FXUS66 KMFR 211130

AFDMFR



Area Forecast Discussion

National Weather Service Medford OR

430 AM PDT Mon Sep 21 2026



.KEY MESSAGES...



* Seasonable temperatures and dry conditions will prevail most of

  the upcoming week but temperatures trend below normal end of 

  week



* Rain chances increase Thurs/Fri (20%-60%) with isolated 

  thunderstorm possible (10%-20%)



&&



.DISCUSSION...



A closed low is passing south of the forecast area today. As we 

reach peak heating today, there is a very small chance for some 

cumulus buildups, and this means we have about a 5%-10% chance of 

one or two becoming a shower/thunderstorm over northern California

where some lift will be possible. Most likely there wont be much 

activity today, and it may end up being cumulus scattered across 

the area. High clouds will likely limit destabilization as well, 

so this is an extremely low chance for lightning today but worth 

mentioning. 



As the low exits to the east, we will experience mostly zonal 

flow over the forecast area which will lead to generally quiet 

weather with very little impacts/hazards for the following 

couple days. That said, by Thursday the upper flow becomes more 

southwesterly as a trough develops over the Pacific. Deterministic

models differ in the trough axis timing coming over the west 

coast and the forecast area, so confidence is low for 

timing/coverage of potential rain and isolated thunderstorms, but 

generally looking at increasing chances for both starting Thursday

and continuing through Friday. Activity at this time appears to 

stay mostly over westside areas. Currently, instability is very 

meager, so not expecting much in the realm of thunderstorm 

chances, but we could see light rainfall across westside areas. 



Thereafter, temperatures drop as the trough pushes eastward. For 

example, Medford may only reach the upper 60s for a high on Friday

with temperatures struggling to reach the lower 70s through the 

weekend. In other words, expecting a cool down later in the week 

to below normal temperatures in the wake of the upper trough

across the region.



&&



.AVIATION (12Z TAFs)...



Along and near the coast a marine layer has brought low ceilings

(IFR) which is impacting KOTH and will likely continue through the

remainder of the cycle with ceilings around 1000 ft. While close

to KRBG, current thinking is these low ceilings wont make it into

Roseburg albeit very close. This means inland TAF sites should 

remain in VFR through this cycle with only high clouds expanding 

across the area from the south where a low pressure system is 

passing.



&&



.MARINE...Updated 330 AM PDT Monday, September 21, 2026...Gusty 

north winds will maintain steep seas south of Cape Arago through 

this evening with very steep seas over the inner and partial outer

waters south of Brookings starting this afternoon as winds 

increase. Winds ease some on Tuesday and conditions will improve 

north of Cape Blanco as seas become less steep and transition to 

swell dominated. However, steep to very steep seas likely persist 

south of Cape Blanco through Tuesday evening. Conditions gradually

improve Wednesday into Thursday.



&&



.MFR WATCHES/WARNINGS/ADVISORIES...

OR...CA...None.



PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT Tuesday 

     for PZZ356-376. 



Hazardous Seas Warning from 2 PM this afternoon to 11 PM PDT 

     Tuesday for PZZ356-376. 



     Small Craft Advisory until 2 PM PDT this afternoon for PZZ350-

     370. 



&&



$$