Area Forecast Discussion
Issued by NWS Medford, OR
Issued by NWS Medford, OR
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341 FXUS66 KMFR 021026 AFDMFR Area Forecast Discussion National Weather Service Medford OR 326 AM PDT Thu May 2 2024 .DISCUSSION...The pattern continues to be progressive into the next week, with several fronts bringing wet and cool weather with brief dry breaks in between. The first system moves through overnight today with light showers lingering into the evening, followed by a stronger front Friday into Saturday. Showery weather continues into next week, with another weak front moving through Monday. A broad precipitation shield associated with a frontal system is moving quickly ESE through southwest OR. Radar returns are indicating some pretty good areas of precipitation, with areas of 40-50 dbZ embedded in the main band. This front will pass through the region early this morning, followed by light, scattered showers which will bring on-and-off again precipitation for the remainder of the day, mostly over the higher terrain. With seasonably mild temperatures, snow levels will remain at or above 5,000 feet and snow restricted to the higher mountains. After a brief break in the weather, the next front arrives Friday and slowly pushes inland into Saturday. Similar to the frontal system today, this front will move in from the west, resulting in much less downsloping for western valleys than in other patterns. Precipitable water associated with this front, however, will be greater with a stronger inflow of moisture, resulting in greater precipitation amounts. Rain amounts of a half inch or more are almost guaranteed for almost all areas in southern Oregon and far northern California, with up to 2 or even 3 inches of rain possible along the coast. Snow levels will initially be quite high at the beginning of the event, rising to above 7,000 feet, before decreasing overnight Friday into Saturday to 3,000 to 4,000 feet as the cold front passes and precipitation becomes more intermittent/showery. This will result in snow lowering down to area passes, including those over the Cascades on Hwys 140 and 138 (where we`re expecting 3-6 inches early Saturday through early Sunday) and Siskiyou Summit on I-5 (likely less than an inch). As road surfaces are still quite warm, a lot of this will melt on paved surfaces, but lower visibilities could still make travel over the mountains difficult. Showery, on-and-off again precipitation continues late Saturday into Sunday as low pressure lingers aloft. Shower coverage will shrink and taper off through the day Sunday as the low moves SE and another transient ridge moves into the area. Another front moves in Monday, this one much weaker with the majority of light to moderate precip falling over northwest portions of the region. Snow levels will generally be 4,000 to 5,000 feet. Onshore flow and lingering moisture will lead to light, scattered showers continuing into Tuesday. About a third of models included in the National Blend indicate periods of precipitation are possible into the mid-week, but the outlook for the late week/following week is for warmer, drier conditions per the Climate Prediction Center. -CSP && .AVIATION...02/06Z TAFs...Ceilings have lowered to MVFR along the coast and just offshore and will likely lower to IFR as a front reaches the coast. Even though the TAF at North Bend shows a prolong period of IFR ceilings, it`s possible there could be brief periods of MVFR ceilings after 15z. Inland west of the Cascades, VFR ceilings will lower to MVFR late tonight north of the Umpqua Divide, confidence on the timing of lowering ceilings indicated in the Roseburg TAF could be delayed by an hour or two. Medford is expected to remain VFR through the TAF period, however the higher terrain will be at least partly obscured towards 11z. East of the Cascades, VFR ceilings will continue into tonight, then MVFR will follow at Klamath Falls as precipitation moves in. Areas of mountain obscuration are expected after 12z until the end of the TAF period. -Petrucelli && .MARINE...Updated 230 AM Thursday, May 2, 2024...A weak front will continue to move through the waters this morning with a modest increase in short period west-northwest swell. A break later today will bring calmer conditions this afternoon and evening; however, the active pattern resumes Friday morning with rain over the waters likely (90% - 100%) and small craft advisory conditions in place through Saturday morning. Weak winds and a slight increase in short period west-northwest swell dominated seas are expected during the weekend with rainfall (no thunder) chances (60%-90%). The next in a series of fronts is likely to arrive on Monday with conditions hazardous to small craft possible Tuesday. -Guerrero && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. PACIFIC COASTAL WATERS...None. && $$