475 FXUS66 KMFR 242106 AFDMFRArea Forecast Discussion National Weather Service Medford OR 206 PM PDT Wed Sep 24 2025
.DISCUSSION (Today through Tuesday)...
Overview:
Overall, weather hazards/impacts continue to be low based on a scale of low/moderate/high. Notable items include the hot temperatures today for westside areas. These temperatures are around 15+ degrees above normal for some locations. This week will also be noted by a drying trend. Lastly, a pattern change could occur Sunday into early next week with more seasonable temperatures, breezy/windy conditions, and rainfall chances. However, uncertainty does exist on some of the finer details so please stay tuned.
Further Details:
An H5 low remains to our south, while high pressure continues over the forecast area. This low will slowly track over southern California tomorrow and Friday and remain in this generally location through this weekend as an Omega Block continues over the CONUS. This week will be noted by mostly high pressure over our forecast area, above normal temperatures, and dry conditions. In fact, a record may be in jeopardy today as we flirt with triple digits over westside areas. The record for Medford is 99 today (set in 1991), and we are forecasting a high of 98. The normal temperature for Medford this time of year is 82 degrees.
After this week of dry and above normal temperatures, our attention will turn towards a potentially strong upper level low which could bring widespread rainfall to the forecast area. There is a lot of uncertainty with regards to rainfall amounts and areal coverage. However, confidence is high for more seasonable temperatures. Cluster analysis indicates high confidence for a trough impacting the region starting Sunday and continuing into early next week, but the finer details are what is currently in question like rainfall and potential breezy/gusty areas. Deterministic models indicate H5 low orientation changes essentially each of the last several runs. Ensemble members are still showing a split of dry solutions and wet solutions, but recently seeing more members indicating a wetter solution. This recent increase in wet members does boost confidence for rainfall. That said, the highest confidence is for temperatures to be more seasonable early next week. For potential wind advisory and rainfall amounts, these details are somewhat in question but recent guidance has increased confidence. NBM is indicating a roughly 40-70% chance for at least 0.50" of rain for much of the westside, but these chances drop off significantly for eastside areas. We will likely continue to see fluctuations as models try to resolve the current blocking pattern. Confidence is also increasing for breezy conditions early next week as the NBM is now indicating a 20-60 percent probability for at least 20 mph sustained wind speeds across the eastside and the Shasta Valley. Still some things to narrow down like timing, areal coverage, and rainfall amounts, but confidence is increasing for these impacts Sun-Tues.
-Guerrero
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.AVIATION (18Z TAFs)...
Along the coast and just offshore, VFR conditions will continue into this early this evening. Marine stratus is likely to reform again between 2-3z at North Bend with IFR ceilings and reduced visibility, with stratus moving up along the south coast between 4-5z. The marine stratus is expected to persist until the end of the TAF period, although some guidance shows improving conditions towards 16-17z. Moderate to strong north winds are also likely at North Bend in the next hour or two and lasting into early this evening before diminishing tonight.
Elsewhere, VFR conditions will continue through the TAF period.
-Petrucelli
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.MARINE...Updated 200 PM PDT Wednesday, September 24, 2025...Gusty north winds will continue today which will result in steep to very steep seas. Winds will remain steady this afternoon, but may see a slight decrease late this evening and overnight. Strongest winds and steepest seas will be across the outer waters today and tonight then across the waters south of Cape Blanco tomorrow as wind speeds increase throughout the day. For tomorrow, the probability of wind speeds 22 knots or greater is about 95 percent for areas south of Cape Blanco. However, the probability for wind speeds of 30 knots or greater drops down to around 5-10% for the same area. Confidence is fairly high wind speeds will not be greater than 30 knots tomorrow. Gusty winds and steep to very steep seas may linger into Friday. Thereafter, wind speeds trend lower on Saturday into Saturday night before the next system starts to impact the region on Sunday.
-Guerrero
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.FIRE WEATHER...Updated 200 PM PDT Wednesday, September 24, 2025...Today will be the hottest day of the forecast period. Dry weather will continue through the weekend with afternoon temperatures trending downward for the interior. We`ll have improved overnight recoveries tonight with less wind for southwest Oregon and western Fire zone 280.
An upper trough will swing through the area Thursday morning with a dry cold front moving through the area. In the wake of the front, the pressure gradient will tighten up with gusty breezes setting up along and east of the Cascades Thursday afternoon and lasting into early Thursday evening. At the same time, relative humidity will be low, but not as low as what were expecting today. Were not expecting critical conditions to be met due to the combination of winds and relative humidity east of the Cascades Thursday afternoon, therefore we`ll continue to headline.
In the wake of the dry front there`s good agreement a thermal trough will set up along the south Oregon coast and models are showing rather robust northeast winds at 925 mb (15-20 kts) along the southwest Oregon coast, and 15-20 kt at 850 mb in portions of Fire zone 280, along with moderate to poor overnight recoveries. However, the combination of the two are not expected to reach critical conditions. There`s good agreement the thermal trough will remain in place Friday night into Saturday morning with continued enhanced winds and moderate to occasionally poor overnight recoveries.
Upper ridging will build southwest of the area Friday. Afternoon temperatures will be cooler, but still above normal. Upper ridging will weaken and shift to the east in response to a large and rather strong upper low sets up over the Alaska Panhandle Saturday. This will bring cooler temperatures and slightly higher humidities to the area.
The upper trough will deepen offshore Sunday with a stronger southwest flow setting up over the area. Winds aloft are expected to increase, especially east of the Cascades where they could experience moderate to occasionally strong winds in the afternoon and early evening. The good news is relative humidities will be higher.
The above mentioned upper low could be a play maker for the weather for early next week. The operational model, ensembles and clusters are all in agreement with a change in the pattern towards cooler and wetter Monday-Wednesday next week. There`s increasing confidence for wetting rain along and west of the Cascades. Meanwhile 700mb winds could be between 30-40 kts east of the Cascades which could result in moderate to strong winds.
-Petrucelli
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.MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...None.
PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT Thursday for PZZ350-356-370-376.
Hazardous Seas Warning from 11 AM to 11 PM PDT Thursday for PZZ356-370-376.
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NWS MFR Office Area Forecast Discussion