textproduct: Portland

SYNOPSIS

Warm conditions through Friday before a more significant cool down this weekend. Highs closer to normal for Saturday and Sunday. Dry conditions Friday and a chance for light showers along the coast on Saturday. Temperatures closer to normal persist into early next week.

DISCUSSION...Now through Wednesday

The weather pattern continues to be in a transition period with the area wedged between an upper level low off the coast and a ridge centered over the desert southwest. More bearable overnight lows tonight dropping into the 50s across the area as onshore flow continues. Also expecting more marine layer cloud cover along the coast and chances low stratus extends into the interior valleys. Friday morning could start off with some cloud cover. High temperatures remain elevated in the mid to upper 80s across the interior lowlands on Friday as the western edge of an upper level ridge remains in place. Heading into the weekend, a more noticeable pattern change is expected with a trough dropping south from the Gulf of Alaska on Friday night into Saturday. This will allow onshore flow to strengthen, bringing a more noticeable cooling trend this weekend, along with a return to more marine influence and night/morning cloud cover. Temperatures trend toward normal on Saturday and Sunday with highs in the upper 70s to low 80s inland along with overnight lows in the 50s. A weak cold front will move onshore saturday, increasing southwesterly winds across the area. Wind gusts up to 25 mph will be possible with locally higher gusts along the coast. There is no notable precipitation signal outside of low potential for light showers along the coast on Saturday. Looking beyond the weekend, more seasonable temperatures hang on into early next week before uncertainty increases during the middle of the week. Cluster analysis favors the ridge slowly building back into the PacNW which in turn would bring an increase in afternoon high temperatures. The NBM 10th-90th percentile shows an 8-12 degree spread for most days next week, ranging from the low to upper 80s for inland locations. There is not a signal for a major warm-up at this point. -19

AVIATION

Satellite imagery and terminal observations as of late Thursday morning depicts a mix of MVFR and low-end VFR CIGs across northwest Oregon. As daytime heating progresses this afternoon, will see increased mixing which should break up stratus and improve conditions to predominately VFR for most terminals. There is some uncertainty with potential clearing at KONP. Onshore flow and moist conditions may keep KONP within MVFR CIGs throughout the rest of the day, however, there is a 50-70% chance for some very brief improvements to VFR through 00z Fri at KONP. After 00-03z Fri, there high confidence that IFR/MVFR marine stratus will return along the coast. For inland locations, once low stratus breaks out, VFR conditions will prevail throughout the TAF period with high clouds. Will note that there is a 20-30% chance for MVFR stratus across the Willamette Valley at any given hour between 10-18z Fri as the low level atmosphere moistens. Winds generally light and west-northwesterly, except for increasing southwesterly winds at KEUG this evening around 10 kt.

KPDX AND APPROACHES...MVFR CIGs through 21-22z Fri. Afterwards, increased mixing will support VFR conditions through the rest of the TAF period. Low-end VFR stratus after 10-12z Fri with a 15-25% chance for MVFR CIGs at any given hour between 12-18z Fri. -10

MARINE

Buoy observations as of early Thursday afternoon depict light southerly winds around 10 kt with seas of 5-6 ft at 10 seconds. Weak low pressure offshore will support light southerly winds through late Friday night. On Saturday, a front will push through the waters and return chances for small craft southerly wind gusts. There is high confidence for at least isolated wind gusts up to 25 kt across the waters on Saturday, and a 40-60% chance that these gusts will be frequent and widespread. At the same time, seas will build to 7-9 ft as wind waves build. By late Saturday night into early Sunday morning, winds quickly weaken below 15 kt and seas fall back down to 4-5 ft through next week. -10

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...None.