FXUS66 KMFR 050456 AFDMFR Area Forecast Discussion National Weather Service Medford OR 856 PM PST Mon Mar 4 2024 .DISCUSSION...No updates planned for this evening. The last system in our series of winter weather storms is impacting the region this evening. Snow levels have risen to around 3000-3500 ft for most locations as warmer air from the south nudges up against the lingering cold air from the north. This boundary lies roughly along a line from Cape Blanco to Crater Lake and has brought an end to most of the low elevation snow concerns, with the bulk of additional winter weather impacts expected above 3500 ft tonight into Tuesday morning. The exception will be along and north of the Umpqua Divide where colder air lingers at lower elevations and winter impacts are expected above 1500 ft. Guidance continues to show rain transitioning to snow at even lower elevations north of the Umpqua Divide with snow falling possibly as low as 500 ft after midnight tonight. Numerous winter weather headlines remain in effect for tonight's event, and details can be found at WSWMFR. For more details on this event and the transition to drier weather followed by additional systems more typical for this time of year, see the previous discussion below. /BR-y && .AVIATION...05/00Z TAFs...Widespread showers are starting to develop across northern California and southern Oregon. Warm air from the south is meeting cold air from the north, resulting in steady precipitation chances for the area through the TAF period. Model guidance suggests the cold air will remain over Coos and Douglas counties, with snow levels of 1000-1500 feet over those areas. Snow levels in other areas are forecast to be 3500-4500 feet. Generally, VFR or MVFR levels are expected although heavier showers can lower ceilings and visibilities as well as obscure terrain. Periods of IFR ceilings and visibilities may be possible around Roseburg and Medford if activity is constant or heavy enough. Snow showers will be possible over Klamath Falls overnight, but snow levels may rise above 4000 feet and bring rain showers over the area on Tuesday morning. -TAD && .MARINE...Updated 800 PM Monday March 04, 2024...Low pressure will move into the waters south of Cape Blanco late this evening and tonight. High res models suggest the area of Small Craft conditions with southwest winds should be confined to areas from about Gold Beach south out to 20 nm from shore, and out to 60 nm from shore south of Pistol River. Meanwhile winds north of Gold Beach are expected to be from the north. The wind direction could vary some depending on the exact location of the low. To account for this, adjustments were made to the areas affected by small craft conditions. Northerly winds are then likely to increase over the outer waters Tuesday night into Wednesday evening, and are likely to reach advisory strength at least south of Cape Blanco. -Petrucelli && .PREV DISCUSSION... /Issued 350 PM PST Mon Mar 4 2024/ SHORT TERM... The radar is starting to fill in ahead of the warm front starting to push into southern Oregon and northern California. Snow will mainly accumulate over 3500 feet, although there are some notable low areas, especially in the Umpqua Basin where it will be lower as models want to bring in some cooler air to that location. The warm front will stall out and the front will become stationary for a few hours leading to cooler air north of Lake, Klamath, Jackson and Josephine counties with warmer air to the south. Our biggest concern over the last few hours has been assessing the risk of low level snow in the Umpqua Basin. There is low probability of a heavy snow event there if snow levels are able to really crash to the valley floors under the heavier precipitation. This most likely solution is snow levels staying around 1500 feet and the heavy snow falling above that elevation. High resolution soundings showed temperatures slightly above freezing around the surface and isothermal at 32 degrees for a few hundred feet above the boundary layer. This suggested at least some risk of this snow making it to the valley floors in the Umpqua Basin later tonight, so we issued a winter weather advisory down to 500 feet with the winter storm warning at 1500 feet. Snow ratios should be pretty low(~7:1) given the surface temperatures and temperatures in the boundary layer. The lower passes on I-5 will also be under threat depending on where the cooler air stops sagging south. In addition, the higher Cascades could see a quick 2 feet of snow in 24 hours. That is a solid 1" an hour snowfall rate and that would likely result in travel difficulties Monday night and Tuesday morning. Locations east of the Cascades should also see some impacts from the snow accumulation as well, especially along highway 97 near Chemult and Crescent. For more details on snow accumulations in certain locations, check out the Winter Storm Warnings on our main page weather.gov/medford. Eventually, this stationary front will dissipate and cooler air will move in from the north by later Tuesday afternoon. Precipitation will dissipate as high pressure gradually begins to build over the forecast area. -Smith LONG TERM DISCUSSION...(Wednesday 3/6 through Monday 3/11)...A stationary front over the area will weaken and shift south during the day Wednesday. Light precipitation is favored across northern California and for areas from the Cascades east in southwest Oregon. Precipitation tapers off Wednesday evening. Northern portions of the area (Coos, Douglas, northern Klamath and northern Lake Counties) are likely to remain dry but colder on Wednesday morning. This will bring a potential for temperatures in the lower teens to northern Klamath and northern Lake counties and low temperatures in the upper 20s or lower 30s to valleys in Douglas and Coos Counties. The National Blend of Models shows a 70% chance of temperatures at or below freezing in the lower Umpqua Basin and Coquille Valley. Additionally, there is a 30% chance of freezing temperatures along the Coos and Douglas coast. On Thursday, models continue show good agreement with a shortwave ridge of high pressure building into the area and have trended weaker with a front moving over the ridge. So expect dry weather on Thursday along with cold morning temperatures and mild to cool daytime highs. Morning lows are expected in the 10 to 20 range east of the Cascades, in the 20s for valleys west of the Cascades. Coastal areas are likely to see lows in the mid 30s with a potential for frost. Friday night into Saturday, an upper trough and frontal system approach from the northwest then move into the region. This will bring rain and snow over the area, Another stronger front, is forecast to move into the area late Sunday into Monday morning with rain, snow and gusty winds. Models are showing snow levels ranging from 3500-5000 feet as precipitation spreads into the area with these fronts. So the highest chance for snow impacts will be over the higher mountain passes. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Winter Storm Warning until 4 PM PST Tuesday for ORZ029>031. Winter Storm Warning until 4 PM PST Tuesday above 1500 feet for ORZ023. Winter Weather Advisory until 10 AM PST Tuesday above 500 feet for ORZ023. Winter Storm Warning until 4 PM PST Tuesday above 3000 feet for ORZ024-026. Winter Storm Warning until 4 PM PST Tuesday for ORZ025-027. Winter Storm Warning until 4 PM PST Tuesday above 3500 feet for ORZ028. Winter Weather Advisory until 4 PM PST Tuesday for ORZ029>031. CA...Winter Storm Warning until 4 PM PST Tuesday above 3500 feet for CAZ080-081. Winter Storm Warning until 4 PM PST Tuesday above 3000 feet for CAZ082. Winter Storm Warning until 4 PM PST Tuesday above 3500 feet for CAZ083. Winter Storm Warning until 4 PM PST Tuesday for CAZ085. PACIFIC COASTAL WATERS...Small Craft Advisory until 4 AM PST Tuesday for PZZ356-376. && $$ MNF/TAD/CZS