Area Forecast Discussion
Issued by NWS Medford, OR
Issued by NWS Medford, OR
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494 FXUS66 KMFR 031620 AFDMFR Area Forecast Discussion National Weather Service Medford OR 920 AM PDT Wed Jul 3 2024 .DISCUSSION... High pressure will continue to build into southern Oregon and northern California this afternoon with temperatures trending about 3 to 5 degrees warmer compared to yesterday`s highs. Weather hazards for today are minimal, although that will change in the coming days as a strong area of high pressure builds overhead. Read the previous discussions below for more information on the upcoming heat wave and fire weather risks. -Smith && .AVIATION...03/12Z TAFS...VFR will prevail through the TAF period. Gusty afternoon winds will return this afternoon, especially along the coast. Stratus is expected to build in along portions of the coast tonight with IFR conditions possible. Confidence is low that IFR conditions will build in at North Bend. Stratus is present in the Coquille Basin this morning, and this will lift later today. -Miles/Hermansen && .MARINE...Updated 800 AM Wednesday, July 3, 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 early Thursday. Winds will be strongest and seas will be steepest this afternoon and evening. Conditions improve somewhat early Thursday as the thermal trough pushes inland and expands northward. North to northeast winds will ease some at 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 likely for at least the inner waters. 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 in the outer waters for Saturday and Sunday. This could lead to lingering steep seas in the outer waters due to lingering fresh swell and continued wind driven seas. The thermal trough rebounds early next week, with more widespread hazardous conditions likely returning at that time. /BR-y/Smith && .FIRE WEATHER...Updated 200 AM Wednesday, July 3, 2024... ..Near critical fire weather possible today through the next week for much of southern Oregon and northern California... ..RED FLAG WARNING REMAINS IN EFFECT FROM 11 PM THIS EVENING TO 8 AM PDT THURSDAY FOR EAST WIND WITH POOR OVERNIGHT RH RECOVERY FOR FIRE WEATHER ZONES 619 AND 620... Fire weather concerns will remain elevated through the week due to two different patterns. First, a strong thermal trough along the coast will persist through tonight. This will bring moderate to locally poor overnight RH recoveries to ridges this morning and again overnight tonight, along with gusty northeast winds of 15-25 mph with gusts to 30-40 mph to the Coast Range/Kalmiopsis Wilderness. 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 this morning, gusty winds will meet the criteria, but RH recoveries won`t quite be low enough (30-50%). The pattern starts to transition late tonight, so winds will be weaker compared to this morning, but RH recoveries will be lower (20-35%). There will be enough overlap for critical fire weather conditions and a Red Flag Warning remains in effect for 11 PM tonight through 8 AM Thursday for portions of FWZ 619/620. In the meantime, this pattern will also lead to near critical conditions for portions of the area this 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 at 10- 15 mph with gusts to 20 mph, and with minimum humidities of 10-15%. However, Intel on fuels remains that the live fuels are not quite there while dead fuels are. Therefore, will continue to headline the near-critical conditions this week. 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, 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 407 AM PDT Wed Jul 3 2024/ DISCUSSION...A ridge is present off the coast and this will continue guiding the short and long term forecasts with warm temperatures and dry conditions. The Chetco effect was once again present yesterday afternoon, and this will continue into this afternoon. Highs near Brookings have been increased to near the mid-90s. On average, highs will be 5-10 degrees above normal this afternoon. This translates to 80s with 90s in more valley locations west of the Cascades. The concern for dangerous afternoon temperatures will begin tomorrow as the thermal trough moves inland. More west side valley locations are on track to break the triple digits tomorrow including Mt Shasta City, Yreka, Medford and Grants Pass. 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 50% probability to reach 115 Saturday in Medford. For reference, 115 is the hottest high on record for 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 Warning and Heat Advisory exists for most locations (with an emphasis on valleys) tomorrow morning through Sunday evening. Please visit the NPWMFR for more information. 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 && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Excessive Heat Warning from 8 AM Thursday to 9 PM PDT Monday for ORZ024-026. Heat Advisory from 8 AM Thursday to 9 PM PDT Monday for ORZ023- 025-029>031. Red Flag Warning from 11 PM this evening to 8 AM PDT Thursday for ORZ619-620. CA...Excessive Heat Warning from 8 AM Thursday to 9 PM PDT Monday for CAZ080-081. Heat Advisory from 8 AM Thursday to 9 PM PDT Monday for CAZ084- 085. PACIFIC COASTAL WATERS...Gale Warning until 8 AM PDT Thursday for PZZ356-376. Small Craft Advisory from 8 AM to 8 PM PDT Thursday for PZZ350- 356-370. Hazardous Seas Warning from 8 AM to 8 PM PDT Thursday for PZZ356- 370-376. && $$