932 FXUS66 KMFR 041735 AAA AFDMFR Area Forecast Discussion National Weather Service Medford OR 1035 AM PDT Fri Jul 4 2025 ...Updated aviation section... .DISCUSSION...The overnight thunderstorms in our area, almost exclusively in Klamath and Lake counties, have been prolific lightning producers, but otherwise have been weak as regards wind speeds and hail production. This isolated to scattered activity will continue this morning, and increase again this afternoon into the early evening from the Cascades and Shasta Valley eastward, with the focus of activity still in Klamath and Lake counties. The Red Flag Warning for abundant lightning remains in effect for south central Oregon early this morning and Lake County this afternoon and evening. Two other noteworthy aspects of today`s weather will be: the slow erosion of low clouds that are presently at the coast into the coastal valleys, Umpqua Valley, and locally in the Illinois Valley. Secondly, while it is reasonable to expect another episode of at least slightly below normal temperatures later this summer, it is not far-fetched that today`s cooler temperatures could be the coolest high temperatures inland until after Labor Day. A strong warming trend starts Saturday with readings of 5 to 15 degrees above normal expected to be common from Sunday for at least the following 10 days. This will result in a lengthy episode of west side valley highs from the lower 90s to around 100 with east side valley highs around 90 to 95. An upper level low has reached the Oregon coast this morning and will continue across Oregon through early Saturday morning. Shortwaves rotating around the low will continue the aforementioned thunderstorm activity today. On a brighter note, a ridge will follow on Saturday with a stable air mass. Our chances are very good for another day without thunderstorms on Sunday, though with the next trough tracking southeast toward San Francisco weak diffluence aloft should support some cumulus buildups over northern California. Perhaps a weak cell or two could develop, but activity would be a far cry from the prolific lightning of yesterday and today. The latest model data is continuing to trend toward increasing instability for Monday and Tuesday afternoons with the trough beginning to move north-northeast up the northern California coast on Monday and across far northern California on Tuesday. But, the extent of thunderstorm development may be hindered by only a moderate amount of mid-level moisture. Model confidence is lower beyond Tuesday, but the general picture is for an active pattern that will keep the notable heat from getting extreme while producing mostly modest thunderstorm risks from day-to-day. && .AVIATION...04/18Z TAFs...Isolated to scattered thunderstorms be the main concern again this afternoon and evening along and east of the Cascades, mainly for Lake and eastern Klamath counties. Isolated showers and storms may extend all the way to the Shasta Valley in northern California. IFR/MVFR ceilings/visibilities are expected near any storms as well as gusty outflow winds and even hail. Also, a mix of IFR and MVFR at the coast extends into the coastal valleys. Expect slow improvement into the afternoon. But, the lower conditions return to coastal areas during the evening. Elsewhere, VFR will continue. -BS && .MARINE...Updated 200 AM PDT Friday, July 4, 2025...The main update was to issue a Small Craft Advisory that will start Saturday morning. First, conditions will remain relatively calm today. The thermal trough pattern returns Saturday, bringing gusty north winds. This will result in conditions hazardous to small craft south of Cape Blanco. The region of steep seas will likely expand early Sunday, reaching all of the waters during Sunday evening, while very steep seas will be possible south of Gold Beach during Sunday afternoon into Monday. Steep seas then are likely to persist into Tuesday morning. The outlook is for a brief improvement in conditions Tuesday into Wednesday. -DW && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning until 8 AM PDT this morning for ORZ623>625. Red Flag Warning from 2 PM until 8 PM PDT today for ORZ625. CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory from 8 AM to 11 PM PDT Saturday for PZZ356-376. && $$