####018007688#### FXUS66 KMFR 040102 CCA AFDMFR Area Forecast Discussion...CORRECTED National Weather Service Medford OR 602 PM PDT Fri May 3 2024 ...New Aviation Section... .AVIATION (00Z TAFs)... A robust system is making its way on shore which will lead to widespread MVFR and IFR conditions across the region. Rain intensity and low level moisture will lead to both visibility restrictions and low ceilings through this cycle. It wont be until tomorrow afternoon that we start to see some relief from these diminished conditions. Until then, expect clouds to increase and rainfall to spread over the region tonight and overnight. We may see a mix of rain and snow on the eastside which would impact the terminal at Klamath falls tomorrow. At times, precipitation rates could limit visibility to 2 miles or less, with IFR to perhaps LIFR at times. Overall, unfavorable flying conditions are expected to start soon for at least the next 18 hours. -Guerrero && .PREV DISCUSSION... /Issued 304 PM PDT Fri May 3 2024/ SHORT TERM...Through Monday morning...An approaching low pressure system is already bringing rainfall to the Oregon coast. Rainfall will continue through the night over Coos, Curry, and western Douglas counties. Precipitation will steadily move eastward across the area through Saturday. Coastal areas will see about 2 to 3 inches of rainfall while west side valleys will get between half an inch and an inch of rain. Klamath and Modoc counties will get similar amounts of rainfall while Lake County will generally get half an inch of rain or less. The heaviest amounts will be late tonight through early Saturday morning. This system is bringing unseasonably cold air aloft, which will bring snow levels down from their current 8000 feet to 3000 feet by Saturday morning. While most snowfall will remain over higher terrain, the amount of moisture and the fast drop in snow levels will bring periods of heavy snow to the Cascades and to western Siskiyou County. Currently, 4 to 6 inches of snow are expected at elevations above 4000 feet for the Cascades and Siskiyou ranges, with a 20-30% chance of more than 6 inches over the Cascades by Sunday morning. Additionally, high resolution guidance shows a 40- 80% chance of snowfall rates of 1 inch per hour Saturday morning. Due to the dangerous travel conditions that these conditions are expected to make, a Winter Weather Advisory is in place for parts of western Siskiyou County from 2 AM to 11 AM on Saturday and for the Cascades from 2 AM to 11 PM on Saturday. This system will also bring elevated winds, especially across elevated terrain east of the Cascades. A Wind Advisory is in place for higher terrain in Lake County from Saturday at 5 AM through 5 PM. Gusty winds reaching over 40 mph are expected in this time, while wind gusts could still exceed 30 mph in other areas of Klamath, Lake, and Modoc counties. One final impact from this system will be a drop in nighttime temperatures from Saturday to Sunday. Temperatures will drop to the high teens to mid 20s for areas east of the Cascades. Below freezing temperatures are also possible west of the Cascades, although right now only the Shasta and Scott valleys look to be significantly below freezing. A Freeze Watch is in place for those valleys on Sunday morning, but below freezing temperatures are possible for the Rogue and Illinois valleys as well. Future guidance will help determine if additional products will be needed, bur right now that looks unlikely. The effects of the system continue through Sunday, but are most likely limited to post-frontal showers over the Oregon coast and the Cascades. Cool daytime temperatures will continue and nighttime temperatures look to warm from Saturday night's levels. -TAD LONG TERM DISCUSSION...Models continue to show a front moving across the area on Monday with high chances (60 to 100 percent) across most the area. Precipitation amounts with this front on Monday will be mainly light with some moderate amounts (0.25 inches or more) over the Cascades, coastal mountains and along the coast. Snow levels will range from 4000 to 5500 feet. Additionally, models and ensembles support a slight chance (20%) for thunderstorms Monday afternoon across portions of southwest Oregon, including Coos, Douglas, Klamath and Lake Counties. Brief downpours and gusty winds may occur with any thunderstorms that develop. Then, moist, onshore flow will allow for lingering showers on Tuesday, especially across southwest Oregon zones with lesser chances across Northern California. High pressure builds into the area Wednesday and remains in place through the end of the wee. This will bring drier and much warmer weather. By Friday, high temperatures will likely be in the 80s for valleys west of the Cascades and in the 70s for valleys east of the Cascades. AVIATION...03/18Z TAFs...Prevailing VFR this morning will drop back to MVFR with local IFR cigs/vsbys as a potent cold front moves in, with periods of moderate to occasionally heavy precipitation this afternoon. VFR will prevail elsewhere inland through late this afternoon/early this evening. The front will spread moderate precipitation across the rest of the west side tonight, reaching east of the Cascades Saturday morning. Expect widespread MVFR conditions and local IFR in rain with higher terrain obscured in rain/snow. A rapid drop in freezing levels will occur overnight (~09-15Z) from west to east and especially around 12Z Saturday morning near the Cascades. Rain will change to snow down to as low as 2500 feet with brief heavy snow in the mountains, reducing visibility to LIFR at times. Breezy south winds are expected with the front too, with peak gusts in the 40-50 mph range. Despite the increasing winds, low level wind shear is not a concern at this time. Conditions should improve a bit behind the front with precipitation becoming more showery, but still with a good amount of MVFR ceilings/visibility through tomorrow morning. -Spilde/BPN MARINE...Updated 200 PM Friday, May 3, 2024...A cold front will move through today into this evening with moderate to heavy rain, gusty south winds and steep seas. Following the front, seas will remain steep, dominated by fresh short period west swell through tonight. Showers continue with a slight chance of thunderstorms (20%) on Saturday. West seas trend less steep Saturday afternoon through Sunday. Another front arrives Sunday night into Monday with the potential for gusty south to southwest winds followed by building west-northwest seas into Tuesday. After that, we expect high pressure to build in mid-late next week with a thermal trough strengthening along the coast. This will bring a return of stronger north winds and steep seas, highest south of Cape Blanco. -Spilde/BPN && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Winter Weather Advisory from 2 AM to 11 PM PDT Saturday above 4000 feet for ORZ027-028. Wind Advisory from 5 AM to 5 PM PDT Saturday for ORZ030-031. CA...Winter Weather Advisory from 2 AM to 11 AM PDT Saturday above 4000 feet for CAZ080. Freeze Watch from late Saturday night through Sunday morning for CAZ080-081. PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT this evening for PZZ350-356-370-376. && $$