Area Forecast Discussion
Issued by NWS Medford, OR
Issued by NWS Medford, OR
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027 FXUS66 KMFR 141108 AFDMFR Area Forecast Discussion National Weather Service Medford OR 408 AM PDT Sun Jul 14 2024 .DISCUSSION... We set a few high temperature records yesterday with Montague hitting 109 degrees, which broke the old record of 105 degrees. Mt Shasta City also hit 104, which broke the old record of 99 degrees. With the arrival of some monsoon moisture, cloud cover will help keep temperatures a few degrees lower on Sunday, although many locations west of the Cascades will remain in the upper 90`s and lower 100`s. Impact from the heat will trend lower with the relatively cooler temperatures as we fall into a more moderate HeatRisk for our region. Otherwise, this warmer than normal trend will persist through the week. Other than the persistent warmer than normal heat, smoke is always a popular topic. With an upper level wave lingering off our coast, upper level flow will still remain out of the southwest for the next few days. This will result in smoke from the Shelly fire continuing to move into the Klamath Falls area. The Scott valley will continue to see plenty of smoke from this fire due to relative proximity of the fire and low level westerly flow. Things should begin to change around the end of the week with a stronger northerly flow setting up sending the smoke to the south. All of this depends on no new fires flaring up over the next few days. This seems pretty unlikely given the thunderstorm activity expected today and tomorrow after a pretty substantial heat wave. The last topic is thunderstorms across the forecast area. More moisture will arrive today ahead of an upper level wave and models are anticipating scattered coverage across the forecast area. The storm activity should remain in northern California and East of the Cascades, although something could build up along the Siskiyous this afternoon. We can`t rule out isolated storms Sunday night as there is plenty of mid level moisture and an upper level wave off the California coast. There are also some ongoing at this time south of our forecast area along the California coast. Thunderstorms will persist into Monday with the main focus area in northern California. It seems Oregon dries out a bit on Monday as a weak ridge builds in overhead. The SREF has close to 0% lightning probabilities across south central Oregon Monday. By Tuesday, the upper level wave bringing all this thunderstorm activity will finally depart the region. There could be some more cloud to ground lightning around Douglas and Coos County Tuesday evening based on the KOTH Forecast Soundings. Based on the negative tilt of the upper level wave, we feel the threat for more thunderstorms Tuesday evening is pretty reasonable. -Smith && .AVIATION...14/06Z TAFS...Isolated lightning in NE Siskiyou, Modoc and into SE Lake counties earlier this evening has ended. There`s still a slight risk of lightning overnight in those same areas as moisture and elevated instability continue to push northward, but dry weather persists west of the Cascades even if some higher level clouds move in. Despite the higher cloud cover, VFR prevails over most of the CWA. However, IFR/LIFR marine stratus/fog continue to impact the coast north of Cape Blanco and also south of Pistol River. These lower conditions will persist through about 17-18Z on Sunday before clearing back to the beaches. North winds pick up in North Bend again Sunday afternoon (up to 25kt). Expect stratus/fog to return to the same coastal areas again Sunday evening, probably around 00z at North Bend. Expect another round of isolated to scattered storms Sunday afternoon/evening with a larger coverage area from western Siskiyou County northward up to the Siskiyou Mtns, southern Cascades (south of Crater Lake) and then over to the east side again. Most activity should remain east of the west side valleys, though can`t rule out a stray storm in southern Rogue Valley near Ashland or up at Mt A. Smoke from the Shelly fire in western Siskiyou County could bring visibility reductions in the immediate vicinity of the fire with MVFR visibility 15-25 miles away, especially to the NE (toward Montague) as S-SW winds carry the main plume in that direction. -Spilde && .MARINE...Updated 230 AM Sunday, July 14, 2024...North winds will trend lower today into Monday. Even so, conditions will remain hazardous due to a continuation of moderate north winds and steep to very steep seas, dominated by wind waves. A hazardous seas warning remains in place through this evening for the very steep wind seas from around Gold Beach southward and beyond about 10 NM from shore (southern half of PZZ376). Models are showing a slight coastward push to around 8 NM for seas near 10 feet between Gold Beach and Port Orford Sunday afternoon, but it`s a small area and not representative of the entire zone. A small craft advisory remains in effect for the southern inner zone (PZZ356) for gusty north winds and steep seas. The same is true for areas north of Cape Blanco, where north winds and seas will produce conditions hazardous to small craft. Tonight through Monday, winds and seas trend slightly lower but expect continued areas of steep seas hazardous to small craft. Winds and seas will gradually subside Tuesday into Thursday. -Spilde/CC && .FIRE WEATHER... ...RED FLAG WARNING IN EFFECT UNTIL 11 PM PDT THIS EVENING FOR ABUNDANT LIGHTNING ON DRY FUELS FOR FIRE WEATHER ZONES 280...281... 282...284...285..621...624... AND 625... ...FIRE WEATHER WATCH IN EFFECT FROM MONDAY MORNING THROUGH MONDAY EVENING FOR ABUNDANT LIGHTNING ON DRY FUELS FOR FIRE WEATHER ZONES 280...281...282...284...285... The scattered thunderstorms are the big topic over the next 24 hours as more moisture arrives from the south and the atmosphere isn`t as dry. The areas impacted by storms will also expand with a northern and western push of all this moisture. Available potential energy isn`t great, although it should be enough for cloud to ground lightning across eastern and southern sections of the forecast area. Therefore, no changes to the Red Flag Warnings for today. The one change that was made tonight was changing the start time of the Fire Weather Watch on Monday in addition to removing the Oregon zones from the watch. Although there is indeed convective available potential energy, the probability of lightning is just too low to justify a watch. The SREF lightning probability is essentially zero over Oregon and the BUFR soundings do show some CAPE, but is very shallow and might not even reach -15C and the equilibrium level. As for the California zones, there is a little more instability there and the HREF is more than happy to pain FWZ 280 with convection. This is also a hot spot climatologically, so we kept the watch there and will let the next shift decide to upgrade the California zones. Finally on Tuesday, the upper level wave bringing all this thunderstorm activity will finally eject northwards. This wave will have a negative tilt, which usually brings some extra dynamics and can overproduce convective activity when the models just don`t buy it. Therefore, we added a slight chance of thunderstorms in northern Douglas, Klamath and Lake Counties Tuesday evening. Nocturnal storms are a serious threat here, although they should be more of a problem north of our forecast area. -Smith && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning until 11 PM PDT this evening for ORZ621. Red Flag Warning until 11 PM PDT this evening for ORZ624-625. CA...Red Flag Warning until 11 PM PDT this evening for CAZ280>282. Fire Weather Watch from Monday morning through Monday evening for CAZ280>282. Red Flag Warning until 11 PM PDT this evening for CAZ284-285. Fire Weather Watch from Monday morning through Monday evening for CAZ284-285. PACIFIC COASTAL WATERS...Small Craft Advisory until 8 PM PDT Monday for PZZ350-356-370-376. Hazardous Seas Warning until 8 PM PDT this evening for PZZ376. && $$