739 FXUS66 KMFR 070415 AFDMFR Area Forecast Discussion National Weather Service Medford OR 915 PM PDT Sat Nov 6 2021 .DISCUSSION...A reminder that we will fall back an hour overnight with the change from PDT to PST. An update has been issued to nudge expected precipitation and snow amounts tonight a bit higher for the Umpqua Divide Region, mainly from north of Prospect to Union Creek, Crater Lake, and Diamond Lake. Snowfall of 1 to 3 inches is expected in that area from earlier this evening through 4 AM PST on Sunday morning. Snow levels are expected to bottom out around 3300 feet MSL. The other area with the most numerous showers is expected to be Curry County. The next shortwave in this onshore flow pattern will bring additional light showers, almost exclusively from the Oregon coast to the southern Oregon Cascades during Sunday...with a few also into far western Siskiyou County. This activity will linger longest at the coast and gradually diminish later Sunday evening into Monday morning. The coast will have about a 6-hour break of dry weather Monday morning into early afternoon. As the new suite of model data continues to filter in, the focus for the next forecast issuance will be on a strong storm to affect our area mainly Monday afternoon into early Tuesday morning. A High Wind Watch remains in effect with the potential for gusts to 60 mph for our usually windiest locales, the coast, the Shasta Valley, and portions of the east side (including the Summer Lake area and Warner Mountains). Though, perhaps not quite reaching high wind criteria, Strong winds are also possible in the Rogue Valley from Ashland to the south and east sections of Medford. Snow levels with this storm will rise to around 8000 feet as it begins inland Monday evening, then fall to around 5500 to 6000 feet as precipitation diminishes early Tuesday morning. Please see the previous discussion below for further forecast details farther out in time. && .AVIATION...07/00Z TAFs...A continued mix of VFR and MVFR cigs are expected through the TAF period, with periods of showers and mountain obscurations across the forecast area. During periods when mid to high level clouds clear, there may also be some IFR cigs over the west side valleys between 06-18z Sunday, with local IFR visibility in patchy fog. Freezing levels should hover between 3000 and 4000 feet above sea level. -BPN/MTS && .MARINE...Updated 800 PM PDT Saturday 6 November 2021...Low pressure remains to the north through Sunday. A deep low pressure center will approach from the west Monday and move inside of 130W off the central Oregon coast by early Monday evening. Despite uncertainty in the forecast models in the strength and timing of this low, it appears likely to produce gales and hazardous seas over the outer waters Monday night. Tuesday should see improving weather with fairly low-end winds and seas from mid to late week. MTS && .PREV DISCUSSION... /Issued 308 PM PDT Sat Nov 6 2021/ SHORT TERM... The radar scope is becoming a little more filled in the last hour as a little moisture and another disturbance moves through. These showers are also putting down some quick wetting rain. Grants Pass saw 0.1 inches of rain over 10 to 15 minutes as a shower moved overhead earlier this afternoon. In addition, a positive cloud to ground strike was just observed off the Douglas County coast this afternoon. Therefore, the slight chance of thunder seems very appropriate into this evening and tonight along the coast. The cold airmass aloft will keep the atmosphere rather unstable with snow levels down to 3500 feet tonight. Snow accumulations from this evening into tonight should be under 1 - 2 inches over the mountains and higher elevations. Locations around 3500 feet should see trace amounts of snow at most. Heading into Sunday, the cool and unstable pattern remains and showers will likely cover most locations along the coast and some of the higher terrain along the Cascades. Rain Accumulation will vary from trace amounts of rain up to 0.25 inches. Overall, no impacts here as the unsettled weather and moisture persists over the area. By Sunday night into Monday, conditions will dry and clear briefly as an upper level ridge builds in briefly overnight. We're forecasting some frost in the valleys west and east of the Cascades. This may require extra time added to ones commute to clear off a windshield. Conditions will begin to change through the day Monday as upper level clouds build ahead of a well developed warm front. Another low will begin to intensify out over the Pacific and southerly winds will subsequently strengthen Monday evening along the coast and eventually over locations farther to the east. Upper level winds from 4500 to 9000 feet are quite strong in some of the deterministic models. Because of this, we decided to keep the high wind watch over many locations within our warning area. View the high wind watch on our web page (weather.gov/medford) for more details on hazards related to the high potential winds. Aside from the wind, snow also remains a concern within northern California specifically Monday night. As is typically with systems which have strong southerly winds up the Sacramento Valley, the Trinity Mountains and locations around Mt. Shasta City have the potential to see some snow accumulation. The NBM has lowered this threat recently as the probability of snow accumulation greater than 4 inches is only 20 percent versus 40 percent yesterday. In addition, our official forecast has about 4 inches of snow along Black Butte Summit on I-5 with roughly 8 to 12 inches over the mountains in Siskiyou County. Overall, we kept the winter storm watch going, although the chance for issuing a warning has diminished based on the latest ensemble data. View the winter storm watch on our web page (weather.gov/medford) for more details on the hazard. Once the front passes through late Monday night, snow levels will rise from 3500 feet up to 5500 feet and the precipitation will decrease into the day Tuesday. -Smith LONG TERM...Wednesday through Saturday...The pattern does not necessarily quiet down Wednesday into Thursday, as a weaker warm front. Snow levels will be on the rise and thus snow concerns lower, though the snow melt is likely to sustain flow in smaller creeks. Friday and beyond, model guidance is hinting at potential ridge amplification later next week, which would deflect the storm track farther to the north and result in a period of drier, milder weather here (albeit at the expense of low clouds/fog, and frost). The trend is going towards less amplification, which would allow for the southern end of decaying fronts to impinge on the coast. Some light PoPs and precip were kept there, but generally places inland from the coast range remain dry in the extended. A squashed ridge would allow for more cloud cover though, which will modulate the amount of fog and frost each morning. -Miles && .MFR WATCHES/WARNINGS/ADVISORIES... OR...High Wind Watch from Monday afternoon through Tuesday morning for ORZ030-031. High Wind Watch from Monday afternoon through late Monday night for ORZ021-022. CA...High Wind Watch from Monday afternoon through Tuesday morning for CAZ085. Winter Storm Watch from Monday afternoon through Tuesday morning above 3500 feet in the for CAZ080-082-083. High Wind Watch from Monday afternoon through late Monday night for CAZ081. Pacific Coastal Waters... Gale Watch from Monday afternoon through late Monday night for PZZ370-376. Small Craft Advisory until 1 PM PST Monday for PZZ350-356-370-376. Hazardous Seas Watch from Monday afternoon through late Monday night for PZZ350-356-370-376. High Wind Watch from Monday afternoon through late Monday night for PZZ356. $$ DW/BPN