Florence to Cape Blanco OR from 10 to 60 NM Marine Forecast
|Today...S Wind 15 To 20 Kt. Wind Waves 3 To 5 Ft. W Swell 14 To 16 Ft At 15 Seconds. Widespread Showers And Isolated Tstms.|
|Tonight...Sw Wind 15 To 25 Kt. Wind Waves 5 To 7 Ft. W Swell 12 To 13 Ft At 14 Seconds...Subsiding To 10 To 11 Ft At 14 Seconds After Midnight. Widespread Showers And Slight Chance Of Tstms.|
|Tue...S Wind 15 To 20 Kt. Wind Waves 4 To 6 Ft. W Swell 10 To 11 Ft At 13 Seconds. Showers Likely And Slight Chance Of Tstms.|
|Tue Night...Se Wind 15 Kt. Wind Waves 4 To 5 Ft. W Swell 9 To 10 Ft. Chance Of Showers And Slight Chance Of Tstms.|
|Wed...Se Wind 5 To 10 Kt...Backing To Ne In The Afternoon. Wind Waves 3 To 4 Ft. W Swell 8 To 9 Ft...Subsiding To 7 Ft In The Afternoon. Slight Chance Of Showers.|
|Wed Night...N Wind 15 Kt. Wind Waves 3 To 4 Ft. W Swell 6 To 7 Ft. Slight Chance Of Showers Through The Night.|
|Thu...N Wind 15 Kt. Wind Waves 3 To 4 Ft. Nw Swell 6 To 7 Ft.|
|Fri...N Wind 10 Kt...Becoming 10 To 15 Kt. Wind Waves 2 Ft Or Less...Becoming 3 Ft In The Afternoon And Evening, Then... Becoming 2 Ft Or Less After Midnight. Mixed Swell Nw 4 Ft And W 3 Ft...Shifting To The W And N 3 Ft.|
| Area Forecast Discussion|
National Weather Service Medford OR
901am PST Monday Mar 8 2021
The forecast remains on track and no updates were needed at this time. Snow is already being reported across N. Cal. and higher terrain of SW Oregon under some prefrontal moisture. A front about 10 NM from shore will continue to advance inland. This will bring a period of moderate to heavy stratiform precipitation to Curry, Josephine, and most of Siskiyou Counties. Behind the front the pattern becomes showery.
We brought the possibility of thunderstorms further inland to encompass all of Josephine and Curry Counties, along with the western portions of Douglas, Josephine and Siskiyou Counties. This was to highlight the potential for accumulating graupel and small hail, even when lightning may be far less likely. And thus far lightning activity has been more muted in the area of post frontal showers than it was yesterday. This is expected to pick up as the cold pool(a region of relatively cold air) further settles into the region and day time heating enhances lower level lapse rates. The peak in lightning potential is probably not going to be until tuesday though. -Miles
Updated 800am PST Monday 08 Mar 2021...Steep and high long period west to northwest swell will persist today, gradually diminishing today and Tuesday. Upper level low pressure will gradually move southward just offshore today into at least Wednesday. This will bring an extended period of unsettled weather with plenty of showers and possibly even thunderstorms or small hail. Multiple disturbances will pass through the region as this upper low moves southward, and this will bring some advisory level south winds, and associated wind seas, beginning this afternoon and persisting into late Tuesday. At the same time, moderate northwest swell will continue and this combined with southerly wind seas will result in steep seas persisting through Tuesday night.
Winds will ease Tuesday night as the upper low moves southeastward into northern California. Afterwards, high pressure builds over the region and winds will turn northerly Wednesday afternoon into Friday. Swell diminishes during this time and seas will become wind wave dominated with the strongest winds and steepest seas expected south of Cape Blanco. -CC/BR-y
Water vapor imagery is showing a vertically stacked closed low out around 48N and 136W early this morning. Fairly benign weather has been occurring across SW Oregon and NorCal overnight, but that will change today as the closed low tumbles southward offshore, sending a front onshore this morning. Expect some showers to break out from around the Mt Shasta region east- northeastward this morning as shortwave energy in front of this system provides enough lift to generate precipitation. These, for the most part, should be light. Another area of precipitation will accompany the cold front onshore later this morning, sometime between 9 am and Noon. Showers are possible just about everywhere this afternoon. It should be noted that our radar atop Mt Ashland (KMAX) went down yesterday. Technicians will attempt to diagnose the problem this morning and hopefully have the radar back up and running at some point today.
Lots of showers will continue across the area through at least Wednesday as the cold upper low settles southward, eventually moving onshore into northern California Wednesday afternoon. While precipitation across the forecast area as a whole will not be heavy, there will be a few favored areas, like Curry and Josephine Counties as well as southern and western Siskiyou County. These areas tend to do better on south to southwest wind regimes due to orographic lift. Of course, on the lee side of these orographically favored locations, there tends to be a minimum in precipitation.
Models have increased precipitation amounts in portions of Siskiyou County during the past few cycles, especially in the Mount Shasta region (Zones 82/83). Since this will be a very cold system, snow levels will generally be 2000-3000 feet during this event, sometimes lower, sometimes higher depending on the time of day and the intensity of the showers. Where precipitation will be more focused, we have upgraded the Winter Weather Advisory to a Winter Storm Warning for elevations above 4000 feet around Mount Shasta. This includes portions of Highway 89 near Snowmans Summit and also the road to Mount Shasta Ski Park. Ten to 20 inches of snow could accumulate in those areas over the course of the next 48 hours. We've also extended it in time into Wednesday morning. The Winter Weather Advisory has been maintained for elevations below 4000 feet for 5-10 inches of snow, including Interstate 5 south of Weed to Dunsmuir and also the rest of Highway 89 to Pondosa. Since it is early March, expect some melting of the snow during the late morning and afternoon Tuesday in those areas, especially at elevations below 4000 feet. We've also added a winter weather advisory to western Siskiyou County for elevations above 2000 feet. Snow amounts are borderline for advisory in these areas, but snow could affect lower elevations at times, especially at night. Difficult travel could also be an impact above 4000 feet (Sawyers Bar Road and Highway 3 south of Callahan).
Precipitation across the area will become convective due to the stronger March sun and the very cold air aloft. We're expecting some thunderstorms over the coastal waters and along and near the coast today, and it appears we may need to add some thunder potential to inland areas for Tuesday and possibly Wednesday. Wednesday we'll be on the western side of the trough, so upslope areas will shift more to those favored under a northwest flow. Altogether, areas that get stronger showers are likely to see some graupel and/or small hail even where we do not get thunderstorms this week.
Looking ahead, we expect the upper trough to be slow to move out of the area, but shower coverage should diminish by Thursday as upper ridging noses into the PacNW. The upper ridge should provide at least a couple of dry days Friday into Saturday, but it doesn't look to last as another trough digs into the area Sat night to Monday. -Spilde
.MFR WATCHES/WARNINGS/ADVISORIES... OR... CA...Winter Weather Advisory from 4pm this afternoon to 4am PST Wednesday above 2000 feet in the for CAZ080. Winter Weather Advisory from 4pm this afternoon to 10am PST Wednesday below 4000 feet in the for CAZ082-083. Winter Storm Warning from 4pm this afternoon to 10am PST Wednesday above 4000 feet in the for CAZ082-083.
Pacific Coastal Waters...Small Craft Advisory until 4am PST Wednesday for PZZ350-356-370-376.