Cape Blanco OR to Point St. George CA from 10 to 60 NM Marine Forecast
| Tonight...Nw Wind 10 To 20 Kt...Backing To Sw 5 To 10 Kt After Midnight, Then...Becoming 5 To 15 Kt Late Tonight. Wind Waves 3 To 4 Ft. Swell Nw 12 To 13 Ft At 13 Seconds. Chance Of Showers And Slight Chance Of Tstms Through The Night. |
| Fri...Northern Portion, S Wind 15 To 25 Kt...Rising To 30 Kt In The Late Morning And Afternoon. Southern Portion, S Wind 10 To 20 Kt...Rising To 20 To 25 Kt In The Late Morning And Afternoon. Wind Waves 3 To 6 Ft...Building To 8 To 11 Ft In The Afternoon. Swell Nw 9 To 10 Ft At 11 Seconds. Chance Of Rain. |
| Fri Night...S Gales 35 Kt. Combined Seas 13 To 16 Ft Dominant Period 11 Seconds. Chance Of Rain. |
| Sat...Se Wind 30 Kt. Wind Waves 9 To 12 Ft. Swell W 8 Ft. Rain. |
| Sat Night...Se Wind 15 To 25 Kt...Becoming 15 To 20 Kt After Midnight. Wind Waves 5 To 8 Ft. Nw Swell 7 To 8 Ft...Shifting To The S 7 To 9 Ft After Midnight. Rain. |
| Sun...Se Wind 10 To 15 Kt. Wind Waves 3 To 5 Ft. S Swell 6 To 7 Ft...Subsiding To 5 Ft In The Afternoon. Showers Likely. |
| Sun Night...E Wind 10 Kt...Backing To Ne After Midnight. Wind Waves 2 Ft Or Less. S Swell 4 To 5 Ft... Shifting To The Sw 4 Ft After Midnight. Chance Of Showers Through The Night. |
| Mon...Ne Wind 10 Kt...Backing To N. Wind Waves 2 Ft Or Less. Mixed Swell Sw 4 Ft And Nw 3 Ft...Shifting To The Nw 3 Ft. |
| Tue...N Wind 10 Kt. Wind Waves 2 Ft Or Less. Swell Nw 4 Ft. |
| Area Forecast Discussion National Weather Service Medford OR 249pm PST Thu Dec 1 2022 .SHORT TERM...The front that brought the rain and snow to the area last night into this morning has moved to the south and east. Snow reports of 10-15 inches were common in the Cascades and also down around Mt. Shasta with 5-10 inches in many areas east of the Cascades. Radar and satellite are still showing some pretty good showers out there this afternoon, especially from the Cascades and Siskiyous westward. This is being caused by an upper trough which will swing through the area late this afternoon and evening. An interesting feature on satellite (GOES-17 Day Snow-Fog RGB) is a nearly stationary convective band of showers coming off of Mt. Shasta and extending south of Tennant to just south of Tionesta, but north of Alturas. This very narrow band (only about a mile or 2 wide) is likely producing heavy snowfall, but it is virtually clear on both sides of it. These bands often form parallel to the upper level flow in areas of cold air advection behind departing cold fronts and can cause snow impacts, despite their small size. This band isn't over largely populated areas and we have no ground truth to know exactly what's going on beneath this band, but it has been wavering near Highway 139 between Canby and Newell at times and it could briefly, but significantly lower visibility in snow into early this evening. Elsewhere, showers could still produce brief heavier snow/graupel down to around 500 or 1000 feet west of the Cascades, but accumulations should generally be less than an inch. Another few inches of snow area possible in the mountains near and north of Highway 140. After sunset, the loss of instability and the passage of the upper trough axis, showers should gradually diminish and end overnight. It will get very cold from the Cascades eastward. Any wet/slushy roads from snow melting today will likely refreeze solid tonight with low temperatures over there in single digits for most locations. But, following the fresh snowfall, and depending on the amount of clearing, we wouldn't be surprised to see some areas (Klamath Marsh north of Chiloquin, Christmas Valley near Fort Rock and perhaps even the Goose Basin near Lakeview and also Alturas) have lows 0 to 10 below zero. West of the Cascades, temperatures will also fall to below freezing in most areas, except at the immediate coast where lows will be in the mid 30s. A few spots could get close, but freezing conditions are not expected for long enough to warrant a freeze warning. Weak shortwave ridging over the area Friday morning will give way to a closed low that will drop southward offshore Friday night into Saturday morning. With each run the last couple of days, model guidance has pushed this low farther and farther offshore such that the front just barely reaches the coast or remains offshore just parallel to the coast. As a result, it won't likely produce much in the way of precipitation during this time period (but some rain chances do exist at the beaches). It will cause increasing pressure gradients across the area and expect south winds to strengthen significantly over the marine waters (gales). Coastal areas will also get winds, but an offshore component will keep the strongest winds offshore. So, we're not issuing a high wind watch. We should see an uptick in winds through the Shasta Valley this weekend, which could eventually lead to advisories there. Breezy conditions could also extend into the southern end of the Rogue Valley. Precipitation will eventually develop across NorCal Saturday afternoon and night as the low wobbles closer to the coast. Snow levels will be low enough for snow in the upslope areas of NorCal, primarily southern Siskiyou County and around Mt. Shasta City. We have held off on winter storm watches for now, since amounts (4-8") over a longer duration (36 hours) look to be handled best by an advisory. But, future shifts will have newer data to help gain confidence. Please see long term section below for more details Sunday and beyond. -Spilde Long Term Sunday 04 Dec through Thu 08 Dec 2022. The GFS (Global Forecast System) and EC ensemble means are similar throughout the extended period. The extended period will commence with a cold upper level low off the northern California coast and strong south to southwest flow aloft over the Medford forecast area. This general scenario was depicted in the Wednesday runs of the GFS ensemble, but this run has pushed the low trajectory farther offshore and slowed it down a bit. It is also bringing the low onshore farther north than the Wednesday run did. The low will weaken to a trough as it moves onshore Sunday night. The trough will then move very slowly south into Wednesday, and the upstream ridge will flop over it, building into the Pacific Northwest. The cold air aloft associated with the low will create unstable conditions over the area, so there will be plenty of showers around Sunday. The air mass will gradually stabilize as the trough sinks south and the ridge builds in, so showers will gradually diminish beginning Sunday night, ending Monday evening. Tuesday and Wednesday will be dry. The ridge will weaken as it moves inland, and the next upstream trough will approach the coast Thursday, moving onshore Thursday evening. The associated front will move onshore ahead of it Thursday, with precipitation beginning at the coast early Thursday and spreading inland during the day. Marine Updated 230pm PST Thursday 1 December 2022...Steep west to northwest swell will persist through tonight. Another strong front will approach the coast Friday, then stall offshore through Saturday, producing an extended period of south gales and very steep and hazardous seas Friday afternoon into Saturday evening. Winds and seas will gradually improve Saturday night into Sunday morning as the front dissipates. Relatively calm conditions will develop by Sunday afternoon with weak low pressure persisting offshore through Monday. NOAA Medford OR Office: Watches - Warnings - Advisories OR...CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory until 10am PST Friday for PZZ350-356-370-376. Gale Warning from 10am Friday to 1pm PST Saturday for PZZ350-356-370-376. |
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