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. --390FXUS66 KPQR 171052AFDPQRArea Forecast DiscussionNational Weather Service Portland OR352 AM PDT Mon Jun 17 2024.SYNOPSIS...
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One more seasonably cool day across the region asshowers continue to taper off behind departing low pressure.Temperatures rebound back to normal on Tuesday, with highpressure then bringing a stretch of hotter weather fromWednesday through Saturday.
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Now through Tuesday Night...Early morning radarimagery shows shower activity mainly confined to the Casacdesand the north Oregon/south Washington coast as the upper leveltrough which has dominated the pattern for the past several daysshifts east of the Cascades. Showers will continue to taper offacross most of the area today as the region settles into driernorthwest flow in the wake of the trough. A few showers maylinger as long as this evening along the Cascades, withadditional model QPF amounts ranging from a tenth to a quarterinch. Temperatures will remain below normal for one more day as850 mb temps of 2-3 C correspond to highs in the mid to upper60s in the interior lowlands. Showers will come to an end acrossthe area and temperatures will rebound back to seasonal normalsin the low to mid 70s on Tuesday as the influence of the uppertrough continues to diminish and 850 mb temps climb to around 8C by Tuesday afternoon. /CB.LONG TERM...Wednesday through Sunday...A stretch ofhotter weather begins on Wednesday as ensemble clusters anddeterministic solutions continue to depict a Rex Block typepattern developing over the West Coast with an upper level ridgeover western Canada and a trough over California. Ensemblesolutions show good agreement on highs in the mid 80s acrossmuch of the area on Wednesday afternoon, though low levelonshore flow will continue to moderate temperatures along thecoast. Temperatures look to peak Thursday into Friday asprobabilistic guidance continues to trend slightly higher, nowshowing a 60-70 percent chance to reach 90 degrees from Portlandto Salem on both days and around a 35 percent chance to hit 90at Eugene on Friday. The upper end of the guidance envelope hasalso trended upward, as the chance to reach 95 degrees fromPortland to Salem has increased to 10-15 percent on Thursday andaround 30 percent on Friday. Despite these higherprobabilities, a look at individual ensemble members from theGFS, Euro, and Canadian model suites still point to highsultimately maxing out in the low 90s both Thursday and Friday.That said, the possibility for temperatures to reach as high asthe mid 90s later in the week can`t be discounted, particularlyfor Friday. Guidance then indicates the start of a downwardtrend on Saturday as temperatures drop back into the 80s, withhighs falling off into the 70s by Sunday as ensemble clustersshow good agreement on the next trough arriving over the region.There is still uncertainty as to if this feature will beaccompanied by any meaningful precipitation, with the latest NBMguidance holding onto a 20-30 percent chance of rain for thenorthern coastal areas by Sunday. /CB
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An upper level trough over the Pacific NW willslide east of the Cascades this morning bringing northwesterlyflow aloft today. Isolated showers expected to continue todecrease as well, with predominately VFR conditions likely bythis afternoon. Highest chances for MVFR cigs this morning atthe coast (60-80%), while inland terminals have closer to a20-40% chance of MVFR cigs between 12-18Z today.PDX AND APPROACHES...There is around a 30-40% chance of MVFR cigsdeveloping between 12-18Z this morning. Otherwise, expectpredominately VFR conditions through the period. Northwest windsincrease to around 6-8 kt this afternoon. /DH
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High pressure offshore is expected to persist throughthe week. Northwest winds 10-15 kt across coastal waters todaybecoming northerly on Tuesday. North winds begin to increase laterTuesday afternoon as a thermal trough strengthens from northern CAinto southern OR. Expect will see periods of winds gusting up to25 kt through Friday during the late afternoon and evenings. Seasaround 4 to 6 feet will generally be wind driven through the week./DH
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OR...None.WA...None.PZ...None
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