FXUS66 KMFR 271040 AFDMFR

Area Forecast Discussion National Weather Service Medford OR 340 AM PDT Sat Jul 27 2024

DISCUSSION
The forecast remains relatively dynamic as a weak mid-level low pressure system pushes northward toward northern California and southern Oregon this afternoon. This is seen via a group of clouds in Shasta and Lassen Counties moving northward.
While this likely will not be bringing any precipitation to the area this morning, ensembles do show around a 15 percent chance for a stray shower or thunderstorm late this morning into this afternoon. The one thing that the ensembles do not forecast for that may inhibit any development is area smoke from wildfires.

After looking at the visible satellite imagery yesterday, smoke from the Park Fire near Chico, California has blanketed most areas east of the Cascades with smoke. The night time microphysics RGB imagery continue to show heavy smoke moving northward across Siskiyou, Modoc, Lake and Modoc Counties, which is relatively impressive during the overnight period. While our hearts do go out to those impacted by this fire, the smoke may very well dampen the instability and may not allow for thunderstorm development this afternoon. At most, areas from the Winter Rim eastward in Oregon and along the Warners in Modoc County could see that 15 percent chance for an isolated shower or thunderstorm this afternoon and evening. Precipitation, if any, would be very light.

The forecast will remain under the general influences of troughs for much of the work week as along with the weak mid-level low coming northward from California, the area also is under the influence of a deep broad trough moving across Canada. This system will continue to allow for breezy winds, relatively low humidities, but also much cooler weather with temperatures near to slightly below normal for the next few days.

Then another front will push through the Pacific Northwest and Canada beginning Sunday night through Wednesday. This will continue to keep temperatures a bit cooler than during the heat waves we've seen over the past few weeks with HeatRisk values only reaching minor. This front will also bring some breezy to gusty winds, but with these winds, humidity values will be a bit higher too, precluding fire weather concerns for much of the week.

That being said, this front is lacking moisture and therefore wetting rainfall is not expected with this front. Sorry folks, we're in the dry season. That being said, there is a slight chance 15-20 percent for some precipitation largely along the coast, Douglas County and in the Cascades north of Crater Lake. I still don't expect this precipitation to be wetting by any means, but any precipitation should be helpful for firefighting efforts ongoing across the area.

Beginning Thursday, the trough is replaced by a ridge of high pressure that retrogrades westward across the four corners region of the US. This could be the start of another heatwave with hot, dry, and breezy conditions once again. Will need to monitor the forecast for updates on the pattern. -Schaaf
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