textproduct: Medford

UPDATED Aviation Discussion

KEY POINTS

- Temperatures trend warmer today and remain warm on Sunday with highs 5 to 15 degrees above normal.

- Breezy winds over the ridges into early next week.

- Trending cooler with chances for very light rain and light snow early next week.

DISCUSSION

A high pressure ridge over the area today will bring a significant warm up with high temperatures 5 to 15 degrees above normal today. Expect highs in the low to mid 60s for most valleys across the area, except for 70s for valleys in the lower Klamath River valley. Guidance continues to indicate that areas in and around Brookings may near 70 degrees today as well. There is a slight chance (10-20%) for showers today along the coast, from Cape Blanco northward.

On Sunday, the high centered over the northeast Pacific will flatten as a low moves into Gulf of Alaska. Models and ensembles continue to support warm daytime temperatures across the area though with only a slight cooling trend for northwest parts of the area (Coos and Douglas counties). There are chances (40-70%) for light rain showers along the coast and into northern Douglas County Sunday into Sunday night.

The pattern begins to change Monday as zonal flow develops as a broad trough develops across the region. This trough will deepen slightly Monday night and Tuesday, allowing some cooler air to move into the area. Onshore flow and continued weak disturbances will bring chances for very light precipitation from the Cascades west (mainly Coos, Curry, and Douglas counties). Higher chances for precipitation area expected north of the area. Models show cold air advection Monday night and Tuesday morning with 850 mb temperatures lowering to -3 to -6 deg C from the Southern Oregon Cascades west. The National Blend of Models (NBM) indicates snow levels will lower from 6000-7000+ feet Sunday evening, down to 3000-4500 ft Monday then to 1500-3000 feet Monday night/Tuesday morning. However, only very light precipitation is likely to move into northwest parts of the CWA (coast, Douglas and south-central Oregon Cascades) during this period. So any snow that falls will be very light and primarily occuring over the south-central Oregon Cascades. The NBM shows 30-60% chance for up to an inch of snow in the south-central Oregon Cascades Monday evening through Tuesday, including the Diamond Lake and Crater Lake area. For lower passes (Canyon Mountain I-5 and there is only a 5-10% chance for measurable snow of 0.10 inches.

The high pressure ridge may strengthen some mid to late week, allowing for temperatures to warm. However, there is variability in the models and ensembles on this pattern and whether we will continue to see more of a zonal flow pattern versus a ridge. A front is also expected to move into the region mid to late week. This will bring additional chances for precipitation.

AVIATION...07/12Z TAFs

Areas of fog and LIFR conditions are occuring along the coast from Cape Blanco northward (including North Bend) and isolated IFR/MVFR in valleys west of the Cascades through around 18z this morning. Additionally, there is a low chance of some coastal showers and MVFR conditions through the TAF period. Areas of fog and IFR/LIFR are expected to return to the coast from Cape Blanco northward and are expected to develop in the Umpqua Valley (including Roseburg) tonight. Elsewhere, expect VFR conditions.

MARINE

North winds will strengthen for areas south of Cape Blanco today with advisory level winds and steep seas expected to develop south of Port Orford. These conditions will persist through the weekend. Then, winds may strengthen on Monday with continued steep seas south of Cape Blanco and a potential for very steep seas south of Gold Beach. Improving conditions are possible around mid- week.

MFR WATCHES/WARNINGS/ADVISORIES

OR...CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PST Monday for PZZ356-376.