Area Forecast Discussion
Issued by NWS Medford, OR
Issued by NWS Medford, OR
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755 FXUS66 KMFR 301550 AFDMFR Area Forecast Discussion National Weather Service Medford OR 850 AM PDT Sun Jun 30 2024 .DISCUSSION...The forecast for today does not need any changes. An upper trough moving to the east is continuing to bring areas of mid-level clouds across northern California and southern Oregon. Marine stratus persists along the Oregon coast, but should clear out into the afternoon. Slight (10-15%) thunderstorm chances remain for Lake and Modoc counties remain, but the areas covered might decrease and will be the focus of today`s considerations. Please see the previous discussion for more details about the short- and long-term forecast. -TAD && .AVIATION...30/12Z TAFS...Low clouds and fog will will impact areas along the coast this morning, clearing to VFR in the afternoon. Low clouds with IFR and MVFR are likely to return to the coast Sunday evening. Inland, areas of MVFR are expected to spread into the Umpqua Basin to Roseburg early this morning. These clouds will clear in the late morning to VFR. Elsewhere, expect VFR across the area. Smoke from a few wildfires could produce some locally low visibility near those fires, otherwise the smoke will not be an issue near terminals. There is a low chance for an isolated thunderstorm east of the Cascades this afternoon. -Miles && .MARINE...Updated 850 AM Sunday, June 30, 2024...Winds and seas will remain low today. However, areas from Brookings south within about 15 NM of shore could observe brief and isolated advisory level seas as winds peak in the afternoon, generating a steep wind wave. If in this area, watch Buoy 27 to monitor conditions to be safe before heading out. A very strong thermal trough is expected to develop next week beginning Monday afternoon and lingering towards the end of the week. A Gale Watch and other headlines have been put in place for this event this morning. The peak should be either Tuesday or Wednesday evening, and the guidance is trending towards Tuesday; although very little drop off in intensity is expected Wednesday. As for the wind speeds expected during the peak of the thermal trough, the gale force gusts of 35 to 45 kt are expected south of Cape Blanco, but there is a 20-40% chance that gusts reach or exceed 50 kt Tuesday or Wednesday evening. With the chance for gale force gusts remaining below 50% between Cape Blanco and Cape Arago, a Hazardous Seas Watch was put in place instead of something for the infrequent gale force gusts. Comparing this event to the past, this is getting into the top end of events, standing out against climatology. And to summarize, this occurrence of the thermal trough northerlies will not be one to mess with. -Miles && .FIRE WEATHER (Updated 300 AM Sunday, June 30th)... .Elevated to critical fire weather possible Tuesday through the weekend... As mentioned above in the discussion, we have a small chance for thunderstorms today mainly on the eastside. Not expecting widespread thunder or severe weather, but isolated strikes could occur late this afternoon and early evening. A strong warming and drying trend will begin Monday night as high pressure builds into the region. This will bring moderate to locally poor humidity recoveries to ridges. The poorest recoveries and hottest temperatures are expected from Wednesday morning into the weekend. Western Siskiyou County in particular could experience critical fire weather conditions starting as early as Tuesday afternoon, but much of the forecast area will have at least elevated concerns through the weekend. Additionally, there is concern for both critically poor night-time ridge top humidity recoveries (higher terrain of Curry and western Josephine counties), and also gusty afternoon winds accompanying a very dry airmass. The limiting factor is likely to be wind speeds, while the hot and dry aspect looks like a "slam dunk" to occur. -Guerrero && .PREV DISCUSSION... /Issued 415 AM PDT Sun Jun 30 2024/ DISCUSSION (Today through Saturday)... Overview: Potential impacts from both heat and fire weather are at the forefront of the forecast for the next week, but early indications suggest we could be in for a rather dry and hot first half of July. By middle of next week, the heat will be ramping up across the forecast area, and there is a high likelihood for some sort of heat risk. In fact, there is the potential for some records to be broken as well. Unfortunately, with the heat comes low RH values that could be coupled with breezy winds, so there is at least some risk for elevated to perhaps critical fire weather conditions next week. Lastly, there will be a small chance for thunderstorms today for mainly areas on the eastside. Not expecting severe weather, but the threat for lightning will exist. Further Details: Pieces of energy are expected to round the base of a passing trough today. This may result in a chance for thunderstorms today, but the problem is we have weak variables, especially the moisture aspect. There is some indication the vorticity field might phase with some limited moisture today, and this could kick off some showers/thunderstorms over parts of Klamath and Lake counties. Not a great chance, but also not a zero chance. Models are suggesting upwards around a few hundred J/kg of MUCAPE could be present today. Again, not expecting severe weather, but lightning may disrupt outdoor activities this afternoon and early evening on the eastside. The heat is coming! The probabilities for 100 degrees or more have gone up (again) for some of the westside valleys with some areas sitting around a 70-80 percent chance for 100 degrees or more on the holiday (July 4th). In fact, by July 5th the probability for 110 or greater is around 30% for both the Rogue Valley and Shasta Valley. In other words, there is a high probability for some sort of heat related headline come next week to account for this threat as the Rogue Valley could go about 7 days or more with 95+ degrees starting Wednesday. Overnight low temperatures might be in the mid 60s for some areas on the westside Fri-Sun, which would not allow for much relief from the heat overnight. Some Potential Records: -------- July 4th -------- Medford: 103 in 2015 (Forecast: 101) Roseburg: 98 in 2023 (Forecast: 95) Brookings: 96 in 1931 (Forecast: 78) Klamath Falls: 98 in 1981 (Forecast: 94) Mount Shasta: 97 in 2007 (Forecast: 99) -------- July 5th -------- Medford: 102 in 1926 (Forecast: 103) Roseburg: 98 in 2023 (Forecast: 98) Brookings: 84 in 1993 (Forecast: 77) Klamath Falls: 98 in 2007 (Forecast: 96) Mount Shasta: 100 in 2007 (Forecast: 100) -------- July 6th -------- Medford: 104 in 1922 (Forecast: 105) Roseburg: 102 in 1960 (Forecast: 100) Brookings: 84 in 1998 (Forecast: 74) Klamath Falls: 96 in 2021 (Forecast: 97) Mount Shasta: 99 in 2007 (Forecast: 101) Unfortunately, the heat (above normal temperatures) may continue into parts of mid July as the Climate Prediction Center is forecasting the chance for above normal temperatures to continue with below normal precipitation chances. This doesn`t bode well for our fire weather conditions as a prolong drying period appears slated for much of the area through at least mid July. -Guerrero && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...None. PACIFIC COASTAL WATERS...Gale Watch from Monday afternoon through late Wednesday night for PZZ356-376. Small Craft Advisory from 5 PM Monday to 5 AM PDT Thursday for PZZ350-370. Hazardous Seas Watch from Monday afternoon through late Wednesday night for PZZ370. && $$