Florence OR to Point St. George between 60 and 150 NM Offshore Forecast
|Today...N Winds 20 To 30 Kt. Seas 4 To 8 Ft.|
|Tonight...N Winds 20 To 30 Kt. Seas 5 To 9 Ft.|
|Sun...N Winds 20 To 30 Kt. Seas 6 To 10 Ft.|
|Sun Night...N Winds 20 To 30 Kt. Seas 5 To 9 Ft.|
|Mon...N Winds 20 To 30 Kt. Seas 5 To 9 Ft.|
|Mon Night...N Winds 15 To 25 Kt. Seas 4 To 8 Ft.|
|Tue...N Winds 10 To 20 Kt. Seas 4 To 6 Ft.|
|Tue Night...N Winds 10 To 20 Kt. Seas 4 To 6 Ft.|
|Wed...N Winds 15 To 25 Kt. Seas 4 To 7 Ft.|
|Wed Night...N Winds 15 To 25 Kt. Seas 4 To 8 Ft.|
| Area Forecast Discussion|
National Weather Service Medford OR
812am PDT Sat July 24 2021
No changes made to the forecast this morning. We are forecasting temperatures generally 2 to 5 degrees below model guidance where we are expecting the thickest smoke blanket today, mostly coming from the Dixie Fire in Northern California. How much of this mixes to the surface is questionable, but we don't expect enough of the smoke to mix to the surface west of the Cascades to bring poor air quality to these areas. The latest HRRR (High-Resolution Rapid Refresh) smoke model suggests some smoke making it to the surface later this morning as the inversion breaks, with worst conditions in Siskiyou and Modoc County and near the Bootleg Fire. We'll learn a lot today in terms of how much this smoke shield affects our weather and air quality, and based on the wind flow for the next seven days, we could be dealing with this smoke aloft for quite a while.
Please take it easy today, as temperature will be well above normal for this time of year, even with slight cooling from the smoke layer aloft. Temperatures will bump above 100 degrees in valleys west of the Cascades today, including Medford. Seek air conditioning or shade, drink plenty of water, and take plenty of breaks from any work planned.
Today we'll be focused on thunderstorm chances for next week as moisture builds over the region due to deep southerly flow. Please see the previous forecast discussion below regarding recent changes to the thunderstorm forecast. Keene
Updated 200am PDT Saturday, 24 July 2021...A typical summer weather pattern of high pressure offshore and a thermal trough near the coast will persist into early next week. This patten will result in gusty north winds and steep to very steep wind-driven seas through Monday. Very steep and hazardous warning level seas are expected from Gold Beach southward, with north gales expected between 5 and 25 nm from shore. Steep seas will expand northward this morning, bringing advisory level conditions north of Cape Blanco today. These conditions are likely to continue into Monday, then improve mid week as the thermal trough pattern weakens. /BR-y
Updated 200am Saturday 24 July 2021... An upper ridge (centered over Utah/Nevada) is building into the area with very dry, hot weather to continue this weekend. Winds won't be nearly as strong the next few afternoons/evenings, so we aren't carrying any headlines for winds/low relative humidity, despite the fact that it will likely remain just as dry. There will be fairly typical upvalley NNW winds during the afternoons/evenings, but also some NE flow during the night. This will be most prevalent over western Siskiyou County and also the coast ranges of SW Oregon, generally averaging 5-15 mph, with gusts of around 20 to perhaps 25 mph. But, we also expect some stronger N-NE flow into this morning and perhaps again tonight into Sunday morning over the east side, especially in the drainages that tend to align with that type of flow. It should also be noted that mid and upper slope RH recovery will be poor to moderate over many areas of norCal and SW Oregon during this time period.
The hot, very dry and unstable conditions will support a high Haines of 5 to 6 east of the Cascades both days of the weekend, but especially on Saturday. As a result, we have issued a Red Flag Warning for the Haines 6 over the Bootleg Fire from 2-8 pm PDT Saturday. It looks like slightly higher moisture will limit the Haines to 5 on Sunday, so will forego a watch for then.
As has been mentioned here the last couple of days, we've been monitoring for the potential for thunderstorms early next week. Model guidance is coming into line showing the initial risk of lightning beginning Monday as monsoonal moisture arrives in southerly flow aloft. Anomalously high PWs rise to near or even above 1.00 inch during this time frame with a short wave disturbance arriving as well to serve as a trigger. The amount of available moisture is likely to reach a peak on Tuesday. Instability is modest, however, with high level cloud-cover limiting instability at least somewhat. There is a slight chance of thunderstorms across northern California and near the Oregon Cascades eastward. Elevated instability Monday night could result in nocturnal activity in advance of another possibly healthier disturbance arriving on Tuesday. We've expanded coverage and increased Probability of Precipitation then. We'll be evaluating the potential for Fire Weather Watches over the next few shifts. -Spilde/DW
The main changes to the forecast were to update the coverage of haze and smoke, and also the coverage of areas with a slight chance probability of showers and thunderstorms Monday through Saturday. This amounted to fine tuning of the Monday and Tuesday risk, and adding some slight chance probability (mainly east of the Cascades) to the afternoons and evenings Wednesday through Saturday). As was the case yesterday, confidence does remain highest regarding the forecast for isolated convective activity Monday and Tuesday.
A third noteworthy aspect of our weather during the next week will be hot temperatures inland, especially this weekend and during the second half of the upcoming week. These highs are expected to be generally 5 to 15 degrees above normal.
At the coast, the weather for the next week will bear little resemblance to inland conditions. Temperatures will be near normal with lows in the 50s and highs in the lower 60s to lower 70s, and it will be the portion of our area with the least amount of/impact from smoke. Besides an influx of high level clouds Sunday night into Thursday, night and morning stratus will be prevalent from Cape Blanco northward.
An Air Quality Advisory (AQA) for Lake County and Eastern Klamath County remains in effect until Monday evening. Please see /PDXAQAMFR/ for more details. Mt. Shasta City and Alturas are reporting reduced visibility due to smoke and haze. A bit of a wild card thrown into the forecast will be the impact of an increasing concentration of smoke this weekend, roughly from Interstate-5 eastward...especially from the Cascades eastward. Besides the impact on air quality, this may hinder both overnight cooling and day-time heating (generally by a few degrees), and beginning Monday it may also hinder thunderstorm development. There is a southerly flow aloft bringing in smoke from the Dixie Fire in Plumas County, California. While there is less uniformity in the lower level wind direction, areas of northerly and easterly winds are also bringing some increasing contribution from the Jack and Bootleg fires in southern Oregon.
With southerly flow aloft, monsoonal moisture in the 700-500 mb layer will make its first modest increase this afternoon, but will not trend significantly higher until Monday.
For Monday, the Short Range Ensemble Forecast (SREF) calibrated thunderstorm probability continues to show a relatively modest 5 to 10 percent for northern California and from the southern Oregon Cascades eastward with agreement from the 00Z and 06Z GFS showing peak amounts of available moisture/instability in northern Klamath County extending to western Lake County in the vicinity of the Bootleg fire. There is also a slight chance of thunderstorms on Monday night into Tuesday morning. This risk should increase, at least modestly, on Tuesday afternoon. Tuesday brings the most moisture into the area with precipitable water (PW) likely reaching an inch.
The thunderstorm threat may shift at least slightly eastward as early as Wednesday. But, there is enough GEFS ensemble support to add a slight chance mention for portions of the area east of the Cascades Wednesday through Saturday.
.MFR WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning from 2pm this afternoon to 8pm PDT this evening for ORZ624.
CA... Pacific Coastal Waters...Small Craft Advisory until 11pm PDT Monday for PZZ350-356-370-376. Gale Warning until 11pm PDT Monday for PZZ356-376.