279 FXUS66 KMFR 110109 AFDMFR Area Forecast Discussion National Weather Service Medford OR 605 PM PDT Wed Oct 10 2018 .Aviation discussion updated. .DISCUSSION...Current satellite imagery is showing the clouds east of the Cascades finally starting to break up with the marine layer also breaking up. This is due to an area of high pressure building into our area, bringing an extended period of dry weather. A piece of the front that moved through a couple of days ago will split off and move southwestward toward southern California, generating one of the more common blocking patterns, known as an omega block. This will ultimately prevent weather systems from reaching the West Coast and will likely take quite a while to break down. In fact, we expect ridging aloft to stick around right through next week. This will bring a transition from northerly flow to a dry east or northeasterly continental flow resulting in a significant drying of the air mass across SW Oregon and northern California along with a warm-up. Tonight, with fewer clouds expected, typically colder spots in the valleys west of the Cascades will have lows in the lower to mid 30s. We're not expecting frost right here in Medford, but some areas of the Rogue Valley, like near Lake Creek, and also in portions of the Applegate/Illinois Valleys (Ruch, Cave Junction) will, so we have are continuing the frost advisory from 200-900 AM PDT. We are expecting things to become even colder tomorrow night, so we have expanded the frost advisory for tomorrow and issued a freeze watch for portions of the Applegate and Illinois valleys. Expect periods of stronger east winds over the ridges, especially west of the Cascades throughout the remainder of the forecast period. This will bring ridgetop drying with moderate to, at times, poor overnight humidity recoveries and general low minimum afternoon relative humidity. That being said, we are not expecting the coastal range to critical conditions. Chilly mornings will continue inland, but afternoon temperatures will be comfortably warm. Southwest coastal areas near Brookings will also have some abnormally warm days with highs in the upper 70s and 80s. Models are showing a disturbance and associated cold front grazing east side areas this weekend. This could bring a slight uptick in winds Saturday and potentially some cooling over there into Sunday, but most other areas won't even notice a change. -Schaaf/Spilde && .AVIATION...For the 11/00Z TAFs...VFR conditions are being observed in most places now, and this should continue through early evening. The marine layer should push back in tonight, and IFR to LIFR conditions are expected once again for the coast as well as for the Umpqua Basin. Otherwise, VFR is expected overnight into tomorrow. -Schaaf/Keene && .MARINE...Updated 245 PM PDT Wednesday 10 October 2018...A thermal trough near the coast will result in gusty north winds and steep choppy seas to the waters south of Cape Blanco through late this week. Steep seas will also affect areas north of Cape Blanco. North winds and seas will likely reach a peak late Friday afternoon into Friday evening. Additionally, long period southerly swell will build tonight, then persist at a peak Thursday into Friday. This may bring rough bar conditions at Brookings and elevated surf at Port Orford. On Sunday, expect the region of strongest northerly winds to shift to the outer waters north of Cape Blanco with seas gradually lowering into Tuesday. -DW && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Frost Advisory from 2 AM to 9 AM PDT Thursday for ORZ024-026. Frost Advisory from 2 AM to 8 AM PDT Friday for ORZ024-026. Freeze Watch from late Thursday night through Friday morning for ORZ024-026. CA...None. Pacific Coastal Waters...Small Craft Advisory until 11 PM PDT Saturday for PZZ356-376. Small Craft Advisory until 11 PM PDT this evening for PZZ350-370. Small Craft Advisory from 2 PM Friday to 11 PM PDT Saturday for PZZ350. Small Craft Advisory from 11 AM Thursday to 11 PM PDT Saturday for PZZ370. $$