textproduct: Portland

SYNOPSIS

A frontal system will bring widespread rain, breezy winds from the south, and a 15-20% chance for thunderstorms today. Rain continues tomorrow with a 20-30% chance for thunderstorms. Any passing thunderstorms may produce lightning, heavy rain, gusty erratic winds, small hail, and/or a funnel cloud. Chances for lingering showers continue through the weekend with cooler than average temperatures. Drier conditions early next week.

LONG TERM...Saturday through Tuesday

Over the weekend, the majority of ensemble members continue to show broad upper-level troughing over the Pacific Northwest. However, there is uncertainty with whether or not we remain dry or continue with lingering showers. While 60% of ensemble members suggest showers continuing over the region Saturday-Sunday, the other 40% keep us dry. What we can say with higher confidence is that this upper-level low will maintain below-average 500 mb heights and keep high temperatures slightly cooler than average for this time of year. Early next week, the majority of ensemble members show the upper low weakening and beginning to move eastward. This would favor drier conditions, but there remains uncertainty with how much high pressure will re-build over our area, and how warm/dry we get. -10

AVIATION...Through 00Z Friday

This afternoon a frontal boundary continues to progress through western Oregon and southwest Washington with a largely MVFR conditions. Once the front passes (00-02z) prevailing VFR CIGs/VIS likely return for inland sites. Shower activity behind the main band of rainfall begins rather sparse in coverage late this afternoon and evening as well before increasing overnight into Thursday morning. It worth noting any stronger showers could temporarily knock CIGs/VIS back to MVFR or lower this evening through Thursday morning. Also, there is a 15-25% chance for thunderstorms Thursday afternoon at all terminals.Any thunderstorms that develop will have the potential to produce lightning, small hail along with gusty and erratic winds.

Expect southerly winds just ahead of the frontal boundary to peek this afternoon with gusts up to 15-25 knots at inland sites. Once the front passes, expect winds to gain a temporary westerly component while decreasing before a slight uptick in winds again overnight into Thursday.

KPDX AND APPROACHES...MVFR conditions are in place this afternoon but once the front passes CIGs/VIS trend back to VFR by 01-04z with only a 15-25% chance for MVFR conditions thereafter. Expect an isolated thunderstorm threat Thursday as well, mainly during the afternoon hours. -99

MARINE

This afternoon a frontal boundary is quickly progressing across the waters with winds peaking through 3-5pm before dropping off this evening - buoy observations show gusts of 35-40 knots. Our largely wind driven seas current sit around 12-14 ft at 9-10 seconds, likely leveling off the next few hours before gradually decreasing this evening and overnight while a fresh west/northwest swell arrives helping to maintain seas around 9-11 ft through much of Thursday. Due to the continued sea state and breezy winds, a Small Craft Advisory is in effect through Thursday afternoon into the evening. There'll also be 15-30% chance for thunderstorms tonight through Thursday with the best relative chances Thursday afternoon. Any of these storms will be capable of producing gusty/erratic winds, small hail, and lightning.

While relatively active weather with lingering rain showers will continue into the weekend, marine conditions will subside by Friday with seas holding in the 4-6 ft range by Friday afternoon. Similar conditions persist into early next week while winds occasionally gust to 15-20 knots. -99

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Gale Warning until 5 PM PDT this afternoon for PZZ210-251>253- 271>273. Small Craft Advisory until 5 PM PDT Thursday for PZZ210-251- 252-271-272. Small Craft Advisory until 11 PM PDT Thursday for PZZ253-273.