FXUS66 KMFR 181404 AFDMFR Area Forecast Discussion National Weather Service Medford OR 704 AM PDT Tue Jun 18 2024 .UPDATE...Updated the aviation section. && .AVIATION (12Z TAFs)... MVFR extends from the southern and central Umpqua Valley (including Roseburg) into the southern Coquille Valley. This stratus is expected to dissipate to VFR by 17Z. Otherwise, VFR is expected through this evening. -DW && .MARINE...Updated 230 AM Tuesday, June 18, 2024...High pressure offshore and a thermal trough along/near the coast will likely remain in place through at least the weekend. This will result in persistent northerly winds and wind-driven seas through this period. Conditions will be worst south of Cape Blanco where winds and steep seas hazardous to small craft will persist. The thermal trough strengthens slightly and expands northward this afternoon, which will result in the small craft advisory conditions south of Cape Blanco this morning, expanding across the waters north of Cape Blanco this afternoon into Wednesday morning. The thermal trough will strengthen further Wednesday afternoon into Friday evening, and this may bring very steep seas and/or northerly gales to the waters south of Cape Blanco Thursday afternoon into Friday evening. Consequently, it is recommended mariners to stay tuned to updates as we move through the week. -Guerrero/DW && .PREV DISCUSSION... /Issued 323 AM PDT Tue Jun 18 2024/ DISCUSSION...Active weather is largely behind us as an upper trough moves to the east with a developing ridge taking its place. For tonight, this stability is allowing for another night of freezing temperatures east of the Cascades. Fort Rock has reached 29 degrees and Cabin Lake is down to 23 degrees. Other areas farther south are still in the mid to high 30s, but clear skies across the area will allow for cooling to continue through the early morning. A Freeze Warning remains in place for areas east of the Cascades through 8 AM today. Please see NPWMFR for more detailed information. Daytime temperatures will increase through the week under the upper ridge. Today's temperatures will be 5 to 10 degrees above Monday's, with mid to high 60s along the Oregon coast, high 70s to low 80s in west side valleys, and mid 60s to mid 70s to the east. Wednesday's highs will see another 5 to 10 degree increase for most areas. The warming trend will continue through the end of the week, although fortunately the rate of warming will slow. Friday and Saturday will be the warmest days of the week, with west side valleys in the low to mid 90s and east side areas in the mid to high 80s. Currently, heat warning products are not expected but individuals who have difficulties acclimating to warmer temperatures will want to be cautious participating in outdoor activities at the end of the week into the weekend. Of course nighttime lows will increase as well, but the only impact here is the end of freezing temperatures east of the Cascades. Thunderstorm chances will be considered through the week. While no significant forcing mechanisms are expected, convective heating is usually good for some slight afternoon thunderstorm chances. For this week, Wednesday afternoon has some 5-10% thunderstorm chances over eastern Douglas and northern Klamath and Lake counties. On Thursday afternoon, those chances spread down the Cascades and into Siskiyou County. There's more uncertainty in thunderstorm chances going into the weekend, but future guidance should help to clarify those chances. Generally, given the weak forcing and absence of available moisture, some isolated thunderstorm cells are possible later in the week but widespread activity is not expected right now. Overall, while temperatures warming quickly always feels unpleasant, there's no signal for anything extremely worrying as far as fire conditions in the current forecast. Afternoon breezes will increase under this stable pattern and dry vegetation is always worth being aware of, but the expected conditions through the week are within normal climate ranges. Of course, any changes to this expectation or any localized hazards will be quickly communicated. Looking to the end of the weekend and into next week, a low pressure system approaching the Canada coast on Sunday will help to push the upper ridge away. A pattern change to zonal flow aloft will result in cooler temperatures down at the surface. This may also bring cloud cover and slight 5-10% chances for showers along the Oregon coast, especially north of Cape Blanco on Sunday morning. Current guidance shows the low pressure system spinning in place into next week, although there are slight variations on its location. Probabilistic guidance for the middle of next week shows a 10 to 15 degree spread in interquartile ranges across the area (North Bend, Roseburg, Medford, and Klamath Falls), indicating some uncertainty in temperatures next week. However, meteograms for both the ECMWF and GFS models expect inland areas to stay dry and only light precipitation for North Bend through Sunday and Monday. -TAD && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Freeze Warning until 8 AM PDT this morning for ORZ029>031. CA...Freeze Warning until 8 AM PDT this morning for CAZ084-085. PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT Friday for PZZ356-376. Small Craft Advisory from 2 PM this afternoon to 5 AM PDT Wednesday for PZZ350-370. && $$