National Weather Service (2024)

Area Forecast Discussion
Issued by NWS Portland, OR

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-- Discussion containing changed information from previous version are highlighted. --008FXUS66 KPQR 130439AFDPQRArea Forecast DiscussionNational Weather Service Portland OR939 PM PDT Wed Jun 12 2024UPDATED AVIATION DISCUSSION.SYNOPSIS...High pressure offshore maintains seasonably warm anddry conditions through Thursday. Low pressure then brings cooland showery weather Friday into the early part of next week,with a slight chance of thunderstorms Saturday into Sunday.Temperatures look to rebound near or above seasonal normals bythe middle of next week.&&.SHORT TERM...
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Now through Friday Night...Now through Friday Night...Plenty of sunshineacross the area today as morning cloud cover has been scouredout by dry northerly flow with high pressure anchored offshoreas of early Wednesday afternoon. This has allowed temperaturesto climb well into the 70s across the interior lowlands. Notmuch change expected through Thursday as high pressure remainsoffshore and maintains warm and dry weather. Continued drying ofthe air mass will result in less cloud cover tonight intoThursday morning, which will in turn allow temperatures to climba couple degrees higher on Thursday afternoon. Generally expecthighs to top out in the upper 70s away from the coast, withprobabilistic guidance showing a 25-30 percent chance to reach80s degrees across the Portland metro for Thursday.Expect a pattern shift back towards cooler and cloudier weatheron Friday as an upper level trough currently over the Gulf ofAlaska descends upon the Pacific Northwest. This will droptemperatures back near or slightly below seasonal norms withhighs in the upper 60s or low 70s and also bring a chance ofshowers as a weak front moves through the area. Shower chanceslook to be generally confined to areas along and north of aLincoln City-Portland-Mt St Helens line through Friday eveningbefore more widespread shower activity spreads across the areaFriday night. Model QPF remains on the light side, ranging from0.25-0.50" in the higher terrain but generally closer to atenth of an inch or less for all other locations throughSaturday morning. /CB.LONG TERM...Saturday through Wednesday...WPC ensemble clustersremain in strong agreement on maintaining upper level troughingand a resulting cool, cloudy and showery pattern over thePacific Northwest this weekend through the early part of nextweek. This is reflected in ensemble temperature forecasts whichkeep the area below normal with highs in the 60s through atleast Monday. Cold air aloft will maintain showery conditionsinto Tuesday, though these look to be mainly spotty in naturewith model QPF amounts remaining light through the period.Guidance indicates a 15-25 percent chance for a few rumbles ofthunder across the north both Saturday and Sunday afternoon,which will largely be dependent on if there are enough sunbreaks to allow for adequate destabilization. Temperatures lookto rebound into the 70s next Tuesday and Wednesday as themajority of ensemble clusters depict the trough starting toshift east of the region by midweek. /CB
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High pressure will remain in control of the area,which is expected to maintain VFR conditions through the TAFperiod. Winds along the coast will remain N/NW at 10-15 kts andgusts around 20 kts late this evening and early tonight. Windswill relax after 8-10Z to around 10 knots through the remainder ofthe night. Winds within the Willamette Valley will also remainN/NW at 5-10 knots, becoming light and variable after 8Z.HREF guidance indicates possible development of marine stratus,mainly in the vicinity of KONP at 30-50% after 8-9Z. There arealso lower chances of 10-20% around KAST and some developmentalong the foothills in the western Willamette Valley with a 20-30%chance near KTTD from 12-16Z. Will hold off on adding any stratusat the inland TAF sites and KAST but will add in a broken stratusdeck at KONP after 10Z based on guidance.PDX AND APPROACHES...Predominantly VFR and clear skies throughoutthe TAF period. N/NW winds will become light and variableovernight. A few wind gusts around 20 kts will be possible at PDXearly on. -Batz
-- End Changed Discussion --&&.MARINE...A Small Craft Advisory for the Columbia Bar will remainin effect until midnight tonight, with winds gusting to 20 to 25kt. Wind-driven Small Craft Advisory will be maintained untilThursday night for the inner and outer waters. Seas are currentlyaround 7-9 feet at 10 seconds, with northerly winds gusting up to25 kt, increasing to near 30 kt this evening into tonight.Thursday, winds will gust up to 25 kt, then decrease below SmallCraft Advisory criteria by Thursday night. Seas will have settledto 5 to 7 ft around this time, but may remain choppy. Next frontwill arrive late Friday, shifting winds back to westerly at 10 to15 kt for late Friday into early Sunday.-JH&&.PQR WATCHES/WARNINGS/ADVISORIES...
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OR...None.WA...None.PZ...Small Craft Advisory until midnight PDT tonight for PZZ210. Small Craft Advisory until 11 PM PDT Thursday for PZZ251>253- 271>273.
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