though a step down or two in the level of risk of thunderstorms, additional isolated to scattered storms are expected each day Saturday through Tuesday. This includes a focus for storms on Saturday from eastern Siskiyou into Modoc and southern Lake counties. On Sunday, a lesser risk over a broader area will bring a 10-20% probability from near the Scott Valley in Siskiyou County extending across the Shasta Valley into Klamath, Lake, and also Modoc counties. Although activity still looks to be isolated yet again. Forecast confidence drops down a notch on Monday, with uncertainty in the location of the next shortwave trough embedded in the flow between a broad trough in the Gulf of Alaska and ridging over the Rockies. The highest probability remains from northern portions of Klamath and Lake counties into central and eastern Oregon. The 12Z GFS has trended faster in swinging yet another trough into central California on Tuesday which could lead to a larger scale event, but for now we will follow the NBM with a broad brush slight chance southward and eastward from the Cascades and Siskiyou Mountains. The complexity of the pattern and model differences increase at mid- week with a trough dominated pattern likely to continue to result in late day instability. -DW && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning until 11 PM PDT this evening for ORZ624-625. CA...Red Flag Warning until 11 PM PDT this evening for CAZ280>282-284- 285. PACIFIC COASTAL WATERS...None. && $$