467 FXUS66 KMFR 162317 AFDMFR Area Forecast Discussion National Weather Service Medford OR 417 PM PDT Mon Jun 16 2025 .UPDATE...Updated Aviation Discussion. && .AVIATION...17/00Z TAFs...VFR is expected across inland areas through Tuesday. An few isolated showers or thunderstorm are expected into early this evening over Lake and eastern Siskiyou counties. Along the coast, expect mainly VFR with areas of MVFR and local IFR possible late tonight and early Tuesday morning. There is a 25% chance for MVFR at North Bend. Due to low confidence have kept mention out of the TAF for North Bend (KOTH) but will monitor these conditions. && .PREV DISCUSSION... /Issued 240 PM PDT Mon Jun 16 2025/ DISCUSSION (Today through Sunday)... Overview: While overall impacts remain low for most of this week, we will start to see potential impacts towards the end of this week as an incoming system brings chances for showers/thunderstorms and breezy to gusty winds. At this time, its a little too early to say with much confidence the overall threat of thunderstorms, but its hard to believe this incoming system does not bring thunderstorms to some areas of the Pacific Northwest. The other notable item with this system is the cooler airmass and clouds that will bring below normal temperatures to the area. In fact, this Saturday areas on the westside might not hit 70 for a high, while areas on the eastside might not reach 60 for a high. Essentially, Fri-Sun will be noticeably cooler for this time of year. Friday night and Saturday night could see low temperatures at or slightly below freezing for overnight lows. Further Details: A trough is passing over the forecast area today and this did bring light returns on radar for eastside areas. A few lightning strikes have been detected with one cell in particular showing vertical growth over Lake County as of ~2 PM. We are not expecting too much more activity today as this weak shortwave exits to the east by early this evening. Not expecting any strong storms to form today but very isolated lightning may be possible for a few more hours. We will then transition to a zonal flow pattern aloft with no notable airmass changes anticipated until the next incoming system develops and pushes into the PacNW later this week. By Friday, a broad area of cyclonic flow will slide south from the Gulf of Alaska into the PacNW and will start to usher in a cooler airmass, increased shower activity, and breezy to gusty wind speeds. We could see wind speeds increase as early as Thursday with the strongest sustained speeds expected on Friday/Saturday (15-30 mph). This may warrant a wind advisory at some point Thurs-Sun, especially if gusts of 45+ mph comes to fruition. Thunderstorms are possible Friday through the weekend, but given the increased cloud cover, it may be difficult for destabilization to occur. MUCAPE values are currently progged to be on the lower end of the spectrum (~100-200 J/kg). Lapse rates are not impressive as forecast soundings show an atypical deep moist column (or deeper than normal for this time of year) for some locations that resemble more of a tropical sounding, and this makes sense given the lower-end CAPE values. That said, the dynamics with the system could prove to be enough forcing and could modify the column to some extent. We still have a couple days to really narrow down the details, but at this time we just cannot rule out thunderstorms across the forecast area. Fortunately, with this system and the cooler temperatures, the overnight RH recoveries are going to be great to exceptional starting Friday night for most areas. But the truth is we are currently seeing dry fuels out there, so any thunderstorms could be problematic this weekend. The flip side is we will see cooler temperatures and great overnight recoveries for the most part, so this should help mitigate any fire starts or spread. This system will bring a much cooler airmass than we typical see at the end of June. To put this into perspective, the record minimum high temperature for Medford is 68 degrees on June 21st (this Saturday). This occurred in 2021. We are currently forecasting 67 degrees which is a record certainly within reach this Saturday. However, most--if not all--of our climate sites will have record minimum high temperatures in jeopardy this Saturday. Furthermore, we may want to consider frost/freeze products for some eastside areas as temperatures could be in the lower 30s overnight both Friday and Saturday nights with enough moisture for potential frost formation. With the cooler airmass, forecast energy release component values (fuels) are expected to decrease. For example, some areas that were around the 97th percentile for fuels just a few days ago, are now expected to go down well below normal for this time of year, and in some cases near the minimum at the end of the week. This is good news and it should help mitigate at least some potential for both fire starts and spread this weekend into next week. MARINE...Updated 200 PM Monday, June 16, 2025...Weak disturbances today through Tuesday night will result in lighter winds and lower seas over the marine waters, but with areas of stratus and possibly even some light rain showers or drizzle. North winds will increase again Wednesday, especially south of Cape Blanco, with a period of steep seas possible during the afternoon that could last into Thursday. Another system could bring showers Friday into the weekend. -Spilde/BPN && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. PACIFIC COASTAL WATERS...None. && $$