Area Forecast Discussion
Issued by NWS Medford, OR
Issued by NWS Medford, OR
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055 FXUS66 KMFR 130533 AFDMFR Area Forecast Discussion National Weather Service Medford OR 1033 PM PDT Fri Jul 12 2024 .DISCUSSION...Satellite imagery is showing some coastal stratus in Coos County and offshore with clear skies elsewhere. Well to the East and the South of southern Oregon and northern California cloud cover associated with monsoon moisture is visible, and this will be one of the main concerns over this weekend as it pushes our way. As the ridge slowly breaks down, area observations remain breezy with very low humidity values being recorded for a lot of inland locations. While the red flag warning was allowed to expire for this evening, another red flag is in effect for the eastside on Saturday and a fire weather watch on Sunday. In other news, temperatures were also hot once again today, with the Medford Airport reaching 100 degrees. Tomorrow will be hot as well, so will continue the Excessive Heat Warning for Siskiyou County and the heat advisory for Jackson, Josephine and most areas east of the Cascades. In all, this forecast is going to be relatively dynamic. For more information, including on the thoughts on thunderstorms, please read the previous discussion below. -Schaaf && .AVIATION...13/06Z TAFS...Marine stratus will impact the coast north of Cape Blanco overnight into Saturday morning with IFR and perhaps LIFR at North Bend. Expect the stratus to push back to the beaches or just offshore again Saturday morning (16-17Z) with VFR returning to North Bend. Gusty north winds develop again in the afternoon, with gusts of 25-30kt. Local LIFR fog is expected overnight into Saturday morning near Brookings. Inland, VFR conditions will continue through the TAF period, except for MVFR visibility between 4-5 miles in the vicinity of the Shelly Fire. Visibility could briefly lower to 5 miles near the Salt Creek Fire, but the prevailing visibility should remain 6 miles or greater. Mid and upper level moisture will move into southern and eastern sections of the area Satuday which could initiate convection during the afternoon and evening in portions of Siskiyou, Modoc, southeastern Klamath and southern Lake counties. Isolated t-storms could produce lightning and gusty outflows. -Spilde && .MARINE...Updated 830 PM Thursday, July 11, 2024...Moderate to strong winds will continue, with the strongest winds 10 to 20 nm away from shore from Gold Beach. Steep wind driven seas up to 14 feet will persist in roughly the same area and locations farther south. Winds will ease some Saturday into Sunday, but gales will remain over the southern waters due to the expansion fan southwest from Port Orford, therefore the Gale Warning has been extended, but the coverage area will be small than it is currently. Moderate north winds will continue into Monday with small Craft conditions likely for the southern waters, then winds and seas will diminish Tuesday through Wednesday with calmer conditions. -Petrucelli/Spilde && .PREV DISCUSSION... /Issued 457 PM PDT Fri Jul 12 2024/ DISCUSSION...High pressure remains in place over the region with an upper level four corners high the dominant weather feature through at least mid next week. Temperatures continue to be generally 10 or so degrees above normal for the middle of July. Breezy northwest winds are expected west of the Cascades...while stronger southwest winds are impacting areas east of the Cascades. We are currently seeing wind gusts near 30 mph...with the short term high res models indicating wind gusts nearing 35 kts across the southern half of Klamath and Lake counties through this evening. These breezy and hot conditions are continuing to lead to fire weather concerns. Please see below for more information regarding a red flag warning. Otherwise...a heat advisory and an excessive heat warnings remain in effect through Saturday evening. Please see our webpage at weather.gov/medford for more detailed information regarding the heat. Otherwise...our main area of concern will be the potential for thunderstorms over the weekend. Mid level monsoonal moisture is slated to move into the southeastern portion of the forecast area...with the best chance (around 20% chance) for thunderstorms over southeastern Modoc county. A slight chance (10% to 15% chance) of thunderstorms will be present across the eastern half of Siskiyou county through far southern Klamath county and the southern half of Lake county. Thunderstorm coverage will expand Sunday afternoon into the evening hours as the monsoonal moisture stretches a bit more north and west through much of Siskiyou...Klamath...and Lake counties. The chance for thunderstorms on Sunday is generally 15% to 25%. Please see below for a very detailed and well written fire discussion regarding this weekend. We are not expected to experience any major changes in the upper level pattern through much of next week. Our challenge will be subtle differences in the location of the upper ridge and a general trough pattern over the Gulf of Alaska. Please continue to monitor the forecast closely as fine detail will be added in daily to especially the 24 to 48 hour forecast. -Riley FIRE WEATHER...Issued 200 PM Friday July 12, 2024... ..Near critical fire weather conditions possible through at least this weekend... ..RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM PDT THIS EVENING FOR STRONG GUSTY WIND AND LOW RH FOR FIRE WEATHER ZONES 624...625...284...285... ..RED FLAG WARNING IN EFFECT FROM 2 PM TO 8 PM PDT SATURDAY FOR STRONG GUSTY WIND AND LOW RH AND ABUNDANT LIGHTNING ON DRY FUELS FOR FIRE WEATHER ZONES 624 AND 625... ..RED FLAG WARNING IN EFFECT FROM 2 PM TO 8 PM PDT SATURDAY FOR ABUNDANT LIGHTNING ON DRY FUELS FOR FIRE WEATHER ZONES 284 AND 285... ..FIRE