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Area Forecast Discussion
Issued by NWS Medford, OR
Issued by NWS Medford, OR
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358 FXUS66 KMFR 121033 AFDMFR Area Forecast Discussion National Weather Service Medford OR 333 AM PDT Mon Aug 12 2024 .DISCUSSION...Much like the last few nights/early mornings, the latest satellite image shows marine stratus along the coast and inland into the coastal river valleys and Coquille Basin. The inland push of the marine stratus has been slow but steady and could move into portions of the Umpqua Basin towards daybreak. Elsewhere skies are clear. The latest water vapor image shows a weak upper low weak upper low near 38N and 139W. The upper low will move inland in northern Cal early this afternoon and it will become negatively tilted late in the afternoon. This along with increasing instability could set the table for isolated thunderstorms east of the Cascades this afternoon into early this evening. The wildcard in terms of thunderstorm coverage or lack thereof will be the extent of the smoke. If the smoke remain extensive, it will put a cap or even result in less instability resulting in a couple of isolated storms or nothing at all. Weak troughing remains over the area for the rest of the week. While most locations will be dry, we cannot rule out a slight chance of afternoon and early evening thunderstorms Wednesday and Thursday east of the Cascades. Afternoon temperatures during this time will be slightly below normal. Friday through this weekend. All of the data remains locked in with a common solution. The clusters still point to the upper low deepening with the center of the upper low just west of the forecast area. The ensemble means and operational models also in good agreement with the placement of the low/trough with it centered slightly to the west. Afternoon temperatures Friday through the weekend for the interior are likely to end up below normal (6-8 degrees) for this time of the year. While precipitation cannot be ruled out, the best chance is expected be east of the Cascades and mainly during the afternoon and early evening hours Friday, and Saturday, with marginal instability, moisture and trigger. Sunday the low is still offshore, but the mid levels are dry and there is little or no trigger, so the threat for storms are low. -Petrucelli && .AVIATION...12/06Z TAFS...IFR and LIFR ceilings have built back into the coast and North Bend as of writing this discussion. These ceilings will likely make a bigger push inland as an upper level wave moves into the coast. Some MVFR ceilings are anticipated to make it into Roseburg as well. Smoke is still out there and a large swath of smoke was heading towards Klamath Falls(LMT). We`re anticipating visibilities to fall there at some time tonight potentially down to IFR thresholds. Otherwise, plenty of smoke is covering northern Klamath and Lake counties yet again tonight. More smoke will be flying around on Monday, although it should have a more eastwards trajectory compared to what we`ve seen over the last few days. There is also a 10-20% chance of showers and thunderstorms east of the Cascades Monday afternoon as a strengthening cold front moves inland. Some modest vertical lift and available moisture should get a few storms going around the region. -Smith && .MARINE...Updated 220 AM Monday, August 12, 2024. High pressure is weakening in the Pacific. Benign wave conditions will persist through most of the week with no thermal trough condition. A weak northerly short period swell will glide through the waters this week. && .FIRE WEATHER...Issued 200 AM Monday August 12, 2024...The forecast period will trend cooler through this weekend with increasing onshore flow. The increased onshore flow will result in good overnight recoveries for the coast, coastal valleys, Coquille and Umpqua Basin, including the complex of fires in central and eastern Douglas County. The latest water vapor image shows a weak upper low weak upper low near 38N and 139W. The upper low will move inland in northern Cal early this afternoon and it will become negatively tilted late in the afternoon. This along with increasing instability could set the table for isolated thunderstorms east of the Cascades this afternoon into early this evening. The wildcard in terms of thunderstorm coverage or lack thereof will be the extent of the smoke. If the smoke remain extensive, it will put a cap or even result in less instability resulting in a couple of isolated storms or nothing at all. Weak troughing remains over the area for the rest of the week. While most locations will be dry, we cannot rule out a slight chance of afternoon and early evening thunderstorms Wednesday and Thursday east of the Cascades. Note: The models Wednesday suggest little or no instability, but with an approaching upper trough and pattern recognition suggest there is at least a slight chance for thunderstorms east of the Cascades. Afternoon temperatures during this time will be slightly below normal. Also higher afternoon relative humidities are expected with fairly good overnight recoveries, even for the eastside and northern California. We`ll still have to deal with gusty breezes in the afternoon and early evening hours, but with higher humidities in the afternoons, were not expecting critical conditions. Next weekend is still shaping up to be cool with higher relative humidities in the afternoons along with good overnight recoveries as a rather strong upper low for this time of the year sets up just west of the forecast area. -Petrucelli && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. PACIFIC COASTAL WATERS...None. && $$