173 FXUS66 KMFR 192047 AFDMFRArea Forecast Discussion National Weather Service Medford OR 147 PM PDT Fri Sep 19 2025
.DISCUSSION...Satellite image the circulation of the upper low just northeast of the Bay area with most of the convective clouds north of the low center. Meanwhile cloud cover in our forecast area for the most part has diminished, but we still have varying amounts of high and mid level clouds, and increasing cumulus build ups east of the Cascades and Modoc County. Thus far, most of the lightning has been offshore west of Capetown California. Radar is also lacking of much activity, but that does mot mean that nothing will happen. Over the course of the afternoon (mid to late), we`ll see cumulus build ups in portions of northern Cal Cascades and portions ofthe eastside, followed by isolated thunderstorms later this afternoon into this evening. Isolated storms are expected to increase in numbers later this afternoon and evening before diminishing and ending later this evening. Most of the action is expected to be in Western Siskiyou County, and northern Cascades. However, steering winds will be from the east, and it`s not out of the question that a few of these storms could come off the terrain and migrate into portions of Josephine and Jackson county towards this evening.
Isolated storms will end this evening, with most hours and locations dry overnight tonight. However, some of the high res showing radar reflectivity shows some showers in the overnight hours in portions of Siskiyou County and into southern Josephine, Curry County, and over the marine waters from Gold Beach south. Right now we don`t expect any storms, but the evening night shift may need to take another look at this.
Saturday, the models are a but more robust with the QPF fields Saturday afternoon. However, were expecting more cloud cover which could put a cap on the amount of thunderstorms. The best chance for storms Saturday could get shifted a bit east compared to today, with Cascades east and northern Cal having the best chance of thunderstorms.
Showers and isolated storms will end Saturday evening with dry weather Saturday night. A weak upper trough and surface front will bring light rain mainly from Cape Blanco north along the coast and northwest Douglas county Sunday morning. The front will dissipate as it moves onshore, with showers ending towards midday with dry weather in the afternoon. Expect breezy winds east of the Cascades and the typical valley winds for the interior westside valleys Sunday afternoon into early Sunday evening.
In the wake of the upper trough, upper ridging will build in for Monday and Tuesday bringing dry and much warmer afternoon temperatures for the interior. However on the flip side with clear skies expected along with longer nights, this will open up the door for temperatures to drop off pretty quickly after dark for east of the Cascades, especially in the valleys with temperatures getting close to or just below freezing Monday night into Tuesday morning. Overnight lows Sunday night will be chilly as well, but were not expecting lows to drop below freezing.
Beyond Tuesday, the operational models and ensembles are in better agreement with the overall pattern. Dry and warm weather will continue Wednesday. However the cutoff upper low will inch just close enough to our area where portions of Modoc County could see an isolated thunderstorms late in the afternoon and evening, otherwise it shaping up to be a continuation of dry weather with above normal temperatures for next week. -Petrucelli
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.AVIATION...19/18Z TAFs...Along the coast and just offshore, especially from Cape Blanco northward, marine stratus is resulting in IFR ceilings. These have broken to VFR at North Bend and this should persist through most of the afternoon. However, expect IFR stratus to move back inland this evening, affecting North Bend. Conditions could lower to LIFR overnight into Saturday morning. Inland, VFR will prevail for the next 24 hours with fairly typical light, diurnal breezes. Isolated showers and thunderstorms will be a concern in northern California, and the Cascades. Steering flow suggests a few of these storms could push off the higher terrain into portions of Jackson county between 23-03z, but we do not expect them to impact the Medford Terminal. Similarly, one could drift close to Klamath Falls. -Spilde
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.MARINE...Updated 230 PM PDT Friday, September 18, 2025...Winds and seas will gradually diminish this afternoon, with conditions falling below small craft early this evening. Relatively calmer conditions are expected tonight through Sunday morning. However, could not rule out a few isolated showers over the southern marine waters tonight.
A front will move through the waters Sunday morning. Behind the front a thermal trough will develop along the south Oregon coast with north winds increasing mainly south of Cape Blanco. At the same time, a northwest swell will begin to build into the waters Sunday afternoon, and the combination of the two could result in Small Craft conditions for the area mentioned above.
The thermal trough will strengthen some Sunday night into early next week with moderate to occasionally strong winds, strongest south of Cape Blanco. -Petrucelli
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.FIRE WEATHER...Updated 200 PM PDT Friday, September 19, 2025...A broad area of moisture will bring isolated showers and thunderstorms today and Saturday. While a stray storm could develop west of the Cascades and over the far east side, the main focus for activity will be in NorCal (especially western Siskiyou County), and also perhaps up along the Cascades. Similar areas will be affected Saturday, except with a slight shift to the south and east. On Sunday, a cold front will move through with some light rain/drizzle along the coast and into NW Douglas County, but it will likely be a dry frontal passage elsewhere. Gusty afternoon west winds are possible, especially east of the Cascades. Our in-house RAWS guidance is still showing peak wind gusts in the 25-35 mph range for some of the typically windier RAWS sites over the East Side. Some west side valleys too could have breezy winds for a time Sunday afternoon/evening.
Upper ridging builds Monday and Tuesday, so it will dry out and warm up. That said, there will be some cool to chilly mornings with steep inversions (coldest east of the Cascades with temps possibly down near freezing). There should be a period of ENE winds (not too strong) on the upper slopes/ridges Sunday night/Monday (with good RH recovery), then again Monday night/Tuesday with poor to moderate RH recovery (winds should be a bit lighter).
After that, what had looked like a wetter period potentially setting up mid-late next week, now looks much less likely. Some guidance was showing a low coming up into our area with showers/t-storms. But, now, most solutions take that low farther to our south and east into the Great Basin, keeping us in a drier, warmer (hotter?) pattern. This low might graze our SE zones with showers/thunder Wednesday (but even that is up in the air now). NBM now has 96F for Medford on Tuesday. And, some guidance now is even hinting that the 90+ warmth could last through the end of the week. With more/less split flow aloft mid-late next week, and a slow lowering of heights should at least bring slightly cooler temps compared to Tuesday`s warmth, but with much less chance at precip. There are still wide variety of solutions at this range, so it pretty much goes without saying that our confidence beyond Tuesday remains quite LOW. -Spilde
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.MFR WATCHES/WARNINGS/ADVISORIES... OR...None.
CA...None.
PACIFIC COASTAL WATERS...Small Craft Advisory until 5 PM PDT this afternoon for PZZ350-356-370-376.
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NWS MFR Office Area Forecast Discussion