Marine Weather and Tide Forecast for Yoncalla, OR

FXUS66 KMFR 222102 AFDMFR

Area Forecast Discussion National Weather Service Medford OR 202 PM PDT Thu May 22 2025

DISCUSSION
Generally, westerly flow will continue in the mid-levels throughout the next week, with periodic waves of energy passing over the area every other day or so. This low- impact pattern will keep temperatures near to above normal for this time of year (with a gradual warming trend as the pattern gradually becomes more ridge dominated), and also provide a few periods of shower and thunderstorm chances.

An weak upper trough passed over the area early this morning, and is now passing to the east. Arriving too early in the day to take advantage of daytime heating, only a few lingering showers remain along the northern Cascades, and these should taper off and end over the next few hours. Shortwave ridging is now building in and drying the area out, but this will be short lived, as the next weak upper trough arrives tonight into Friday morning. This impulse isn't expected to have much, if any affect on the weather, other than increased clouds and breezes, and perhaps a few showers or maybe even a lightning strike or two well east of the Cascades tomorrow afternoon.

A stronger ridge then builds in for the weekend, with dry conditions across the region on Saturday and Sunday, and temperatures rising to levels more typical of late June or early July.

The next upper trough will slowly move east towards the coast late Sunday afternoon, and if it gets close enough before the end of the day, it could trigger a few showers along the coast and an isolated thunderstorm or two in the northern Cascades. Otherwise, most shower activity will be along the northern portions of the forecast area through the overnight and morning hours. By Monday afternoon, the trough will shift to the east, and shower activity will intensify along and eats of the Cascades. With the cooler air aloft, and daytime solar heating in the afternoon, some modest instability is forecast to develop, so some isolated thunderstorms are possible, mainly across Klamath and Lake counties. Any precipitation should dissipate through Monday night as the trough exits to the east. Temperatures will be a little cooler Monday, with clouds and showers helping to keep temperatures right around normal for this time of year.

Models are indicating that ridging will then enter the area and remain in place through at least Wednesday or Thursday, keeping the area dry and pushing temperatures back to above normal.
Another trough may be lurking just offshore, however, and could enter the area late in the week with another round of showers and cooler temperatures. There is a fairly large spread in the model guidance regarding the timing and strength of the trough and how far inland it will push, so changes and updates regarding this part of the forecast are likely over the next few days. -BPN
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