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. --744FXUS66 KPQR 130954AFDPQRArea Forecast DiscussionNational Weather Service Portland OR252 AM PDT Thu Jun 13 2024.SYNOPSIS...
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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 laternext week.Key Messages...- Increasing onshore flow later this afternoon.- Cooler, with increasing clouds for Friday. Chance of showers along the coast (Tillamook northward) and west Washington.- Cool, with showers for Saturday through Monday. A small chance (15-25%) of afternoon/evening thunderstorms on Sat.
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(Today through Friday night)...Not much change thismorning, as still have high pressure offshore and dry north tonorthwest flow aloft. Overall, another pleasant mid-June day on tapfor the region today, with highs in the 60s along the coast, and mid70s for inland valleys. A few spots in the Willamette Valley mayreach 80 this afternoon. But, not all that sold on that possibility.Main reason will be the increasing onshore flow this afternoon.Onshore pressure gradients will tighten this afternoon, as surfacehigh offshore moves toward the coast. This will increasing the coolermarine air invasion through the gaps in the Coast Range and WillapaHills this afternoon into this evening. So, temperatures will likelypeak in the 2 to 4 pm timeframe, then drop back a bit as the marineair spreads into the interior lowlands.May be breezy in the usual spots in the western Willamette Valley asthe marine air spreads inland. Such spots like the Philomath gap, VanDuzer Corridor, Siuslaw River gap to west of Eugene, will see gustywest to northwest winds later this afternoon, with gusts 20-25 mphfor a time. In addition, will see up tick of west to northwest winds(though not as strong) along the Columbia River from Portland toKelso. Breezy west winds likely in the mid-Columbia River Gorge fromBonneville eastward as well later today into tonight.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 to 0.50" over the higher terrain, but generally a tenth of aninch or less for all other locations for Fri through Sat am..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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VFR conditions continue to dominate, with fairly clearcloud cover for most terminals. The southern coastal terminals(KONP) see a 10-30% chance of some low scattered cloud coverdeveloping in the latter half of the night, clearing by 20z Thu.Regardless, no chance for MVFR ceilings as this is expected to bescattered and patchy cloud cover.Light northwesterly flow is in place, with winds generally below 7kts at all terminals. Winds pick up slightly through Thursdayafternoon, with top winds up to 25kt inland and 30kt at the coast.These will decrease by 05z Thu, becoming fairly light afterwards./JLiuPDX AND APPROACHES...Predominantly VFR and clear skies throughoutthe TAF period. Weak northwesterly winds up to 7 kts currently,increasing around 17-18z Thu. These peak in the evening, withnorthwesterly gusts up to 20 kts possible around that time. Windsdecrease again going into Thursday night back to weak winds. /JLiu
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Wind-driven Small Craft Advisory continues untilThursday night for the inner and outer waters. Seas are currentlyaround 7-9 feet at 9 seconds, with northerly winds gusting up to25 until Thursday evening, when they begin to decrease. Windsdecrease enough to end the SCA at that time. Seas will havesettled to 5 to 7 ft around this time, but may remain choppy. Nextfront will arrive late Friday, shifting winds back to westerly at10 to 15 kt for late Friday into early Sunday.-JH/JLiu
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OR...None.WA...None.PZ...Small Craft Advisory until 11 PM PDT this evening for PZZ251>253-271>273.
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