219 FXUS66 KMFR 052323 AFDMFR Area Forecast Discussion National Weather Service Medford OR 423 PM PDT Sat Jul 5 2025 ...Updated AVIATION discussion for 00Z TAFs... .SYNOPSIS... An upper level low will bring a chance for thunderstorms across our forecast area between Monday and Wednesday. Temperatures will then trend warmer towards the end of the week. .DISCUSSION... Plenty of cumulus buildup east of the Cascades and along the Cascades this afternoon as there is still some lingering moisture and weak synoptic lift across the region. The weather will remain fairly quiet tonight as some cooler temperatures in the mid 50`s settle into most locations overnight. By Sunday, A cutoff low will settle right along the central California coastline by mid day. Temperatures trend a bit warmer with highs in the mid 90`s here in Medford. Brookings should be on the warmer side as well with 10 to 15 knot north east winds over the southern Coastal range. That will result in highs between the mid 70`s to perhaps mid 80`s over spots in Curry County. We should see more cumulus buildup during the day, although we`re not expecting any thunderstorms at this time. This will change by Monday as a small chunk(~30%) of ECMWF ENS members are predicting some precipitation, which should come in the form of thunderstorms given the pattern and surface temperatures anticipated Monday. The NAMnest and NAM soundings show about 400 j/kg of convective available potential energy(CAPE) with little convective inhibition(CIN). Some of these storms could be elevated and again hedge towards the dry side. Storms are anticipated to be isolated. The upper level low nudges just a bit farther north giving us some pretty good upper level divergence on Tuesday afternoon. The environment shouldn`t change much frankly and the ECMWF ENS members are again picking up on thunderstorms a little farther north on Tuesday in our Oregon zones. Again, it`s looking more isolated on Tuesday. Finally by Wednesday, the upper level low begins to move eastwards and we should see some more thunderstorms around the region. Locations in northern California and east of the Cascades will see thunderstorm activity during the day yet again. Essentially, we should see some cloud to ground lightning somewhere in out forecast area between Monday through Wednesday. After the low finally departs the region, Temperatures will likely warm towards the 100`s on Friday and Saturday. It will be a warm period and there are hints a thermal trough could build over us during next weekend, which usually leads us to some hot, dry and unstable weather. -Smith && .AVIATION...06/00Z TAFs...VFR levels persist across northern California and southern Oregon this afternoon and evening. Cumulus clouds are developing over area terrain, but these pose no threat. Marine stratus looks to return to the Oregon coast tonight, with IFR or LIFR levels possible. This layer looks to clear on Sunday morning, with gusty winds developing along the coast just before the afternoon. Inland areas will remain under VFR levels with normal diurnal winds. -TAD && .MARINE...Updated 200 PM PDT Saturday, July 5, 2025... Winds will continue to increase into this evening as the thermal trough rebuilds. Winds and seas will be hazardous to smaller crafts south of Cape Blanco this evening. These hazardous conditions will then expand northward with steep seas across the waters by Sunday evening. However, gales are anticipated south of Port Orford by Sunday evening through Monday. Conditions improve slightly by Monday evening. -Smith && .FIRE WEATHER...Updated 200 PM PDT Saturday, July 5, 2025...An upper ridge will continue to move in over the area the remainder of this weekend. This will bring dry, stable conditions the rest of today and through Sunday with temperatures getting back above normal levels. A few fair-weather cumulus are out there this afternoon, but no thunderstorms. On Sunday, there can be a few buildups over the SE mountains (Warners) during the afternoon/evening, but there doesn`t appear to be enough instability/moisture to produce deep convection. As such we`ve kept thunder out of the forecast. Otherwise, the forecast will be for continued near to slightly above normal temperatures, seasonal humidities, and the typical diurnal wind patterns, although general east flow late this weekend into early next week leading to drying, especially across the ridgelines, where poor to moderate recoveries are possible. Heat builds further Monday and Tuesday with high temperatures in the mid to upper 90s and even some readings in the West Side/NorCal valleys exceeding 100F. Low pressure will then develop off the California Coast setting up just west of SF Bay Sunday night into Monday. This is a similar set up to the pattern that brought convection to the area for several days this past (last) week. One difference though is that the deep southerly flow of moisture available during the last event appears to be less with this one and, as such, a limiting factor for convection. That said, latest guidance continues to show at least a slight chance (15 to <25%) of thunderstorms each pm/eve beginning Monday and continuing through Wednesday. NorCal seems to be favored, but also portions of the Cascades and East Side. It should be noted that model PWs with this potential convection are around 0.50-0.75" (esp southern and eastern areas, where values could be below 0.50" at times), so any high-based convection that does develop might not produce any rainfall. We`ll continue to monitor the guidance to hone in on lightning potential and areas that stand the best chance over the coming days. The low will get a kick onshore Wednesday and move through NorCal and into NW Nevada during the afternoon/evening. Still could be activity in NorCal and east of the Cascades then, but do expect drier westerly flow to move in Wednesday night and the thunder risk to end. Expect slight cooling Wed/Thu, but a return of hotter weather again by Friday. There also could be a period of weak offshore E winds Wednesday night through Friday morning. -Spilde && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory from 11 PM this evening to 8 AM PDT Monday for PZZ350-370. Small Craft Advisory until 8 AM PDT Monday for PZZ356-376. Gale Watch from Sunday morning through Monday morning for PZZ356- 376. && $$