Marine Weather and Tide Forecast for Kalama, WA

SHORT TERM
Now through Sunday...Upper level ridging persists today which has lead to warming temps and eventually clearing skies. Stable conditions though have maintained coastal stratus and instability along the Cascades is promoting cumulus. This surface ridge is coupled with a low aloft which will be a weather maker on Saturday...though not all locations will see active weather. On Saturday the low aloft will drop southward getting hung up along the Oregon/California border coast in the afternoon.

As it pushes southward moisture will be added to the atmosphere and instability will be increased considerably. This instability can be displayed looking at the CAPE and omega values. Omega drops meaning there is support aloft for lift, and the CAPE builds to near 1000 J/kg which is very high for this area. In fact, some areas will see CAPE greater than 1500 J/kg.
The Cascades will be the hardest hit with the warming temperatures and elevated instability therefore have increased the threat for thunderstorms in the forecast. Models were suggesting around a 10% chance, but have increased closer to 25% for the Lane County Cascades with decreasing probabilities as you move northward. The most likely scenario is elevated thunderstorms which would produce minimal rain which is also supported by the lower than desired precipitable water amounts.
Elevated storms too make strong outflow gusts difficult.
However, cannot rule out lightning and periods of heavy rain.
Hail is a lesser threat as there is less moisture within the hail growth zone aloft. A limiting factor will be the shear amount of dry air above 1000 ft.

As any isolated storms die out, ridging once again builds in on Sunday. The flow aloft is southerly which will usher in much warmer and drier air to the region. Looking at record breaking high temperatures on Sunday with areas within the greater Portland-Vancouver Metro area seeing highs easily near 90 degrees. Recent runs of the NBM 5.0 are suggesting a median temperature at Portland Intl Airport of around 90 degrees F, with a 10% chance of highs greater than 95 degrees. If we do in fact hit 90 degrees in Portland, then it officially will be the 2nd earliest 90 degree day on record. Overnight temperatures (both Sunday morning and into Monday morning) will fall into the 50s so there will be very good overnight recovery. Daytime highs though are high enough within the Portland-Vancouver Metro area that a Heat Advisory has been issued. Other portions of the area too will be quite warm with highs in the mid to upper 80s so there will be very little escape.

While this is just a one day heat spike, many will want to hit the water to find some relief. Please remember that area lakes and rivers are still very cold with temperatures in the mid-40s. These temperatures are cold enough to cause cold shock and fatalities. Please be cautious around water and always use a life jacket. For those seeking a break from the heat along the coast, there is still an elevated chance for sneaker waves along the beaches through Sunday. Sneaker waves can sweep you off of your feet and dislodge logs causing hazardous conditions. Never turn your back to the ocean. -27


LONG TERM
Monday through Friday...By the beginning of the workweek, ensemble guidance continues to favor moderating temperatures as the upper ridge axis moves inland. A southerly wind reversal will increase marine stratus coverage along the coast, with broader onshore flow cooling inland areas as well.
There is general consensus in dry conditions across most of the region, however a minority of ensemble members depict very light rain or drizzle within the shallow marine layer, most likely in the overnight hours.

On Friday an upper level longwave trough will begin to advance towards the region which will begin to disrupt the overall pattern. Will see the ridge begin to flatten and temperatures lower even further to much more seasonable highs in the 70s.
-27/36



AVIATION
Northwest flow continues to support marine layer clouds along the coast with MVFR CIGs between 1-1.5 kft. Could see a pullback in cloud cover this afternoon between 21z Fri through 2z Saturday as clouds shift just offshore. For the most part, MVFR or lower CIGs expected with northwest winds gusting to 20 kt this afternoon and evening.

Inland terminals can expect mainly VFR conditions. High level clouds around 20-25 kft will continue to stream in from the southwest. West to northwest winds 5-10 kt through the evening, becoming light and variable overnight. Expect slowly lowering CIGs down to 6-10 kft by 00-06z Sat, with 25-30% chances for showers or possibly thunderstorms late in the period. These showers or storms are most likely to develop over the Cascades and track northward, resulting in increasing chances heading east from the Willamette River. The location and timing of any showers is uncertain, and impacts to terminals remain very low confidence.

KPDX AND APPROACHES...VFR flying conditions beneath increasing high clouds expected through the period, with CIGs falling from 20-25 kft to near 10 kft by this evening. Chances for rain showers increase to 15-20% late in the period, after 06z Sat, with very low confidence in any terminal impacts. Northwest winds to 5-10 kt this afternoon before easing below 5 kt again this evening. -19/36

MARINE
High pressure will support northerly winds through the weekend, peaking this evening. Wind gusts of 20-25 kt are most likely for all waters south of Cape Falcon and north of Cape Falcon beyond 25-30 NM A Small Craft Advisory is in effect for these zones through 2 AM Saturday with wind gusts easing below 20 kt after that time. A wind gusts around 20 kt is still possible over the waters within 25-30 NM north of Cape Falcon but the frequency is expected to be much less compared to the rest of the waters. Seas remain around 6-8 feet through the weekend though the period will increase from around 11-12 seconds to around 16-17 seconds Saturday as a long period northwest swell moves in. A wind reversal on Monday will see southerly to southwesterly flow develop early next week with increased low marine stratus and overnight drizzle or light rain. More seasonable northerly flow redevelops in the latter half of the week with persistent seas of 4-7 ft. -19/36

CLIMATE
Daily record high temperatures for Sunday, May 3:

Location Forecast Record (Year)

Astoria 75 81 (1992, 1944)
Vancouver 89 84 (1944)
Portland Int'l 92 89 (1992)
Hillsboro 90 82 (2017)
McMinnville 87 87 (1992)
Salem 89 86 (1992)
Eugene 85 83 (1944)

PQR WATCHES/WARNINGS/ADVISORIES
OR...Heat Advisory from 8 AM to 11 PM PDT Sunday for ORZ108-109-111- 112.
WA...Heat Advisory from 8 AM to 11 PM PDT Sunday for WAZ204>207.
PZ...Small Craft Advisory until 2 AM PDT Saturday for PZZ252-253- 271.
Small Craft Advisory until 8 AM PDT Saturday for PZZ272-273.