Area Forecast Discussion · National Weather Service Medford (MFR) · issued Thursday, July 16 at 4:50 PM PDT.
Revised in 2 passages since the 2:02 PM discussion. See every revision.
Messages
Temperatures trend warmer Friday into the weekend, peaking on Sunday with highs in the 90s to low 100s across inland valleys.
Gusty winds and low humidities will bring elevated fire weather conditions today and Friday. Critical fire weather conditions are expected on Friday in portions of southeast Klamath, Lake and Modoc counties.
Hot, dry and breezy weather this weekend.
Unstable with potential for thunderstorms Monday through Wednesday, mainly from the Cascades east and Siskiyous south.
Smoke from the East Evans Creek Fire will result in continued impacts downwind of of the fire.
Discussion
An upper low just off the coast will gradually move northward tonight then inland over British Columbia late Friday. As this low gradually moves northward along the PacNW coast, breezy to gusty winds are expected for many inland areas this afternoon/evening and again Friday afternoon and evening, strongest east of the Cascades and in the Shasta Valley. The combination of gusty winds and low humidities will result in elevated fire weather conditions. Please see the fire weather discussion below for details.
High pressure will build across the area late Friday through Sunday, with a upper trough staying further north. A significant warm up is expected on the weekend with highs peaking on Sunday 5 to 10 degrees above normal. Inland valleys are expected to reach the 90s to low 100s on Sunday. The National Blend of Models indicates a 60% chance for reaching 100 degrees at Medford and a 25% chance for reaching 100 degrees at Yreka.
High pressure remains in place across the region Monday and Tuesday. Meanwhile, a low well off the coast of Baja and southern California is forecast to move northward on Monday. Ensembles show significant variability in the track and strength of this low. The operational the American global model is stronger with the low and brings it northward off the coast of northern California Monday night into Tuesday. This would result in more southerly moisture aloft moving into the area Monday and Tuesday with chances (10-20%) for thunderstorms. The operational the European model keeps the low further south and as a result shows a drier pattern. However, even under this pattern, monsoonal moisture may move up the Sierra crest and into eastern portions of the area, bringing a slight chance for thunderstorms. The track of this low and the amount of moisture and cloud cover will factor into whether thunderstorms develop as well how hot temperatures will be early next week. We are continuing to monitor this pattern for the potential of thunderstorms and ongoing heat.
Smoke from the Evans Creek Fire is expected to continue to bring impacts to air quality across portions of southwest Oregon, and potentially into areas in Northern California. Smoke impacts have been greatest downwind of the fire in northern Jackson, eastern Douglas and Klamath Counties as west to northwest winds spread smoke to the east and southeast. The Rogue Valley near Medford and Ashland may seen daily pushes of smoke, especially in the evenings. This pattern will likely continue through Friday. On the weekend, some light northeast winds during the overnight and morning periods may allow additional smoke to spread into the Rogue Valley. Otherwise, daytime northwest to west winds from the Cascades west are likely to allow smoke from the fire to continue to impact areas in southwest Oregon (including northern Jackson, eastern Douglas and Klamath counties).
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