WEATHER WATCH NOW IN EFFECT FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR ABUNDANT LIGHTNING ON DRY FUELS FOR FIRE WEATHER ZONES 280...284...285...624 AND 625... Hot, breezy, low humidities, and unstable afternoon conditions will persist through this weekend. For today, a weak upper level wave will bring some strong gusty winds to the area this afternoon and evening, especially east of the Cascades. Daytime humidities will continue to be in the low teens and single digits, and with the stronger winds expected today, this will result in critical fire weather conditions for portions of Fire Weather Zones (FWZ) 624, 625, 284 and 285. Breezy west to northwest winds are expected west of the Cascades with a potential for brief or local critical conditions, especially in portions of central and western Siskiyou County. After today, the focus turns to the potential for thunderstorms Saturday and Sunday, and potentially into early next week. Strong high pressure will linger over the Great Basin region into next week and a weak low pressure will move northward just offshore of the California coast. This is a pretty classic thunderstorm pattern for this area as the flow turns more southerly and moist unstable air moves into the region. For Saturday, we expect isolated thunderstorms to be focused over our southeastern zones (284, 285, southern 624 and 625). We upgraded the Fire Weather Watch to a Red Flag Warning (RFW) for these zones for abundant lightning on dry fuels. It should be noted that the RFW for FWZs 624 and 625 is actually a combination of critical concerns. Gusty southwest winds will shift northward on Saturday and humidities will remain a very low across the northern portions of those zones. So north of a line from roughly Chiloquin to Paisley, we expect critical fire weather conditions due to gusty winds and low RH, while south of there the concern is due to lightning on dry fuels. Though confidence is higher for isolated coverage vs scattered, any lightning in the area right now should be highly efficient fire starters thanks to the recent prolonged stretch of very hot and very dry conditions. Additionally, any storms that develop on Saturday will be high based and have very little to no precipitation with them. As we head into Sunday, the potential for thunderstorms shifts westward. It`s not out of the question we see some isolated, elevated convection continue Saturday night into Sunday morning, but Sunday afternoon and evening looks like the day for the most coverage of storms as the moisture field shifts westward. Have left the Fire Weather Watch in place for FWZ 624, 625, 284 and 285, but have also included FWZ 280, to include the Shelly Fire. For now, confidence is higher for the zones covered by a watch, but it`s not out of the question for an isolated storm along the Cascades or Siskiyous. Once this timeframe is covered by the high resolution models, will make further decisions on upgrading or adding more zones. Storms should trend wetter on Sunday, but still be a mix of dry and wet storms, with lightning strikes outside of precipitation cores a real possibility and cause for concern. The focus of today`s efforts has largely been on the weekend setup, but it`s possible we see isolated thunderstorm chances continue into Monday or even Tuesday. There is some uncertainty due to model differences regarding where these chances are focused, which could include west of the Cascades or even nocturnal thunderstorms at some point. We`ll have to monitor model trends closely as each day passes, but we`ll be in a thunderstorm pattern Saturday through at least Monday, and subtle shifts in model trends could lead to big changes in the forecast. /BR-y AVIATION...13/00Z TAFS...Marine stratus along the coast north of Cape Blanco will edge inland this evening with IFR/LIFR at North Bend. North winds with gusts of 30-35 kt will ease overnight. Expect stratus to push back to the beaches or just offshore again Saturday morning (16-17Z) with VFR returning to North Bend. Gusty north winds develop again in the afternoon, with gusts of 25-30kt. Another area of LIFR is expected tonight into Saturday morning near Brookings. Inland, VFR conditions will continue through the TAF period, except for MVFR visibility between 4-5 miles in the vicinity of the Shelly Fire. Visibility could briefly lower to 5 miles near the Salt Creek Fire, but the prevailing visibility should remain 6 miles or greater. -Spilde MARINE...Updated 200 PM Thursday, July 11, 2024...Moderate to strong winds will continue, with the strongest winds 10 to 20 nm away from shore from Gold Beach. Steep wind driven seas up to 14 feet will persist in roughly the same area and locations farther south. Winds will ease some Saturday into Sunday, but gales will remain over the southern waters due to the expansion fan southwest from Port Orford, therefore the Gale Warning has been extended, but the coverage area will be small than it is currently. Moderate north winds will continue into Monday with small Craft conditions likely for the southern waters, then winds and seas will diminish Tuesday through Wednesday with calmer conditions. -Petrucelli && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Fire Weather Watch from Sunday morning through Sunday evening for ORZ624-625. Heat Advisory until 9 PM PDT Saturday for ORZ024-026-029>031. Red Flag Warning from 2 PM to 8 PM PDT Saturday for ORZ624-625. CA...Excessive Heat Warning until 9 PM PDT Saturday for CAZ080>082. Fire Weather Watch from Sunday morning through Sunday evening for CAZ280-284-285. Heat Advisory until 9 PM PDT Saturday for CAZ083>085. Red Flag Warning from 2 PM to 8 PM PDT Saturday for CAZ284-285. PACIFIC COASTAL WATERS...Small Craft Advisory until 5 PM PDT Sunday for PZZ350-356-370-376. Gale Warning until 5 PM PDT Sunday for PZZ356-376. && $$