Marine Weather and Tide Forecast for Minnehaha, WA

DISCUSSION
Wednesday through Tuesday...Low overcast deck remains over the Willamette Valley and inland valleys, keeping temperatures in the upper 30s during nighttime hours and lower 40s during daytime hours. Inversion keeps this into Thursday as high pressure remains in the area. Air Stagnation Advisory remains on track for the central and southern Willamette Valley as limited mixing is expected. A slight uptick in easterly winds through the Columbia River Gorge will keep the north Willamette Valley from seeing similar conditions, and no Air Stagnation Advisory has been issued for Portland Metro area.

Still on track for a potential weak decaying surface front moving through the area from the north on Thursday, pushing the high pressure farther west over the Pacific. Moisture associated with this front is limited with only 50% chance of any accumulating precipitation over the region. Slightly better chance over terrain due to orographic lift. This wave should be enough to finally mix out the stratus layer, though that may be temporary as ensemble clusters suggest strong high pressure over the eastern Pacific will begin moving closer to the coast Friday into the weekend, allowing for a surface inversion and fog/stratus formation once again.

NBM is confident that colder air will also be funneled into the PacNW behind this front, though just how cold will be determined by the exact setup of the ridge. For the interior lowlands, NBM has a 40% chance of low temperatures falling below 30 degrees on Friday morning but much higher chances at 85%+ Saturday through Tuesday mornings. For probabilities of 25 degrees, cities have a 10-40% chance Saturday through Monday mornings, highest probabilities on Sunday, but outlying areas have higher probabilities up to 70%. Temperatures along the coast are expected to be in the low 30s, and higher elevations are expected to fall into the mid teens to low 20s. -HEC/JLiu

AVIATION
Strong high pressure continues over the region, maintaining low stratus and areas of fog at all inland terminals Wednesday morning. Winds will remain light and variable through the 12z TAF period, with the exception being KTTD where easterly winds will develop after 16z Wednesday with gusts up to 25 kt.
Note these easterly winds will bring clearing skies to KTTD, and likely to KPDX, KHIO and KUAO as well Wednesday afternoon.
Meanwhile, expect the ongoing low stratus deck to remain in place at KEUG through the day. Note confidence is high for stratus to remain in place at KEUG, but confidence is a bit lower at KSLE as this terminal will likely be near the northern edge of the stratus deck as it erodes from the north Wednesday afternoon. Suspect KSLE will clear out in the mid to late afternoon, but only briefly before stratus expands back to the north Wednesday evening.
Mostly clear skies will continue at the coast through at least 06z Thursday before cloud cover pushes in from the west thereafter.

PDX AND APPROACHES...Expect LIFR cigs to continue through 19-20Z Wednesday with cloud cover scattering out thereafter and giving way to VFR flight conditions. That said, LIFR cigs and reduced visibilities with likely return Wednesday night, especially towards 10Z Thursday. -TK

MARINE
High pressure remains in place over the waters through the weekend, resulting in persistent northerly flow with winds generally staying under 20 kt. A northwesterly swell will also remain in place with wave heights generally ranging between 6 to 10 ft with a dominant wave period between 13 and 17 seconds. With seas near 10 ft through Wednesday morning, a Small Craft Advisory remains in effect for all marine zones until 10 AM Wednesday. A Small Craft Advisory remains in effect for the Columbia River Bar for the same time period.

A weak frontal passage Thursday through Thursday night will likely bring breezier northerly wind with gusts between 20-25 kt, mainly for the outer coastal waters. Otherwise, conditions will remain relatively quiet. -TK

PQR WATCHES/WARNINGS/ADVISORIES

OR...Air Stagnation Advisory until 10 AM PST Thursday for ORZ114>118.

WA...None.
PZ...Small Craft Advisory until 10 AM PST this morning for PZZ210- 251>253-271>273.