Area Forecast Discussion
Issued by NWS Medford, OR
Issued by NWS Medford, OR
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848 FXUS66 KMFR 021547 AFDMFR Area Forecast Discussion National Weather Service Medford OR 847 AM PDT Tue Jul 2 2024 .DISCUSSION...The forecast is on track for today. Warmer temperatures are forecast across northern California and southern Oregon, with highs rising between 2 to 5 degrees from Monday`s in most areas. Temperatures will continue to rise through the week, with hazardous heat present at the end of the week and into the weekend. Please see the previous discussion for more details about the short- and long-term forecast as well as for critical fire weather concerns. -TAD && .AVIATION...02/12Z TAFS...Areas of MVFR or IFR ceilings are present in the Coquille Basin,and this will lift later this morning. Elsewhere VFR will be present through the TAF period. Gusty afternoon and evening winds will continue today, especially west of the Cascades where gusts could reach 30 kt. -Hermansen/CC && .MARINE...Updated 845 AM Tuesday, July 2, 2024...A strong thermal trough will maintain strong north winds, reaching gales south of Port Orford, and steep to very steep and hazardous seas for all areas through late Wednesday. Winds will be strongest and seas will be steepest during the afternoons and evenings. Conditions improve somewhat late Wednesday night into Thursday as the thermal trough pushes inland and expands northward. North to northeast winds will ease some during this time, but seas and winds will remain hazardous to small craft through the end of the week, with hazardous warning level seas likely lingering through Thursday night. Conditions improve further over the weekend with sub-advisory conditions possible. Strong high pressure aloft will disrupt the thermal trough pattern, keeping winds in the 15 to 20 kt range with about a 15% chance of winds approaching advisory criteria on Saturday and Sunday. The thermal trough rebounds early next week, with hazardous conditions likely returning at that time. /BR-y && .FIRE WEATHER...Updated 400 AM Tuesday, July 2, 2024... ...Elevated to critical fire weather possible today through the next week... ...FIRE WEATHER WATCH IN EFFECT FROM WEDNESDAY EVENING THROUGH THURSDAY MORNING FOR OREGON FIRE WEATHER ZONES 619/WESTERN 620 FOR GUSTY NORTHEAST WINDS AND POOR HUMIDITY RECOVERY... Fire weather concerns will remain elevated through the week, though due to two different patterns. First, a strong thermal trough along the coast will persist through Wednesday night. This will bring moderate to locally poor overnight RH recoveries to ridges along with gusty northeast winds of 15-25 mph with gusts to 30-40 mph to the Coast Range/Kalmiopsis Wilderness tonight and again Wednesday night. As is typical with this pattern, it tends to take a night or two of persistent northeast winds to bring down RHs enough to present critical conditions, and that will be the case this time as well. Of the winds/RH combo required for critical conditions tonight, gusty winds will meet the criteria, but RH recoveries won`t quite be low enough (30-50%). The pattern starts to transition Wednesday night, so winds will be weaker compared to tonight, but RH recoveries will be lower (20-35%). This combination could lead to critical fire weather conditions and a Fire Weather Watch remains in effect for Wednesday night into Thursday morning. In the meantime, this pattern will also lead to near critical conditions for portions of the area this afternoon and again Wednesday afternoon. Minimum humidities of 10-15% are expected in western and central Siskiyou County with north winds of 10 to 15 mph and gusts to 25 mph (strongest in the Shasta Valley near Montague). Similarly, northeast winds also be near critical thresholds in the Illinois Valley on Wednesday afternoon at 10-15 mph with gusts to 20 mph, and with minimum humidities of 10-15%. Strong high pressure aloft moves over the region for the latter half of the week and through the weekend. The thermal trough will expand northward, with weaker winds expected along the coast. Very hot temperatures (100-110 degrees) and very low (low teens/single digit) humidities are expected during this time away from the immediate coast. While afternoon breezes won`t be quite as strong as today and Wednesday, the extreme heat, and long duration of the heat will allow even typically breezy afternoon conditions to result in dangerous weather that is favorable for rapid spread of fire. /BR-y && .PREV DISCUSSION... /Issued 434 AM PDT Tue Jul 2 2024/ DISCUSSION...A ridge is building and this will guide the short and long term forecasts with warm temperatures and dry conditions. The Chetco effect was present yesterday afternoon, and this was not presented well in the forecast. With this in mind, the highs for Brookings the next few days have been increased and now show highs in the 80s and near 90. The streak of 90+ degree days in Medford started Monday afternoon with a high right at 90. The concern for dangerous afternoon temperatures will begin Thursday as the thermal trough moves inland. Thursday`s main areas for the heat will be in the Rogue Valley and in Siskiyou County valleys with highs in the low 100s. After, the heat expands to more west side locations including the Illinois Valley