764 FXUS66 KMFR 102339 AFDMFR Area Forecast Discussion National Weather Service Medford OR 439 PM PDT Tue Jun 10 2025 .UPDATE...Updated Aviation Discussion. && .AVIATION...11/00Z TAFs...Along the coast, IFR/LIFR expected to return by early this evening and continue through Wednesday morning. Conditions will clear to VFR in the early afternoon Wednesday. Inland, conditions are VFR except near isolated to scattered thunderstorms this afternoon and evening. These storms will develop south of the Umpqua Divide and from the Cascades east in southwest Oregon and across Siskiyou and Modoc counties in northern California. Heavy rain from thunderstorm cores could briefly lower visibilities to MVFR, but the main hazards with these storms will be strong and erratic outflow thunderstorm winds and lightning. Hail is also possible and there is a 5% chance of large damaging hail of 1 inch or more diameter, and strong winds of 60 mph, including for Medford (KMFR), Klamath Falls (KLMT), Montague (KSIY), and Lakeview (KLKV). The probability of strong/severe thunderstorms, and storm coverage will diminish late this evening, but thunderstorm chances (15-30%) will persist tonight into early Wednesday morning for Klamath, Lake, northeast Siskiyou, and northern Modoc counties. && .PREV DISCUSSION... /Issued 153 PM PDT Tue Jun 10 2025/ DISCUSSION (Today through Monday)... Overview: Main item of interest for this forecast is today`s severe thunderstorm possibility. The main threats today are lightning and strong wind gusts (50-65mph), but a couple isolated storms could produce hail around 1.00". Otherwise, the forecast is seasonable with warm temperatures and dry conditions forecast beyond today. Will need to monitor fuels this dry stretch. We have seen some increased drying lately in the fuels across the forecast area, and this next stretch of dry weather will only further dry fuels making them more receptive to fire starts. Further Details: The H5 disturbance we are tracking for today`s severe weather threat is well off the coast over the Pacific around 130W and 40N as of writing this. The PVA associated with this small embedded shortwave within the westerly flow is not going to phase well with other variables, but the timing will be conducive for thunderstorms. Some of these thunderstorms could be severe. If this shortwave was about 6 hours earlier, we would likely be looking at a higher risk of severe weather today/tonight. DCAPE values are very high today given the inverted-v forecast soundings, and in some cases approaching 2000 J/kg. This amount of DCAPE can easily produce a severe wind gusts if a updraft can maintain long enough. The fact the shortwave will not phase well today, and shear values are on the lower end of the spectrum, updrafts may struggle to maintain today. However, there is no reason to believe we wont see at least a couple strong to severe thunderstorms this afternoon and early evening. MUCAPE values are around 500 to upwards near 1000 J/kg with bulk shear (0- 6km) around 25-30 knots. This is plenty to work with today as we hit convective temperatures. This means timing of severe thunderstorms will likely be associated with peak heating. That said, we are seeing returns on radar as of writing this, so convective initiation has occured for some eastside areas where convective temperatures are lower than other areas. Lastly, since the shortwave is late to arrive over the forecast area, this does open the door for overnight convective, mainly on the eastside where upper level divergence will be associated with this wave. Convective allowing models are showing some consistency with convection around 10Z-14Z for areas mainly in Klamath and Lake counties. Its tough to say how much the atmosphere will be "worked over" from this afternoon/early evening convection. In other words, there is at least a chance (30%-40%) for a couple thunderstorms to develop, and these could be strong to perhaps severe overnight into early morning on Wednesday. Beyond today, weather impacts are very limited as we experience dry and seasonable temperatures. Some of the warmer days may be in the mid to upper 80s for our "warmer" areas, but really temperatures are very close to normal for this time of year. There are a couple breezy afternoons in the forecast, but not seeing any need for wind hazard headlines at this time. The bigger impact through this stretch of dry weather will be the fact energy release component values (fuels) are only going to further dry and become more receptive to fire starts. -Guerrero MARINE...Updated 130 PM Tuesday, June 10, 2025...High pressure offshore and low pressure inland are expected to persist into the weekend. Breezy north winds will persist this week, hovering at or just below advisory criteria. The strongest winds and steepest seas are expected south of Port Orford to around Pistol River and out 30 nm from shore, with the highest seas expected today into tonight. Seas will remain dominated by a mix of northerly wind wave and fresh swell, with steep seas across all areas through Wednesday evening, then south of Port Orford at least through Thursday evening. -DW/BR-y && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT Thursday for PZZ356-376. Small Craft Advisory until 11 PM PDT Wednesday for PZZ350-370. && $$