221 FXUS66 KMFR 190301 AFDMFR Area Forecast Discussion National Weather Service Medford OR 801 PM PDT Mon Oct 18 2021 .UPDATE...The high clouds well ahead of the next front are already beginning to move overhead this evening, while the last vestiges of yesterday's system finally exit the region. The night should be relatively quiet, although by daybreak, winds will begin to increase as the front edges ever so closer. No changes were necessary this evening, with everything on track. For information on the rest of the forecast, see the previous discussion below. -BPN && .AVIATION...19/00Z TAFs...Ceilings are gradually improving as the upper low departs and weak high pressure builds in. Stratus remains persistent at North Bend, portions of the Coquille and Umpqua Basin, but this should gradually burn off with VFR ceilings expected between 21-22z. Elsewhere VFR ceilings re expected through this evening, however the terrain is expected to remain partly obscured until at least 21z Tonight, model soundings are somewhat surprisingly devoid of low- level moisture given recent rainfall. However some recent guidance hints at low stratus with IFR ceilings developing towards daybreak Tuesday in the Coquille, Umpqua Basin, including Roseburg and North Bend which could be a result of a later arrival of mid and high clouds. To lean on the side of caution, decided to introduced the lower conditions for those TAF sites. Confidence is not as high to add the lower conditions at Medford, but we'll have later shifts take another look at this. Skies should clear enough over the East Side this evening to allow for good radiational cooling and the potential for fog development in some of the lower valleys. Even though it's beyond the TAF period, it's worth noting winds aloft will increase at the coast Tuesday morning, and surface winds will increase Tuesday afternoon, with moderate to strong winds possible in the Shasta Valley and Rogue Valley. Gusts in the Shasta Valley could approach 40 kts and 30 kts in the Rogue Valley. -Petrucelli && .MARINE...Updated 800 PM PDT Monday, 18 October 2021...Seas diminish tonight, but southerly winds will increase late tonight and early Tuesday morning ahead of a very strong cold front. Gales are expected Tuesday into Tuesday night with seas becoming very high and very steep and hazardous. Some storm force wind gusts are possible beyond 5 nm from shore at peak intensity Tuesday night. Seas are forecast to peak at 18 to 23 ft on Tuesday night. After this system moves through, seas remain chaotic with southerly fresh swell moving through the waters mixed with a relatively high 10 foot westerly swell. Another storm is expected to move into the waters around the Thursday time period. At this point, the winds are not expected to be as high, although gale force winds are possible later this weekend. -Smith && .PREV DISCUSSION... /Issued 250 PM PDT Mon Oct 18 2021/ DISCUSSION...Satellite imagery depicts a mix of clouds and sun across most areas this afternoon, with more sun east of the Cascades and more clouds west of the Cascades. Quiet conditions will continue through the night. On Tuesday an uncommonly strong October front will approach the forecast area, and south winds will become gusty, in the Shasta Valley first, then the coast, Rogue Valley, and areas east of the Cascades. We've issued Wind Advisories for the Shasta Valley and portions of the Rogue Valley, and portion of the East Side. We're confident these areas will see wind gusts to 45mph. At the coast, there's potential for a band of strong winds to impinge upon the coast, especially if the GFS model solution comes to fruition with low pressure deepening and moving towards the coast. Therefore, we have a High Wind Watch out for portions of the coast, generally from Cape Blanco south to Pistol River, including Gold Beach and Port Orford. Rain reaches the coast Tuesday evening and spreads inland. Due to the strong southerly flow, we expect the coast and Siskiyou County to see the brunt of the precipitation. We lowered snow levels down to around 4300 feet in the Mount Shasta area because of expected heavy precipitation there, but we think any snow impacts will be limited to areas above 5000 feet, based on the early season nature of this system and expected road temperatures. We'll keep an eye on this for any potential winter weather impacts to the Snowmans Summit area on Highway 89. Many valley areas, including the Rogue Valley, will see a lot of downsloping and drying under this wind regime, and rain totals here will be much less than high terrain areas. Conditions will dry out late Wednesday into Thursday morning, though continued moderate southerly wind flow will keep precipitation chances going in the Mount Shasta area. South winds will continue in many areas Thursday, and it's likely we'll have additional wind hazards in places like the Shasta and Rogue Valleys. A deep low well off the coast will be weakening some Thursday, and the trajectory of this low will likely prevent high winds from affecting the coast Thursday, but this another area we'll be monitoring. The moisture with the front that arrives late Thursday into Friday morning has IVT values around 750 near the coast, placing it in the moderate- strong category in terms of how much moisture is being pushed into the forecast area along the front. We've increased forecast rain totals in the Brookings area Thursday evening and overnight to account for this strong onshore wind and high moisture content. Snow levels with this second system will be very high, peaking around 10000 feet before dropping Friday behind the front. The regime will likely shift to westerly-flow type systems over the weekend, and snow levels will begin to lower. Those areas that see little rainfall during the first southerly flow systems will begin to see more precipitation over the weekend and into early next week. There's additional potential for wind impacts too, as some models hint at some deep low pressure development off the coast. In short, the active, wet weather will continue into early next week. Keene && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Wind Advisory from 9 PM Tuesday to 2 PM PDT Wednesday for ORZ030-031. High Wind Watch from Tuesday evening through late Tuesday night for ORZ021-022. Wind Advisory from 5 PM Tuesday to 5 AM PDT Wednesday for ORZ026. CA...Wind Advisory from 9 PM Tuesday to 2 PM PDT Wednesday for CAZ085. Wind Advisory from 11 AM Tuesday to 8 AM PDT Wednesday for CAZ081. Pacific Coastal Waters... Small Craft Advisory from 11 AM to 5 PM PDT Tuesday for PZZ350-356. Small Craft Advisory from 5 AM Wednesday to 5 AM PDT Thursday for PZZ350-356-370-376. Gale Warning from 5 PM Tuesday to 5 AM PDT Wednesday for PZZ350-356. Small Craft Advisory from 3 AM to 11 AM PDT Tuesday for PZZ370-376. Gale Warning from 11 AM Tuesday to 5 AM PDT Wednesday for PZZ370-376. $$