and Umpqua Basin, which equates to highs in the 100-110 degree range. The heat will be the worst Friday into the weekend. The probability of reaching highs of 110 degrees in Medford is 70-80% Friday and Saturday afternoons. There is even a 35% probability to reach 115 Saturday in Medford. There will also be a factor of low temperatures west side only falling to the low to mid-60s Friday and into the weekend. With this in mind, it is crucial that precautions are taken to prepare and deal with the heat. With the heat concerns in mind, an Excessive Heat Watch exists for most locations (with an emphasis on valleys) Thursday morning through Sunday evening. Will continue reviewing the heat risk this week, but for now west side valleys are certain to be under an Excessive Heat Warning by the end of the week. Early next week the ridge will move inland and temperatures will fall from the weekend peak, although it will still be warm with highs in the triple digits for the Rogue and Illinois valleys. - Hermansen AVIATION...02/12Z TAFS...Areas of MVFR or IFR ceilings are present in the Coquille Basin,and this will lift later this morning. Elsewhere VFR will be present through the TAF period. Gusty afternoon and evening winds will continue today, especially west of the Cascades where gusts could reach 30 kt. -Hermansen/CC MARINE...Updated 200 AM Tuesday, July 2, 2024...A strong thermal trough will maintain strong north winds, reaching gales south of Port Orford, and steep to very steep and hazardous seas for all areas through late Wednesday. Winds will be strongest and seas will be steepest during the afternoons and evenings. Conditions improve somewhat late Wednesday night into Thursday as the thermal trough pushes inland and expands northward. North to northeast winds will ease some during this time, but seas and winds will remain hazardous to small craft through the end of the week, with hazardous warning level seas likely lingering through Thursday night. Conditions improve further over the weekend with sub-advisory conditions possible. Strong high pressure aloft will disrupt the thermal trough pattern, keeping winds in the 15 to 20 kt range with about a 15% chance of winds approaching advisory criteria on Saturday and Sunday. The thermal trough rebounds early next week, with hazardous conditions likely returning at that time. /BR-y FIRE WEATHER...Updated 400 AM Tuesday, July 2, 2024... ..Elevated to critical fire weather possible today through the next week... ..FIRE WEATHER WATCH IN EFFECT FROM WEDNESDAY EVENING THROUGH THURSDAY MORNING FOR OREGON FIRE WEATHER ZONES 619/WESTERN 620 FOR GUSTY NORTHEAST WINDS AND POOR HUMIDITY RECOVERY... Fire weather concerns will remain elevated through the week, though due to two different patterns. First, a strong thermal trough along the coast will persist through Wednesday night. This will bring moderate to locally poor overnight RH recoveries to ridges along with gusty northeast winds of 15-25 mph with gusts to 30-40 mph to the Coast Range/Kalmiopsis Wilderness tonight and again Wednesday night. As is typical with this pattern, it tends to take a night or two of persistent northeast winds to bring down RHs enough to present critical conditions, and that will be the case this time as well. Of the winds/RH combo required for critical conditions tonight, gusty winds will meet the criteria, but RH recoveries won`t quite be low enough (30-50%). The pattern starts to transition Wednesday night, so winds will be weaker compared to tonight, but RH recoveries will be lower (20-35%). This combination could lead to critical fire weather conditions and a Fire Weather Watch remains in effect for Wednesday night into Thursday morning. In the meantime, this pattern will also lead to near critical conditions for portions of the area this afternoon and again Wednesday afternoon. Minimum humidities of 10-15% are expected in western and central Siskiyou County with north winds of 10 to 15 mph and gusts to 25 mph (strongest in the Shasta Valley near Montague). Similarly, northeast winds also be near critical thresholds in the Illinois Valley on Wednesday afternoon at 10-15 mph with gusts to 20 mph, and with minimum humidities of 10-15%. Strong high pressure aloft moves over the region for the latter half of the week and through the weekend. The thermal trough will expand northward, with weaker winds expected along the coast. Very hot temperatures (100-110 degrees) and very low (low teens/single digit) humidities are expected during this time away from the immediate coast. While afternoon breezes won`t be quite as strong as today and Wednesday, the extreme heat, and long duration of the heat will allow even typically breezy afternoon conditions to result in dangerous weather that is favorable for rapid spread of fire. /BR-y && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Excessive Heat Watch from Thursday morning through Sunday evening for ORZ023-024-026-029>031. Fire Weather Watch from Wednesday evening through Thursday morning for ORZ619-620. CA...Excessive Heat Watch from Thursday morning through Sunday evening for CAZ080>082-084-085. PACIFIC COASTAL WATERS...Gale Warning until 5 AM PDT Thursday for PZZ356-376. Small Craft Advisory until 5 AM PDT Thursday for PZZ350-370. Hazardous Seas Warning until 5 AM PDT Thursday for PZZ370. && $$