Area Forecast Discussion
Issued by NWS Medford, OR
Issued by NWS Medford, OR
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068 FXUS66 KMFR 230404 AFDMFR Area Forecast Discussion National Weather Service Medford OR 904 PM PDT Wed May 22 2024 .DISCUSSION...Winds have dropped below advisory conditions this evening in Lake County, where our Wind Advisory has been allowed to end. Winds throughout the region have begun to calm, though some mild breeziness can be expected for the next hour or so. Conditions will calm fairly rapidly overnight as the upper level disturbance moves out of the PNW and a weak ridge builds in behind it. The air behind this is quite dry, and observations this evening show low dewpoints. With stable conditions aloft and dry air, radiational cooling will be quite efficient tonight and low temperatures early Thursday morning will be quite cool for the time of year. In other words, the frost advisory in parts of the Illinois, Applegate, and northern Rogue valleys for early Thursday morning looks to be on track this evening. For more details, please see the previous discussion below. -CSP && .AVIATION...23/00Z TAFs...Gusty northwest winds will continue to diminish overnight. Otherwise, fairly quiet and non-impactful aviation conditions are expected through Thursday. Sandler && .MARINE...Updated 900 PM Wednesday, May 22, 2024...Conditions hazardous to small craft will continue through Wednesday evening then seas and winds lower overnight. Conditions improve under high pressure Thursday with gusty north winds developing nearshore south of Cape Blanco in the afternoon. Another low pressure Friday brings light rain, then fair weather and benign winds and seas are expected through the weekend. && .PREV DISCUSSION... /Issued 251 PM PDT Wed May 22 2024/ DISCUSSION...An upper level low pressure system has moved past the area, but northwest flow behind the system will guide conditions this evening. A Wind Advisory will continue until 8 PM tonight for most of Lake County tonight to address gusty winds associated with this system. This flow will also bring cooler nighttime temperatures, with lows in the mid 20s to low 30s east of the Cascades and in the low 30s to low 40s west of the Cascades. A Frost Advisory is in place for Thursday morning between 3 AM and 8 AM for the Illinois and Applegate valleys as well as areas around Rogue River and between White City and Shady Cove. The pattern looks to remain active but unimpactful into next week. A weak ridge will bring seasonal warmth on Thursday and a weak trough will follow, lingering over the area to start the weekend. will cool temperatures again on Friday. The trough will bring slight precipitation chances over the Cascades (25-50%) from Friday evening to Saturday evening. And for Friday evening, upper level instability supports slight (10-15%) chances for thunderstorms over Lake, Modoc, and eastern Klamath and Siskiyou counties. A more resilient upper ridge follows on Sunday, bringing above average temperatures across the area into the middle of next week. Next Wednesday`s daytime highs will reach the mid 60s along the Oregon coast and low to mid 80s in west side valleys. Areas east of the Cascades are expected to reach the mid to high 70s. Considering Brookings specifically, models show periods of easterly winds that may cause a Chetco Effect and bring higher than forecast temperatures, but that much detail is difficult to determine with any confidence this far out. There is substantial uncertainty in the forecast past next Wednesday. Both the ECMWF and GFS models show the ridge moving east with an upper trough related to a low pressure system bringing more cool weather and scattered precipitation. The timing on this pattern change varies by about 12 hours, with the ECMWF having the trough arrive late Tuesday morning while the GFS expects a Tuesday evening/Wednesday morning arrival. This uncertainty is also reflected in NBM statistical guidance. For Thursday, the interquartile range for Medford`s high temperature (25th through 75th ensemble percentile) is 72 to 88 degrees, and then 75 to 93 degrees next Friday. This indicated a fairly large degree of uncertainty. Long-term precipitation meteograms for both models show a similar lack of confidence in a single outcome. This disagreement grows into the end of next week, with ECMWF deterministic imagery showing a developing ridge while the GFS brings a low pressure system over the Pacific Northwest. -TAD AVIATION...22/18Z TAFs...Gusty northwest winds will impact Medford and Klamath Falls through early this evening then fairly quiet and non-impactful aviation conditions are on tap through Thursday. Stavish MARINE...Updated 230 PM Wednesday, May 22, 2024...Conditions hazardous to small craft will continue through the evening then seas and winds lower overnight. Conditions improve under high pressure Thursday with some gusty north winds developing nearshore south of Cape Blanco in the afternoon. Another low pressure Friday brings some light rain, then fair weather and benign winds and seas are expected through the weekend. with && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Frost Advisory from 3 AM to 8 AM PDT Thursday for ORZ024-026. CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT this evening for PZZ350-356-370-376. && $$