637 FXUS66 KMFR 151552 AFDMFR Area Forecast Discussion National Weather Service Medford OR 852 AM PDT Mon Aug 15 2022 .DISCUSSION...No major updates are needed this morning. Fine tuned the sky cover to be better in line with observations. Coastal stratus lingers along the coast and into the Coquille Basin as well as the coastal valleys south of Gold Beach. Elsewhere, skies are clear this morning. We'll see one more pleasant, summer day today with seasonable temperatures and typical afternoon breezes. Temperatures start to ramp up on Tuesday, then peak on Wednesday and Thursday before ebbing over the weekend. Today's efforts will continue to be on these hot temperatures, and any necessary heat related headlines, as well as the thunderstorm potential for Wednesday into Thursday. For more details on current thoughts, see the previous discussion below. /BR-y && .AVIATION...15/12Z TAFs...IFR/MVFR ceilings are impacting portions of the coast and the coastal waters early this morning. Some LIFR ceilings are also present at Brookings. These conditions will persist through mid-late morning, then become VFR for several hours this afternoon. Low ceilings and/or fog will likely return again this evening, then persist overnight into Tuesday morning. VFR will prevail for the next 24 hours over inland areas. -Spilde && .MARINE...Updated 800 AM PDT Monday, 15 August, 2022...Conditions hazardous to small craft are expected into Tuesday south of Cape Blanco due to gusty north winds and steep, wind wave dominated seas. Beginning late Tuesday afternoon and evening, gales and very steep, hazardous seas are expected south of Gold Beach with gusty north winds and steep seas spreading north of Cape Blanco. Gusty winds and steep to very steep seas persist into Wednesday, then are expected to lower a bit Wednesday night into Thursday. That will probably be short-lived, however, since stronger north winds may return Friday into Saturday, especially south of Cape Blanco. -Spilde && .PREV DISCUSSION... /Issued 335 AM PDT Mon Aug 15 2022/ DISCUSSION...High pressure resides over the region with uneventful weather expected today. Temperatures will be near-normal over the west side while east-side readings climb to 4-8 degrees above normal. A strengthening thermal trough over the south coast will allow for increasing north winds over the nearshore waters through afternoon. Tuesday, things will change with south flow aloft overtaking the region with some increasing moisture as the center of the upper high over the Great Basin budges west and north. Temperatures will increase 3-5 degrees area-wide and some thunderstorms may impact Modoc County by late afternoon and evening. Increasing temperatures are still on tap for Wednesday as upper heights increase further. The latest NBM forecasts aren't too dissimilar from recent runs indicating that interior west side areas, especially south of the Umpqua, will climb well into the triple digits. The most likely NBM forecast is about 105 for Medford, while the upper quarter of the ensemble members are indicating that highs could hit 107+ in Medford. A Heat Advisory issuance is likely. The Western Region Heat Risk images indicate that Jackson County, the Klamath Basin, and areas from the Shasta Valley westward in Siskiyou County will be the strongest candidates for this highlight. The headline could persist in to Thursday. Thunderstorms are expected to become more numerous and spread north and west on Wednesday. South flow is expected to bring in appreciable moisture so any storms that begin as dry should transition to west. Precipitatable water values look to increase to around .80" over the east and upwards of 1" over the west, so heavy rain will actually be possible despite the deep sub-cloud dry layer. We should be concerned with gusty outflow winds with this setup, with an "inverted-v" sounding type. The dry and unstable lower atmospheric layer, lightning potential, and gusty outflow winds should all be of heightened concern for fire weather interests. See fire weather portion and headline below. Some thunderstorm probabilities were increased a bit for southwest Oregon and Northwest CA to include a mention, i.e. 15-20 percent. Storms may continue overnight into Thursday morning as the atmosphere will remain unstable with steep mid level lapse rates. In addition, a short wave moving up from coastal northern CA will keep some driving dynamics in play so the typical decrease in activity due to nocturnal cooling may not be sufficient to settle the atmosphere. Due to some rain Wednesday and increased cloud cover Thursday, some high temperatures Thursday may not get as warm as anticipated. Will just have to adjust as necessary. Friday-Saturday should remain mainly dry and only 4-8 degrees or so cooler as the short wave moves inland and a stronger marine influence affects the coastal region. Another low off the coast is a common picture in the longer range for Sunday into next Monday, and this should usher in more south flow and thunder possibilities for some areas. Stavish AVIATION...15/12Z TAFs...IFR/MVFR ceilings are impacting portions of the coast and the coastal waters early this morning. Some LIFR ceilings are also present at Brookings. These conditions will persist through mid-late morning, then become VFR for several hours this afternoon. Low ceilings and/or fog will likely return again this evening, then persist overnight into Tuesday morning. VFR will prevail for the next 24 hours over inland areas. -Spilde MARINE...Updated 200 AM PDT Monday, 15 August, 2022... Conditions hazardous to small craft are expected into Tuesday south of Cape Blanco due to gusty north winds and steep, wind wave dominated seas. Beginning late Tuesday afternoon and evening, gales and very steep, hazardous seas are expected south of Gold Beach with gusty north winds and steep seas spreading north of Cape Blanco. Gusty winds and steep to very steep seas persist into Wednesday, then are expected to lower a bit Wednesday night into Thursday. That will probably be short-lived, however, since stronger north winds may return Friday into Saturday, especially south of Cape Blanco. -Spilde FIRE WEATHER...Updated 300 AM PDT Monday 15 August 2022... Monsoonal moisture will begin to feed into the region Tuesday with increasing temperatures and instability. This will isolated thunderstorm to the Modoc area Tuesday afternoon and evening. In addition, generally dry and unstable lower atmospheric conditions over the east side will result in the potential for plume dominated fire activity for any existing or developing fires. Thunderstorms will be most widespread Wednesday, most numerous from the Cascades east and Siskiyous south, with scattered coverage forecast over higher terrain east of the Cascades. A slight chance mention of storms was added to some of southwest Oregon and Western Siskiyou county Wednesday due to unstable conditions, increasing moisture, and south to southeast flow. The entire forecast area should be aware of a potential for increasing fire behavior activity possible Wednesday due to the lightning chances and potential for new fire starts, gusty and erratic outflow winds from thunderstorms, and dry and unstable lower to mid atmospheric conditions (Haines 6). Thunderstorm activity may continue through Wednesday night. There will be isolated thunderstorms Thursday from the Cascades east. Stavish/Sven && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Fire Weather Watch from Wednesday afternoon through Wednesday evening for ORZ624-625. CA...Fire Weather Watch from Wednesday afternoon through Wednesday evening for CAZ285. Pacific Coastal Waters... Small Craft Advisory from 5 PM Tuesday to 11 PM PDT Wednesday for PZZ350-370. Small Craft Advisory until 11 PM PDT Wednesday for PZZ356-376. Gale Warning from 5 PM Tuesday to 11 AM PDT Wednesday for PZZ376. $$ MNF/MTS/MAS