030 FXUS66 KMFR 280957 AFDMFR Area Forecast Discussion National Weather Service Medford OR 257 AM PDT Sun Apr 28 2024 .DISCUSSION...Satellite imagery this morning shows some scattered cloud cover west of the Cascades with some cirrus streaming over the region. Radar shows some light showers along the coast, into the Umpqua Basin, along the Cascades north of Lake of the Woods and into the Douglas County Foothills. These showers are generally light with only a few hundreths being reported at observation sites. Onshore flow will maintain a 30-60% chance of showers north and west of the Umpqua Divide today, with PoPs diminishing quickly south and east of there. It looks like a mainly dry, at least partly sunny day elsewhere (including here in the Rogue Valley) with gusty breezes (25-35 mph) developing in the afternoon. An upper trough will swing through Monday morning and this will bring a shot of showers (60-90% chance) to the coast eastward to the Cascades. We can't rule out a shower or two around the Rogue Valley/Medford area Monday, but most of the time should be rain free. Snow levels will drop to as low as 3000 feet by Monday morning, but any snow accumulations will be confined to the mountains generally above 4500 feet. Highest amounts will be from about Crater Lake northward, where 2-5" could accumulate. Up to an inch of snow is possible over Highway 140 near Lake of the Woods with a skiff also possible on parts of Highway 97 north of Chiloquin. So, if traveling early Monday morning, be aware of the potential for some slick spots in those areas. South of the OR/CA border, we don't think much precipitation will make it over the mountains and it will just be partly cloudy. As such, it'll be cold first thing Monday morning with some frost in the lower Klamath, Scott and Shasta valleys. This system exits to the east Monday evening, so shower chances diminish, but it will be followed by another upper disturbance that will swing through northern Oregon Tuesday and into Idaho Tuesday night into Wednesday. Once again, we'll be on the southern fringes of this system, so PoPs (for showers) remain highest across the north, lowest across the south. Snow levels bottom out near 2500 feet Tuesday morning, but again most, if not all, snow accumulation will be in the mountains north of Crater Lake. Overall, temperatures will remain near to below normal. Frost/freezing conditions west of the Cascades are becoming more likely given the main area of precip potential is north of the Umpqua Divide. Frost (lows 33-36F) chances (50-80% chance) are highest for a few hours in the typically colder locations (Illinois/Applegate Valley/Grants Pass areas) both Tue/Wed mornings. Freezing conditions (<=32F) are possible (20-30% chance) in the Illinois Valley as well, but much will depend on how much cloud cover lingers during the overnight hours. Clearing looks more widespread Tuesday night/Wednesday morning, providing a better chance for frost/freeze for the Illinois/Applegate Valley and Grants Pass areas. As the upper trough shifts to the east, things dry out on Wednesday with some sunshine and a slightly milder afternoon (high temps back closer to seasonal normals). Models maintain some degree of uncertainty after Wednesday with NBM still showing some PoPs (20- 30%) across NW portions of the CWA. This stems from a smaller percentage of model members (GEFS/Canadian and to an even lesser extent ECENS) showing a flat upper ridge and a weak trough, you guessed it, skimming over the top Wednesday night into Thursday. More plausible scenarios feature a bit stronger ridge and no precip along with a more significant warm up. We'll see how it shakes out, but it does appear that temperatures should rebound to above normal levels Thu/Fri. Models are showing a potentially more substantial trough moving in next weekend, but confidence in the details is low at this point. -Spilde/BR-y && .AVIATION...28/06Z TAFs...A front will continue some light rain showers from the coast to the Cascades overnight into early Sunday morning. VFR will be the predominant condition, though areas of ceilings/visibilities could lower to MVFR (perhaps even local IFR) at times at the coast and into the Umpqua Valley. Higher terrain will also be occasionally obscured. For Medford and areas to the south and east, expect mostly VFR through Sunday evening. Breezy westerly winds will be locally gusty (20-25 kt) again during the afternoon into the evening. These winds will be strongest east of the Cascades, including at Klamath Falls. -DW && .MARINE...Updated 220 AM Sunday, April 28, 2024...Weak high pressure southwest of the waters will result in light to moderate west winds and calmer seas. A weak front will move into the waters Monday with increasing west winds, with low end small craft conditions possible. The pattern will remain active Tuesday with an increasing northwest swell between 8-10 feet moving into the waters, but all indications suggest this will be short lived with seas diminishing Tuesday night. Calmer conditions are expected by mid week and could last into the end of the week with light to moderate winds. -Petrucelli && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. PACIFIC COASTAL WATERS...None. && $$ MNF/MAP/MAS