FXUS66 KPQR 211758 AAA AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 1058 AM PDT Sat Mar 21 2026 ...Updated aviation discussion... .SYNOPSIS...Light rain showers continue early Saturday morning, clearing by 9 AM. Dry weather and near normal high temperatures through Monday with morning low temperatures in the 30s, producing widespread frost Saturday and Sunday nights. A weather system brings widespread rain and breezy winds Tuesday into Wednesday along with light Cascades snow Tuesday night into Wednesday. No snow or flooding impacts expected. Dry weather returns Thursday into Friday. && .DISCUSSION...Saturday through Friday...At 2 AM PDT Saturday, radar imagery shows a band of light precipitation slowly moving southeast through NW OR, stretching from Florence along the coast to the Dalles. This band will continue moving southeast over the early morning hours, ending by 7-9 AM. Ensemble guidance indicates upper level flow becomes more zonal over the PacNW as surface high pressure spreads inland from the eastern Pacific this afternoon into Monday. This will bring dry weather along with high temperatures right around daily normals for late March, mainly in the mid to upper 50s for the interior lowlands. Winds will also be light, especially during the overnight hours each day. The light winds will be in conjunction with clearing skies in the overnight hours, resulting in an ideal set- up for radiational cooling. As such, expect colder than normal forecast low temperatures for the interior lowlands Sunday morning and Monday morning. Tonight into Sunday morning remains the coldest with widespread lows in the low to mid 30s. Widespread frost will likely develop as a result. Sunday night into Monday morning will be chilly once again, though low temperatures will be a few degrees warmer in the mid to upper 30s with less widespread frost development. Those with sensitive outdoor plants should take precautions to protect vegetation from frost this weekend. Note that NWS Portland will not begin issuing Frost Advisories and Freeze Watches/Warnings for agricultural purposes until April 1st as this is when the growing season begins to ramp up and impacts from frost and freeze conditions become more significant. Widespread rain and breezy winds are expected to return Tuesday into Wednesday as ensembles are in good agreement of a Pacific low pressure system moving east into British Columbia with the associated cold front pushing east into WA and OR. Ensembles are in much better agreement on the initial timing of precipitation beginning on Tuesday with rain continuing into Wednesday. Latest guidance is hinting at the possibility of another, weaker surface low pressure system and associated upper level shortwave pushing another burst of rain into the region late Wednesday into Thursday morning, and NBM is hinting at this as well by keeping probability of precipitation around 30-50% for the interior lowlands and 50-70% for the coast and terrain Wednesday night into Thursday morning. Uncertainty still remains on exact precipitation amounts Tuesday into Thursday, though high confidence remains in limited flooding impacts. Even the wettest possible scenario suggests less than 1 inch of rain in the wettest 24 hour period over the coast, Coast Range, and Willapa Hills, and less than 1.25 inch over the Cascades. Breezy winds are also expected with the frontal passage on Tuesday. Strongest winds will be along the coast where there's a 50-60% chance of wind gusts over 40 mph and a 10-20% chance of gusts over 50 mph. Inland areas could see peak gusts up to 30-35 mph as there's a 50-70% chance of gusts over 30 mph. In terms of Cascade snow, the heaviest precipitation is expected to fall ahead of and along the cold front when snow levels are generally higher than pass level. Snow levels will fall quickly after the front passes late Tuesday into Wednesday to around 3500-4500 ft. However, the lowest snow levels will be in SW WA Cascades with snow levels rising moving south into the central OR Cascades. As showers will continue into Wednesday, there is the potential for some accumulating snow, though due to the current sun angle along with warmer road temperatures, it might be difficult for much accumulation in scattered showers. Snow levels will continue falling through Wednesday, especially Wednesday night, falling to around 2000-3000 ft by Thursday morning. The 10th percentile (only 10% chance of snow levels this low) does indicate snow levels could fall as low as 500-1500 ft by Thursday morning. However, if precipitation really is decreasing by this time, then there will be limited precipitation to even cause snow. NBM probabilities for 6 inches of snow or more in a 48-hour period ending at 5am PDT Thursday continue to back this expectation up, as chances are only around 5% at Willamette and Santiam Passes, and 10-20% along highway 26 near Government Camp. By Thursday afternoon into Friday, the weather system is expected to move out of the area with upper level flow becoming more zonal. Expecting dry conditions with clearing skies by midday Thursday, which could allow for temperatures to warm into the upper 50s on Thursday and right around 60 on Friday for the interior lowlands. -03/23 && .AVIATION...Satellite imagery and terminal observations as of late Saturday morning depicts dry conditions with lingering MVFR/low- end VFR stratus across the Willamette Valley and north Oregon coast. Low stratus is expected to gradually burn off by 21-22z Sat as daytime heating progresses. Afterwards, VFR conditions prevail with high clouds as dry westerly flow persists. Tomorrow morning after 09- 12z Sun, a weak front will brush far northwest Washington. While impacts are not expected for the majority of our area due to this front tracking north, CIGs will trend low-end VFR Sunday morning at KAST along with a westerly wind shift. Elsewhere, winds remain northerly to northwesterly and under 10 kt throughout the TAF period, with occasional gusts up to 20 kt along the coast today. KPDX AND APPROACHES...MVFR/low-end VFR stratus (2.5-4 kft) through 21-22z Sat, then becoming predominately VFR with high clouds for the rest of the TAF period. Northwesterly winds under 10 kt today, becoming variable and under 5 kt tonight. -10 && .MARINE...High pressure continues building in over the waters early Saturday morning, turning winds more northerly over the waters. Pressure gradients have tightened a bit behind the cold frontal passage, allowing for a period of north wind gusts up to 21-25 kts outside of the Columbia River Bar. As high pressure continues building east into the waters into the weekend, the pressure gradient decreases over the waters and wind gusts fall below 21 kts by 8 AM this morning. A Small Craft Advisory remains in effect for all waters through 8 AM Saturday due to marginal small craft wind gusts. An exception is the Columbia River Bar, where a Small Craft Advisory is in effect between 5-10 AM Saturday for a very strong ebb current that will bring seas to around 9 feet. Benign marine conditions continue through Monday as high pressure persists. Seas of 7-9 ft at 10 sec today fall to 5-7 ft by late tonight, but re- build to 8-9 ft heading into Monday. However, confidence is growing for pressure gradients tightening again Sunday afternoon and evening, bringing another round of small craft northerly wind gusts up to 21-25 kts, mainly south of Cape Falcon. The next robust weather system returns Tuesday into Wednesday. This system will bring a return of breezy southerly winds across all waters. Current guidance suggests high confidence (70-90% chance) for widespread and frequent small craft wind gusts of 21 kt or greater, and a 25-45% chance for widespread and frequent Gale force wind gusts of 34 kt or greater on Tuesday. Chances for isolated Gale force wind gusts are around 75-90%, with the highest chances beyond 20 NM offshore. Seas on Tuesday and Wednesday are also expected to build to around 14-16 ft in response to increasing wind waves along with an increasing westerly swell. There's a 30-60% chance seas could exceed 15 ft with a 15-25% chance for seas exceeding 20 ft. Chances increase from south to north, peaking across the waters north of Cape Falcon and mainly beyond 40 NM offshore. -10/03 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from 5 AM to 10 AM PDT Saturday for PZZ210. Small Craft Advisory until 8 AM PDT Saturday for PZZ251>253- 271>273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland