648 FXUS66 KMFR 031214 AFDMFR Area Forecast Discussion National Weather Service Medford OR 514 AM PDT Fri May 3 2019 .DISCUSSION...A Frost Advisory and Freeze Warning remain in effect this morning for portions of Josephine and Jackson Counties. Right now, temperatures across the area vary from a few degrees cooler to a few degrees warmer than they were 24 hours ago. For Saturday morning, they should be nearly universally warmer. Remaining sufficiently warmer that west side valleys are indicated to be frost-free for the next week, with above normal lows on the east side as well beginning on Sunday morning. The recent spell of above normal high temperatures inland will kick it up a notch today, continue to trend more modestly higher during the weekend, then likely persist near those levels for the next week. The warming trend of a few to several degrees through the weekend will also be present with low temperatures. Meantime, temperatures at the coast will remain near normal with the exception of a warmer than normal readings at Brookings. The warming is in response to the trough that has been centered over the Rockies tracking eastward while a ridge far offshore builds toward the Pacific Northwest and a closed low heads toward southern California. Model agreement is quite good through Tuesday. By Tuesday, the ridge will still be centered far offshore while the southern stream trough moves into Arizona. The approach and arrival of the low into California will bring a modest increase in moisture in the 700mb-500 mb layer, generally highest for far southern portions of Siskiyou and Modoc Counties with a few late day low-topped cumulus buildups likely today and Saturday. A shortwave in the north to northwest flow aloft will likely track across far eastern Oregon on Sunday while the trough reaches the California coast. This should bring an increase in mid and upper level clouds, but the large majority of convective showers and thunderstorms will remain south of our area. There is a slight chance of late day showers for southern Siskiyou County. Future sets of data will need to be scrutinized as it would not take much of a shift in the pattern to expand the risk of thunderstorms during late Sunday into at least Siskiyou county. The pattern will likely stabilize on Monday as the southern stream trough moves farther inland, and the ridge more fully dominates our weather. The 06Z GFS has trended closer to the 00Z ECMWF with a north to south steering flow setting up farther to the east, sufficiently so to keep the more substantial regions of instability and higher mid-level moisture south and east of our area. But, confidence is still in the low to moderate range. Beyond Tuesday, model differences increase with varying extents to which a low will retrograde into Nevada and southern California. This would at least bring a very noticeable increase in east side wind speeds, and could also bring the possibility of showers and thunderstorms. We will stick with a dry solution for now, given the drier ECMWF, as well as that a majority of GEFS members are dry, and with some small respect for persistence. In any case, the probability of showers would be highest over the far eastern portions of Lake and Modoc Counties. The interplay of the Great Basin trough and eastern Pacific ridge will dominate the latter portion of the forecast with east side winds likely remaining at least breezy during Thursday and Friday and the highest probability of any instability remaining higher the farther that one travels eastward (perhaps solely over the Warner Mountains, perhaps east of our area). && .AVIATION...For the 03/12Z TAFS...Over the coastal waters and along the coast...Areas of MVFR/IFR cigs offshore will move onshore Friday evening, then burn back offshore by Saturday afternoon. It will be windy, especially in the afternoons and evenings with the strongest winds south of Cape Blanco. Over the remainder of the area...VFR conditions will prevail through Saturday afternoon. && .MARINE...Updated 215 AM PDT Friday 3 May 2019...Offshore high pressure and a thermal trough near the coast will both persist through Tuesday and beyond. This will bring strong north winds and choppy wind-driven seas to the entire area. The winds and seas will peak in the afternoon and evening hours, with the strongest winds and steepest seas south of Cape Blanco beyond 5 NM of the coast, except closer in near the capes. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Frost Advisory until 8 AM PDT this morning for ORZ024-026. Freeze Warning until 8 AM PDT this morning for ORZ024. CA...None. Pacific Coastal Waters...Small Craft Advisory until 5 PM PDT Sunday for PZZ356-376. Hazardous Seas Warning from 11 AM this morning to 5 PM PDT Saturday for PZZ356-376. Small Craft Advisory until 5 PM PDT Sunday for PZZ350-370. $$ DW/JRS/DW