textproduct: Portland

SYNOPSIS

Showers persist today dissipating overnight as high pressure builds. Clear days and mostly clear evenings will set the stage for fog/frost development tonight and Thur night/Fri morning. Increasing temperatures on Saturday will be above normal. Frontal system arrives Sunday through early next week.

LONG TERM...Saturday through Wednesday

Saturday will be another springy day giving us a break before the next rain arrives on Sunday. High pressure will usher in warmer air from the south aloft, which will mix down causing highs to increase into the upper 60s to lower 70s. Along the coast, will remain seasonable, but sunnier than we have seen the last week. Inland areas will be warmer than normal. Models still have some discontinuity with the overall high temperature forecast. For example, the NBM ranges from 70 deg F to nearly 76 deg F (the 90th percentile). The deterministic forecast though sat right along the 25th percentile and in some areas even below this value. Decided to incorporate and nudge to the 50th percentile in the forecast in the Willamette Valley, Clark County, and the lowlands of Cowlitz county. If easterly winds are elevated, these temperatures may be less if close to the Cascades or the Gorge.

Enjoy the sun as a frontal system will move in Sunday night with a series of shortwaves through Wednesday. Overall troughing is not necessarily well realized by models at this point, and precipitation amounts will be low in comparison to what we typically see this time of year. The coast though will be the exception as the ECMWF is depicting anywhere from a quarter of an inch in 24 hours, to some of the ensembles of greater than 1.25 inches. The GFS is less wet with much lower amounts (closer to 0.25 inch). -Muessle

AVIATION

Current VFR conditions are expected to persist through the period. Isolated rain showers continue to move onshore within moist northwest flow at AST/ONP, with latest high-resolution guidance suggesting additional light showers may continue through the morning. While sct clouds at 3-4 kft are anticipated, there remains a 30% chance of MVFR cigs at 2-3 kft at coastal terminals overnight. Inland, dry conditions are expected throughout the period. With modest clearing and calm to light and variable winds expected, fog may develop near bodies of water and within sheltered valleys overnight, most likely around sunrise, 13-15Z Thu. There is a 10-20% chance of vis less than 1SM within fog or mist from Portland-area terminals south through the Willamette Valley. VFR conditions are otherwise favored overnight, and are expected to be widespread by 16-18Z Thu. Winds will increase to 5-10 kt out of the north to northwest after 16-18Z Thu.

PDX AND APPROACHES...VFR conditions are expected throughout the period. Potential fog overnight supports a 10-20% chance of IFR vis, mostly likely around 13-15Z Thu, particularly immediately along the Columbia River. Any restricted vis will lift by 15-17Z Thu, with clearing skies and VFR conditions then prevailing through the remainder of the period. Calm to light and variable winds tonight will increase out of the northwest at around 5 kt after sunrise, and then diminishing tomorrow evening. -Picard

MARINE

High pressure over the northeast Pacific and lower pressure inland will maintain northerly to northwesterly winds under 15 kt through the end of the week. The next front arrives Saturday evening into Sunday and that will bring a return to breezy southerly winds across all waters. As the front approaches, there is a 15-30% probability for Gale-force southerly wind gusts up to 40 kt on Sunday. Seas generally 3 to 6 ft through Sunday. As the front approaches the waters, seas will build towards 10 to 12 ft as a fresh westerly swell pushes into the waters.

Another strong ebb is expected Thursday morning; however, seas with this ebb are forecast around 4 to 5 ft. -42

PQR WATCHES/WARNINGS/ADVISORIES

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