Area Forecast Discussion
Issued by NWS Medford, OR
Issued by NWS Medford, OR
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659 FXUS66 KMFR 082147 AFDMFR Area Forecast Discussion National Weather Service Medford OR 247 PM PDT Sat Jun 8 2024 .DISCUSSION... .Short Term...Rest of Today through Monday Night...A trough will approach the coast this afternoon and evening, move onshore tonight, and pass over southern Oregon and far northern California tomorrow. This trough is responsible for the cooler temperatures today, and it will also be the lifting mechanism the atmosphere needs to tap into some relatively significant instability in the low to mid levels, while also providing enough shear to enhance thunderstorm chances. A few convective cells have already formed today, and activity is expected to intensify and become more widespread through the afternoon, mainly along and east of the Cascades and in northern California. Some of these storms could be strong; while severe storms are not expected, they are not out of the question, with around a 5 percent chance for any given storm to produce strong winds and/or large hail. Elevated instability is expected to continue through tonight and into Sunday afternoon as the trough passes onshore. Convective activity is therefore expected to continue all the way into Sunday afternoon as well, although over time it will be concentrated more to the east, ahead of the trough axis. Ridging returns Sunday night into Monday, along with a reintensifying thermal trough along the coast. This will dry things out and bring an end to thunderstorm chances, and it will also allow temperatures to bump back up, reaching about 10 degrees above normal for this time of year as we head into the extended period. -BPN .LONG TERM...Tuesday 6/11 through Saturday 6/15...The extended forecast begins with zonal flow (west to east) at the middle levels of the atmosphere. While weak disturbances will pass largely to the north of the area, expect dry weather to continue across southern Oregon and northern California through the extended period. However, temperatures will be much slightly above normal with highs in the upper 80s to low 90s east of the Cascades and lower 80s to upper 70s east of the Cascades. The coast will be cooler with temperatures in the 60s. Then, for the weekend, the general flow pattern will turn to become more unsettled as a low pressure system approaches the Pacific Northwest. The general front ahead of the low will be relatively weak and precipitation is not expected that far south. However, some precipitation in showers will be possible within the low itself. Ensembles do show some timing differences, but the general thought is that temperatures will be even cooler over the weekend, winds will be breezy, and that a slight showers will be possible largely north of the Douglas/Lane County Border. However, this could change as the details of this system become more clear. Have gone with the National Blend of Models for this forecast package. -Schaaf && .AVIATION...08/18Z TAFs...An isolated thunderstorm has already popped up this morning ahead of an upper level wave and some modest mid level moisture. Thunderstorm activity will pick up into the late afternoon and early evening as the atmosphere destabalizes. The bulk of the activity will develop east of the Cascades and in northern California. The thunderstorm threat will persist overnight east of the Cascades and in the central Cascades as the upper level wave approaches the Oregon coast. Some models also show a bulk of moisture around 7000 to 9000 feet above sea level, which could aid in initiating convection overnight. Right now the threat of overnight thunderstorms remains low, although these events are sometimes underdone in the models. Overall, be on the lookout for thunderstorms across the forecast area, especially farther to the east through the TAF period. Lower ceilings around 1000 feet are anticipated near the coast overnight as high pressure begins to build. IFR ceilings are most likely, although periods of LIFR ceilings also remain possible. -Smith && .MARINE...Updated 200 PM Saturday, June 8, 2024...Gusty north winds will bring steep seas to areas south of Ophir and a few miles away this evening. Then, a moderate west swell moves in tonight through Sunday. During this time, the thermal trough will restrengthen, bringing increasing north winds and steep to very steep seas Sunday into early next week, especially south of Cape Blanco. Conditions will at least remain hazardous to small craft south of Cape Blanco through midweek. Conditions could worsen again around Thursday as the thermal trough builds strength. -Smith && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT Monday for PZZ356-376. Hazardous Seas Warning from 5 AM Sunday to 11 AM PDT Monday for PZZ356-376. && $$