Area Forecast Discussion
Issued by NWS Medford, OR
Issued by NWS Medford, OR
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979 FXUS66 KMFR 302153 AFDMFR Area Forecast Discussion National Weather Service Medford OR 253 PM PDT Thu May 30 2024 .DISCUSSION...Satellite imagery shows only the slightest scraps of cirrus clouds moving over northern California and southern Oregon this afternoon. A building upper level ridge will generally keep skies clear and bring warming temperatures across the area today and Friday. Today`s highs will be very near seasonal norms. The Oregon coast will be in the low to mid 60s today, with the exception of Brookings. The Chetco effect is already clear today, with an observed temperature of 78 degrees already. West side valleys will be in the high 70s to low 80s, and areas east of the Cascades will generally be in the low to mid 70s. Friday`s highs are forecast to rise another 5 to 10 degrees over inland areas. Then an upper trough will push the ridge to the east, bringing Saturday`s temperatures back down to seasonal levels. Precipitation chances are generally slim to none through Saturday, although slight (~5%) thunderstorm chances remain in small areas. Model guidance has these chances in place in southern Siskiyou county on Friday afternoon and in eastern Lane and Modoc counties on Saturday afternoon. On Sunday morning, a cold front will use moisture from an atmospheric river to bring substantial rainfall over the area that will continue through Monday morning. Coastal areas will see the highest rainfall totals, with cities forecast to get 1.5 to 2 inches of rain while the coastal ranges in Curry and Coos counties could see 2 to 3 inches of rainfall. Northern Douglas and inland Coos county will see between 0.5 and 1 inches of rainfall. Other areas will see lower amounts of rainfall. This front will also bring gusty (but non-advisory) winds to east side areas, especially over elevated terrain. This event is definitely impressive, with precipitable water amounts in the 99.5th percentile per NOAA ensemble tables. While no specific hazard products are currently being issued for Sunday and Monday, localized water flow or ponding is not impossible. This is especially true in urban areas. Extra caution is encouraged while traveling, especially along the Oregon coast or over higher terrain. Conditions beyond Monday`s front remain uncertain. Both ECMWF and GFS deterministic patterns show an upper ridge, but the placement varies. The ECMWF outcome puts Oregon squarely under a large ridge, while the GFS model puts the area near the back of a slightly weaker ridge. The uncertainty is reflected in ensemble meteograms for both long-term models, with a mix of precipitation and dry outcomes failing to indicate any clear signal. The NBM is also showing uncertainty, with interquartile ranges of 10 to 15 degrees in daytime highs from next Wednesday and beyond. For example, Medford has a 45% chance of seeing 100 degrees next Thursday, but could also see temperatures as low as 91. -TAD && .AVIATION...30/18Z TAFs...VFR conditions prevail over the region and are expected to persist through the day. Northerly winds will pick up again this morning and afternoon, and gusts could reach 20-25 kts. Some low clouds could form in the valleys of Coos and western Douglas County, but are not expected to impact the North Bend or Roseburg terminals. -Miles && .MARINE...Updated 145 PM Thursday, May 30, 2024...A thermal trough will peak this evening, and persist through at least Friday evening; resulting in gale force winds for most areas south of Cape Blanco and for isolated instances across the waters between Bandon and Cape Blanco. Meanwhile, small craft conditions exist north over the rest of the waters and will last into at least Friday evening. The thermal trough will weaken overnight Friday into Saturday and north winds will diminish as an upper trough approaches. Calmer seas are expected on Saturday after the wind waves have diminished. Sunday, a front with the energy more similar to a late winter/early spring front will move through the region. Gusty (20-30 kt) south winds will exist ahead of and along the front, while behind it, a moderate west swell (7-9 ft around 10 sec) will build into the waters. The result will be a period of at least advisory conditions from roughly Sunday evening through Monday evening, along with rainy conditions. -Miles && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...None. PACIFIC COASTAL WATERS...Gale Warning until 11 PM PDT Friday for PZZ356-376. Small Craft Advisory until 11 PM PDT Friday for PZZ350-370-376. && $$ TAD/JWG/MCB