


Area Forecast Discussion
Issued by NWS Medford, OR
Issued by NWS Medford, OR
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638 FXUS66 KMFR 022353 AFDMFR Area Forecast Discussion National Weather Service Medford OR 453 PM PDT Wed Jul 2 2025 .DISCUSSION...Updated Aviation Section... && .AVIATION...03/00Z TAFs...Marine stratus is developing towards Coos Bay this evening and will continue through the night with IFR/LIFR conditions. Marine layer depth could increase enough to bring some clouds to the Umpqua Valley after midnight and into the morning, but flight levels are expected to stay at VFR. Inland areas have gusty winds, and this will weaken through the evening. VFR conditions are forecast to remain at VFR through the TAF period, though isolated to scattered thunderstorms east of the Cascades could briefly lower conditions. Any thunderstorms can produce gusty outflows of 35-55 kt. -Spilde/Hermansen && .PREV DISCUSSION... /Issued 132 PM PDT Wed Jul 2 2025/ DISCUSSION...Low pressure continues to move inland across southern California this afternoon with an elongated trough axis to its north which extends across south-central Oregon. This will swing through east side areas this afternoon/evening, which, with decent instability due to daytime heating, should be enough to kick off isolated to scattered thunderstorms. Satellite imagery is showing congested cumulus developing in portions of eastern Klamath/Lake counties and expect these to continue to do so there this afternoon, but also from around Medicine Lake eastward across NorCal. These areas stand the highest probability of lightning this afternoon/evening before drier air and westerly flow aloft pushes this activity eastward and instability wanes around sunset. Storms this afternoon and evening will move a little faster than the ones yesterday due to increasing steering winds aloft, so there could be some dry strikes, and thus, a Red Flag Warning is out until 8 pm PDT this evening. Gusty outflow winds and hail beneath the stronger cells also pose a risk. We`ll be dry overnight, but marine layer will deepen again along the coast, where we expect the usual infiltration of stratus/fog. This will be most prevalent from Cape Blanco northward, but also in an area south of Pistol River near Brookings. Model soundings show moisture pooling in the Umpqua Valley too, where patchy low clouds could form toward sunrise (near and primarily to the NW of Roseburg). Other than some cirrus remnants from today`s storms, skies should turn out mostly clear elsewhere. Fast flow across the north Pacific will allow another shortwave disturbance to approach the coast on Thursday. Once again, models are showing enough forcing and instability to generate isolated to scattered showers/t-storms for areas primarily from the Cascades eastward. While a pop-up shower/storm is possible before 2 pm, most of the activity will occur after that as the trough gets closer. The trough axis takes on a negative tilt Thursday night and this will keep a chance of showers/isolated thunder in the forecast, even during the night. This activity will last into Friday as the axis of the trough pushes through. For areas west of the Cascades, moisture and instability are more limited, so shower chances are minimal during this period and generally less than 10%. Temperatures the next few days (through Saturday) should be right around normal, which for Medford would be highs in the mid-upper 80s and lows in the mid-upper 50s. The 4th of July will be the coolest day across the area, which is a stark difference from last year (2024) when some record highs were set for the date, including 105F here in Medford. Our current forecast for Medford on the 4th is a pleasant 83F! Short wave ridging sets us up for dry weather Friday night, which will be the coolest night of the stretch. This lasts into Saturday, but you guessed it, another trough will approach the coast from the NE Pacific. This one has less moisture available and current model data suggests instability will also be low in advance of it. As such, we are carrying a dry forecast. We`ll keep watching guidance to see if there are any adjustments necessary here. We may have to add showers/thunder to the forecast, especially Sunday as some moisture tries to move in, but at this point, activity looks isolated at best. Model ensembles/clusters maintain a weakness/trough near the area or just offshore through early next week, but they also show heights rising and the Four Corners upper ridge retrograding back to near the Great Basin. This would send temperatures back up to near or even above 100F here in Medford in the Monday-Wednesday time frame. -Spilde MARINE...Updated 200 PM PDT Wednesday, July 2, 2025...Gusty northerly winds and steep seas continue for waters south of Cape Blanco. Latest models have now held onto the weakening thermal trough through through tonight and into Thursday, keeping small craft advisory conditions in place for about 24 hours longer than previously thought. Relatively calm conditions are expected Friday, then the thermal trough pattern returns with gusty north winds and steep seas by Saturday afternoon and persisting into early next week. -BPN FIRE WEATHER...Updated 230 PM PDT Wednesday, July 2, 2025... Thunderstorms continue to be the main concern. We saw another roughly 1000 lightning strikes across the forecast area yesterday, on top of the nearly 1000 strikes seen the previous day. We expect to see another round of thunderstorms this afternoon and evening, mainly along and east of the Cascades, followed by more thunderstorms Thursday afternoon and evening, again mainly east of the Cascades, but concentrated more towards central and northern Lake and Klamath counties. A Red Flag Warning remains in effect for FWZs 284, 285, 624, and 625 today. Storms today should behave much like yesterday, generally in a pulse- like manner, but should have more motion associated with them, trending towards southwest to northeast movement. This means some storms could be dry, and there is less chance for wetting rains as the cells are not expected to remain over the same areas for very long. Keep in mind, lightning strikes outside of the precipitation cores are possible. Due to the prolonged period of dry and warm to hot weather, lightning efficiency will be high to very high for fire starts. We also have to be mindful of gusty and erratic outflow winds near and away from the core of thunderstorms. Thunderstorms will be a concern again tomorrow (Thursday) afternoon and evening, and many models are showing convection continuing into the overnight hours and even into Friday morning. Any overnight storms are much more likely to be high-based, and would then have much more likelihood of being dry. While most guidance, and the typical pattern, shows showers and thunderstorms during this time still concentrating on Klamath and Lake counties (and perhaps a bit into Modoc), one or two models have a band of convection running up the Cascades from Mount Shasta to Bend late Thursday evening into Thursday night. This is the outlying solution, thus unlikely, but something to consider. Additional thunderstorms are then possible again Friday, and again, concentrated on Klamath and Lake counties. Due to this, another Red Flag Warning has been issued for portions of Fire WX zones 624 and 625 north of highway 140 and east of highway 97 for Thursday afternoon and evening. Should nocturnal storms continue, especially dry ones, this Red Flag may be extended out through Thursday night. All of this is due to the slow moving overhead trough and continuing monsoonal moisture inflow that has stuck around all week. Fortunately, it does appear that the trough will exit by Saturday, and it appears that this will be the first day with no thunderstorm chances anywhere within the forecast area. This break in the action may be short-lived, however, as another upper level trough arrives late in the weekend, and convective chances may once again return Sunday into Monday. The deep southerly moisture flow should have ended by that time, so with the lack in moisture, convection may not be as widespread or as active, if it occurs at all. Otherwise, the forecast will be for continued near to slightly above normal temperatures, seasonal humidities, and the typical diurnal wind patterns, although general east flow late this weekend into early next week could lead to drying, especially across the ridgelines, where poor to moderate recoveries are possible. -BPN && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning until 8 PM PDT this evening for ORZ624-625. Red Flag Warning from 2 PM to 8 PM PDT Thursday for ORZ624-625. CA...Red Flag Warning until 8 PM PDT this evening for CAZ284-285. PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PDT Friday for PZZ356-376. && $$